eolson

I've noticed now that I'm on less boost again, but had JBA shorty headers, more open H pipe, as well as 60lb injectors and a larger 2600 type Mass Air meter put in, that I'm getting worse or terrible in city gas Milage, even with a great running quality custom tune.

Even when I was on my JDM/Saleen extreme tune with a 2.85 pulley putting out 14.5lbs boost, or my other 12lb JDM tune, when I still had stock exhaust and 39lb injectors and a standard JDM Mass air meter and cold air kit, my city gas milage seemed a lot better.

Has anyone had a change for the worse in city driving milage, with the above or other changes to their set up??? I'm stumped! Thanks, Erik

danzcool

Why are you surprised your gas mileage is worse? You went from 40LB to 60LB injectors, so you can technically supply 50% more gas to you engine than before. Your exhaust is more free flowing, and your MAF is capable of correctly calculating more airflow. You've got a good tune which means you are not going lean with all that extra airflow, so of course more gas is being used.

eolson

Thanks Danzcool, that's what I was afraid of.

Why I'm frustrated, is that I was running a great JDM 12lb set up tune, but wanted to come down to a 10lb set up with a custom tune, I thought would be better in the long run for the car.

Knowing that with a Saleen Supercharger and only slightly open exhaust, a 10 lb pulley and set up with a custom tune was only going to yield 450-460rwhp, a particular shop insisted that I change out my 39lb injectors to 60lb for a lower duty cycle, as well as going with the larger mass air meter 2600 type set up, from the standard JDM (lightining) 90mm mass air set up I originally got for my set up years ago. The 90mm mass air never came close to pegging even at 500rwhp on a previous dyno run. After all this, this shop's custom tune was terrible and had cold start and other fuel table issues. I went back to a real tuner, and he wrote a very good tune, that has no issues now.

He mentioned though that he saw no reason at my current 10 psi power level to have to have 60lb injectors or the larger mass air set up. He said in fact that the larger mass air actually restricted his tuning parameters and made things more difficult to tune.

I'm actually thinking of going back to the 39lb injectors and going back to the 90mm mass air, and have an appropriate tune with efficient "easy driving" parameters dialed in for standard rpm driving. I used to get 15mpg in the city which included bursts of boosting and having fun, now with the same behavior I'm getting 10 maybe even 9mpg.

So basically I love driving my car as much as possible, and I'm waisting about 21 dollars a tank on getting only 66% of the city milage i used to with expensive 93 octane. It will take a lot of tanks to make up for the cost of replacing the injectors and mass air again plus labor. Either way, I feel crappy and am suck because of these A holes. Erik

Rainson

Eolson, that guy is right. There's no reason to push your injector to 60lb and mass air with only 10psi. Save that for future use if you are to go bigger power. I dun know which shop you went to, if you were in Detroit area, Livernois Motorsport in Dearborn is the best place for you.

eolson

Rainson, that's who cost me all that money, bad tune, and needlessly had me pay for and change out the injectors and 90mm mass air. They had my car for nearly 8 weeks as well. Horrible!
Don Walsh from Walsh Motor Sports is the most honest, reasonable and and knowledgable tuner in my area. Hands down. I didn't go back to Don initially, and that really cost me. Erik