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Nissan Altima Engine Failures



  • I have been thinking about buying a new 4 cylinder nissan frontier. I am wondering if anyone on here knows if the same problems with altima 2.5 transfer over to the frontier with the same engine? Or have the problems been resolved by now?
  • I would suggest that you go back and look over the previous messeges to see what the problems are and and WHAT causes them. If you go back and look at messge #75 in this Forum, you will see that I wrote my theory on the cause of most of these engine failures and excessive oil consumption.

    From text near the end of that messege:
    "So, what does all this mean? I believe the problem originates with the design of the exhaust system, having the 1st catalytic converter so very close to the exhaust ports. I don't know of any other car that has the 1st catalytic converter built into the exhaust manifold so close to the exhaust ports. The problem doesn't seem to arise until there is backpressure in the system that can cause the precatalyst material to blow back into the engine.
    I have not seen anywhere, where anyone has given a practical explaination as to why this is occuring, but this is the most sensible theory that I have been able to come up with. I believe that since the Nissan exhaust system design may have caused the problems with the engine, Nissan should pay the cost of fixing these cars. So I'm ready to jump on this band wagon too."

    On the 2.5L 4 cylinder Altima engine, the Pre-Cat is built into the exhaust manifold (one piece). This puts it too close to the exhaust ports, allowing the contents of the Pre-Cat to flow back up into the engine "under certain conditions". The heat shield on the front of the engine covers the exhaust. If you remove the Heat Shield that covers the exhaust on the front of the engine (4 small bolts), you will plainly see what I am talking about. You can plainly see the top and bottom of the Pre-Cat, as there is an Oxygen Sensor at the top of the Pre-Cat, and then there is another Oxygen Sensor at the bottom of the Pre-Cat. There is a 2nd Cat with no Oxygen Sensors farther down the exhaust system under the car before the muffler. The way it SHOULD have been designed FIRST would have been to have the individual exhaust pipes (manifold), come into one common collector pipe that went down to the flexible connection near the bottom of the engine, and then put the Pre-Cat under the car, farther away from the exhaust manifold. This greater distance would insure that the contents of the Pre-Cat would no get blown back up into the engine, eliminating THAT threat to the engine. The SECOND thing that needed to be done was to make the Cat of sturdier construction, so that the contents of the Cat do not leak out. The chemical material is held in place on each end by a screen. The material escapes because the screen breaks, cracks or collapses. It seems like it happens at about 60,000 miles to 90,000 miles, on the reports that I have read, before the screens break and the chemical material is released into the engine. If the screens at each end were made stronger and better, the chemical material would be contained and not destroy the engine.

    So Mr Kamikazejoshua, I would take a long hard look at the exhaust system on the 2.5L Frontier engine to see where the Cats are. If the arrangement is like it is on the Altima, you might get the same problems. I have not seen the Frontier, and I have not been on the Frontier Forms, so please let us know what you find out.
    Good Luck,
    E.D. in Sunny Florida
  • I was able to find a picture online of the manifold with the cat. converter. It seems to be the same as the altima, that is, it is extremely close to the manifold. Thanks, for describing in detail what happens so I knew what to look for. How common is it for this to happen?
  • I have not seen any numbers or percentages to indicate how common this occurance may be. I know that it happened to my daughters 2002 Nissan Altima 2.5S at about 90,000 miles and I have read that many others have had the same complaints of the Cats failing, exhaust clogging and exessive engine oil consumption, generally ranging from about 60,000 miles to 90,000 miles. I have read of the same problems that others are having with the same car on other sites. I do not know what the percentages are, but I would like to know, but have not found a good source for information. Time will tell, we should have good information in a year or two, but it will be too late for too many by then.
    I would think the the most logical first step that the manufacturer would take is too increase the reliablity of the Converter, by using better screens on each side of the chemical in the Converter, to be sure that the chemical does not get released into the engine, or breaks loose and clogs the exhaust systems at the next component downstream. Hopefully they are doing that allready, but Nissan is remaining silent about this issue. I have been hoping that they would address this issue, but so far nothing. It seems that once it is out of warrenty, you are are on your own. I would suggest if you have not done so, to go back to the begining and read all the posts in this forum, and read all that you can find about it on the Internet.
    I expect a car to last a lot longer than the 3 year manufacturer's warrenty, and I expect the Cats to last a lot longer than the 80,000 mile federal warranty. I buy my cars with 90,000 to 100,000 miles on them and drive them to about 200,000 miles, and I still have the original exhaust system, original mufflers, original Cats, original paint, original engine and original transmission that run and shift like new. Thats what I expect, but maybe it's because I drive Ford V8 Explorers. I will buy my next car for my wife this year in a about a month or two, and will likely be a 2004 Toyota Highlander with V6. I will hate to have to sell my wifes 1997 Ford Explorer XLT 5.0L V8, because it has been such an excellent vehicle, but someone else will be enjoying it for a long time. No Nissans for us!
    Good Luck,
    E.D. in Sunny Florida
  • Enjoyed your letter. I agree with your version, that Nissan is being very quiet. If the problem is not that wide spread, you would think that Nissan would assist the complainers and not issue any recalls. But they do not even return phone calls.
    I have 3 of these and one affected so far. The other 2 will be up for sale by the end of the winter. I am also going with Toyota or Honda in the future. Glad you have good luck with Fords, I hear from body repair shops that they are slapped together. I guess it it like anything else, maybe the cheaper vechiles are the ones they are talking about. Have you heard anything on a class action filed on Nissan for the Altima's?
  • Thank you electricdesign, you have been very helpful
  • Hey E.D.,

