IMG_8404.jpgThanks for the add. This is my home built custom. Originally built with a baby lt1. Currently aluminum head rebuilt lt1. Ported & polished heads, t-bucket style long tube headers, CAI, 2800 stall converter, 3.73 gears, emissions, vats and ac deleted, running on a b-body harness. Base tune was for a 4.3 so far reset flags, cyl. volume for the 5.7 and speedo calibration. I would like to get a bit more in-depth with this. Every aspect of this car was home built so I would like to tune it on my own also. Since the motor swap I have had an idle stall at closed loop. Any tips or guidance would be greatly appreciated.
Thanks. So I've got a 16188051 ECM from a 1995 Caprice with a 4.3 ( the vin stored matches a 95 b-body with a 4.3).The bin is 16209421. Which seem weird because on Eehack that bin is listed for a 94 F-body. I've reset the flags, cyl. volume for the 5.7, cooling fans, and Speedo. I was originally going to start with a F-body bin. I liked the idea of a perf. Shift button but wasn't sure what issues I would run into. I'm running a modified b-body harness. With 2 1995 caprice know sensor and a 95 4l60e. Any guidance would be greatly appreciated��
Most of my learning has been on OBDII stuff. There are several people here that have extensive experience with the OBDI platforms.
At idle, when it tries to die, what do your oxygen sensors tell you. Are they going lean, or rich? Lean will point you towards a probable vacuum leak, rich could be extra fuel coming from the EVAP system, or a fuel injector/regulator issue. Would deal with your known issues first before trying to massage a couple extra ponies out of your engine.
Good luck
Definitely makes sense. My initial thoughts bring me to the fact that I didn't have this issue when I had the 4.3 baby lt1 in the car. It ran well. I had rebuilt a5.7 Lt1 and threw that in same sensor, intake, throttle body. Drove pretty good except in CL at idle the RPM's were hunting and it will eventually stall. I had a big car show coming up so I left it alone( it was in the 2023 Hotwheels Legends Tour chosen as 1 of 10 Global Semi Finalist). So I left it alone. It was running with the 4.3 bin. So I assumed that could have been the issue or I also read about the long tubes causing o2 issues(which I have not adjusted for yet). Although I adjusted cyl. Volume for the 5.7. Theirs probably more involved. I think my next move will be trying to use a closer bin from a 5.7 and adjusting for long tubes. Then proceed with some diag if it's still present. Would you have any knowledge of weather a F-body bin would be a problem with my current knock sensor setup or anything else? Thanks for your help.
Awsome thanks for your time and help! I've been on Eehack that's what let me hear. I'm gonna do a bit more reading and research. Then dive right in starting with fixing the idle hunting and stall at CL. If I have any questions I'll post something on the GM EFI forum or possibly try to reach out to Steve. Thanks again!!!
I think you are on the right track with the long tube headers. You might try increasing the response time to even 3 times the normal amount to give time for the adjustment to register at the oxygen sensor. You also might try adjusting the "steps" that the adjustment makes to have it make smaller steps in that way it won't over adjust and then over adjust the other way, if that makes sense.
Reply With Quote
Bookmarks