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Thread: 94 Buick RoadMaster Estate Wagon LT 1 issues

  1. #76
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    There is no scanner data that would tell you an individual cylinder is rich.
    I agree. I also know from using a Snap-On scanner for many years that they do not always have correct data for a particular ecm. And the vehicle being worked on is so old Snappy has no interest in updating it.

    Whomsoever wields the answer, wields the power of one can of pop.
    It's killing me. There's more suspense here than between episodes of Breaking Bad.

  2. #77
    Fuel Injected! steveo's Avatar
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    there are four choices here since you've gone so far and run around in circles and found nothing

    #1 go back to the beginning and forget everything, redo every test that's been done and don't use any original diagnostic data. you have no idea what subsystem is causing the fault, or even what the fault is, so you'd need to determine that and diagnose things in a tree shaped flow chart, there's a reason every service manual has logical trees for workflow.
    #2 cut your losses and go buy a wrecked car, swap the engine, wiring, and ECM. save all the new parts you've put into the other engine.
    #3 sell the car as 'needs tune up' and it's someone elses problem or profit or whatever, use that money to buy something that's already running and more reliable
    #4 hire a real mechanic to find the problem

    these are in order of hardest to easiest, but what they will cost you depends both on your negotiating skills and current market in your area. the lt1 is over 25 years old and despite what condition its in, it's going to require constant fiddling and tinkering.

  3. #78
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    You are absolutely right.
    I got the car back today and drove it 60 miles over various roads and uphill and down hill so I have a fresh feel for the the way it performs.

    It’s got a dead miss on the right bank. It idles rough but steady. Does not overheat or under heat. It does not like to operate in 4th under 60 mph if there is any load like a slight hill.you have to manually down shift to third. The trans seems to perform correctly in that it will downshift if you keep giving more throttle.The car feels like it wants to run but it’s being held back. Gas mileage is terrible.

    So I agree we are going to square one like a new project problem. We will test everything and take notes on a fresh note pad. I even got a new pen.

    I’m very suspicious of the OptiSpark right from the start.
    I’ve already looked at several videos on testing the Opti but what is lacking is exactly what happened. There was a misfire that got progressively worse but what was shown on the scanner was not mentioned. The tester used was a device that could vary the resistance the spark had to overcome the gap. Ok what if you closed the plug gap some amount? Does the Miss go away?
    Since this unit was replaced due to an oil leak that leaked oil into the Opti possibly this has happened again. So I want to really get into this thing.

    Question here is,, is it easier to get at the Opti by removing the radiator so you don’t have to fight tight quarters?
    Last edited by Bentwings; 11-24-2019 at 03:11 AM.

  4. #79
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by Bentwings View Post
    I’m very suspicious of the OptiSpark right from the start.
    My recommendation as it relates to the optispark is to pull it and check the trigger wheel for arc holes caused by coolant infiltration. It would take a really massive oil leak to cause a problem with the opti, but if there's coolant getting in the housing you need to first make sure your trigger wheel is intact and then fix your water pump. An arc hole in the trigger wheel could cause grossly retarded spark fire on the cylinder adjacent to the arc hole (causing a dead miss), but the rest of the cylinders would run fairly well.

    Edit: after some thought, I believe arc holes in the trigger wheel would very likely set a code. Whatever the case - considering the work involved to get at the opti, I didn't mean to suggest diagnosis by way of "throwing parts at it".

    With that said, I would strongly recommend the "start from square one" methodology mentioned by steveo. Your mechanic was either grossly mislead by telling you 3 out of 4 cylinders on one bank were "dead rich", or he was feeding you a busload of bullshit.

  5. #80
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    The tester used was a device that could vary the resistance the spark had to overcome the gap.
    I use spark testers frequently. But for your problem I believe you may need other methods. An inductive timing light can be a great tool to check for consistent spark. Connect the light using the coil wire instead of a plug wire and the light will be triggered every time spark is generated by the coil. Your eye is good enough to see any missed or doubled pulses caused by an ignition problem. If the leads are long enough you can take the light with you on a road test. Aim the bulb at a piece of paper in the car so you can watch the flashing while the misfire is occurring. If the light is blinking consistently you can then move the inductive lead to a plug wire and drive. Check each plug wire one at a time. If the light flashes for every wire you should discount ignition and move to fuel or compression. If the light doesn't work correctly at one cylinder you should check wire integrity and plug condition then suspect the opti.

  6. #81
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    Measurements to take:
    1) cylinder leakage test (not a compression test)
    2) vacuum reading at idle (does it fluctuate too?)
    3) results of spark output test per plug wire (also test ignition coil separately)
    4) exhaust backpressure test per side (in PSI)
    5) fuel pressure KOEO and KOER (does it bleed down?)

    get lisle #20700
    Attachment 14841

    get backpressure tester
    HTB1A3vyHf1TBuNjy0Fjq6yjyXXaF.jpg
    And......remove nothing except the spark plugs and o2 sensors to do the tests. Be efficient.
    Last edited by vilefly; 11-24-2019 at 06:05 PM. Reason: tweaking the display

  7. #82
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    I really appreciate the help here.

    There is a new water pump that was installed when the new Opti was installed. Yes there was a huge oil leak in the Opti because of a bad seal. I didn’t actually see it however. Looks like a gasket set is in order at least. We’ll get to the Opti as testing progresses.