    I appreciate the info that you've put out on this forum. It has helped me understood technically what my engine problem is. (since I know very little about car mechanics.)

    I talked to the dealership service manager recently and this is how I summarized it. The dealership is well aware of this issue with the Nissan 2002 Altima 2.5L engine problem but because Nissan corporate won't do anything about it, the dealerships are pushing cost of repairs to the customers and of course not tell customer's that this is a common problem.

    I don't what kind of system Nissan is running but it seems like everyone is on their own, the dealerships are on their own, the customers are on their own, etc. I had no luck with consumer affairs just like everyone else but to be honest, I think it would have been better if they didn't have consumer affairs because they wasted my time. I think Nissan thinks, we will only buy one car in our lifetime. Bottomline, I will never buy nissan, my family will never, my friends and so on etc.

    Anyways, I am seeking advice. I am deciding whether to fix my car or trade it in as in a few months from now I am due for new vehicle. The impression I get from your posting and other posting from other people on the internet is that even if I get the engine problem fixed, I will still run into the same problem and because it's just a design flaw with engine. Also, it seems to me that some Nissan dealerships are barely just gettting up to speed with this issue and usually fix one issue instead of fixing all the issues.

    I prefer to fix and keep the nissan but if I will run into the same or more problems down the road in the next few months, I will definitely trade it in.

    Any info will be greatly appreciated.

