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Saturn S-Series: code p0101

moparmaniamoparmania Posts: 9
edited June 2014 in Saturn
I have a 2002 SL1 and keep getting the p0101 code (misfire on cyl 1 and code p0507 idle high for engine situation). I changed the plugs to platnium and new plug wires, also, swapped the coils. I checked the compression all cyls are okay. When I pull the 1 cyl plug wire the engine doesn't hardly react unlike if I pull any other plug wires. since it is only happening in cyl 1 I am assume it is a fuel injector? it idles around 1300 and you can hear it missing at the tail pipe, however when I turn on the A/C the idle goes down to about 900 and smoothes out, and then you pull the plug wire on cyl 1 and it reacts like you any of the other cyls with the wire pulled. Any suggestions?????????


  • Karen_SKaren_S Posts: 5,095
    I did a search of the entire forums and found that code for other make/models, but not for the S-Series. However, it apparently has to do with the massive air flow sensor. You probably knew that already. :blush:

    If you don't get a response here, you might try posting over in Got a Quick Technical Question? on the Maintenance & Repair board.

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  • I have a 2001 SL1 same problem did you get a solution to your problem.
  • not yet, I seen one back in april 2006 (message 1333) in the forum and it said they changed the throttle positioning sensor and still the same problem?
  • booboo6booboo6 Posts: 46
    I have same exact problem, waiting for warmer weather to troubleshoot. Likely the IAC not operating right. Won't know until I clean it and possibly change it. I have '02 SL1 also, same exact problem. I have theories, here goes:
    1. As the car idles/starts fine cold, and runs smooth during fast idle, the operation is fundamentally fine. With hood opened, just when the AIR system blower is commanded to stop and the IAC closes on same command (coming off fast idle), misfire occurs. Likely too rich, not enough air for that gas dose. As we have waste spark, the spark also happens on exhaust, combined with exhaust heat, the charge is burned, for that "pop".
    2. Cyl-1 is at far end of the intake manifold, and gets least air givent he straight design, so if there is air starvation, cyl-1 gets the least air and richest mix. A general problem of too rich would show up first here.
    3. When A/C or fast idle is commanded-on, the IAC opens to let more air in, and the fuel dose may be different, settling matters.
    4. Throttle position switch is also suspect: if it fails to tell PCM that it is in idle, system may try to operate in close-loop control and the mix will falter at low rpm.
    The readily accessible IAC is likely problem as I exhibit some on and off gas during deceleration, suggesting that the IAC is oscillating, let in more air as it should, and then not, etc.
  • chris81chris81 Posts: 2
    If you are getting a missfire in one cylinder and a high Idle. I fixed my problem by replacing the intake manifold gasket. The gasket was only $27.00 but It took me 6 hours to replace. The book hours was 4.6. Get a book on how to change it because you have to take of some wheel well parts to reach the bolts. I used a Chiltons. It sounds wrong but to test it take some water and spill around the gasket and you will hear some gorgling. The air fuel mix is bad because the gasket is bad. I went to a dealer mechanic and he was very helpful. He knew right away what the problem was.
  • booboo6booboo6 Posts: 46
    Thanks, but my problem is very slow idle, as if operating on 3 cylinders, but the car often runs perfectly and not getting worse. When it idles a bit fast, it does not misfire. Saturns are known for their problem IAC.
    The signal from PCM is duty cycled, so even at idle speed, it suggests that the total air delivery is part via the set screw path, and the balance of air flow via the duty cycled IAC. (IOW, idle air flow is not a stay-closed IAC and the idle screw path all the air it needs for idle). This gives the PCM some ability to control idle speed between the Drive (loaded) or in Park (unloaded) modes. But if IAC sticks and sluggish, and not letting its share of air thru, misfire is to be expected. Normal intake manifolds, especially with throttle body injection (as well as carbed cars) use centrally located inlet for even flow to the cylinders. Saturn uses simple manifold... air comes in from cyl-4 end and with straight manifold, air is the least at the distant cyl-1 end, so general air starvation results in richest mix at cyl-1. I am planning to remove intake hose and just hit the IAC with WD-40. If instant improvement, the problem is there.
  • booboo6booboo6 Posts: 46
