Lean air/fuel mixture on 95 Eagle Vision (difficult cold start)

Discussion in 'General Motoring' started by sorin trimbitas, Jan 28, 2004.

  1. Hi, all,
    Here's my current suffering, and I'll try to keep it short. Bought
    this 95 Eagle Vision 3.5 ESI (Intrepid clone) about 1 1/2 yrs ago, 79k
    miles on. Currently at 92k.

    Ever since I bought it had a rough idle (shudder, trembling when in
    idle). Back then, tried to fix it, replaced plugs, wires, battery, air
    filter, PCV valve, intake manifold gasket. Nothing gives, shudder
    still there today, but note that allthose items are barely 1 year old.
    Occasional history of not starting in cold weather (teens and below)
    but I attributed that to fuel line freeze.

    To top that, in the past couple of weeks due to extremely cold weather
    car won't start again, this time had a full tank of BP 93. Tow the car
    to my garage, heat up the garage, nothing gives, car would turn, crank
    but not start. A few days later still very cold in the garage, but I
    floored the gas pedal, keep cranking the key(suggestion from the
    group), some 20-30 secs later car starts in a cloud of smoke (probably
    flooded). Still starts and runs today, but with an apparent loss of
    power, check engine light on. I did the key trick, read the codes, 51
    twice (lean air fuel mixture).

    So I figure it's the O2 sensors (also from reading the group), bought
    2 new ones and proceed to replace the old ones. BEFORE taking the old
    ones out, I just disconnected them, and I crank the key again, fully
    expecting not to start. Wrong! Car started as if nothing has happened.
    So, I postponed changing the sensors. Now, car is running but still
    sluggish, still check engine light on, still code 51. I'm afraid it
    won't start again in cold.

    Would welcome advice: could the O2 sensors still be bad and in need of
    replacement? If so, how come the car started with them disconnected?
    (Granted, car was warm at the time). If not, any other suggestions on
    what might be wrong? I only mentioned the shudder because I think it
    may be realted to the lean air/fuel mixture. Your help is greatly


    Note: due to bad experiences with local shops, I'm reluctant to take
    the car to a local shop, until I find one trustworthy and
    knowledgeable, so I welcome suggestions in that department as well (I
    live in NE Ohio, Cleveland/Akron area). I found an excellent local
    mechanic for my Passat but he won't touch anything NOT European.
    sorin trimbitas, Jan 28, 2004
  2. sorin trimbitas

    Neil Nelson Guest

    Certainly. If they're shorted low, they're going to report back
    to the PCM a lean fuel condition, the PCM is then going to
    erroniously add more fuel possibly carboning the sparkplugs, the
    addition of an erronious lean condition is going to skew the fuel
    trim strategy so that even during a cold start when the O2
    sensors aren't being monitored, too much fuel is injected.
    What you get is a flooding condition from compounded problems.
    Because simply, the O2 sensors are not a necessary component to
    whether the engine will start.
    Ideally you'd want to scan the engine data with the appropriate
    tool to see what is actually happening, as an alternative, you
    could back probe into the O2 sensor signal circuits with a DVOM
    and watch the sensor response as a way to confirm whether they're
    stuck low giving a false lean report to the PCM.

    In addition, you may want to check the fuel pressure regulator
    and verify the cam timing because these three items (O2 stuck
    lean, fuel pressure regulator, cam timing) have been the only
    causes that I've seen that create a hard start condition on the
    3.5 engine.
    Perhaps you can get recommendations from friends, cow-orkers or
    Neil Nelson, Jan 28, 2004
  3. sorin trimbitas

    Ted Guest

    Suspect leaky manifold gasket, very common on 3.5L engines.
    Ted, Jan 28, 2004
  4. sorin trimbitas

    Steve Guest

    And maybe the lower intake manifold gasket.... it might leak enough to
    lean the car out enough that it would be hard to start.
    Completely O/T- I had a GM rental this week. 3.4L, only 8200 miles, but
    that thing was a hard-starter (in only 48 degree weather, no less). Ran
    great once fired up (well, not as good as a Chrysler 3.5), but took
    several re-tries to get going. By the way, I noticed that GM cars no
    longer put the driver in control of the starter directly- once you bump
    the key over to 'start,' even if you release the key the engine will
    keep cranking until the engine starts. If the engine doesn't start, it
    gives up after about 5 seconds. Really surprising the first time you let
    go of the key and the sucker keeps merrily cranking away!
    Steve, Jan 30, 2004
  5. sorin trimbitas

    Neil Nelson Guest

    Except that the OP already mentioned that he had the intake
    gaskets replaced a year ago, and that there was no change in the
    rough idle condition, although that doesn't mean that it was done
    (job is pretty gravy, so I can't imagine how one might screw it
    Hmmm. copying Mercedes?
    Neil Nelson, Jan 31, 2004
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