TBI-TPI

Recently I changed a 1991 K11500 from 5.7 TBI to 5.7 TPI. I have the engine running but have a problem. Rolling idle (intermittent die at idle)and lack of power. I used the TBI ECU and the TBI map sensor. All the other sensors and switches are from the donor car and engine(1987 IROC Camaro. I have tried several things to get the idle to straighten out with no success. The owner of the truck states that he had the same problem with the 5.7 TBI.I am leaning toward the MAP sensor or the ECU. It appears that the timing is advancing and retarding during idle. The vehicle seems to run great on the road. Any help will be greatly appreciated.:mad1:

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Originally Posted by kevin.l.miller@cummins.co

Recently I changed a 1991 K11500 from 5.7 TBI to 5.7 TPI. I have the engine running but have a problem. Rolling idle (intermittent die at idle)and lack of power. I used the TBI ECU and the TBI map sensor. All the other sensors and switches are from the donor car and engine(1987 IROC Camaro. I have tried several things to get the idle to straighten out with no success. The owner of the truck states that he had the same problem with the 5.7 TBI.I am leaning toward the MAP sensor or the ECU. It appears that the timing is advancing and retarding during idle. The vehicle seems to run great on the road. Any help will be greatly appreciated.:mad1:

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I would have a very different plan for converting TBI to TPI, see attached .pdf. Nothing easy, quick, or low cost about my plan for successfully converting to TBI to TPI. I've done several TBI to TPI conversions using the 2nd generation TBI computer, the 93 ~ 95 TBI PCM. My experience clearly showed to me, the older 1st generation TBI computer is woefully inadequate for TPI!!!!!!!!!

Ever wonder why Edelbrock stopped offering the MPFI 3506? http://www.summitracing.com/parts/edl-3506

I think I know why!:thumbsup:

dave w

Thank you very much for the info. This is the first TBI/TPI I've done in the 40 years on mechanical work I've done.

"FYI-ONLY"

There is a link at the Third Gen site outlining the TBI to TPI re-pin process:

http://www.thirdgen.org/forums/tpi/2...d-density.html

I'm in the process right now, figure it's a lot easier to locate stock replacement TPI components rather than modifying TBI parts (that's just me).