  • I am glad that you posted your comments, it has shown me that I need to make some important clairifications. I assume you have read all the messeges from at least #75 on to this one. If not, please be sure to do so.
    Now to clear up the misconception. I understand how this could be misunderstood by non technical people, because that is who this forum is mostly for. I've worked on cars all my life, I've worked as a line mechanic in 3 american car dealerships in the 1970's and at a national transmission repair chain, but I retired from that work and found a better way to make a living. I still do all my own work however, and maintain a well equipped garage to work in. My prescence here is to help people and give advice if I can. I have been especially angered by this Nissan Altima 2.5 engine problem because it directly involved my daughters car and has costed me time and money (but not nearly as much as most of you). I have heard of the needless problems and pain of the Nissan Altima owners, and I do deeply sympathize with you.
    Here is the misconception, many owners are thinking the engine is bad, BUT it is NOT the engine that is bad. It is the EXHAUST SYSTEM that is bad. The Cats are in the exhaust system, and when the Cat goes bad, it ruins the engine by contaminating the engine. If the Cats were made correctly and did not throw their contents into the engine, the engine would probably live a "normal" life. The REAL solution should have been for Nissan to use quality made Catalytic Converters, that would permanently contain the chemical. It may have just been a poor choice by Nissan to use that particular Cat. I don't know where they get them from, and I don't know where they are made, but I hope that they are now using better Cats in the new Altimas.
    Once the Cat messes up the engine by throwing the chemical into the engine, which causes the piston rings and clyinders to wear out, then the engine IS BAD, and usually has to be replaced.
    The solution to the problem is to NOT let the CAT eat up the engine. This is a touchy subject, because the CAT is required by law, because it reduces pollution. It also depends on where you live and if you are required to subject you car to emissions testing. What happens sometimes is that the chemicals and screens inside of the CAT breaks apart and the contents of the Cat is blown down the exhaust pipe. If the material happens to be blown out the muffler and out the tailpipe, then the material is no longer a threat to the engine, because it is gone. However, since it is gone, the oxygen sensors in the exhaust system, one before the Cat and one after the CAT, will detect that the CAT is not working and will throw the Diagnostic Trouble Code "Catalytic Converter Efficiency below threshold" or some such messege, and will cause the "service engine soon" light to come on. If the CATs get blown out, the engine will run fine, you would have to live with the "SES" light on all the time, if you can.
    Last but not least - Don't ever let your Altima engine overheat. The heat will warp the head and blow the head gasket, maybe crack the head, requiring the engine teardown for head gasket replacement and cylinder head rebuild (read messeges #103 - #113).
    About the issue of whether to fix the car or trade it in, that is a matter of money, compare the cost of repair and aggrevation against the trade in value. Unfortunately, I think you lose either way, it's just a matter of how much you lose. Only you can decide how to spend your money.
    Hope this helps,
    E.D. in Sunny Florida
  • ken75ken75 Posts: 52
    With all these lovely problems that Nissan is having, is there a web site or government program which lists all recalls or problems in the auto industry. Nissans reticence to address these problems has put something of a burr under my saddle even though I have not had a problem, and should not have a problem, with our 2008 Altima 2.5 SL. As my Dad used to say, "something smells rotton in Denmark" and Nissan had better step up to the plate before the issue really starts to effect there bottom line. America's pocket books are tightening up and any whisper of poor product performance can and has squashed a product line. Now that I have spent a bundle on this car, which I really like, it pains me to see the potential for future problems and I hope that either changes have been made in the 2008 model or Nissan will start to take care of business.
  • Any not aware of any design changes for the 2008, if fact the 2006 is now showing engine problems, the same engine that is in the 2002-3-4-5-6-7. I have 3 of these-(1) 2002 and (2) 2003 in this family, and we like the car. Only the 2002 has hit the 80,000 mile mark when all the problems surface. Nissan had not returned any of my calls, and I call routinely. The dealer has been simpathetic but "oh well the car has miles on it and these things happen". Some of the service men working for the dealership in town, it's rumored, that there are several engines being replaced at a cost to the customer of $4000.00 each. Of course, Nissan is very closed mouth about this. I think this is a crime! I reported my problems to Nissan North America, Consumer Affairs, the National investagative division for auto recalls, and the attorney general in my state. I am looking for a class action filing against Nissan on this problem. They are already in a class action for another issue. I wish you well. Enjoy the car while you can.
  • I would like to keep my 3 Nissans also, but do we take the chance? Look at the recalls on the 2006 motors. These are the same one used in the 2002-3-4-5-6. What can you expect? I chose to repair the 2002 that was down, I had to.I am looking for a Toyota or Honda to replace it. The other 2 Nissans will be gone before fall. And I have purchased Nissan most of my life, from the days of the Datsun (300,000 miles) and I sold it. But never again. This family will be going to a more reliable auto.
  • I have a 2002 Altima S as well. I have had unexplained oil consumption and was told that I needed the valve cover gasket replaced. I did that. Then my Piston # 3 was misfiring. I had my #3 coilpack and plugs replaced. Piston #3 kept misfiring. Was told by another mechanic that I should have had a Nissan coil pack and platinum plugs put in. I did that. Piston #3 still misfiring. Was told that the piston is fine, no scoring, no water coming through. Compression is fine. had the ECM re-programmed and then got a surge problem. Had Nissan re-program the idle. So far, surge problem gone but not the misfiring. No one can seem to find the problem! The Nissan dealership won't even look at my car, ever since I told them the probs. they just say to get a new engine! I used to love this car, but not anymore. I will NEVER buy another Nissan again.
  • jd10013jd10013 Posts: 779
    I'd go to another dealership. I doubt there is anything major wrong, and you certainly don't need a new engine. To the best of my knowledge, a misfire means the piston is in the wrong place when the plug fires. usually its a sensor or something that cause that. It can, however, be quite a pain and quite time consuming to track down. It sounds as if the dealership your dealing with simply doesn't want to take the time.

    You say its an 02, which would make it just barely 6 yrs old. Is it still under warranty? even if you bought it used, most of the extended warranties transfer to the next owner.

    anyhow, find yourself a good mechanic who knows how to properly diagnose a car.
  • Thanks for the input jd1003. My car is no longer under warranty. I have been looking for different mechanics and found this particular one who, I guess, I want to stay with since he seems up-front and honest, but cannot seem to fix the prob. The other 4 mechanics I went to could not fix the prob either. I have high mileage on the car (116K), bought it at 39K and have taken very good care of it. I thought Nissans were supposed to give longevity. BUT, not this make/model. Could this simply be either sensor or electrical? That's kind of what I think (and have been all along), but who am I - not a mechanic! My hands are tied here... :( Has anyone else had this same prob? Help!!!
  • jd10013jd10013 Posts: 779
    nissans usually do last a long time, but you never know with any car. I knew somebody who had the exact same problem with a chevy blazer or something. they eventually got it to go away, but it took forever, and they don't know what did it because they replaced a lot of stuff.