    I started looking for potential vacuum leak in the cyl-1 runner as that is still a good possibility as suggested. Outright cyl-1-only misfire does point to vacuum leak at this cylinder. When not idling and throttle opened all the other operating conditions, vacuum is reduces by this and enough to avoid the misfire if it is a smaller vacuum leak. I measured -18 in-Hg for vacuum via the EGR port, which may be in proper range. Does anyone know what is the proper vacuum for the '02 Saturn SL1. A local minor vacuum leak may not affect this overall figure enough to show a vacuum loss, but -18 in-Hg is pretty good. On this subject, there's a lot of chatter in misc. forums about coolant leak and intake manifold gasket leaks. What's the connection I wonder. The matter is about air and sealing around the head intake ports, and not sure why coolant loss is involved for these cases. General manuals for old Saturns do show a heater hose going into the intake manifold. Baffling...
  • booboo6booboo6 Posts: 46
    All set. Thanks all. Intake manifold gasket leak. Involvement with coolant is that the fabrication holes of the cylinder head needs the manifold and gasket to cover up!
  • dreuterdreuter Posts: 1
    I have an '01 SL1 with only 50K miles, and I get two codes, like many other people have. They are that the idle is high, and cyl-1 is misfiring. The car idles high (~2000 RPM) when started, and sometimes when put back into park. Lots of people say that the idle control valve (looks like little motor on right (driver's side) of engine intake manifold) is dirty or needs to be replaced. This usually isn't the case. It IS the manifold gasket leaking at the #1 intake. Try spraying carb cleaner on the #1 intake (passenger side) while the car is running. If the engine begins to die, then you know you have a leak. You can spray the entire intake manifold, and you'll probably only find that #1 is the problem. I have a friend that bought the same '01 SL1 I did, at the same time I did (brand new), and he had the same problems at 18K miles. The techs couldn't figure it out, and they even brought in some of Saturn's engineers to try to help. They all know what the problem is now. He gave the car back after his 3 year lease. I don't blame him.
  • booboo6booboo6 Posts: 46
    No doubt it is intake gasket leak. I can hear the leak! Spraying on some SAE90 did the trick for a while, as the oil got dragged in and the thick oil temporarily sealed the leak! The IAC valve is not the problem. If IAC is stuck closed, that is the correrct condition for warm idle. If IAC is stuck open, one would get faster idle, but no misfire. The fast idle comes from fact that there is no air flow sensor and available air is based on the manifold vacuum sensor and the throttle position switch. So air slight leak of the vacuum will be sensed and fuel added as if fast idle is intended. I have new Fel-Pro gasket to put in shortly. It is much thicker than the one supplied with the car. I don't think problem is insufficient clamping of gasket, but more like an inferior gasket material. This problem is starting to show up all over for the '02 SL1. The job is about 3-4 hours. Should not be bad to do. Car is not bad, just poor gasket. Not safety matter, so I expect no general recall.
  • Yes, I have already replaced the intake gasket with a new Felpro one and it now runs great. Back to getting 40+ mpg. I even asked the service writer if there were any issues with this car and the problem showing up, and he said not that they new about, just wanted $85 for diagnostic (which I didn't do). I was told about this issue some how linked by "check engine light" fourum some place inside
  • booboo6booboo6 Posts: 46
    In a way, we lucked out, in that our leak is sensed by the manifold absolute pressure sensor (MAP) so the Saturn may burn a little rich overall, which is much less of an issue than had we a hot-wire sensor in the throttle body and the leaked air unsensed, resulting in extra lean burn and hotter exhaust (catalyst damager, exhaust valve damage, etc). From what I read, this problem is a known "occasional" problem with the L24 engine. The OBD-II knows which cylinder misfires because it studies the crank rotation speed via the crank position indicator. It knows when there's a missing power pulse and which cylinder loss a power pulse (i.e. misfire) this manner, especially at idle speed when there's not enough momentum to flywheel effect smooth out the crank spin. OBD-II is pretty smart. Identification of misfire is pretty accurate! I've not put my new gasket yet, but will do so and time my tasks. I think I can finish in 3 hours if the old gasket comes off clean. From sound of things, it should drop right off! I have a 90 deg geared drive so I should be able to spin the nuts on and off quickly (let's not waste time ratchetin on and off so many nuts on long studs, let alone dropping and searching for them)! Cheers.
  • I have a 99 SW2 with the 1.9 DOHC and have a very similar problem. When the engine is cold, it will start and run fine in idle and park. As I drive and it warms up it will misfire under lightly loaded conditions-cruising and when stopped at lights etc. I narrowed it down to the Nr. 3 cyl. by removing spark plug wires. I have just changed out all the plugs and wires. Went back and rechecked, still have the same problem. The cylinder is getting good spark as best I can tell, it was checked by pulling the plug and grounding it to the block. So, I changed the fuel injector next. No improvement.