    My son has an adjustable spark tester as well as a leak down tester he uses on the funny car. So we can do those tests we’ll have to get the car on his hoist so we can mark the damper or at least measure it and I’ll get a tape. I don’t have a back pressure tester but I think a very low pressure gage could be fitted toe exhaust pipes. Jut drill for 1/8 npt and carefully tap. Easy to plug afterwards.

    I’m concerned with intermittent spark. So some way to check that. There’s about one spark per second (check my math) so it’s possible to see a misfire at idle if you watch the sparks carefully. You could get with a timing light if you can guarantee the pickup.
    My son has fuel pressure tester kit. So we can do that.

    Some of the other tests are going to be a bit more involved but we’ll try our best to to run each one and document results.
    I know this is going to be a tedious process but I want this car fixed, once and for all.

    I’m just getting ready to run the car out to my son’s shop.We’ll try a few basic tests today. He may want to do a preliminary road test to get a feel of the issue beyond my description.
    Byron

  8. #83
    Fuel Injected! vilefly's Avatar
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    The o2 sensor threads are 18mm x 1.50mm pitch. Find a bolt, drill a hole in it, npt tap, install brass nipple....done. Tool for life.

  9. #84
    Fuel Injected! steveo's Avatar
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    It’s got a dead miss on the right bank.
    woah there.... back up. how did you determine it was a miss simply while driving? what does a miss feel like? and then how did you determine what bank was missing?

    do one test at a time in logical order, you're already completely polluting your diagnostic process by assuming you know what's going on or where the problem might be located it. you've already whizzed right past the cause several times.

    i'm not convinced its a miss. convince me.

    maybe through convincing me you'll realize some things you need to check

  10. #85
    Fuel Injected! steveo's Avatar
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    also you have eehack, right? where are the logs? show us a log of where it's acting up and we'll rule out a lot of stuff for you.

  11. #86
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    yesterday I drove the car out to me son’s shop. It’s 65 miles mostly freeway. I was able to run solid 70-75 mph excep a few miles at 55-60. I used cruise control for the first time as an experiment to see how it handled the lack of power. You could feel a shudder on the level and when it required power to go up hills. Sometimes down shifting to direct. It took a lot of throttle to maintain speed. About a mile from the shop the check engine light cane on.

    We let the car cool off before checking it over.

    Drove it into the shop with a heavy miss. The car was shaking and very smelly exhaust from the right side.

    We decided to just look over the motor for errors.
    Found EGR vac line disconnected.
    Fuel pressure regulator disconnected.
    MAP sensor gasket mangled and leaking.
    The three vac lines that run from the manifold right side to a connector block have cracked and leaking connectors.
    Three wire harnesses were not routed correctly so we fixed that . Not a performance issue.
    The O2 and spark testers were loaned out, they will be back today. Then test each separately.
    Cyl 2 and 4 are weak. We’ll test the injectors tonight of tomorrow. The
    Vacuum tested at 16 inches at idle. Rock steady.
    The Optima yellow top is going to be gone. It’s weak.

    I admit to not having a lot of experience with this system. That’s why I’m here. I've already learned a lot from y’all and I appreciate the help.
    As far as scans I’m new to that too since I haven’t had the car for over 6 months. We spent a good part OF the afternoon going over EEHACK. My grandson who is a mechanic and body man grasped it pretty quickly. Once we get these basics fixed we’ll create some usable scans. I have a neat memory stick that works on my iPad plus a dedicated one for thr buick and EEHACK and it’s computer. I’ll post them as we get them. It may be the week end before I get out there as I have doc appointments this week. I have one shortly so I must go now

  12. #87
    Fuel Injected! steveo's Avatar
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    Cyl 2 and 4 are weak.
    if cylinder 2 and 4 were truly weak, why no fluctuation in vacuum? how are you testing them as 'weak', by pulling plug leads off?

    Fuel pressure regulator disconnected.
    MAP sensor gasket mangled and leaking.
    yeah that vac line to the regular does needs to be connected, and vacuum leaks are bad

    The three vac lines that run from the manifold right side to a connector block have cracked and leaking connectors.
    you have lots of vacuum line issues and the visual inspection might have missed something. disconnect everything that's connected to the intake manifold and test each item for vacuum holding (mityvac or similar). if you don't have that, disconnect everything from the intake manifold and cap them off securely. you only need fuel pressure regulator and pcv but you could leave the pcv hanging temporarily, it wont hurt anything.

    About a mile from the shop the check engine light cane on.
    what's the error code

  13. #88
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    #2,4 were shown weak on the test using EEHACK. Interesting that the other guy said 2,6,8 were weak with #4 not far behind.

    We haven’t pulled the plug wires off yet but will. Their spark tester should be back tonight so that will get tested soon too.
    I’ll ask also if my grandson noted the manifoldvac on EEHACK And if there was a number. I noted 10 inches earlier in my own test

    We were doing as you noted, checking every connection. Both ends where possible.

    Unfortunately I didn’t see the error code. It may have been cleared while I was doing something else. I’ll ask tonight when I call out there.
    They will continue on it while I’m gone. I asked that they record everything no matter how small.

  14. #89
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    Sorry for this simple question but I have not done this before.
    When I get ready to post scans. Can I just copy them and post them here or do I need to do something else?

  15. #90
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    Eedata files should be zipped so that they can be attached to your post.

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