Ever since the MREV install I have had a huge drop in my MPG. It isn't the way I drive. I tried granny driving and I think i still get less than 13 mpg. I've been filling up so much more often. The thing is, when i turn the engine on, I get this huge (maybe 1/3 of an increment) drop in fuel level. What could possibly be the problem? Does a vacuum leak do this(maybe the bolts on my MREV have come loose)?

bump

although I don't know the answer to your question, if you had a vacuum leak large enough, you would notice that your idle rpms are higher than normal. The larger the leak, the more noticeable the rise in idle rpms.

I know that doesn't answer your question, but thought I'd help where I could...

I don't think theres a rise in rpm but the needle's not really staying dead still... I don't remember if it was supposed to stay still when idling pre-MREV. I think I can feel slight vibrations when sitting in the car but thats probably normal?

try resetting the ecu using the pedal method or by disconnecting the battery with the headlights on. its easy enough to do, so this could be the first step.

I got MREV+ installed but I don't have that problem...........so how do you know that MREV caused it?

its just a speculation, don't get me wrong MREV i great, but the change in fuel consumption is just too noticeable.

You gotta try taking it off man and looking at the symptoms, only way to know for sure. I know this helps you ZERO, but I have mrev and plus allong with Stillen CAI and actually my mpg has increased by about 0.5-0.8MPG. This makes more logical sense because increased air intake = running leaner = less fuel consumption.

+1, it's easy to try...

I hope you can solve the problem soon.....it sux to run 12-13mpg......

It doesn't sound like a leak at all. An air leak would tend to make it run leaner if anything.

Sounds like something else. The MREV won't make it run richer.
And your idle description is normal for even stock.

Did you make any other changes? Have you checked the MAF sensor? ECU and TB reset?