    my advice would be to take it to a garage that specialized in foreign cars, or another nissan dealership. It's most likely something in the electrical system, and electrical problems are a pain in the [non-permissible content removed] to track down.
  • Thanks jd. It's so frustrating. The current mechanic I am using is supposed to be a foreign specialist. Imagine? Yeah, I'm hoping that's it's only mechanical. The funny thing is that every time a mechanic "fixes" the prob (or so they think) it runs absolutely great and then I get my hands on it and it craps out. I've recently named my car "Christine". Starting to creep me out! LOL (just have to have some humor here - going nuts!)
  • jd10013jd10013 Posts: 779
    Being able to properly diagnose a problem is what separates a good mechanic from the rest. Any mechanic can fix something on a car. but, only the good ones can track the problem down and find out what it is..
  • So true.... I actually meant to say in my last posting that I hope it's electrical (not mechanical) LOL I guess I haven't found that "good" mechanic yet. Looking in the South Shore, MA area. Can anyone recommed a good mechanic?
  • laura19,
    I have read your original messege #174 and all the following messeges to date, 175 through 180. I have not checked in here for a couple of days. I am a semi-retired mechanic, and I just just did major rebuild work on one of these same 2002 Altima 2.5L 4 cylinder inline engines in December 2007, my daughters car with 100,903 miles on it. It had all the typical problems that we are seeing in some of these cars today, such as problems with the catalytic converter failing and/or plugging, begining to use more oil problem and leaking head gasket problem. I fixed all those problems and now her car is running perfect every day. I am familiar with this engine and all the sensors. Looking at the original information and the following comments, I see a lot of holes and/or gaps in the information about your car. The reason that the several mechanics have not been able to fix your car is because something is being overlooked. We need to go back to the basics and start from the begining and work our way through the problem to find the solution. I will be able to help you by steering you in the right direction if you can just give me the correct information that I need, and fill in the blanks or gaps. The better information that you can give me, the better I can help you.
    First, you need to be familiar with what is going on with this engine, the problems that are showing up and why the problems are happening. It may sound far feched, but your engines problems are likely related to these problems that have been discussed on this forum so far. If you have not done so, please read all the messeges in this forum, or at least messege #75 on to this one.

    Here are a few questions to get started. Please gather up all the information that you can and reply back with your answers. I'll check back in a couple of days.

    1. What were your original complaints that led you to think anything was wrong with your car? Having to add oil frequently? Engine misfiring or running bad? Subsequent compaints or anything else? Is the current milage about 116,000 miles?

    2. You stated that "I have had unexplained oil consumption". But no further comment has been made about that. Since the oil consumption is "unexplained", I would assume that there is not an oil leak anywhere on the engine after the valve cover gasket was replaced. How much engine oil is the engine losing in 1000 miles? How often do you check the engine oil level? How often are you having to add engine oil, and how much? If you don't know exactly, try to give an estimate.

    3. Then you brought up the problem of misfiring on cylinder #3. Was misfiring an original complaint? How was the misfiring determined to be on cylinder #3? Did the technician read the DTC's (Diagnositic Trouble Codes) with a Scanner? Find out what codes were scanned and please report them here. Tell me all you can about this misfire. Does it happen all the time or just some of the time? Does it miss when you first start the engine after it has been sitting for a long while or over night? Does the miss go away after you drive it a short distance?

    4. Have you had a noticable loss of power from the engine, and if so, did it seem to ocurr suddenly or over a period of time? Have you had any known problems yet with the Pre-Catalyic Converter or the Catalytic Converter, or had any trouble codes pertaining to them?

    5. You were also told "no water coming through". I would assume that is referring to any coolant leaking inside the engine. Has the engine ever run hot? Have you had any instance where the engine got hot because a hose blew or the radiator blew? Where does your temperature gauge normally register with normal driving down the road (Normal is in about the middle of the temperature gauge). Does the temperature gauge vary very much once it is warmed up? Does it read at about the same when sitting at a light with the motor idleing? Check the coolant tank reservior tank level often when the engine is cold. Does the level of coolant in the coolant tank reservior stay the same level, or does it go low. Do you have to add any coolant to the coolant reservior? It is normal for the coolant level to be lower when the engine is cold and higher when the engine is at operating temperature.
    Your mechanic should have a handheld scanner that is capable of monitor mode, being able to see and read the functions that the computer monitors, such as coolant temperature, ignition timing, intake air temperature, intake air volume, fuel trims, oxygen sensors, etc. He can have this connected to the car and observe these things while the car is stationary or while driving the car. With the car stationary and engine idleing, the coolant temperture should rise up to about 200 to 203 degrees, then both the electric fans behind the radiator should come on, then the temperature should drop down to about 188 degrees and then the fans turn off. This cycle continues, but when moving down the road, the fans may not need to come on because of the wind blowing through the radiator.

