Why would you need to swap the PCM? There are no electronics in the block or head. The PCM would be controlling the fuel and spark feeding the motor, and you'd be keeping the later hardware for all of that. If you're swapping in an older block and/or head but keeping the coil rail, it wouldn't run with the older PCM.
Where's Cruiser? This is about the time he usually shows up to set everyone straight.
Too right! I am gracefully bowing out. I haven't swapped a motor yet, just thought I was spotting the motor type for the OP. Exit stage left.
I did not get a misfire code, like the guy I bought the vehicle off of said he got with his tester. he may have been using a higher quality tester.
I ran a compression test and the cylinder 6 is only at 50 psi, i'f I'm not mistaken that means the rings are bad in that cylinder? All other cylinders fall in the mid to high 120s.
I also found a wire that was cut going into the pcm, its tan with white stripe and I cant for the life of me find what its for.
That is PCM connector C1. The Tan/White tracer wire is the 1/2 O2S signal wire. It looks like Bubba didn't like the California O2S system, judging by what you said about removing the two front bank O2S' and welding a piece of pipe downstream of the 3rd CAT. Bubba tried to convert it to a Federal Emissions exhaust system. Problem is, if he retained the California Emission PCM, the PCM would be looking for all 4 O2S signals. And, the rear bank (2) only pics up three cylinders, not six. What a red neck.
#6 low on compression: Try adding about a teaspoon of oil to #6 cylinder through the spark plug hole and check the compression again. If it comes up the rings may be bad. If it doesn't come up part of the piston could be blown away, or the rings are really bad.
Try a compression loss check. Apply about 80 psi to #6 cylinder with it at dead nuts at TDC compression. Listen for air escaping from the crankcase (through the oil filler cap) - bad rings or piston. Air escaping out the TB - bad intake valve. Air escaping out the exhaust - bad exhaust valve.
Quote:
Originally Posted by Trustintherust
Hello everyone its been a couple weeks, thanks for all the responses!
I did not get a misfire code, like the guy I bought the vehicle off of said he got with his tester. he may have been using a higher quality tester.
I ran a compression test and the cylinder 6 is only at 50 psi, i'f I'm not mistaken that means the rings are bad in that cylinder? All other cylinders fall in the mid to high 120s.
I also found a wire that was cut going into the pcm, its tan with white stripe and I cant for the life of me find what its for.
I forgot to add into the last post, that I add a little oil to the cylinder and the compression came up to just about 100 psi, the compression tester I was using was old and probably leaking at the the plug whole a little, was holding the rubber plug in with a screwdriver... If i trust what the guy said when he put a new head on, he said the piston, and piston wall were in good condition.
I'll try and run the other tests you mentioned to make sure I don't have other issues cause this thing got hot enough to melt the plastic right off of the stud of the housing holding the injector wires.
I'll check the part number on the pcm to see if its the California emissions one.
Again thanks a ton, this was the only problem that was kicking my butt. Hopefully I wont find any other surprises and be able to bring this thing back to life.
