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Poor Running, Worse Cold - Never 100%

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  • MauiM3Mania
    replied
    Originally posted by n15wb View Post
    You do understand that what you are describing in this post is normal behavior for an S14, right?
    The text you quoted is from 14 months ago and before numerous changes and 'fixes' had been applied, as described later in the thread. If your car runs as poorly as I described back then, read the balance of the thread. Lots of great input in this thread!

    My car is performing significantly better than that point in time, the biggest improvement was the intake gaskets replacement I applied a couple days ago.

    Leave a comment:


  • Bastosbill
    replied
    Originally posted by MauiM3Mania View Post
    Aloha and an update:



    Cold, the car runs terribly. It idles very rough, when accelerating it seems to be operating on 2 1/2 - 3 cylinders and will randomly 'lurch' as all four come on board. This behavior lasts for about 90 seconds, and it comes around to a reasonable smooth running state, decent idle, etc.

    As I understand it, neither problematic crank position sensor or O2 sensor would exhibit this behavior.

    In short, car runs poorly when first started and much better after a minute or two. Ideas and suggestions are welcomed.
    You do understand that what you are describing in this post is normal behavior for an S14, right? You start the car, idles rough and runs rough for aproximately 90-120 seconds, then the O2 sensor reaches operating temperature and comes online and it all smooths out and runs right. That describes the normal start sequence for our DME's and the S14.

    When I start my car, I back out of the driveway. I run the engine at 2000 rpm in second gear ( aprox 25mph's ). I can predict to within about 10 feet as I leave my neighborhood when the DME and O2 sensor will come online and the engine smooths out. Very normal and predictable.

    Your engine is running rough because it is running rich and your O2 sensor is offline. If you are old enough to remember what a choke is, think of it like that.

    If you have any other variations in that sequence with idle or running issues, then you start looking to replace parts IE: O2sensors/temp switches/intake blocks/ICV's etc.

    Been there done all that many times in my 16 years and 177,000 actual road miles/2engines. But the start sequence is the same and exactly as you are describing it.

    You also know to limit your engine RPM's to under 4000 until your oil temp is above 120 F right? I'm not giving you a hard time, many M3's no longer have the owners supplement manual with them.

    Cheers,
    Bill
    Last edited by Bastosbill; 06-16-2012, 06:55 PM.

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  • MauiM3Mania
    replied
    Originally posted by EvoErik View Post
    No.

    Where exactly is the leak located?
    I cannot say for sure which side, head or throttle bodies, the gasket is leaking. But using a mirror as we were running the smoke machine made it clear it wasn't coming from below.

    Originally posted by 1990m3 View Post
    An e8 socket for the tb removal is needed
    Thanks... if I don't have that, I'll pick up one.

    Leave a comment:


  • 1990m3
    replied
    An e8 socket for the tb removal is needed

    Leave a comment:


  • EvoErik
    replied
    Originally posted by MauiM3Mania View Post
    Anyone, is a sealer needed at the intake gaskets?
    No.

    Where exactly is the leak located?

    Leave a comment:


  • MauiM3Mania
    replied
    Originally posted by 13blackknight View Post
    glad you found your problem
    I'm hoping it is the major source of the poor part throttle performance! Every other potential sensor, etc. has been addressed!

    Anyone, is a sealer needed at the intake gaskets?

    Leave a comment:


  • 13blackknight
    replied
    glad you found your problem



    Originally posted by MauiM3Mania View Post
    In my long journey in the search for poor running, a vacuum leak was recently discovered after a smoke test of 18 months ago showed no leaks. Sooo... it appears it is time for intake gaskets.

    I've got a pair of TB to head gaskets, new o-rings for the injectors and o-rings for the intake to throttle bodies. Any special, out of the ordinary tools required for this job? I have a decent set of wrenches, ratchets, sockets, etc.

    Is gasket sealer suggested? Hondabond, etc?

    Leave a comment:


  • MauiM3Mania
    replied
    In my long journey in the search for poor running, a vacuum leak was recently discovered after a smoke test of 18 months ago showed no leaks. Sooo... it appears it is time for intake gaskets.

    I've got a pair of TB to head gaskets, new o-rings for the injectors and o-rings for the intake to throttle bodies. Any special, out of the ordinary tools required for this job? I have a decent set of wrenches, ratchets, sockets, etc.

    Is gasket sealer suggested? Hondabond, etc?
    Last edited by MauiM3Mania; 06-11-2012, 03:06 PM.

    Leave a comment:


  • MauiM3Mania
    replied
    About a year ago (see post #23) I swapped in a spare DME. No more spares.

    I need to go down the road of replacing the transistors in the DME.

    Leave a comment:


  • EvoErik
    replied
    Do you have access to another ECU?

    Leave a comment:


  • MauiM3Mania
    replied
    I've not accessed the car since the weekend when a new ICV replaced an older cleaned valve, but will check the throttles for smooth operation. I have operated the throttle at the engine and it's as if I'm using the pedal. I can not cause the engine to idle slower at the engine throttles.

    I'll gladly replace the o-rings and intake gaskets if it is suggested as an issue, but I must ask: Is there a reason to replace either is a vacuum leak is not present? It's been some time, but my tech bud ran a smoke test on the beast and no intake leaks were found.

    Everyone's input is appreciated!

    Leave a comment:


  • Mmark
    replied
    With regard to the high idle, perhaps the throttle bodies could be examined for sticky/binding linkage, bent butterfly shafts plus a sticky throttle cable.

    m

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  • mtony
    replied
    Might not be a bad idea to replace the gaskets and O-rings in the intake and throttle bodies given the fact that your idle is high. The parts are very cheap and it's not that difficult to replace them.

    Leave a comment:


  • MauiM3Mania
    replied
    One of first things we did was smoke test the engine. No vacuum leaks were found.

    Leave a comment:


  • 13blackknight
    replied
    Have you checked the intake manifold gaskets? If there original it's time for a replacement.

    Leave a comment:

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