    6. You said "Was told that the piston is fine, no scoring, no water coming through. Compression is fine". How were these things determined? If the compression was tested on the cylinders, it is important to know what those are. My daugthers 2002 Altima 2.5 had 190 pounds of compression in each cylinder, which is very good. This indicated that the pistion rings were good and holding compression well. Also good is the fact that the compressions on all 4 cylinders was the same. The maximum compression variation between cylinders is 20%, which in this case would be about 38 pounds, so the acceptable range of compressions should be about 152 to 190, the closer the better. Howerver, compressions alone are not the sole indicator of engine condition, all factors must be considered together to arrive at the proper conclusion. In the case of my daughters Altima, even though the compressions were good, the head gasket was still bad, because it had a very small leak in the head gasket that allowed coolant to flow into one cylinder when the engine was shut off. When it was restarted from a cold start, the coolant in the cylinder caused that cylinder to miss for about a minute until the spark plug dried off and started firing, then it ran fine. The problem was found because the coolant reservior ran low and combustion gas was found in the radiator.

    7. Referring to the scoring, how was it determined that there was no scoring. The only sure way to tell is by taking the engine apart, removing the cylinder head and examining the cylinders. Other that that, it may have been assumed that the pistons were ok and that there was no scoring due to good compression readings.

    Continued on next messege
  • Continued from messege #181:

    8. Since you have taken your Altima to the dealer to be checked, I would assume that they put in the Recall with the updated Crankshaft Position Sensor and the updated Camshaft position sensor. Is this correct? I would also assume that they did the Recall for the Intake Manifold Power VaIve, where the upper intake manifold is removed and the power valve screws are checked and tightened. I would check and verify if these recalls been done, and let us know.

    9. You said "Then my Piston # 3 was misfiring. I had my #3 coilpack and plugs replaced. Piston #3 kept misfiring. Was told by another mechanic that I should have had a Nissan coil pack and platinum plugs put in. I did that. Piston #3 still misfiring".
    What was the condition of the original spark plug on #3 cylinder? Fouled? Dirty? Wet? Oil? Coolant? Were all 4 spark plugs replaced? If it is still missing, all 4 spark plugs should be carefully removed and looked at. The condtion of each one should be noted. They should be clean and dry, light tan in color, electrodes not bent, all look the same.

    That is enough questions for now. Please gather up what you can and let us know what you find out.

    If you or anyone else would like to see pictures of the 2002 Altima 2.5L engine being taken apart and put back together, I posted links below that can take you to the photos. The site is for photographs of all types, and the basic service is free, pictures can be stored on albums there for free. They only charge if you buy photos from them. If you are not registered, you can simply register to gain acess to viewing the pictures. There are hundreds of photos of taking the engine apart and hundreds of photos putting the engine together.

    2007-12-10 2002 Altima eng teardown pictures =85874609

    2007-12-17 Altima eng rebuild pictures =85874609

    Good Luck,
    E.D. in Sunny Florida
  • Thanks E.D. I appreciate your help. Here are the answers to your questions:
    1. My original complaint was no heat at idle and some hesitation at 40MPH. Had heat issue fixed, plug 3 oil fowled. 116K miles on car.

    2. Had gasket under valve cover replaced (leaking oil). Was losing about 1qt. oil every 1000 miles. Haven't had any loss of oil since gasgket replaced. I was checking my oil once a week.

    3. Misfiring on cylinder#3 started about 2 weeks after orig. issue. Had codes read and Cylinder#3 misfire detected. This is the only code that comes us. Had o2 sensore checked and was fine. Then had platinum plugs and new coil pack installed. It only happens when I reach 40mph. Although, two mechanics had it for a day or two and they said it didn't happen. Some times it can go a day before happening - only after driving it a while. It never happens after first starting the car. Now when cylinder#3 misfire is detected, the plug are carbon fowled - not oil fowled. Had my ecm reprogrammed at dealership along with other recalls (headlamps, erar subframe, fuel screen)

    4. There has been no loss of power. I have not had any probs. w/catalytic convereter (as far as I know).

    5. The mechanic just told me that no water came through piston #3. The heater gauge has never varied from the middle of the gauge. Coolant seems to be just fine in resevoir.

    6-7. I really think the mechanic was just assuming that there was no scoring etc on piston #3. The compression of all cylinders is 150.

    8. The dealer never told me about recalls on crankshaft position/sensor or the Intake Manifold Power Vavle. I will call them - thank you.

    9. The condition of the plug (3) was carbon fowled.

    today, they are re-dagnosing (I hope) my car and will post the results as soon as I hear something.

    THANK YOU so much for all this helpful information. I really appreciate it. I wish you lived up here!!! I really need someone who knows what the heck they are doing!!!
  • i am havin the same problem with them telling me that i am fluding the engine what did you do to fix yours??? please help me
  • That's a lot of good answers. Here is what I think so far:

    It is very good that your engine oil consumption/leak has stopped and that you have had no catalyic converter problems, but please be very aware of these problems, because if the catalyic converter goes bad, it will mess up your engine. Still no oil loss? It is also good that you have had no loss of power and no loss of coolant.

