First off I want to apologize if I have posted this in the wrong place as I'm new to the forums here, if it needs moved to a more appropriate place feel free to move it. Second, both "I'm sorry" and "thank you" for reading this entire post as it'* a bit long and complicating! I am still a novice when it comes to cars so I will be as detailed as I can while I explain my problem.
I have a 1989 Buick Electra (Park Avenue sub-model), it came with a V6 3800 (this one to be precise), and it has 145k miles on it. Back at the beginning of October I found I had a leaking head gasket, oil had leaked all through my radiator and back to my coolant reservoir before I got it home to get fixed. The advice from my other mechanically-inclined family members was to replace the engine itself instead of the head gaskets (which by the way this is the one and only time I ever make that mistake, if this happens again I go with my gut and change the gaskets). I had the old motor replaced with one of the exact same, another V6 3800 Pre-Series that was pulled from a 1990 Buick Reatta. I looked over both engines and they are similar from top to bottom, every single plug, mount, bolt, hole, etc from what I could see is identical between the two. I bought it used, it has only 45k miles on it, and looks to be more in shape than my old one. The yard I got it from said the Reatta it used to be in was totaled from the side and that it sat on their shelf for a little over a year before I bought it. I'm inclined to believe them about the mileage on it because this engine does in fact run, it makes no obscene or out of place noise, and looks well kept.
The problem I am having right now is that we have misfires on cylinders 4 and 6, and if I change gears the car will stall unless I hold the pedal down. We have tried pulling my car'* engine codes and the only two codes we got were 12 and 34; my mechanic said 12 was not important because the engine was off when the codes were pulled and 34 is Mass Air Flow Sensor. Before replacing the Coil Pack and ICM my car would backfire and idled terribly (and my old coil pack, showing its age, straight up overheated and melted! haha), and with all these new things on it it is certainly running a lot better at idle and we've eliminated the backfiring.
This is the layout for my cylinders and coil pack. Cylinders 4 and 6 (top right corners) are the ones misfiring.
We do not know if it will be worth our while to change the Cam/Crank sensors and EGR Valve because these would not cause only two out of six cylinders to misfire. Of course the MAF Sensor wouldn't do that either, but since it pulled a code for that specifically we changed it. We're pretty much down to changing these simply because we can, because they're the only things left to change before we're completely out of ideas. What'* baffling is that we have spark, fuel pressure, and compression in all 6 cylinders and yet are still having problems with misfires. I even did research to see if we had unknowingly swapped an even-fire with an odd-fire engine because my mechanic faintly remembered there being this issue in older cars, but from what I found the odd-fire V6'* were dropped from the Buick line back in 1979, nowhere near the 3800 series of the late 80'*.
If anyone has any remaining ideas on how to fix this problem I would be grateful beyond belief, I just want Mable to run again. She was my first car and I'm not ready to let go! She'* got lots of life left!
The code for the MAF sensor has cleared since we put it in and has not come back. Now we have no codes popping up at all aside from the one we get because the car is off. As far as fuel issues we know all 6 of my fuel injectors are working properly as I have proper fuel pressure, and the fuel rail/injectors on the engine now were on my old one and my old one had no problems at all aside from its head gasket leak.
I believe part of the problem we're having with the stalling is because when we reset the codes my car is having a hard time figuring its timing out; it is all done automatically and can't be manually adjusted and now that the computer is trying to re-establish it from being wiped, it is doing so on top of the misfire problem. So for it to properly re-learn its timing we've got to sniff out the culprit for the misfire.
it takes a while to relearn idle after you disconnect the battery, that is pretty normal. so what exactly is it doing now? stalling at idle? stalling when you give it gas? and by missfire you mean running rough?
i can only think maybe something that got disturbed didnt get put back right. plugs for the icm, ckp, cam sensor, could have loose wires or something got pinched in the harness changing the engine. or a ground was corroded and isnt making proper connection now. maybe for the icm/coil pack
I have reservations about the head gasket diagnosis on the original engine, it is practically unheard of under normal and most extreme circumstances, however it doesn't help us here.
Essentially, you need to find out what is missing, properly timed ignition, fuel, or compression.
One thing I did notice right away is that cylinders 4 and 6 are directly adjacent, which has me suggesting to check the compression just so that the engine mechanicals can be ruled out. Also the magnavox ignition system (the kind you have with the single coil assembly for all 3 coils) is pretty notorious for failure, both the coil packs and ICM. Many swap to the newer variant consisting of 3 individual coils, as found on the 92-93'*.
Of course, I typed all this, and read your post over again, discovering most of this was checked. Silly me. How long was the car parked, and what do the vitals look like, such as fuel pressure psi, compression numbers, etc? what are they?
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Have to agree with rjolly87....hopefully, you didn't trade in one engine, for the same problem with another engine....head gasket problem between 4 and 6...
How do the plugs look on 4 and 6, compared to 1 and 3?
As suggested, was spark to both cylinders check with a spark tester, like an ST-125? If OK, then compression has to be checked, with all plugs out, fuel and spark disabled, and at wide open throttle...if compression is ok, then those injectors have to be checked out....rare to get two at the same time, next to each other, but could happen....tough to measure fuel flow from an injector without special tools......if ohm reading is ok on all, about 12 ohms cold, then you might have to remove the fuel rail, swap those injectors to the opposite side, and see if the misfire follows the injectors....the other possibility is a bad ECM, or the wiring between the injectors and the ECM....
Last edited by Tech II; 12-04-2014 at 01:26 PM.
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In looking at this, I wanted to also suggest checking your transmission, just to make sure there is no coolant in it. I am having a heck of a time figuring out how engine oil could possibly get in to the coolant. I was thinking the only engine oil pressure is in the valve pushrods, which sprays in to the rockers, and then runs down. Most everything it could be should put coolant in the oil, but not oil in the coolant. The exception being the transmission cooler, which would exchange coolant and transmission fluid, depending on the circumstances.
@ Tech - Spark plugs are all new, I bought 6 of them as well as a new box of wires, so without a doubt they are all working. My mechanic and I will be back at it sometime this weekend hopefully so I will get readings again on the fuel pressure, spark, etc and bring it back with me. They were all checked with gauges though I don't remember any of the numbers off the top of my head. Is ECM the same thing as Ignition Control Module? If so, I have a brand new one on the car so I'm ruling out the possibility of that being faulty at the moment.
@ rjolly - In reply to your first post, my car was not parked at all before we started working on it. I was driving it back and forth to work up until Oct 8th, and it rolled into the shop that night. It didn't run for about 5 weeks (took the first group so long to swap engines), and upon arriving at its current mechanic he had it running and moving within an hour. It'* been started almost everyday since then with the same problem; runs but misfires at idle, stalls in gear. It runs, just gives under load. As far as the transmission goes we had removed the transmission when swapping the engines out and we gave it new fluid and a new filter, the old fluid had no sign of coolant in it. I'm beginning to second-guess the diagnosis of leaky head gasket on my old engine as well because everyone else I have asked says that coolant gets into the engine, not oil getting into the coolant. I've still got my old engine and if I can't get this thing working with new injectors, I've half a mind to put my old one back in and just drive it around again until i either get a check engine light or see leakage spring up again. Whatever it was I had black sludge all through my radiator and coolant reservoir, nothing at all in my oil.