Hey guys,
I posted this in another part of the forum, and after I used my brain a little, I realized it should be posted here. I did a little searching and did not find a clear answer to my problems/concerns.
I recently blew the 302 out of my 1991 F-150. I picked up a 302HO out of a 1991 Mustang for next to nothing. Checked main and rod bearings, replaced oil pump, timing chain, and harmonic balancer. Everything looked good.
Installed the engine, reusing all my other parts.
Problem is, engine will not idle now. From a cold start, it will fire right up and idle at around 1500RPM. Once it begins to warm up, the RPMs drop to around 600 and stays running. Once I shift it into gear, it dies. If I fire it up with no throttle it will die immediately, or surge a few times, then die. After a few startup attempts, it will surge, then begine to idle remotely smooth at about 500-600RPM. However, everytime I shift into gear, it dies. It dies when I come to stoplights, stop signs, etc...
Also, when letting it idle for about 30 seconds or so (at a stop light) it hesitates when giving it gas, then its fine.
When I unplug the IAC there is no change in idle.
Does this sound like a computer problem with the new setup?
Or could something else coincidently have gone bad at the same time (EGR, IAC, etc...).
Any input will be greatly appreciated.
Thanks,
Dan

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what did you set the timing at .My buddies mustang had the same problem adjusted the tps and it cleared up

 

Timing is set right at 10deg BTC.
Have not touched the TPS yet. How do I go about adjusting it?
How about the IAC motor. Is carb cleaner or brake cleaner okay to use when cleaning it?
Other than that, I am completely out of ideas.

 

go up to the 87-95 truck forum and do a search on how to set the tps they are very helpful on that forum I would bum the timing up to 12-14 deg

 

did you use the f150 wiring harness or did you get the harness and ecu from the mustang? they are diferent, and your engine wont run right if you use the truck 5.0 harness with the 5.0 HO engine and vise versa. Just food for thought.

 

still using the truck ecu and harness.

 

I would try to find the fuel injection harness from a 5.0 HO and try that on your engine, There are some different threads on this swap, you might want to look them up and compare notes. but your stock harness is probably starving the HO for fuel.

 

two things here replace the comp and the harness with the stangs.
You could "limp" the truck with swapping the h.o's firing order to regular 5.0 firing order but doubt that will work, it did on mine for a while but expect a little blow by from wrong firing.
You may also get away with using the stock harness and the h.o comp if you repin a few leads on the trucks harness, as i did but found the info at www.coolcats.com.

 

your problem is definately the ecu---you must use one for the mustang all the parameters are different.I did this swap for my buddies dad a couple weeks ago.