Hey there everyone, Ive got an issue with my 89' sr5 pickup. I recently bought the truck and did an engine swap in it (3.0 v6). Every time i go to start it up, the engine will run at about 500 rpms, and if i try to give it any gas it will die. If I let it warm up a bit the idle will drop even lower (about 400 or 350) at this point the engine starts to run a bit rough, but will respond to the gas pedal, sometimes after I rev it up a bit it will go to the normal idle speed (850ish) for a few seconds, then go back down to about 400 again. Also if I rev it the check engine light comes on...
I'm guessing the problem is something electrical (bad sensors maybe?) but I have no clue as I have no experience with these engines... Anybody have any suggestions as to what the problem could be?
Thanks,
Alex

 

P.S.
I forgot to mention that occasionally the engine will bump up to a higher idle speed on its own, then decreases again after about 30 seconds

 

First things first- get the engine warmed up and adjust the timing and idle speed properly so that the engine does warm starts as if nothing is wrong. After that, if any problems remain with cold starts, troubleshoot those issues.


Also, since you said it's lighting the CEL, knowing the code(s) would help as well.


Otherwise, top-of-the-head thing would be check for vacuum leaks.

 

Could try checking out the tps. Mine was out of spec at closed throttle but the other tests were fine. Had crappy idle and throttle response. Swapped it out with a good one and idle is rock solid at 800. Throttle response is back to normal. Makes driving the truck nice again.

 

+1 Start with timing. Make sure you follow fsm procedures or you will not set the timing correctly. You will need a small piece of wire or paper clip to perform this task.