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All About Exhaust Systems

124

Comments

  • mg45mg45 Posts: 8
    Thanks for the reply. There are no engine or service lights lit on the dash.I had the car car scanned for codes at auto zone a few times but no codes are coming up.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 45,986
    Okay, so then we sit down and play Sherlock.

    What throws no codes on an engine that sounds like it is running well, but could result in awful gas mileage?

    (I'm thinkin' I'm thinkin' :confuse: )

    Excessive fuel pressure from the FP regulator?

    Leaking injectors?

    Not shifting into high gear?

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  • kiawahkiawah Posts: 3,666
    - Dragging brake pistons, or mis-adjusted parking brake.
    - underinflated tires
    - my first thought when I heard that whinning, was a bearing going bad on air compressor, waterpump, or alternator
    - and that is a really throaty exhaust tone....got any back pressure?

    What is the color on the interior of the tail pipe? Is it a really rich black substance, showing as running too rich?
  • mg45mg45 Posts: 8
    I jacked up each wheel today and the brakes are not sticking. The tires also have 32psi listed on the tag in the door jam. I removed the front o2 sensor and the car drove the same if not worse, so i don't think the cat is clogged. I also put my hand over the tailpipe, but it kept getting pushed off from the pressure, so once again i don't think thats clogged.

    The inside of the taipipe does have a good amount of black substance, that it actually left a black line going down the exhaust pipe and onto the muffler, but the car is not blowing black smoke. I also removed the spark plugs and took some photos of each, as well as the exhaust pipe. Here are the photos:

    http://img20.imageshack.us/gal.php?g=96655802.jpg">
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 45,986
    You're running rich all right.

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  • mg45mg45 Posts: 8
    Ok, as you can see from my first post those are all the things ive replaced. What should i do next? The only sensor i haven't replaced is the cat o2 sensor, but there are no engine lights on. Im thinking injectors? Should i pay the 65 bucks to have them professionally removed and cleaned, or could it be something else as well?
  • watkinstwatkinst Posts: 122
    It's a saturn!

    Any chance its leaking gas when its rolling down the road? I worked for saturn in the early years. Only saturns that didn't burn oil were the ones in the shop getting the fuel pumps replaced or the one's at the scrap yard being scrapped. Hence not running.

    Later years the Honda motors were nice but the rest was well what can I say GM parts.

    Its a fuel system issue not an exhaust issue or break issue or tire issue. Given your car has no engine lights on would indicate that the car has more than just a fuel system issue given the GOV mandated engine management systems are failing to pick up an obvious fuel issue. When was the last time you had it smoged? Did it pass?

    The fuel goes some place :-)

    Is your kid or neighbor syphoning your tank? I'd consider that a very big possibility given its nearly impossible for that car to burn that much fuel without very obvious problems.

    Get a locking gas cap! See if your milege improves - they cost like $8 :-)
  • mg45mg45 Posts: 8
    I tried that before except with a clear piece of tape on the gas tank cover at night to see if anyone was siphoning my gas. As for leaks, i looked under the car while it was running and after a drive but i don't see anything leaking, (one of the first things i suspected. I also revved it while looking underneath but once again, i didn't see any leaks. Are there any special places i should look for leaks at that are most likely going to leak? What about the pictures i posted, does it look like it's running rich? Also I've been getting this gas mileage since day one when i got the car in April 2009. It was inspected then and passed. I live in New York and its due for inspection in April.

    Don't they just hook something up to the OBDII and scan for codes? And if nothing comes up then they pass the car? Thats what all the mechanics i talked to over here said, unless the car is older and doesn't have OBDII. Here are the pics again:

    http://img20.imageshack.us/gal.php?g=96655802.jpg
  • watkinstwatkinst Posts: 122
    No engine lights - would mean essentially no codes to pull if NY inspection is only doing a non run - check the codes inspection. I'm not familiar with NY inspections.

    Do you live in the city? I didn't know people owned cars there? HA HA Wife lived in NY for 7 yrs.
  • srs_49srs_49 Posts: 1,394
    The cat O2 sensor (in back of the cat) has nothing to do with how the car runs. It's just there to monitor the efficiency of the catalytic converter. It's there to make sure the cat is doing its emissions thing.

    Shifty/anyone else - Don't you think if he's running that much excessive fuel through the engine, it would fry the cat in short order, and so set the CEL? Cat's are not tolerant of fuel-rich exhausts, IIRC.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 45,986
    Cats can take a certain amount of excessive fuel-burning--what it can't take is RAW fuel. Cats can ever tolerate lots of oil burning.

    I'm quite puzzled by this problem. I would have suspected a bad ECM module except he passed the smog test.

    Very often these types of difficult problems lack a critical detail that has not been reported (or perhaps observed) by mechanic or owner, and once that detail is known, we all slap our foreheads and say OF COURSE! :P

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  • srs_49srs_49 Posts: 1,394
    Me too, puzzled that is.

    I mean, if the engine was really running that rich, and the front O2 sensor was working correctly, wouldn't the ECU try to lean things out to try and keep the air/fuel ratio at the stochiometric point (what's that 14:1?)? Then if it couldn't do that, throw a code?
  • mg45mg45 Posts: 8
    How do they do the smog test? The car was inspected before i drove it off the lot on April 6th 2009 and it apparently passed. Unless the dealer forced the pass, because after all they did sell it to me with a bad tranny. I'm getting it inspected at the end of march and I'm thinking it will pass if they just do the inspection by scanning for codes, which i don't have. I am really hoping it fails, then they have to find out and tell me whats wrong with it.
  • obyoneobyone Posts: 8,065
    I am really hoping it fails, then they have to find out and tell me whats wrong with it.

