I bought a mail order tune but noticed my engine still running rich at part throttle (ported maf). I adjusted the maf tables to lean out part throttle and successfully gained 2 mpg. Question: Did changing my maf tables affect A/F ratio at WOT?

 

Doubtful because the range you changed for part throttle should be well below what youd ever see at WOT.

 

When I changed the tables I changed the entire map at the same rate. I did notice injector duty go through the roof at WOT

 

what are you blms at?
if you leaned it out too much the computers going to add fuel at wot to make up for it.

 

the blems are right at 128.

 

If you scaled the entire maf table than yes it will affect the afr at wot. You will need to add to the pe table to compensate.

 

Thanks. Not what I wanted to hear although what I expected. Do you guys have a method for tuning WOT A/F, without dyno?

 

do you have a wide band o2 sensor?

if your going to do any tuning yourself i would get one, if you dont have one, your just guessing.

 

no wideband. Aren't they like 400 bucks still?

 

summit has them for 350 or so
yeah its exspensive, but takes the guess work out of it.

 

Put your MAF table back to stock and just lean out the part of the table you use for cruising to the extent of getting your BLM's as close to 128 as possible. Leave the rest alone.

Also, have you tried just leaning out your VE tables some and leaving the MAF all stock? Again you'd only adjust the VE tables in the ranges where you cruise. Sometimes VE adjustments work and sometimes they just don't ....depends on year and whether or not it's OBDI or II. If it's OBDI supposedly it uses the VE tables so you would see a change ...supposedly. If it's OBDII it will only use the VE tables if the MAF fails ...again, supposedly. Best way to find out is to try for yourself. For me, the VE tables don't appear to affect anything, but the MAF table does very significantly with very little change required for the effect.

 

I think changing the maf tables above 3000rpm is a good idea. But I have MADZ28 tuning and a ported maf. If I change back to stock it will still be off because the PE tables are setup for a ported maf. I don't think I saved the tune he sold me.

 

E-mail Ion, he should be able to send you a copy of the tune again.

 

hopefully. BTW does anyone know what the stock MAF tables look like? I was just looking at, what I thought was a stock bin file, and realized my values are actually lower. Shouldn't it be the other way around?

 

Lower seems to make sense to me, since you're seeing more air than you should due to the porting and stock tuning is already rich.