Afr

[Lextreme II]

What is the optimal AFR for cruising and WOT on a FI 1UZFE? Right now my AFR is about 13.2 to 15 and certain area of the map will dip into the mid 12s. At WOT its about 11.8. What is your take on that.

 

[cribbj]

David, FWIW, I think you're close to being spot on - at least the 11.5:1 AFR at WOT is what most Supra guys run for safety's sake. You could increase the AFR a bit for cruising for economy's sake.

Only monitoring the plugs and EGT's could tell you otherwise. BTW, How much timing are you running?

Here's an excerpt from a standalone ECU manual with suggestions for initial AFR setups. Note the WOT AFR's are somewhat higher than you're running, but it all depends on how brave you are, and how much confidence you have in your setup.

 

[Lextreme II]

John,

I am only pulling back 3-4 degrees during high psi and rpm. I was pulling back 1 degree per psi but slowly reducing that. I am trying to get in the low 12s during WOT but alot of street tuning time.

 

[JustenGT8]

12.5:1 is what i aim for at WOT and what i'm currently at for 388rwkw.

Richer doesn't mean safer, just means more fuel out the tailpipe

Timing is what you need to focus on...good timing makes power and bad timing kills engines.

 

[cribbj]

Justen, I too am at 12.5 at WOT with my Supra and AEM standalone, but I wouldn't do it if I was running a piggyback like David. The OEM ECU's have a nasty way of relearning, and upsetting the piggyback's settings.