I've tried searching, but couldn't find a definitive answer. I'm having a problem with my car running really rich at idle. The cam is a 236/236 .555/.555 112lsa and I had Herter write up the program.
The car seemed to be fine with the stock TB on it, but now with a BBK 58 it runs rich at idle.

Now my question is, if I want to lock the BLMs to prevent it from running rich at idle would I just open the program and adjust the Max BLM to 128? Currently the Min BLM is 108 and the Max is 160.

i also read on LJ's website that you can close the TB a little more, and have the IAC open up some which helps, has anyone done this? I've mostly just read about people adjusting the BLMs.

Thanks for any help!

 

You may need to open the throttle plates more. I had to do that when I put the BBK 58mm on my Impala SS.

 

What I got from reading LJ's page was that when the problems of split BLMs and a rich idle arise, you'd want to close the TB's to make the IAC work more. By getting the IAC to open up more it uses the already atomized "rich air" rather than bringing in "fresh air" which would only perpetuate the problem....
Am I off by thinking of it like this?

 

Do you know what your IAC counts are? If your IAC is maxed out and it's not able to get enough air, the idle mixture will get uncontrollably rich.

 

My IAC's are low, no where near the 160 limit... I think they are usually around 30 or so at idle.

 

What are your idle BLMs? Are they bottomed out at 108?

 

They sometimes will duck down to there. At one point my long term trim was at 160 on the left bank and 108 on the right! I was thinking it maybe that an O2 is bad, but they seem to fluctuate normally. I was thinking about switching the O2s around and scanning it to see it the right bank is running the higher BLM. If that's the case a pair of O2 should solve this problem.

EDIT: For what it's worth, at the end of my datalog session the car was idling with LT trims @ 160 and 145. The ST Trims where @141 and 132 respectively.

 

Ok, thanks for the clarification. In addition to swapping the O2s, I would check for a vacuum leak, exhaust leak, or an injector problem.

 

Ok, thanks man!

 

UPDATE:
Well Vince, I finally got to swap the 02s and datalog the car. At idle the LT Trim has switched banks. It was 160/108 and is now 108/160. So I going to replace the 02s and try again... lol I don't expect the 02s to fix everything, but I think they should be able to help a little bit.