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1995 M42 idle issues

Discussion in 'E36 (1992-1999)' started by steven s, Nov 1, 2013.

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    charlson89

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    Are you able to clear adaptations?
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    steven s

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    steven s

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    Bypassed the cat since it had 164K miles on it anyway.
    Idle still bad.
    I'm still suspecting the MAF. I have a buddy who can send me one.
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    charlson89

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    Yes do try the swap that would be best. Your car still has those adaptation values even though it is OBD 1.
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    steven s

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    Can I clear them without a computer?
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    charlson89

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    No that information is stored in the DME some aftermarket scan tools can clear them.
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    steven s

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    Below is the knock sensor for cylinders 1 & 2. Of course the fault I originally had was for 3 & 4 which is buried.

    Attached Files:

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    steven s

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    Well being pissed at the car all week I had to move it out of the driveway to swap out a set of tires on my 96. Car wouldn't start. I knew the battery was old and it was only a matter of time. I jump start it and move it out of the way and let it run while swapping tires on my 96.

    Oddly I noticed the idle stayed constant. ??
    Could it be fixed?
    I drove for a few miles and the car felt normal except for the exhaust sounding like a motorboat. It's a SuperSprint.

    I get back to clear the fault codes.
    Drive the same route and I still have a knock regulation fault.

    I'll drive it back and forth to work this week because previously the CE would come and go. I want to see if that at least is fixed. Suspecting it was an O2 sensor.
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    steven s

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    OK. Back to this.
    Car running like crap. O2 sensor replaced. Still bad.

    Suspecting a bad MAF. I hate K&N filters.

    A club member buddy of mine drops off a spare MAF at http://www.auto-heaven.com/ in Sacramento who is also a club member to deliver it to me at Legends of the Autobahn. :)

    I get home and install. Car runs good. Exhaust still sounds like it has a hole, but it accelerates as best as an M42 will do. I drive it a week and swap out the MAF for the original MAF. Car still runs OK. WTF?!?!? I was really hoping that the problem would revert back.

    Still have the knock regulation fault. Over the winter I'll replace the 2 knock sensors and look into a replacement exhaust.
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    steven s

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    This is odd. I don't remember where I left off.
    Gas filter, swapped MAF. ICV. Car was idling fine except for when I had the AC on.

    Now I leave my car in my driveway on an incline and have the same erratic idle as the last time it was on an incline. ?????????
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    charlson89

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    Steve have you checked the fuel pressure regulator on the rail to make sure its not leaking into the vacuum hose?
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    steven s

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    I haven't but in both instances the problem started after the car was on an incline for a week.
    How would I do that?
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    MGarrison

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    steven s

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    Thanks. I have a feeling I already replaced it, but will check.
    New regulator lists for $78.98.
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    steven s

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    If I replace the FPR it says to relieve fuel pressure.
    Is that simply removing the gas cap?
    I haven't looked at Bentley yet.
    I suppose it would be prudent to replace the o-rings also.

    I was going to leave this ti and drive my E30.
    The E30 has a dead battery. I'd have to move the E30 to get to my other ti.
    Old cars can really suck. Then again, I here people have problems with new cars too. :)

    Add:
    No fuel is coming out of the FPR when I remove the vacuum hose.
    Of course the idle changes.

    After driving for about 20 minutes the car just dies as soon as I take my foot of the gas.
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    charlson89

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    Then it's not the FPR did you check for any intake leaks?
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    steven s

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    I have replaced every vacuum hose I can see.
    The odd part it was fine for months until parking on an incline for a week.
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    MGarrison

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    Looks like fpr not needed - If you ever do, though, I'm not sure what you'd have to do to relieve fuel pressure; completely different of course, but on my M20, letting it sit overnight let's fuel pressure bleed down; if you start pulling fuel lines off the fuel injector rail or elsewhere, you want to wrap a rag completely around the hose/fitting junction to catch fuel that might spray out under pressure, and of course some gas is going to run out anyway (use catch pan at your discretion). Good idea to wear nitrile gloves, good chance of getting hands saturated w/ gas - also eye protection, just in case system pressure is still up. Charlson ought to be able to tell us if the fuel routing, accommodates relieving fuel pressure in some fashion besides bleed-down over time. I don't think gas cap has much, if anything, to do w/ releasing fuel line pressure, unless the gas tank was completely empty and the fuel pump(s) sucked air.

    If your other car's ECU is compatible, you might try switching ECU's - again, different engine, less possibilities on M20, but had a really annoying idle surge, turned out something in the brain w/ the idle circuit was bad; swapping in a different ecu fixed it, after replacing ICV and just about anything else related to idle control. I'd consider that an outside possibility. If you can find an electrical troubleshooting manual for your car, or wiring diagrams, looking at all the i/o's for idle control might yield some things you haven't tried yet.

    Get a battery tender ;)

    For the heck of it, park the car on the incline in the opposite direction for awhile, maybe some diaphragm will go back to the way it was. ;) Seems really unlikely tho! Wish I knew more about M42's to have better insight!
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    steven s

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    I tried parking the car in the opposite direction. :)
    Didn't fix anything.

    I wish I knew if it was a vacuum or fuel problem.
    The 95 is going in the garage.
    I'm taking about the intake manifold to inspect all the vacuum hoses, AGAIN.
    Wonder if it's a knock sensor?

    The E30 got it's battery charged.
    My 96ti is getting dragged out the garage so I can drive it as long as it's not too cold.
    All I have on it are Toyo T1S tires. They don't work well in cold.
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    charlson89

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    Does it fluctuate when the car is sitting on a level surface or only when on a incline?

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