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Thread: 94 Buick RoadMaster Estate Wagon LT 1 issues

  1. #46
    Fuel Injected! vilefly's Avatar
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    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 ......it'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 introduce......like 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; 10-02-2019 at 05:23 AM.

  2. #47
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    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
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    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; 10-09-2019 at 07:36 PM.

  4. #49
    Fuel Injected! vilefly's Avatar
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    Reviewing post #12......."There is low manifold vacuum. It measures in metric by the scanner and I recall about 10-11 inches by conversion. Also vacuum gage."

    I am wondering if this was a MAP sensor reading instead of a vacuum gauge reading, for they are opposites. Map sensor reading = Barometric pressure - vacuum reading. So if I assume this has been posted wrong...... baro pressure (29.89) - 10" MAP = 19.89" Hg vacuum reading. Which would be a normal vacuum reading. 10-8" Hg of MAP pressure is normal.

    The statement "also vacuum gauge" might not hold any weight. This is disturbing. I suggest you clarify.
    Last edited by vilefly; 3 Weeks Ago at 04:12 PM.

  5. #50
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    Ok so we have the right bank at max rich ness so the car barely runs. Actually runs better at speed.
    Also very low manifold vacuum. So obviously a leak somewhere causing the computer to try and compensate. However it’s already maxes out on the right bank. The O2 reads only unturned oxygen. It is showin lots of unturned oxygen, so doing it’s job.
    More air is getting into the motor and exhaust system than can be burned or combined in combustion.
    Where is this coming from? Intake air tubes are in excellent condition. No leaks around any joints ,confirmed with fluid tests . Injectors and orings have been replaced. With no effect. EGR is operating, Pvc is operating. No leaks here. Brake vacuum line is good. Exhaust manifolds seem ok, no broken bolts, joints have been cleaned .That leaves only the intake
    Gaskets. The manifold has been removed and gaskets are being installed.

    I hope this fixes the problem. I only had a brief look at the gaskets but there was no indication of blow out or “squeeze out as some indicated. The IDLE AIR spider did hav some carbon in it that has been cleaned out.

    Keep in mind that this car probably was not driven much of its life. Mostly short trips. So the chance for carbon in various places is possible. The cyl bores and intake ports were previously checked as ok.

    Well in a day or two I should get the car back and we”ll see if it is finally fixed.

    I appreciate the help and it’s caused me to investigate issues myself. IE educate me. I’ve learned a lot and if this fixes the car I’ll try and do weekly scans with my computer just to see howThe car is working.

    A side note, recent medical issue has left me with double vision up close so typing is not perfect.

  6. #51
    Fuel Injected! vilefly's Avatar
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    I was only questioning whether or not an external vacuum gauge agreed with the MAP sensor readings or not. The formula (MAP reading + Vacuum reading = Barometric pressure) should prove there were no erroneous readings.

  7. #52
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    I’m not sure he tested that way exactly. There was very low vac 10-12 In max. I’ll ask the exact number today when I call.
    There was definitely low gage reading however.

  8. #53
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    There are several vacuum lines, mostly on the passenger side of the manifold and throttle body (not only the PCV lines), that are either hard plastic or junky rubber.
    Many of these lines and connections can appear to the naked eye to be ok, yet are invisibly cracked or too stiff to hold vacuum.

    The MAP sensor's nipple itself is also notorious for being too stiff to hold a proper vacuum.
    THEY are NOT Lying to You. You are NOT Lying to Yourself. You ARE Being Lied to - BY Your Self
    The Last Psychiatrist, aka … Alone …


  9. #54
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    Thanks . As I dont

  10. #55
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    Thanks. As I don’t have a convent place to work on the car I’ll take it to my son,’s shop some 60 miles away and look it over.

  11. #56
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    First I want to thank every one that’s trying to help me. Believe me every test that has been noted has at least been considered and tested if possible. I’m starting from scratch on this EFI I’d like to think y’all have taught me enough that I can struggle through this. This car should have been an easy one to learn on. It has not. And not to give excuses, I’m coming off a mild stroke, if there is such a thing. It’s left me with double vision in one eye so my typing is very difficult. Spell check try’s to help but misses sometimes. Thanks.

    Well today he finally got the Buick back together and briefly road tested it.

    It’s got new intake gaskets and valve cover gaskets, new O2 sensors, fresh anti freez.

    I wasn’t there for this however.

    He said It started perfectly, ran a few minutes but then when he road tested it was back to the same three cyl very rich, not as bad but enough to cause the cats to ignite excess fuel and pop slightly.

