Swap Gone Wrong
 

95 GMC Jimmy: Swapped to a 305 throttle body out of a 1991 Pontiac Firebird and put a 1995 350 5.7l Tahoe PCM because it was a throttle body as well and a had a 4l60e in it. Starts great, idle is a little lopey but it has an RV cam in it. If you rev beyond 3 grand it loses its mind and blows the charging circuit and the gauges go nuts it will continue to run until the battery gives up. Any ideas or advice would be greatly appreciated. Thank you.

why didn't you use a 5.0L PCM from a '95 era truck?

when you mention "If you rev beyond 3 grand it loses its mind and blows the charging circuit and the gauges go nuts it will continue to run until the battery gives up." does the engine rev out of control, or does it just blow the main fuse and not charge anymore? if it is driveable after that happens, do the gauges still work properly, or do they crap out as well?


sure sounds like it's all related to having the wrong computer in there, but i didn't do the electrical, so i can't say if it's all correct or not.

I concur with old skool. Did you try to get the PCM tuned to the 5.0 or did you just hook it up and hope for the best?

Unsure of what model carried a throttle body and a 305 any suggestions there would also be great. In response to your question yes the whole dash cluster goes dead.

Unfortunately I don't have the money or know where or who will tune a PCM. So yes in response to your question I did unfortunately hope for the best. I'm basically just a half way educated, mechanically inclined (due to the failure and repair of my own junk), hilljack 25 yr old.. so more often than not I just hope for the best.

Sorry to hear things didn't go smooth. Around here a couple people have just taken their ECMs to a dealer to get 'em re-calibrated. I don't think it cost that much and it was done pretty quick. Hope this helps and good luck.