AdamSaint

ok i have a '90 C1500 automatic and the engine was (shot) so i got found a '92 ck1500 with a standard and did an engine swap. i assumed the engines were the same but maybe i was wrong. ever since i dropped it in its been running rough. at idle it idles down low then it sounds like it revs up some then does it again that only happens in park not in gear or neutral. when driving it runs fine except at a certain rpm it sounds like its missing. i cant figure out the reason. any help or suggestions will be appreciated.

mudmaniac

Did you re-use most of the bolt on stuff like the throttle body and distributor, or are they from the donor truck?

Speedy650

timing?

AdamSaint

the distributor was reused from the original engine but not the carb. tried swapping the distributor and carb with no change. timing is correct (i think).

more info: the problem with missing only happens when it warms up

mudmaniac

That would tell me it is an issue with the electronics, it will run open loop untill the truck warms up.

AdamSaint

i had hoped it wasnt an electronic problem because i dont think i can fix it

could it be a single broken sensor?

mudmaniac

I had a similar problem that was caused by a faulty connector on the temp sensor located at the manifold gooseneck. Mine would cause the SES light to come on.

AdamSaint

yeah i smashed the exhaust temp sensor when stabbing the engine in and the ses light is on but i wanted another opinion before paying for a new one. ill replace it and see if it helps.

mudmaniac

That should take care of the problem.

f-bodyfreak

iv done lots of swaps and iv seen many times that the ecm from the doner car should be used most of all when dealing with diffrent years