I've been tuning my 746 ecu for a while now and suddenly it has gotten in the 90's here in Memphis. All my BLM's have dropped from where I had them in the afternoon when it's hot out. I see the IAT temp is much higher than in the morning. I tried changing the IAT vs. BPW multiplier and it believe it helped the BLM issue, but now I noticed the AE feels sluggish like it's not getting leaned out vs. IAT.
How does the IAT effect things in code?

 

Sounds like you pay attention to details

The IAT correction in the '746 has pretty limited adjustment but as you found out does have an effect. The problem that you have noticed is that the AE routines don't use the BPC to calculate how much fuel to inject....so the IAT BPC modifier isn't going to effect your pump shot. Your AE is pretty much a set amount of time the injectors are open regardless of what other settings such as your VE and BPC are set to. This is pretty evident when some one slaps on huge injectors and just changes the BPC to compensate. Your pump shot is going to be off by a mile.

What to do....this is a tuff one. Probably your best bet is to have your pump shot set on the lean side for cooler weather so that when it warms up you're not going to have an overly rich pump shot. This may be a good case for having a summer and winter chip. You've stumbled into one of the limits of the stock code, there really isn't a correct way to fix this, just have to make the best of what you got.

 

Thanks for the response BmMonteSS.
I was hoping that wasn't the case, but this is an early computer. It sounds like making a summer and winter chip is what i will need. I might be putting one of our XFI units on soon anyways with the new motor.

 

Wow, been forever since I posted here.