Alright, I started a thread a few days ago about me having bank2 rich at idle. Turns out it was a bad exhaust leak near the bank2 O2. However my mpg on the highway suffers greatly still. It has been bad for some time. 21-22 at best between 70-80mph. Of course the car has been tunned. Mods are LG street headers, vararam, corsa exhaust, custom grind 234/242 .603 .610 112+3 and of course all valveterrain supporting mods. Im at a loss for whats causing this. No codes. Car has fresh oil, fuel filter has less than 8k, diff fluid changed, 1 O2 sensor that is 1 year old and the other is brand new. I keep the filter clean and oiled. For good measure I even clean the maf just incase for over spray. Plugs are less than a year old and the MSD wires connecting them are 4-5years old. No signs of corrosion whatsoever. Knock sensors and harness replaced last year. (pinched o-ring on manifold???) My STFT at those speeds are double digit neg on both banks. Any where from -8.x to -13.x Not sure if that is normal for the amount of air at those speeds. There much closer to 0 around town. The 2 couplers on both sides of the maf are sealed tight. Now the vararam box seal is not in the best of shape but not sure if that could cause problems hence the reason im asking. If so what can I do to help it seal better. Any help on what direction I should take would greatly be apprectiated.

 

No advice?

 

It would wait until things have settled down from the exhaust leak. 21-22mpg at 70+ MPH with a heavily modded engine doesn't sound bad to me. I only get low 20's on the mine. You also have to give people more than 8minutes before you post a follow up wondering why people didn't respond.

 

Still running the 3.42 gear ratio? As stated, it doesn't sound that bad to me, unless you were getting better with all these things done, and now suddenly it's dropped.

My car gets 25mpg at those speeds with a 220/228 cam. Yours is significantly larger. But whats killing it for me it the 3.42 gears behind my A4. So several factors to take into consideration.

 

lol chasse my org post was yesterday. I posted that this morning. Anyway im almost certain it was better than that when the new cam was first installed. Im still very curious about those fuel trims being so neg a those speeds. I dunno its just weird. 50-60mph weather its 5th or 6th gear(6th not often obviously due to duration of the cam) ill see 25-27mpg and in 5th the rpms are around the same as in 6th around 70ish. Yet the mileage drops off a solid 3mpg and sometimes 4. That's why I lost and confused. I mean can a MAF be...lazy?? Like I said b1 and b2 are more neg at those speeds than 50-60mph.

 

I only get 27-28ish on a basically stock motor