FVD DME 996 TT Flat spot in power and missing

[jasonstturbo911]

I just had a new DME from FVD and EVO divertor valves installed in my 2003 911 TT, the power is amazing I love how it woke up my car however there is a flat spot in the power between 4000 and 5000 rpms. The car also seems to miss and studder when under full boost, 1.1 to 1.2 bar, finally today after a bad episode the check engine light came on. Any suggestion on what this might be.

Thanks Jason

[Dus10R]

I just had a new DME from FVD and EVO divertor valves installed in my 2003 911 TT, the power is amazing I love how it woke up my car however there is a flat spot in the power between 4000 and 5000 rpms. The car also seems to miss and studder when under full boost, 1.1 to 1.2 bar, finally today after a bad episode the check engine light came on. Any suggestion on what this might be.

Thanks Jason

Might need colder sparkplugs, but more likely might need higher flow fuel pump. It could be a lot of things; when increasing boost that much on a stock set-up without any sort of data logging (wide band AFR, knock count,fuel injector cycle duty,exhaust gas temp, etc) you could be asking for trouble. The car might have a fail safe too that tries cutting boost when it gets near 1.3 bar. I don't have a lot knowledge when it comes to Porsches but I have dealt with lots of modified turbo cars in the past and they all seem to have the same quirks when you go for the quick and easy bump in horsepower. Just because they change the fuel maps and boost pressure maps doesn't mean the fuel injectors or the fuel pump can keep up. And if it's a generic program that wasn't built spec. for your car it could be doing all kinds of things.

In my Evo I had to detune the factory map because it would start to knock at WOT at around 155+ , our crappy 91 octane fuel can't quite resist the urge to detonate. Of course most people without data logging equipment would have no idea and they assume that the factory maps are safe. So just be cautious; if reliable horsepower was that easily attained why would Porsche come out with an $18k dollar upgrade just to get 36 more HP like the X50 package?

[fastboydave]

I'd suggest that if it is the 'standard' Turbo (Non X50) it is now running too much boost/advance timing for your grade fuel and conditions?? I obviously dont have any experience with your octane fuel, but the fuel over here apparently is much higher octane. Most of the company's that 'tune' TT here, will only put the non-X50 to max 1bar boost. Although i agree with most of what is said above, I suspect the fuel pump and injectors etc are perfectly within their working capacity (for only an ECU remap) but the advance and turbo pressure is too high and the safety parameters of the ECU etc are being exceeded. Just my thoughts.......... Dave.

[Danyol]

You may be getting to the limits of the K16 turbo on the standard non-X50 car. It could just be the fuel delivery too causing lean running at 4-5k, typically these upgrades are completed as a "package".

Could simply be plugs, many others including myself replaced the plugs much sooner than the factory 30k (away from factory Beru, also checked out the coils for cracks ect; they are a cheap replacement at plug time). Have you done anything with the intake, others have had issues with EVO intakes causing MAF errors?

There are a lot of people running modded TTs over on Rennlist with a boatload of experience. I like this board for the 996 info sharing but spend time over there when things get more turbo specific.

I'd suggest that if it is the 'standard' Turbo (Non X50) it is now running too much boost/advance timing for your grade fuel and conditions?? I obviously dont have any experience with your octane fuel, but the fuel over here apparently is much higher octane. Most of the company's that 'tune' TT here, will only put the non-X50 to max 1bar boost. Although i agree with most of what is said above, I suspect the fuel pump and injectors etc are perfectly within their working capacity (for only an ECU remap) but the advance and turbo pressure is too high and the safety parameters of the ECU etc are being exceeded. Just my thoughts.......... Dave.

[wross996TT]

It's plugs...

[jasonstturbo911]

Thanks for all of your comments. I had my spark plugs changed and the car has never run better. The DME from FVD is amazing the car spools much faster and maintains the boost throughout the RPM range.

[Danyol]

Good news Jason.

For reference, how many miles you have on the car?

[jasonstturbo911]

Danyol,

I have 25,000 miles on my car. Now that I have the new DME I am going to change the plugs with every 15k service, with all things considered.

[r34dy2fly]

for studders under boost its always either 1. plugs 2. MAF.