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Thread: 94 Buick RoadMaster Estate Wagon LT 1 issues

  1. #46
    Fuel Injected! vilefly's Avatar
    Join Date
    Sep 2017
    For now, it's just me and one other guy at the shop, and we are trying to keep up with demand. Basically, it's full-on resurrection season in the fall season, and's fall. My boss is the other set of brains for the shop, and he has been away from the shop trying to fix sell his deceased father's house. Not sure if he'll ever get it done, being a perfectionist and all. I have lots of people dropping off cars as if we have a layaway plan or something. I get it done, they take forever to pay for it or pick it up. I could take a look at it, but I cannot dedicate myself to it completely. I tend to put these kind of "somebody else's diagnostic failure" cars in a rotation pattern in between the straight up "turnkey" vehicles which pay the bills. I try to get the straight jobs done in a decent amount of time, then I allow some diagnostic time for the mystery vehicle in between jobs. So, promising a solution to a mystery problem in a certain scheduled time and date won't happen. It contains too many variables at this time.

    We are located in south kansas city, mo. Not sure if you are hundreds of miles away or not.

    Here's one thing I never heard throughout this discussion. Has the computer's powers and grounds been checked out electrically, under load conditions, at the computer connector? Does this guy have access to schematics, and know how to test for these things?

    As to the changing of the entire harness to fix one wire.....the answer is NO. Don't do it. Not worth the new problems you will the other hole in your wallet.

    Granted, you still claim to have a low vacuum reading, which still indicates a mechanical problem, but I am starting to wonder about the mechanic in question.
    Last edited by vilefly; 2 Weeks Ago at 05:23 AM.

  2. #47
    Fuel Injected!
    Join Date
    Jun 2019
    Today I stopped by the shop to see progress. He had the manifold off and soaking in cleaner. We looked at the gaskets. These are thin steel with something between. Very smooth. There was a slight sign of maybe leaking on two adjcent ports. Just a slight discoloration. Otherwise they looked ok. You could see the intake surface machine pattern but not really feel it. The chins wall sealer simply fell off with some leakage ther. Otherwise the motor looked pretty clean inside. The head ports looked ok even with flashlight shining not much carbon. We looked at the throttle body where the IAC is and you could see the entrance to what must be the IAC spider. They are not very big but there was some carbon build up. He said he would clean that up on assembly.

    I sure hope this fixes it .....but I have my doubts.

    So maybe that’s the issue. Hopefully he will have it done Monday. He is very busy with winters prep things on cars.

  3. #48
    Fuel Injected! vilefly's Avatar
    Join Date
    Sep 2017
    Hook up a vacuum gauge when you are done to see if it returned to normal (18-20" of Hg).

    Had a 94 firebird come in with the opposite symptom yours had. It kept adjusting lean in closed loop on one side until it started missing out, because the BAD o2 sensor stayed stuck at .56V, and it RELENTLESSLY believed the o2 sensor without setting any code for it. Replaced the sensor, and cured it. I seriously wonder about your O2 sensor wiring, but we still had a bad vacuum reading, which trumps the electrical with a physical problem. A shorted-to-ground O2 sensor harness may be your other problem. There should be a .45V reference sent from the computer to the O2 sensor's output signal. Unplug the O2 sensor and look for that exact voltage +/- .05V. If it is out of range, begin the hunt for a bad ground or short to ground or open circuit.

    The latest beta version of EEHACK 4.8.2 lets you reset the fuel trims, which is a great tool for finding the truth about O2 sensors. Reset, and see if it smoothes out.
    Last edited by vilefly; 1 Week Ago at 07:36 PM.

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