Need advice, bad PCM, Harness or ???
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Teching In
Joined: Jun 2022
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Need advice, bad PCM, Harness or ??? Hey guys,
I posted a while back about a cam sensor issue. Its not an issue anymore, however I am still having issues. I rebuilt the engine in 01 WS6, its a 408 iron block lq4 with 823 heads and a pretty big cam 251 @50 duration .630+ lift. Now my issue is kind of unique I think, it cranks and spits out the intake once or twice and then stops spitting and begins to hit, like it about to fire. If i can get it to fire up it runs funky, and you cant get it to rev or anything. break pedal is hard, its weird. Same cam and heads and the tune was verified by a local tuner, he said it looks very good as far as the tune. the plugs were pretty nasty from all the cranking and he suggested replacements, so i did that. Everyone is stumped including me, it has a battery drain, all cyl showed 152-154 psi on compression test. Most were 152, only one was154, but with a brand new stroker kit and rings that does not surprise me. I am looking for advice on my next move. I'm chewing on buying a new harness or trying a PCM or both. I do know for sure the main harness that goes over the top of the bell housing was smashed a bit by the engine and trans going in when attempting to line up with the mounts but I didn't think anything of it at the time. Other symptom's include low oil light on (has aftermarket 7 quart pan) check gauges light is on, smokes a bit out of the pipes when it hits but i imagine its just fouling. Additionally the oil pressure gauge does not work, I assume its a bad sensor. Ill replace next time I have the intake off. it hits hard sometimes like its about to roar to life but dies immediately. Thinking maybe the crank is walking and its cutting spark or there is a bad ground somewhere and its causing the pcm to mismanage something, Any suggestions welcome, simple or not, thanks!!
I posted a while back about a cam sensor issue. Its not an issue anymore, however I am still having issues. I rebuilt the engine in 01 WS6, its a 408 iron block lq4 with 823 heads and a pretty big cam 251 @50 duration .630+ lift. Now my issue is kind of unique I think, it cranks and spits out the intake once or twice and then stops spitting and begins to hit, like it about to fire. If i can get it to fire up it runs funky, and you cant get it to rev or anything. break pedal is hard, its weird. Same cam and heads and the tune was verified by a local tuner, he said it looks very good as far as the tune. the plugs were pretty nasty from all the cranking and he suggested replacements, so i did that. Everyone is stumped including me, it has a battery drain, all cyl showed 152-154 psi on compression test. Most were 152, only one was154, but with a brand new stroker kit and rings that does not surprise me. I am looking for advice on my next move. I'm chewing on buying a new harness or trying a PCM or both. I do know for sure the main harness that goes over the top of the bell housing was smashed a bit by the engine and trans going in when attempting to line up with the mounts but I didn't think anything of it at the time. Other symptom's include low oil light on (has aftermarket 7 quart pan) check gauges light is on, smokes a bit out of the pipes when it hits but i imagine its just fouling. Additionally the oil pressure gauge does not work, I assume its a bad sensor. Ill replace next time I have the intake off. it hits hard sometimes like its about to roar to life but dies immediately. Thinking maybe the crank is walking and its cutting spark or there is a bad ground somewhere and its causing the pcm to mismanage something, Any suggestions welcome, simple or not, thanks!!
Well you said that the brake pedal is hard. ? Vacuum leak somewhere? Have you sprayed this down with carb cleaner as it's trying to run?
So do you have HP Tuners? Have you data logged anything? Where's the timing at? Are you sure the O2 sensors are on the correct side? Same with injector harness?
So do you have HP Tuners? Have you data logged anything? Where's the timing at? Are you sure the O2 sensors are on the correct side? Same with injector harness?