    He said he scanned it and it’s ok except for the front cyl and the. back two on the psssenger side just like before.

    So tomorrow after doc visit I’m going out there with my lap top and EEHACK and try and get a scan cold and one warmed up.
    I can’t believe this as the intake was thoroughly cleaned, rodded out and blown dead dry. All seemed good.

    I need the car I’m out of time. It’s dam cold here and I just can’t drive the el Camino any more. I need the wagon space and I hoped the cold weather starting ability. My buddy has a Camaro Z28 with the same motor and nearly the same mileage and it starts effortlessly at -25 f.


    So I need more ideas.
    Is it possible to have bad valve seals/ guides? With unmetered air coming in.

    It’s obviously getting unmetered air from some place. But where?

    Any air coming in the intake is metered and fueled according to the computer program. The O2 sensor reads only oxygen, no other products. According to what I’ve gathered here and on other forms, the O2 are seeing too much oxygen I.e. lean mixture, therefore it’s asking for more fuel but the computer has a max that it will allow on that bank. So this means to me that unmetered air is getting in somewhere and causing a false indication. I’m sure there is a less wordy way of saying this.

    Now the test would be to disconnect both O2 and run pre programmed, open loop I think. Never the less with no information coming from the O2. There may be a code , I don’t know without trying.

    One other detail, I believe EEHACK a,lows you to force open loop or running without 02. It also allows clearing the fuel condition and clearing the BLM back to its default. 126 I think. Must disconnect the battery to do this. I have not done myself...no car can’t test.

    The man has been very good to me working on the car after hours and not charging except R&R of new parts.

    Again I’m out in the cold with no convent place to work on my cars. It’s 10 deg f and 20 mph winds down here on the water front.

    Byron
    Last edited by Bentwings; 5 Days Ago at 08:51 PM.

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  13. #58
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    Thanks, that is what I want to focus on. He was going to unplug the O2 sensors tonight and unhook the battery. Then hook the battery only back up in the morning.. EEHACK also allows the forced open loop.

    I’d guess the CEL will come on but I’ll know what that is. I hope there is not a “limp mode” on this Vintage.



    As a side, I went to two local auto repair shops and neither wanted anything to do with either the el Camino or the Buick. Their guys have no experience with carbs or OBD1. I even offered to operate the EEHACK for him.

    I also called two hotrod shops, one is in the process of closing the doors and not taking new work, the other didn’t do motor work, just fabrication.

  14. #59
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    @#$&%. ......I’m absolutely lost . He did exactly as noted. Unplugged both O2 sensors, disconnected the battery. Let the car sit over night. Hooked the battery up and started the car. THE SAME @#$&% PROBLEM....NO CHANGE.

    WHAT THE .......IS GOING ON.?

    I’m frustrated beyond belief.


    Can there be an ignition issue? The Opti Spark is new old stock. New wires new plugs.

    If there is an intermittent misfire, could this cause this? The mis fire would leave excess oxygen in the exhaust. However , with the O2’s not reading, why do I still have a very rich mixture? The computer has no feed back with the O2 disconnected..
    Say 700 rpm divide by two= 350 sparks per minute, divide by 8 = 43+ sparks per cylinder in one minute. So you might not feel an individual mis fire, probably not even several misses if they were not aback to back',' this might be enough to cause the motor roughness.

    It would take a ‘scope tester to see this. Now.. the guy just received the SnapOn addition to his new scanner that will allow this to be seen.
    I have to call him back shortly to see if he was able to test this. He said he would work after hours on this again. He really wants the car out of there but not until it’s right. He is even more tenacious than I am.

    Let’s do some logic,
    If the cam were flat (it’s a stock roller), the cylinders would not fill completely but in open loop the computer would inject programmed fuel causing a rich mixture. With no O2 to modify it it would stay rich. low oxygen content, Correct?
    How would the BLM affect this ? In closed loop the O2 would indicate excess oxygen because of incomplete burning of available fuel.the BLM would attempt to correct this by inrichining the mixture, but but it would be an error because there was no fuel to be burned.

    I’m probably wrong altogether and just over thinking the situation.

    JUST WANT THIS @#$&*% THING FIXED. IM about ready to replace the whole motoror just part the car out. Wirite the whole thing off as a bad deal. People lose more in depreciation the moment they drive out the door on new cars. Sadly LOL

  15. #60
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    On the right and left side disconnect all AIR pipes that comes out from the exhaust header and plug the holes on the header. It is very likely the air is sucked from there.
    It could also comes from the exhaust header egr pipe so check that one too. You need a massive amount of fresh air for the pcm to act like that.

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