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Thread: 3.3 Century Often rough starting & initial idle, don't know what to check next

  1. #1

    Default 3.3 Century Often rough starting & initial idle, don't know what to check next

    Hi any suggestions would be welcomed:

    My 92 Buick Century 3.3 V6 103K, symptoms:
    Just inherited from my father. Engine was missing under certain loads so replaced plugs and plug wires and that resolved the problem.
    Other problem: Starting often requires the accelerator pressed down like an inch to "clear" the engine out a bit just till a solid idle is obtained.
    Otherwise if started without touching the gas pedal, seems half the time either the engine will start and idle just fine OR will not start without excessive cranking where it will almost start or start and idle very rough and low and die or then rpms will pick up and there will be a bit of smoke out the exhaust like the engine flooded a bit.. Doesn't seem to matter if the engine is cold or hot..

    Also several weeks ago the check engine light came on and then off a few times during coasting, once while just coming to a stop. Checked for codes, the fan came on and gave error code 26 "quad driver".
    Could not find more detail about the code but some suggest lock up torque converter.. Cleared the code and the light has not come on since..yet.

    The 3 speed auto's lock up torque converter seems to work great, I can barely perceive it, the trans works great for its age.
    Suspected injectors were leaking gas upon shut off so replaced them with some refurbished exact oem ones on eBay. Starting problem the same.

    Looked for the EGR valve to clean but the net seems to say there is none for 92 and I couldn't find it.
    Removed and cleaned the idle air control valve seemed to be not that carboned. Previously spray cleaned Ma's/map sensor.
    Starting problem has not been resolved.
    Don't know where to go next...
    Maybe the expensive throttle position sensor has some dead spots...?



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  3. #3
    Senior Member CorvairGeek's Avatar
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    The Buick 3300 is an oddity of simplicity and modern performance of 1992 standards. Even though there are parts 'book' references to it having EGR and a MAP sensor, they are incorrect. It does have a Mass Air Flow (MAF) sensor.
    Jerry

  4. #4
    Senior Member 85_Ciera_Rebuild's Avatar
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    I would suggest turning ignition switch to on...listen for fuel pump, then crank engine.

  5. #5

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    Thank you for your replies I still have the problem. I think I hear the fuel pump and it seems definite that the engine floods a bit because the exhaust smells very gasoline and the engine sputters and idles too low and needs the gas pedal pressed to clear it out when it starts roughly with a low idle.

    Because this starting problem can be completely avoided by pressing the gas pedal down about a quarter of an inch while starting, I assumed perhaps the tps sensor had a dead spot.
    So I replaced the throttle position sensor using these instructions from another poster https://www.a-body.net/forums/showth...sor+adjustment.
    However this did not make any difference. I rechecked the trouble codes since I cleared code 26 a month ago and I now only get code 12 no problems.

    Is it just the idle air control that raises the idle on this engine? I previously removed and cleaned the iac but there was no difference. Perhaps the iac is bad if it is the only thing that increases the idle for cold start because this intermittent problem seems to definitely have a too low idle perhaps is the cause of this all although I would have thought cleaning it would have made a difference. The engine seems to idle fine otherwise...
    Thank you for any help.

  6. #6
    Senior Member 85_Ciera_Rebuild's Avatar
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    Quote Originally Posted by Jimtmcdaniels View Post
    Because this starting problem can be completely avoided by pressing the gas pedal down about a quarter of an inch while starting.
    Engine Coolant Temperature Sensor (the one that connects to ECM) fails by suggesting engine is colder than it actually is...as such, more fuel is added to compensate for a perceived colder engine temperature.

    Older EFI vehicles tended to have two coolant temperatures...one for instrument panel, and one for ECM

  7. #7
    Senior Member Keiths1976's Avatar
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    Have you checked the ohm resistance of the ignition coils ? Any off balance would throw a wrench or a bad ignition control module . As 85 Ciera said the CTS ( coolant temperature sensor) does play tons of havoc on start up ,gm used that sensor as a main key function based off the temp of the coolant then will adjust the fuel/ air . I fixed many of them on my own gm car and friends a simple quick check is a ohm meter to get the resistance value of it on a cold engine . Look up the conversion on google ohm - Celsius to F see what the temp states as roughly the temp outside . Or just change it it’s 15 bucks not a bad price . Being a 92 a lot of stuff will have to be changed as maintainance . Hope it helps Keith

  8. #8

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    Ok I did get the engine light coming on and off again and got the code 26 again which besides the TCC can be "poor drivability due to 100% evap purge".. So I checked the purge valve operation using a 9volt battery and it seems to open and close just fine...I then also sprayed some wd40 into it in case it might be sticking.. is there any other cause besides the purge valve for "poor drivability due to 100% purge" does anyone know?

    Ok just saw your posts thanks I will check or replace the ecm temp sensor would explain too rich start up and will check the coil packs as well.

  9. #9
    Senior Member
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    Tell tale sign of a bad or weak coolant temp sensor is black smoke or raw gas smell at cold startup. A bad sensor will drive your car nuts on a cold startup. Once warm those symptoms disappear. It was a common problem.

  10. #10
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    Besides the possibility of a failed CTS, it would be wise to ohm the injectors. There could be one or two taking a dump.


    I thought the "quad driver" code was for the injector circuit in the ECM?

  11. #11
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    I had a quad driver code on my 92 Trans Sport van once. A bunch of things weren't working. If I remember right, according to the wiring, there was a path through the ignition switch that failed, one of the things it powered was the quad driver. Replacing the switch fixed it.
    1989 Celebrity CL 4 door, 3.1 MPFI, 4 speed auto, summer daily driver
    1989 Cutlass Cruiser wagon, 3.1 MPFI, 4 speed auto, special summer ride
    1996 Cherokee XJ 4 door, 4.0, 5 speed, winter daily driver & towing vehicle
    1991 Tracker 2 door, 1.6, 5 speed, needs work
    Previously several Celebritys, 6000s, & 2 U-vans

  12. #12
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    Other than coolant temp sensor......Sometimes when a fuel injected engine runs rough on startup, especially after sitting overnight it could be a sign that an injector or injectors are bleeding down overnight and flooding the cylinders out. Hence the hard start in the morning. Pull the plugs in the morning and see if they are wet. Bad fuel pressure regulator too can cause this if it's leaking.

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