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Rough running AN - maybe a dodgy sensor ?

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  • Rough running AN - maybe a dodgy sensor ?

    I'm trying to eliminate a very rough running car ( seems to be either too rich or too lean). It was fine, let it sit for a few months and now its not. I've noticed that if I disconnect the air temp sensor in the carbon airbox / snorkel that little changes - I seem to be able to drive around with it either connected or disconnected with little or no difference. Is this normal, or should I look to replace this as likely cause ?

    If I pull the blue coolant sensor the revs rise, so I presume this one is working okay.

    Thanks !!

  • #2
    I dont run MAXX which is I assume what you are talking about, I use a much older chip based AN on my cars, but I think the basics are the same.
    These things have so few inputs into the ECU I think you may be thinking in terms of modern ECU systems and not thinking about how brutally simple it is.

    My red street car runs rough as hell when I initially start it many times if its been sitting a while, I usually guess a dribbling or sticky injector. If I tap on them or let it idle a minute they usually clear up.
    I would take a good look at the actually ignition and fueling components before the sensors.
    I think the ATS barely does anything, I've forgotten to plug mine in and it rarely seems to matter.
    The CTS does matter but I thing you have verified that its doing something.
    If you still have an ICV check that, I dont but that might have some say in the idle or fueling.

    Check your TPS, make sure your base (closed throttle) setting is correct.
    I'd poke around all the normal components that could make a car run rough even if it still had an AFM.
    I'm betting it has little or nothing to do with any of AN elements of the engine operating system if it did run fine at one juncture.
    Those systems are pretty simple.
    Just my thoughts, as I said there are MANY guys way more experienced with MAXX than me.
    Happy troubleshooting.
    jimmy p.
    3 x e30 m3s All with S14s
    Last edited by jimmy p.; 12-16-2021, 10:09 AM.
    jimmy p.
    87 E30 M3 Prodrive British Touring Car
    88 E30 M3 Zinnoberot - Street
    88 E30 M3 Lachsilber - Race (#98 SCCA SPU)
    92 E30 M Technic Cabrio - S14 POWERED!
    98 318Ti M44, Base - Morea Green
    04 Ford F350 - V10