need diagnostic experts on icp issue...

i got an issue with an 03 that i jus cant seem to figure out. im down to swapping out a wiring harness but would like to confirm diagnosis first. i did an engine swap on this truck and used the wiring harness on the engine that i got. same year and all no reason y it shouldnt work... so i get it running and wen cold it wants to do this surging high idle thing right off the bat. wen u try to rev it sounds like its got a big cam in it real choppy and not very smooth. when it warms up it idles somewhat normal and drives better and better the hotter it gets. immediately throws icp codes one is 2286 and 2287 which one is a circuit code and one is signal intermittant. watched icp voltage and it fluxuates bad wen running from .8- 4.0 volts back and forth all around. so i swapped 2 diffeent icp sensors no change.. i put the scan tool on it and watched icp volts its a steady .25 volts koeo and went out under the hood and did a wiggle test and it never moved. swapped the pigtail no change(had been changed already). i swapped another known good icp and pcm from my personal truck with the same results. only thing i think is left is the wiring harness. i thought about cuttin it open to try and find the issue. but i have another harness to swap in if need be. my question is what tests can i do to pinpoint the issue. everything seems normal untill the truck is running. i cant get volts to bounce around with koeo, which kinda throws me off on thinking its wiring related.

It sounds like the timing is changing. Is it possible the crank trigger sensor is touching and screwing up the timing.

u mean the crank sensor behind the ac compressor? i never messed with it or even gave it a thought. it reads rpm fine on the scan tool. how would that screw with the icp volts and set the codes im getting?

I would pull up a wiring diagram and make sure the icp pigtail you already replaced is wired up correctly.

I replaced an icp pigtail and got a wire crossed with another and it acted similar.


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u know thats exaxtly what im gonna do next. i know i wired it the same as it was but it was rewired before so who knows if it was right or not from the beginning

speedracer1000 said:

u know thats exaxtly what im gonna do next. i know i wired it the same as it was but it was rewired before so who knows if it was right or not from the beginning

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Exactly. Let us know if it works.


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another thing to check, pull the harness back further from where the ICP pig tail was spliced in. we had one not too long ago that got a new sensor, same issue, pulled the wiring back further and found chaffing wires about 8-10 inches back I the harness.

checked today they are wired correctly. found no bare wires anywhere niether. does anyone know wut other sensors share that 5v ref ? rest of sensors look ok on scan tool but idk

5v ref is map, baro, ebp, app, icp, egr i think. Only one im not sure of is the egr valve. Possibly throttle plate as well if it has one.

does anyone think this issue could be anything other than an electrical issue? i dont see how but maybe i need to mention the engine i installed was originally mated to a manual. and i used the wire harness and all the sensors that were on it. i personally dont think there is any difference but maybe im wrong. i dont know of anything else it could be im going to swap the harness out within the next couple days

Have you swapped in a different ipr valve? And checked the connector on it?


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i have not. someone else mentioned that too but im not sure why that would set a circuit code

swapped wiring harness today... didnt help. where to now? i cant see it being ipr valve but ive changed everything else. gonna swap ipr and see. if anyone else has any ideas throw em out there cuz im at a loss

Did you ever swap the ipr


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