Okay, a few of you guys have seen previous posts where I was explaining the notorious SBCMSS. (small block chevy motor swap syndrome) It's the one where you remove the 5.0 and put in the 5.7 and you get crappy idle and surging...all that good stuff. I have taken some suggestions to heart. I asked if maybe the sensors from a 91 caprice would work and someone said no. Not unless I replace the 8746 ECM with the 6965 ECM. After replacing the ECM I could then use all the sensors that work in accordance or else I would have to find a chevy with a 5.7 TBI that had a 8746 ECM and use those sensors. For future reference to all those out there that are like me, If you are going to do an 5.0 to 5.7 TBI swap, the best car to use is a 1990 Caprice for all your sensor needs. It has a 8746 ECM just like the 91 camaro and any other years that have the 8746 ECM. It is equipped with a 5.7 TBI (actually it is equipped with a 5.7HP TBI)
Someone said my surging problems are probably due to the ESC module being made to handle the demands of a 5.0 not a 5.7. so I used the ESC from a 90 caprice. still a little rough but, not as bad. Also the TPS from a 90 caprice has a different connector harness. so I used the TPS from the 91 caprice (the one with the 6965 ECM) Again, things are clearing up for me. Unfortunately, I can't find a listing for a knock sensor for the 90 caprice so I may again revert back to the 91.

The point of this post is to try and help anyone who has the notorious SBCMSS in their car. this is a start for you. I plan to put up a detailed list of sensors I used so that hopefully noone will ever have to troubleshoot this much again. they can come, check out the list, know what they need to buy and permanently cure their car of SBCMSS.

Someone told me I may have to mess with my PROM chip even if I get through the surging and crappy idle to help tighten things up. If this is true I will find it and try to give a guideline on where to adjust the curves. of course each car differs due to individual mods but, I figure posting my config should at least give others a jump start in the right direction.

I'd would once again like to thank all those that helped. especially pablo and shifty capone. Thanx Guys. your info is treasured. Because of them telling me what to aim for, I no longer have to hold my gas pedal to get my car started. (which was one of the symptoms outside of crappy idle and surging) That went away with the TPS swap and idle is smoother with the ESC swap. I'll replace the knock sensor and see what kind of justice that brings and post the results here.

 

your remaining problems are probably entirely in the tuning of the ecm. The stock calibration will pretty much be way off for even the mildest 350 setups. I had alot of trouble with the idle. The stock idle speed is 550 rpms, which is mad slow. My engine would lope really bad when the ecm would begin to close the IAC after cold start. Alot of problems where remedied by just moving the stock idle speed up, resetting the min air setting, and leaning out the mixture at idle. Replacing the sensors wont do much good, unless your trying to use the 305 knock sensor and module, in which case replacing them would be a good idea. Id get the bin from one of the 9C1 cop cars and use that as a start for tuning. I havnt tried it yet since it wont work with my ecm but i imagine it will probably get you closer to where you want to be initially.