Having an intermittent issue and would like any thoughts before I take it to the dealer (warranty) or the shop I use for maintenance.

A little background on the car, 08 997 Turbo, purchased last fall with about 34k. I knew it had the GT2 slave conversion and a LWFW, was then pleasantly surprised to discover it previously had a GIAC flash, aftermarket exhaust and coolers and upgraded turbos. The flash, exhaust and coolers had been removed at the end of the lease but the turbos remained. (anecdotal evidence leads me to believe they are EVOMS, but I really don't know)

GIAC would reinstall the same software that was already customized for the car, so I purchased a fabspeed exhaust, the new design GT2 coolers, and had the flash reinstalled. First dyno showed 630+ hp on the pump program.

I then went to my first DE and the car chewed up the track like nothing I had ever driven. Flipped it to race mode, pumped in some 104 (unleaded) octane, and really cut loose...only to have it go into limp mode on my last run of that weekend. Long story short, the dealer was convinced that somehow my DME had fried from being flashed multiple times. They attempted to flash it back to stock and still could not get it out of limp mode, so I ended up paying for a new DME which, once installed, appeared to solve my problems.

Of course, I immediately returned to my tuning/maintenance shop and had the GIAC program flashed back on once again and all was well in my world! Until, the car intermittently began to stall while decelerating...

In each case I think the same conditions existed - although they caught me off guard each time so I'm not entirely sure. Seems to occur while I am slowing in gear - so the engine has the throttle closed and is compression braking - and when I engage the clutch to shift into neutral that is when the stall occurs. I am guessing the RPM's are dropping too low before trying to settle at idle.

I have an email into GIAC to see if the idle speed can be adjusted via the flash, but also don't know if this could maybe be something like a clogged fuel filter or some other maintenance item. Or, maybe something totally different that is a warranty issue. So, I'm basically looking for any educated guesses so I can decide which order to use to try and fix the issue between GIAC, the dealer, and the tuning shop. Incidentally, the plugs were checked about 3k miles ago before I had the flash reinstalled and they appeared good, so I think we can at least rule those out. Also, seems to be running very strong so I'm thinking there are no boost leaks either.

Any other thoughts? Thanks in advance for any help!

 

Dealers are often wrong, Ive had terrible luck with them diagnosing things, in fact my car is still in the shop as we speak!

I would def have GIAC take a peek and simply not reflash what was on it prior, I would also ID the exact turbos on the car and their capabilities.

 

I'm having similar problem as we speak, the car is actually at the dealer now. I think it is a MAF or throttle body issue. Will keep you posted.

 

with all those mods did you check to see if previous owner installed plenum and larger throttle body perhaps?

 

Interesting that you mentioned that, both MAF's were replaced under warranty a few months ago and the dealer thought they might have gone bad again when I went into limp mode before the DME was replaced. They said the MAF's went bad the first time because the aftermarket/reusable air filter that was installed was too heavily oiled. When they were 'guessing' they might be bad a second time they hypothesized that the flash was sending 'bad' voltage to the MAF's and might be frying them out...which sounds like a complete load of BS to me and is one of the reasons I have lost trust in the judgement of the dealer...

If I remember correctly, isn't there a way we can spray some time of cleaner on our MAF's that is supposed to correct a lot of sporadic problems like these? Anyone know of a DIY showing how to access them, which product to use, etc?

It does not look like it. Why? How do you think that could have affected it?

 

Larger throttle body would require specific tuning / flash to compensate.

Ive cleaned my MAF's a while back, very easy job, use CRC mass air flow cleaner.
Remove airbox and y pipe to gain access, philips and some smaller sockets is all you need. Remove from car to clean, spray and let sit for a while to dry, be sure to cover ends with lintfree rags so nothing blows in there while drying.

 

I think it's the MAF, I also have one of those high flow filters and I believe they are known for this.

 

If your running high flow filter consider simply replacing it vs. cleaning and re-oiling. This way less chance of fouling the MAF. Of course the added 2-4 hp probably is not worth the hassle to begin with, at least if your running stock turbos when the paper filter is fine.

 

I don't know if this will help, or if the 997TT is the same, but I was reading the other day and came across something I had never seen before. It said that after a power interruption, the car must be put through an adaptation cycle by switching the ignition on for 60 seconds{don't turn on the engine}, then turn off the ignition for 10 seconds. That completes the adaptation. Then turn on the engine for a few minutes which lets the ECU re-learn the idle speed and mixture values.

Can't hurt to try it. I'm sure your car had a power interruption when they changed the ECU.

 

Been thinking the same thing myself, these MAFs just seem much more 'fragile' than I am used to. Ordered an OEM filter and will switch it out this weekend when I try cleaning the MAFs.

I appreciate the thought - I actually do this each time that I change the GIAC software to a different tune. If I remember correctly, the system will eventually clear the cache and change all the maps on its own, but the method used above forces the switchover to occur immediately.

 

Just a thought and kind of a long shot.

For those with the problem, are you all running Lightweight Flyhweels? If so, where did you get it and what is the weight? If it is too light of a flywheel, there might not be enough mass to keep the engine turning and therefore you will stall.

Again, this is just conjecture. Just wanted to throw it out there. I could be totally way off base here.

Reason I mention this is that back in the 993 days, users would put in really lightweight flywheels and when you cam to a stop and pushed the clutch, the car would just die. GIAC would then do specifc programming to raise the idle so this would not happen. Problem solved.

***The flywheel we sell is the slightlly heavier version from Aasco. I am almost 100% positive they have two types. We have sold countless flywheels and tested them in our shop cars. We have never needed anytime of special programming to keep the cars from stalling. Just an FYI for any AWE clients that have purchased these from me.***

 

BMC filter? I just put one in my 2008 TT and am now worried that I have something else to be concerned about.

 

This is another thought I have had. I do not know which LWFW was installed as it was done by the previous owner. I 'think' it might not be the problem because stalling has not seemed prevalent with others that have a LWFW (as far as I know) and I never had the car stall once on the old DME and it has been the same flywheel the whole time.

Having said that, if the MAF cleaning is ineffective I am planning to ask GIAC to raise the idle speed as my next step unless anything new is suggested...

 

I'm not sure what brand mine is, but I believe the issue is due to over-oiling the filter, not with using a reusable filter in general. It may just depend on your TT as some seem more sensitive than others.

Considering that with my tune, upgraded turbos, exhaust, etc. I am already pushing about 30% more HP than the factory, I think I can live without whatever minimal gains that filter is providing for me now.

 

filters from the factory (BMC) are probably fine, you will see the GT3RS 4.0 is running high flow filters now. I would just not take the chance and clean / oil it, rather toss it away and replace.

I personally found the filter made zero difference to me, in fact the car felt better without it - totally unscientific of course.