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1995 M42 idle issues

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

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    steven s

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    I haven't looked at it today.
    Today was fix the Mini's front seat day. :)

    Driving to work there is some surging.
    Driving home after 15 minutes it would stall when I took my foot off the gas.
    I had to restart the car in the middle of turns.
    BUT, there was a slight upward hill just before my turn and that's when the stalling started.

    I probably need to let the car run for a bit. Maybe I'll let it run with the front end propped up?
    It has something to do with the incline.
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    charlson89

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    Have you check fuel pressure? Also what type of Mass airflow do you have?
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    steven s

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    I swapped the MAF already.
    I was thinking about fuel pressure.
    How would I measure it? Need something inline?

    Was also thinking is there such a think as vapor lock on these cars.
    Car was fine. Car parked on an incline. Idle problems. Same symptom twice. Same incline twice.

    I changed so many worn parts the first time around that it may have corrected itself.

    Fuel pump?
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    MGarrison

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    Swap out the tires for what's on the other 'ti?
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    steven s

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    I just don't like driving the other ti on the street so much. Too low to the ground.
    Thank goodness it has an x-brace to protect the pan.
    Don't really want to but 15" wheels on it either.

    But I may swap the fuel pump. :)
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    MGarrison

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    charlson89

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    yes fuel pressure should be checked in line you could do it at the fuel filter and most auto parts stores have one you can rent for no charge.
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    steven s

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    That's how I'll spend my next staycation. :)
    Harbor Freight has them cheap enough.

    Add: Doesn't look like I can monitor fuel pressure while driving.
    What I really need is an electronic gauge but those are costly for just testing.
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    MGarrison

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    If the tubes are long enough, you can tape the gauge to your windshield (on the outside).
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    steven s

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    That's what I did when I was monitoring oil pressure.
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    steven s

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    So I pulled the sender and fuel pump to inspect the tank.
    The screen on the fuel pump looks clean.
    I scrape the bottom of the tank with a rag. Looks clean.

    Change the filter anyway.
    Fuel looks clean.

    When I replaced the fuel filter I notice
    .
    The small metal piece may be a rivet from a past repair on my door, but I don't recall ever seeing the roundish metal part. Could that have been in the fuel line?

    Car still stalls. I picked up the wrong pressure gauge. Need to still work on that.
    The car is very sluggish for a few minutes then will stall if I let off the gas.
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    MGarrison

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    The fuel lines aren't all that big, I think if that was in a fuel line, it would block it entirely. Weird, whatever it is. Forgot if we mentioned this before, have you looked at your fuel injectors?

    Another reason to get a gander at an ETM, to check all the electronic paths related to fuel system, fuel delivery, ignition, idle, etc.

    I don't know the specifics on M42's - but, on my car, the pumps basically run and pressurize the fuel lines (thru the filter), up to the fuel pressure regulator (fpr), which I guess has some pneumatically-actuated diaphragm that, based on engine vacuum, modulates the amount of fuel pressure to the fuel rail, which the injectors are plugged into. Afaik, the metal pinhole the fuel squirts through can become clogged &/or dirty w/ carbon accumulation or whatever, negatively affecting the spray pattern &/or volume delivered. Your injectors may have filter screens, and if so, those can get some degree of clogged over time - fuel injector reconditioners, some of them, mention replacing the screens. I have no idea if your injectors are similar in construction to the prior-era bimmers, but I'd kinda think so. After that, the dme/ecu, based on its variety of inputs, delivers the signal which opens/closes each injector at the right time, for the correct amount of time. Excess fuel from the fuel rail is then run back to the tank, and somewhere in the loop, maybe you have a carbon canister filter, at least E30's do. So, you have the physical fuel delivery system, and you have the car's brain controlling the operation of the fuel injectors. That's two areas to run down, with tracing & testing the ecu inputs possibly being the more tedious part.

    Then there's everything related to the ignition system & controlling/providing spark to the plugs. Fuel, spark, air - y'know you got air, as the car runs. Maybe Charlson can elaborate on what I'm missing and what else to look at in light of what all so far....!
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    charlson89

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    Ok you say after 10 mins then the cars acts up and start the idle issue. For those first 10 mins how does the car idle and run?
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    steven s

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    Runs like crap the 1st 10 minutes. Revs high and low power.

    When I pulled the rear seat out to get to the tank I found sand underneath the rubber mat.
    I think this car was under water during Hurricane Sandy. :(
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    charlson89

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    After the first ten minutes then does it run smooth? Also is there any black smoke out the back of the car during the first 10 mins of running while driving it?
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    steven s

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    Nope. It stalls when I take my foot of the gas.

    Exhaust seems OK.
    I guess I can swap fuel pumps since I have the same one in my other car.
    Idle is also a bit erratic when I first start.

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