    The original complaint of no heat is a common one for this car, the heater circuit gets air trapped in it and therefore no hot coolant flows through the heater core. The solution to that is to purge the air out of the cooling system.

    There was some conflict between items #1, #3 and #9.
    In #1 you said "plug 3 oil fowled", and in #3 you said "the plug are carbon fowled - not oil fowled" and in #9 you said "The condition of the plug (3) was carbon fowled". So I guess you meant to say that the plugs are dry black with dry carbon on them, not wet black? If that is so, and it is only occuring on that one plug, then the problem is obviously related to that cylinder. Since it is dry carbon, I would first suspect a RICH FUEL MIXTURE. The most likely cause of this is a bad fuel injector, causing more fuel to go into that clyinder. It can cause the fouled plug and could be the source of the engine miss. The fuel injectors are difficult to see or reach, as they are "trapped" under the upper intake manifold. Once the upper intake manifold is removed, they are very easy to reach. Two small bolts hold the fuel rail on to the lower intake manifold. The fuel injector wiring plug is unplugged at the passenger side of the engine, the two bolts holding the fuel rail are removed (don't lose the 2 spacers under the fuel rail, one at each bolt), and then the fuel rail with the injectors attached can be gently pulled from the lower intake manifold, then the fuel injectors can be replaced, use new seals lubricated with a little oil when putting them gently back in. A good prevention for this problem is to put a bottle of fuel system cleaner or Gas Treatment in your gas tank at every oil change. This should be part of every service for every car. When the Upper Intake Manifold is OFF, be SURE that the POWER VALVE SCREWS are checked to be SURE they are tight, there are 4 valves, 2 phillips head screws on each valve. They are plainly visible and accessable only when the upper intake manifold is off.
    2. Review the following cleaning recommendation for the intake and exhaust systems when you replace, repair or check an engine:

    ^ Visually inspect for debris, water, or other foreign material inside the entire intake system, from the air filter intake through the intake manifold; clean as needed.

    ^ Inspect the intake manifold "runners" from the cylinder head side. Make sure that no particles of metal (broken pieces of piston, valve, etc) have stuck to the walls of the runners.

    ^ Visually inspect the "flange" portion of the manifold, where it attaches to the head. Make sure there are no scratches or burrs that might cause a bad seal seal.

    ^ Visually inspect the "power valves" inside the intake manifold (if applicable). Make sure all retaining screws that attach the "butterflies" to the shaft are in place and tight.

    ^ Make sure the exhaust ports are clean and free of debris.

    ^ Inspect the entire exhaust system for debris or other foreign material. Clean or replace as needed.

    Another reason for the plug fouling black could be a weak spark. Even though they have replaced the coils, I would have them check the strength of the spark, by comparing each spark against the others. They should all be able to make the same length of arc. A weak sparks means a weak coil or a problem in the circuit.

    Another reason that the fuel injector may flood the clyinder (much less likely), is the computer sending it the wrong signals, due to a computer or sensor malfunction. That is why you want to be sure that the voluntary sensor recall was done on your car. The recall covers two different sensors, the camshaft position sensor, shown photos #07219 and 07335, on the drivers side of the cylinder head, and the crankshaft position sensor, no picture, located on the back side of the engine. The replacement parts come in a kit called QR25DE sensor kit P/N 23731-6N225. Both parts look identical, but they are NOT, the Crankshaft Position sensor has a white paint mark on it. Do not mix up the parts.
    December 19, 2003



    2000-03 Sentra (B15)
    2002 Altima (L31)
    2002-03 Maxima (A33)
    2003 Murano (Z50)
    2003 350Z (Z33)

    The compression on the cylinders (150) sounds low, but depends on how it was done. Are they sure that they were all the same? Verify how they were taken, if you can. All plugs out, battery charger on the battery to keep it charged up during the test, Throttle valve on the intake plenium blocked open, test one cylinder at a time at full cranking speed, using a good quality screw in compression tester. I was expecting 170 lbs per cylinder or more. As I said, my daughters 2002 2.5L tested at 190 in each cylinder at 100,900 miles. After the head was milled and the engine put back together, they all tested at 205 to 210 lbs per cylinder. 150 may work, but a higher compression indicates a healthier engine. Your numbers may be low due to how they did the test.

