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I found the restriction in the cylinder leak down tester was in the quick connects I will see if there is a way to work that out maybe a better quality quick connect I let you know.
Well to answer my on question yes if you disconnect the ICM B wire it will run at base timing. I had painted a line on the harmonic balancer and observed when #1 was at TDC when doing the cylinder leak down test and by the use of a timing light I could see the mark move as I connected and disconnected the wire. I also got a buick/ GM specific code p1352 that meaning the pcm knew the bypass circuit was open. Now why did I do this you ask. I wanted to see if the timing was the cause of the misfire. Rather it was advancing it too far or not. Result was it still misfired even with the timing advance pull out out. So still at square one. Any help offered is very appreciated.
I dont have a real way to test them but I removed the cover and checked for maybe a broken valve spring everything looked good. Then I tried useing a small crow bar to lift the rocker and push the valve down just to feel how much it took to move the valves while at TDC on each of the cylinders on that side they all take a gut load to move them even a little. I know that'* not a proper way to test them but it'* the best I could figure out. With out a proper tool.
I then changed the oil and filter because it was near that time. Cleard the codes and drove it it ran fine again for a day or so then started missing again while I was at a stop light today finally threw the code after the next red light. I would think if it were a week valve spring it would be more likely to miss at higher RPMS it only misses at idle between 650 up to around 1000 RPMS when it is missing. Once you rev it up a little it runs fine. Let it idle for a moment it starts to miss again. Runs great up top plenty of power no miss have ran it up to around 80 mph with no issues.
The misfire had gotten worse so I rechecked a few things found the #1 injector o ring had a leak on the intake side pulled the fuel rail put another new set of of o-rings on all the injectors cleaned the holes the set in put a dab of dielectric grease on all the o-rings and reinstalled the fuel rail it is much better now but still misfires on #1 when stopped at a red light about ever 3 or 4 seconds.
I made up a rig to test back pressure put it in the upper o2 hole revved it to 3000 RPM only had around of 1 psi back pressure show on a 0 to 30 psi gauge. So back were I started.
I know you have done this many times but in view of it running somewhat better, if you cleared the code would it immediately come back? Also I would like to say that I admire your hard work and dedication in trying to solve this issue. It has been a fantastic job of testing and quite educational for all involved.
