I had this problem, and recently uninstalled the IPD plenum and went back to stock. It had a small leak, I tried various methods to seal the brass connection while on the car, and got tired of messing with it. Personally I'd prefer they do away with the 3 threaded connections on top, but that just my opinion.

Maybe I will send it to them and see if they can fix it.

 

1508 hey? i'd say a leak or your MAF is toast

 

Requested load/torque is an extremely complex model in the me7.8 ecu. When you remove the MAF, you dumb down an amazing control system into basically a single alpha N based map. Its not surprising throttle manipulation at low/part load is poor....the car has no idea how much air is being introduced.

 

Tony,

The strange part is that my car ran worse with a tune that uses a MAF.

Today while doing a high load roll on, the car when into limp mode but did not throw a code. Usually, when this happens I get a P1508 code. This is the second time the car goes into limp mode without throwing a code while doing roll ons.

 

This a really supportive community and I know so many people are trying to help including the Cobb team. You have been extremely vigilant and patient man. I know it doesn't help to say all the other cars with several of maps we tried are running great. But at least we know we are not crazy. I wish I could just transport the car here. We will catch this gremlin one way or another, hang in there.

 

I highly doubt you have a bad DME. I would be shocked actually. Check to make sure all your clamps are secure on your intake plenum and y-pipe / throttle body connection. Couple of months back I was chasing a p1508 code and it ended up being a completely loose clamp on the y-pipe / TB rubber coupler. I simply forgot to tighten it. It would seal ok and allow to build up about 0.9 bar of pressure and then suddenly pop releasing the pressure. This would trip the p1508 code and car would go into limp mode. The coupled never unseated from its groove in the Ypipe and I didn't catch it initially. Here's the link I posted when I was chasing it down.

https://www.6speedonline.com/forums/...tric-guys.html

Mafless is tricky and I doubt will ever run all around as well as a properly tuned MAF based set up. I agree with Tony on that one. I'm sure it can be done to work well as many run it but it's more finicky as everything is an approximation when you can't accurately measure the amount of airmass entering the engine. Sort of like fine tuning a violin with a sledge hammer. I've been tracking the hell out of my car with numerous revs beyond 8000 rpm and countless visits with the rev limiter and not once in 6 years have I blown a MAF. Not once...

 

It has nothing to do with mafless. But can be tune related. I had one client with the same code and it turns out one of the vacuum lines popped.
What's your elevation ?
Can't be the Ecu don't worry.

 

i fixed it this way!

 

Hi, Markski,

I'm at sea level. A few people have mentioned a vacuum leak. Wouldn't that show up when I do a boost leak?

I've done both boost leak tests(many times). The one at the Y pipe is right as can be, no leaks, holds pressure for very long time.

The test from the turbos is good as well but doesn't holds pressure as well and long as from the Y pipes. I can't find any leaks on any lines(soapy water) but I do hear what sound like blow by deep in the bowels of the engine.

 

Vacuum leaks found by performing a smoke test. If you dont have access to a smoke machine incense sticks work great

 

only because you're messing w intake stuff another source of a vac leak often overlooked if it isn't badly or obviously damaged is the #16 check valve at/near the plenum. if it IS bad it will usually "hiss" while pressure testing but a hairline crack in that 30$ plastic piece can cause a leak that will confound without any other clues.

 

Thanks for your input...I replaced every check valve including that one.

 

My mechanic did a smoke test and said it was tight. That was a few months ago. Maybe I'll him to another one.

 

My mechanic did a smoke test. He said everything was tight. That was a few months ago. Although the car runs the same as it did a few months ago, maybe I will have him do another one.

 

ya, it sucks man.. especially after all the recent mods and you cant reverse engineer each one to chase the issue down! sorry to hear, hope ya get it sorted soon.