    That is enough for now, getting late,
    Good Luck,
    E.D. in Sunny Florida
  • Hey guys, I'm new to this forum but I am experiencing the same problems as you are. It all started with the check engine light showing catalyst deficiency. I replaced the top converter w/an aftermarkert that lasted 4 months before it feel apart. It was covered under warranty, so a new one was put on and the check engine light is still showing catalyst deficiency. Took the car in last week for the crank position sensor recall and the computer was reset. They checked all fluids and everything was as it should be. We got home the following evening and the car just wasn't running good. Checked the oil and it was empty. Put 5 quarts back in it, talked to my mechaninc and he said try the simple fix first. So, I changed out the PCV valve and put on a new valve cover gasket and changed the oil. Car ran excellent after that. Two days later, checked the oil and it was empty again. Put 5 qts. back in it, checked the oil and is solid black. The car does not have an oil leak, its all going out the exhaust. It appears that I need a new engine and converter to the tune of $5500. I'm not really sure what I should do. I would like to try to fix this myself, and I am hoping E.D. in Sunny Florida might send me his pictures. Please let me know if you can help E.D.
  • Thanks E.D. Referring to my plugs being fowled. Initially, plug 3 was oil fowled due to a minor leak through the valve cover gasket, which is now repaired and not leaking. Oil situation seems fine now. The problem now is that plug 3 is carbon fowled. My mechanic just told me that it may be the ingition module or the computer itself. He also thinks that my remote starter may be the culprit to this problem. He is looking to see how it was connected (i.e. to the cyliner#3 coil possibly?). My mechanic also swapped all associated with cylinder 3 and cylinder 4 just to see what happens and engine light comes on and reads clyinder 3 misfire. He is saying this is no mechanical, but electrical. We shall see. He also tried new injectors and that wasn't the problem either. I may hear more today and will report back. It's so nice to have people interested in helping out on this site. Thanks!
  • winsanwinsan Posts: 36
    1-2 years ago my car was recalled because of 'faulty sensor design that may cause engine shut off during normal operation'. Right after the reprogram, the engine light was on. I took back to the dealer and the service manager said that they forgot to let the computer learn the idle state.
    Hope this helps you.
  • winsanwinsan Posts: 36
    Did you turn on the rear window defroster while you were listening to the radio? Mine plays the radio well as long as the rear window defroster is not used.
  • You forgot to mention how many miles is on your 2002 altima and what engine. I will assume for now that you have high miles (over80K) and a 2.5L 4 cylinder engine.
    Please read the previous messeges in this forum to understand the nature of the complaints and possible solutions.
    I am sorry to say I can't help you, I want to help you, but it sounds like your engine is too far gone, but check a few more things.
    There might be one more thing to check, since you seemed to notice improvement when you changed the PCV valve, there just may be a small possiblity that the oil could be getting sucked up by the PCV valve and the oil gets burned up in the engine and goes out the exhaust. 5 quarts of oil is all the engine holds, so you use a tremendous amount of oil for such a short time. How many miles do you goes in this 2 days and is it highway driving? I would check the PCV valve again very closely to be sure the oil is not getting sucked through it. At this moment I can't remember exactly how the hoses all went, an I don't have time to look at the pictures, but you could trying pulling the PCV hose and vent hose off the engine while it is running to see if you see "blowby" (pressured gas or smoke) coming out of the engine crankcase. That could be a sign of piston ring failure. If you see no blowby, then it just might be the PCV valve sucking oil out of the engine. If so you could trying leaving the hose off the PCV and driving to like that to see if it stops using oil. Watch it very carefully and check often to be sure oil does not leak out. If you are not sure about how to check the PCV, have a mechanic check the PCV and also check the engine crankcase for any blowby. If blowby is found, check cylinder compression to verify the engine condition. Test the compression on each cylinder, as I have outlined in previous messeges. If the results are very low, under 150 lbs in each cylinder, I would think you have a serious problem with wear in your pistons and rings and cylinders. If the compressions are NOT LOW, then there may be hope for your engine yet.

    I may check into the possibility of the PCV causing this, but I do not get acess to the car very often, I will check the pictures later, but may not be able to tell much by them. If I find anything that could appear like it may cause this to happen, I will address this later after I have all the facts. This would be a very unsual problem, but may be worth looking into.

    If you do have heavy wear in the piston and cylinders, you will need another engine, because if it uses that much oil that fast and not leaking and low compression, that means your pistons and piston and cylinder walls are all worn out. They have been eaten up by catalytic conveter spewing it chemicals into your engines exhaust ports, Once the engine parts are eaten up by the abrasive chemical, the engine is destroyed. It's like if you ate sand all the time, how long would you last?

    Check that PCV. Have you read the previous messeges? Particularly #169, I spoke about what the problem was and what to do about it. Unfortunately, you have to do somethihg about it early on, before it is too late.