    By the sounds of previous discussion here, I think I am looking in the wrong area now. But I have no clue as to where the IAC sensor is at, much less the rest of the sensors. Autozone has check it and came up with a P0303 code-cylinder 3 misfire detected. Any help would be a huge help, as it sounds very similar to what you have dealt with already. Thanks.
  • Your '99 model is a bit older model than I'm used to fooling with, but if Saturn/GM also used the same material fiberglass gasket in your model, you almost certainly have a leak from a crumpled, sucked-in gasket as I suffered (and many others). I would say going to Saturn dealership to make repairs is probably not good idea if they are going to put in the same GM intake gasket part. Maybe possible to specify Felpro gasket with whatever shop you go to if you don't do the repair yourself. I would not go too long with your car in that condition as there is localized leaning at your cyl-3, that could cause a burnt exhaust valve there. The exhaust is extra hot venting out that cylinder. P0303 is misfire at cyl-3. Mine was P0301 (cyl-1). You may get P0507 once in a while when PCM fails to control the fast idle caused by the leak under certain conditions. Most of the time, it is very slow idle caused by 3 cylinders running. You run smoother in cold idle because the IAC opens up to increase idle and end up lowering the manifold vacuum, so the reduced vacuum causes less leaking at the failing intake manifold gasket.

    As the misfire is not random across the cylinders, you can almost bet your last dollar it is vacuum leak at cylinder 3 intake gasket. OBD2 is quite accurate, especially for 4-cylinders. If anything like my '02 SL1, the job is a less than 3 hour do-it-yourself job. All I had was Haynes manual for guide. Good luck.
  • Thanks, I think I'll head down to autozone and get a quality gasket then do it myself. In the meantime, guess I'll park it and save myself and wallet from a big repair. Thank you for the advice, I'll let you know how it turns out.
  • I've always used Felpro gaskets all my life. It's metallic cored and expands similarly to the aluminum manifold as well as aluminum head. Fiberglass probably thermally expands/contracts too much and a mismatch. Cost for Felpro: $18. Original gasket is $15, so only $3 between junk and good stuff. If you drive mainly on the highway, the leak won't hurt you too badly. With opened throttle, most of the air is let in via the throttle, so the leaked air from the gasket gets to be in the noise and out of the picture. It's if you idle a lot that there could be issues of burnt exhaust valve and damaging the catalytic converter. The misfire is from the unburned/lean gas mix getting fired after it fines hot exhaust manifold. The burn may not be complete, so expect a lot of work for the catalytic converter and lots of water coming from the tailpipe (could increase corrosion). If you send me your E-mail, I'll send you a pic of my gasket. I still have the pieces and positively located the point of leakage. The gasket will fall right off, so you don't need a scraper! Some acetone is all that is needed to clean the surfaces.
  • thanks, the email address is:
  • I think I'm having the same problem on the same car...faulty intake manifold gasket on a 2002 Saturn SL1. The car is idling high, and a recent diagnostic test revealed a misfire of the #1 cylinder. I replaced the plugs and wires, hoping for a quick, easy and cheap fix, but with no results. I checked out the EGR and IAC valves and they seem to be clean and functioning fine. I haven't looked at the throttle body, but then again that would not explain the misfire.

    So, I'm concluding that I will have to replace the intake manifold gasket. I'm going to spray carb cleaner around the gasket to determine if this is really the problem before I go at it. I plan to pick up a Haynes manual to attempt to do this on my own. This is the first larger project I've undertaken on this car, but I really would rather spend the $300 a shop wants for labor on tools and learning how to do it myself. Is replacing this gasket something that someone with good diy skills can tackle with a repair manual, a will and a weekend, or should it be left to a mechanic? Any tips?
  • You almost certainly have the same problem and it is chronic. You likely have code 0507 showing PCM inability to control the fast idle. Your '02 Saturn (like mine), does not actually have an EGR. '02 and possibly '01 eliminated EGR. That valve you identified as EGR is nothing but a control valve that opens to let the DC blower inject air into exhaust manifold for fast catalyst heat up. When the PCM calls for shutdown of the fan, PCM will close that valve at same time to prevent exhaust from baking the fan.

    It is not a major job at all. Don't take apart all the things mentioned in the Haynes manual, which is for outright manifold removal from car. Only remove what you have to and slide the very lightweight assembled intake manifold straight back and off the studs. No scraper needed as with other cars. This gasket will come right off. I'm in NYC on travel. Can send you my checklist and whatever else and pics when I get back home in Boston, including my gasket's leak point, etc. If I do it again, can do in 2 hours. Don't take to Saturn dealer, which will put in another same gasket with possible reoccurance. The plastic gasket just doesn't adhere to the clamped surfaces and gasket probably expands/contracts too much with each engine heat up. The gasket just flows and distorts, creasing and whatever, letting in air. Car will run like new with gasket work!
  • yeah the list of parts I have replaced so far:

    coolant temp sensor, 4 injectors, idle air controller, air filter, spark plugs, plug wires, ignition coils, ignition module, and many more that I can't remember. Also have had to do 4 oil changes because of fouling in the engine oil. I've only had the car for a month now, and I have to get an emmisions test done to get the car plated and on the road, but without this fix, it's not road legal.
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