Hello All! I've been a frequent reader of the forum (especially recently), but never registered. I have a 1994 K1500 5-spd that I'm trying to finish up a 4.3 to 5.7 tbi swap on. I'm new to working on SBCs and not finding a lot of useful help here in WV.

I found the Jasper 5.7 in a 1990 Cadillac Fleetwood with 89k documented miles. Engine started and ran great in the donor. I have the 5.7 in my truck and running. Trying to button up a few things to get it running great. I'm using the 4.3 wiring harness and ECM with 5.7 sensors.

I'm currently getting a code 43 (ecm/knock sensor) and low idle. I've talked to some other people who have completed a 4.3 to 5.7 swap and they claim that the 4.3 chip can be used for the 5.7. The truck is running "ok," but I think it could be better. I ordered a Jet 29404-S chip and realized it wouldn't fit my 16197427 ECM. Jet tech support told me that I needed a chip for the 5.7 that their performance chip could piggyback on.

I'm having trouble finding the correct chip for my ECM. I figured it was time to join the forum and ask for expertise from someone who knows. Any help would be greatly appreciated.