tbi swap

[67chevtbi]

I have instaled a 16197427 comp and harness on my 72 355 I have two comps one has a BJWX prom and the other is BJYL what are the diferences? One runs rich and idle's eratically and the othe is kinda lean and idles great.

[poconojoe]

I have instaled a 16197427 comp and harness on my 72 355 I have two comps one has a BJWX prom and the other is BJYL what are the diferences? One runs rich and idle's eratically and the othe is kinda lean and idles great.

The first one BJWX is from a 4.3, the second one BJYL is from a 350, both are from automatics

[67chevtbi]

thank you. Now with the bjyl but I am having a intake backfire with more than 1/4 throttle no power likes its loading up idle is also a little loopy. I jave headers and a holley tbi. I added a new coil and heated o2 but no change. Any suggestions?

[67chevtbi]

I now have a little better diagnosis. reset the computer runs well. But intermitenly my timing is retarding to 0 and causing the backfire. Cant seem to figure why? any sugestions

[dave w]

Are you using data logging software? I use DataMaster data logging software on my 1993 GMC. I might need a few more details about the tbi swap? I'm working on swapping a 16168625 ECM for my CJ Jeep Chevy 350 conversion. I am using the 16168625 ECM because it's the same ECM in my 1993 GMC. I've programmed my own chips for the 1993 GMC and CJ Jeep 350 conversion. Without knowing what modifications you have done to the Chevy 355, I might not be able to help very much?

dave w

[dimented24x7]

Sounds like it needs tuning. You can tune those with a G1 adapter + programmer from moates.net. There is also datastream and prom definition files for those for Tunerpro RT (tunerpro.net). Theyre not real hard to tune, and a scanner can be made by hand using parts from radioshack for around 10 dollars or so if you have a laptop with an older serial port.

As for which PCM is best, the 8625 is the one to have as it has better hardware. I have conversion software for all the 93-95 PCMs that can even make them directly interface with an LS1 MAF so you can use mass airflow instead of SD with TBI.