    You should get an "A" for creativity as I've never heard of that one before... ;)
  • mg45mg45 Posts: 8
    My 2007 camry failed when i brought it to the dealer for inspection and they called me saying what needed to be done to get it to pass. it cost 200 bucks, something with emissions, but it then passed. I don't know if the same goes for the saturn, but i did buy it from that same dealer.

    I just was looking under the hood, searching for any fuel and or vacuum leaks when i noticed this weird noise coming from the manifold when i rev it. Heres the video:

    http://www.youtube.com/watch?v=KoBqgFVNhEQ
  • kiawahkiawah Posts: 3,666
    Personally, I don't like that sound, or the whining. That would bug me until I either concluded it wasn't a problem, or found what the problem was.

    Try popping the accessory belt off, and then start the vehicle and run it briefly to see if the whining stops (then proving it's external to the engine), or continues to whine. I don't know the saturn specifically, but look on the tensioner pulley assembly for either a wrench or pry bar attachment point. Take the tension off the belt, slide the belt off, then slowly release the tensioner to it's rest position. Take note of how the belt routes, so you can put it back the same way.

    If the whining stops with the belt off, turn the engine off, and with your hand slowly turn/wiggle each accessory to see if you can feel which bearing is a problem.
  • mg45mg45 Posts: 8
    Ok, i figured out the noise was coming from the pcv valve. It just the little ball in the valve bouncing around. As for the gas mileage issue i think i made have cracked the code.

    As I listed I recently replaced the fuel filter. I bought one from auto zone for 35 bucks. The fuel regulator for the 98-02 s- series is located in the fuel filter. The 35 buck one is JUST the filter, no regulator. Basically the cars running with no fuel regulator. The previous owner must have done the same thing and put in a filter with no regulator, which is why I've been getting the bad gas mileage since i bought the car. That would also explain the black soot on the exhaust pipe.

    I have no idea how the car is running practically perfect with no regulator, but the map sensor must be making up for it enough not to throw a code. I'm gonna order the OEM 92 dollar regulator/filter from RockAuto.com and see what happens.
  • tjh1990tjh1990 Posts: 4
    hi can u help please i want to buy a after market back box not expensive 1 but i just wondered how to fit and how easy is it?
  • tjh1990tjh1990 Posts: 4
    hi i am wanting to buy a after market back box how and how easy is it to fit?
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 45,986
    How difficult it is depends a lot on the type of car and type of system. Usually the vendor can give you some idea of labor involved. Often the hardest part is getting under the car if you don't have a lift. Then there's the problem of whether your present exhaust system is all rusted up or not. Sometimes a muffler shop will install it for you for not too much money. If you're just buying the back muffler and not pipes, this is usually pretty easy to fit.

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  • tjh1990tjh1990 Posts: 4
    thats what i want how do i fit the muffler
  • tjh1990tjh1990 Posts: 4
    i want to fit a muffler how do i do this and what difference will it make
  • obyoneobyone Posts: 8,065
    A low restriction muffler will give you a higher maximum rev point usually accompanied by a louder sounding exhaust at the expense of loss of low end torque. Depending on what vehicle you're talking about you could have one installed for under $100.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 45,986
    It'll just make more noise basically. There's no power inside a muffler itself. If you put on an entire cat-back system, maybe, depending on the car, you'd get a few more HP. Is it worth the money?? Probably not, unless you like the louder exhaust note.

    But anyway, fitting just a rear muffler to most modern cars is usually just a matter of undoing some clamps and hangers. But you'd best check to see that yours isn't welded up, especially if it's an older car. Muffler shops often weld in replacement mufflers.

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  • obyoneobyone Posts: 8,065
    Actually if you want to remove restriction, knocking the honeycomb out of the cat works better than any low restriction muffler. Course you'd have to get dummy o2 sensors and live in a nonemissions state.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 45,986
    You'd probably get the most horsepower from no mufflers at all, presuming back pressure was sufficient in the exhaust header tubes. But that would be quite noisy :P

    Getting any real HP boost is generally expensive.

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  • is this illegal though?
  • obyoneobyone Posts: 8,065
    edited June 2010
    is this illegal though?

    Yes it is. Does that stop someone who can't afford a new cat or looking to cheaply increase performance? Nope not in a state that doesn't have emissions testing.
  • New poster here with more of a statement than a question and looking for feedback.....
    I run a fleet of 127 GMC and Chevy 3500 cutaway box trucks. The 2 issues that have cropped up consistently over the past few years are fuel pumps (inadequate design) and exhaust manifolds that crack before 100,000 miles. I researched every manifold repair I had done and noticed a pattern of prior O2 sensor failure of some sort in nearly every instance. Out of the 9 documented cases, 4 of the trucks also had to have new catalytic converters. My theory is this: Faulty O2 sensors or deteriorating cat converters are the culprits. I believe it's a domino effect starting with the sensor which in turn destroyed my converters and subsequently cracked the manifolds.

    Thoughts?
  • srs_49srs_49 Posts: 1,394
    IMO, I do not think a bad cat would damage an exhaust manifold.

    One way to kill a cat is to have a overly rich fuel mixture , or misfire, which leads to high amounts of unburnt fuel in the exhaust, which in turn "burns" in the cat, overheating and destroying it.

    So, maybe the crack in the manifold occurred first. This may have led the O2 sensor to think the engine was running too lean, so it caused the ECU to richen then air-fuel ratio, which results in high amounts of unburnt fuel in the exhaust stream.

    Just a theory.
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