    Below is some key text from that messege. It says what to do about the problem and how to avoid having the problem, but you have to read between the lines, Everyone with the 2.5L engine should read this:

    The solution to the problem is to NOT let the CAT eat up the engine. This is a touchy subject, because the CAT is required by law, because it reduces pollution. It also depends on where you live and if you are required to subject you car to emissions testing. What happens sometimes is that the chemicals and screens inside of the CAT breaks apart and the contents of the Cat is blown down the exhaust pipe. If the material happens to be blown out the muffler and out the tailpipe, then the material is no longer a threat to the engine, because it is gone. However, since it is gone, the oxygen sensors in the exhaust system, one before the Cat and one after the CAT, will detect that the CAT is not working and will throw the Diagnostic Trouble Code "Catalytic Converter Efficiency below threshold" or similar messege, and will cause the "service engine soon" light to come on. If the CATs get blown out, the engine will run fine, but you would have to live with the "SES" light on all the time, if you can. Can you?

    About the pictures of the teardown and rebuild of the 2.5L engine, I posted the links to both sets of those pictures at the bottom of messege #182.
    ANYONE can view those pictures. All you have to do is click on the link in the messege and it takes you to the photo album at the site. All you have to do is log in to the site (you will have to register, if you haven't before, it's free), it will automatically take you to the photo album where you can view the photos individually, view a slide show for free or buy prints of any that you may want. There are over 300 photos in each set.
    If clicking on the links does not work on your computer, copy and paste the link to your browser and click GO, to get to the photo site.

    Good Luck,
    E.D. in Sunny Florida
  • I noted a strange thing in your messege:
    "Initially, plug 3 was oil fowled due to a minor leak through the valve cover gasket".
    I am not aware of any way that a valve cover gasket leaking could allow oil to get into any cylinder or combustion chamber. They are simply not related.

    I assume the mechanic just switched the ignition coils between cylinders #3 & #4 and the same problem occured? The problem may be the primary circuit feeding the coil, which comes from the computer. It could be the connector is bad, or the wiring is bad, or an input to the computer is bad, or the computer could be bad, in that order. HOWEVER, I would be sure to test the output of each coil first, just like I said in my previous messege. If the coil is putting out a weak spark, whether it is the coil, wiring, or computer, it will show up in the coil output voltage test. You can compare the relative voltage output of each coil by the maximum length of the spark it makes.
    Here is how I do it.:
    To test the coil output voltage, you test one coil at a time. The engine is going to run on 3 cylinders while you test the fourth coil. Remove the small bolt that holds the coil in place. Unplug the connector from the coil and pull the coil up off the spark plug and out of the valve cover. Plug the coil back into the connector. Place a good insulator under the coil to hold it up off the engine (like a dry block of wood). Make sure the coil has the long boot on it that goes down to the spark plug. Get a good flexible test wire with an alligator clip on each end. securely fasten one alligator clip to a GOOD Ground in the engine compartment. Be sure that it won't come off. If it comes off while you are doing this test, you will recieve a tremendous shock! So be sure it stays on. At the bottom of the coil boot, insert a piece of wire or rod or screw that when in place will connect to the metal inside the boot and act as a conductor protruding a short distance out the end of the boot. Clip the other end of the alligator clip test wire to this metal. When all set, have an assistant start the car, keep yourself and wires away from moving parts. The motor will run a little rough since it is running on 3 cylinders. Carefully loosen the alligator clip from the metal protruding from the coil boot, and slowly withdraw the alligator clip away from the metal. It will draw an arc, should be bluish-white with some some tinges of red or orange color. Continue to slowly draw the arc longer and longer, noting how long it is before the arc starts to fail. Measure with a WOOD ruler if you need to. Clip the aligator clip back on the metal and have the assistant shut off the engine. Write down the arc length and cyinder number. Remove the test wire and metal and assemble the coil and plug back into the original correct position and install the small coil bolt.
    Do this same procedure on the other coils and compare the arc lengths. The longer the length, the higher the voltage. they should all be about the same are length. Any coils found with short arc lengths should be investigated for weak coils or problems in the primary circuit.

    What's this about a remote starter? I had not heard you mention that before.

    Did your engine have all the sensor recalls done to it?

    Good Luck,
    E.D. in Sunny Florida
  • The car has almost 106,000 miles on it. It is burning all five quarts within driving 200-300 miles. I've never seen anything like it before. When I changed the pcv valve there was no noticeable blowby, but I will double check by pulling off the pcv hose and vent hose. When you say vent hose, are you talking about the other hose on the valve cover? I haven't checked the compression yet either. My intentions are to rebuild if possible or to buy another engine, but in doing this should we expect the same problems in the next 100,000 miles. Has Nissan done anything about the top cat, or should we all expect it to malfunction again. If not, it seems a fresh rebuild or new engine would be a complete waste of time and money.
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