Originally Posted by Trannyman95
Russ I like this idea, and am yet to try it but I have a very interesting question about this maf tuning method.... I have had HPT since ver. 1.2 when it first came out for the V6 Grand Prix guys and I have always manually edited the maf scale to fix fuel trims by driving and watching the fuels at different given areas and making adjustments until I am within a few percent of zero, since always keeping a constant zero seems near impossible with other variables outside of the car, nontheless this has worked great for me but I like your writeup and am sure it would ease tuning but here is my concern... If the front or B1 02 sensor is out of the loop and the car is run in open loop and you DONT have a wideband in place and have no idea of what the AFR is while driving, even if you set commanded afr at 14.7 and say installed a large cam, heads, and headers on the car and obviously airflow will be very far off from stock, sure the maf will show difference in the error table but how do you know this is what will put the cars fuel trims close to zero after a drive or two? What if the car is running very lean in open loop? I am not trying to complicate your great idea, I havent tried it yet and I know you install a wideband but it is not used by the pcm in any way for fuel trims. So I guess to simplify what I am trying to ask is this, How is the maf error % pasted into the maf table going to put fuel trims close to zero when the pcm cannot control fuel trims in open loop and probably wont be running the correct AFR to start with while in open loop? I know this works clearly as you have stated and I have read of other guys on other boards talking about it but I am just trying to reason with how the airflow differance on a car with incorrect afr is going to correct fuel trims. I do love the writup and next car I tune I am going to try this, and yes it will be with a wideband in place of the front 02. I still have the old serial cable and need to upgrade to the new one so I can put the WB input on my scans instead of eyeballing things sepearately. Thanks in advance!
Dave