Loss of power at WOT

[jackchung]

Hello all. I have a 2002 996TT, 6 speed manual with X50 and FVD chip, FVD 100 cell cats and FVD exhaust. In first, second, and sometimes in third gear at wide open throttle, engine seems to lose power around 4,500 rpm. The sensation feels like if the engine is misfiring or hesitating, but I am still accelerating, just not as fast. My boost gauge still shows 0.9 bar when this happens and it does not drop off until I lift on the gas. The normal boost is 1.0 bars at WOT. In higher gears on the freeway, it seems to accelerate smoothly and consistantly at WOT. One time in fifth gear at full WOT on the freeway, the engine sputtered a few times before I lefted on the gas. I have 68,000 miles on the car and put new plugs in at 60,000. I am not getting any check engine lights. I have checked all hoses and they all seem fine. The dealer checked out the car and it had no fault codes. They thought it was the MAF sensor so they put in a new one and it still had the same issues so we put the original one back in. They are still researching and trying to contact FVD. I also have new billet blow off values and tried 100 octane race fuel. Being in Colorado with higher altitude and low oxygen, I thought it might be a air/fuel issue. Any ideas? Can it be a traction control issue? No traction control light comes on. Oxygen sensor? Sometimes at start-up and gear changes, I do get a puff of white smoke from my tail pipes. And, there seem to be a minor oil leak (see previous post). I also suspect maybe a waste gate issue but at this point I am lost. If anyone has any suggestions, please let me know. Thank you in advance!

Edited January 27, 2009 by jackchung

[ScottArizona]

Jack, what kind of plugs did you use for your replacement. Sometimes software is written for a specific plug /plug type. I know for my giac flash, according to GIAC the car would not run as well if I ran something like an iridium plug. You might want to check with FVD to see if your plug selection was acceptable. Just a thought.

[deepblue5280]

That was my first thought as well...check the plugs and cracked coil packs.

Jack, what kind of plugs did you use for your replacement. Sometimes software is written for a specific plug /plug type. I know for my giac flash, according to GIAC the car would not run as well if I ran something like an iridium plug. You might want to check with FVD to see if your plug selection was acceptable. Just a thought.

[jackchung]

Thanks for the quick replies. I am running Porsche plugs by Beru. If you do a search on "Pulstar" on RennTech, you will get my thread on the bad experience I had with them. I will check with FVD to see if they have any sugeestions. Does a coil pack damage cause a misfire and/or a fault code? Thanks!

[wross996TT]

First get your codes read...you do not need to get lights to throw codes. Next lose the Beru's....quick. Go with at least Bosch FR6.

[jackchung]

No Codes. Stevinson Imports in Littleton said it was clean.

[wross996TT]

OK, still change the plugs...

[ohberlin]

Hello all. I have a 2002 996TT, 6 speed manual with X50 and FVD chip, FVD 100 cell cats and FVD exhaust. In first, second, and sometimes in third gear at wide open throttle, engine seems to lose power around 4,500 rpm. The sensation feels like if the engine is misfiring or hesitating, but I am still accelerating, just not as fast. My boost gauge still shows 0.9 bar when this happens and it does not drop off until I lift on the gas. The normal boost is 1.0 bars at WOT. In higher gears on the freeway, it seems to accelerate smoothly and consistantly at WOT. One time in fifth gear at full WOT on the freeway, the engine sputtered a few times before I lefted on the gas. I have 68,000 miles on the car and put new plugs in at 60,000. I am not getting any check engine lights. I have checked all hoses and they all seem fine. The dealer checked out the car and it had no fault codes. They thought it was the MAF sensor so they put in a new one and it still had the same issues so we put the original one back in. They are still researching and trying to contact FVD. I also have new billet blow off values and tried 100 octane race fuel. Being in Colorado with higher altitude and low oxygen, I thought it might be a air/fuel issue. Any ideas? Can it be a traction control issue? No traction control light comes on. Oxygen sensor? Sometimes at start-up and gear changes, I do get a puff of white smoke from my tail pipes. And, there seem to be a minor oil leak (see previous post). I also suspect maybe a waste gate issue but at this point I am lost. If anyone has any suggestions, please let me know. Thank you in advance!

HiJack, I am not a mechanic nor experienced in anything worldwild, but what you describe sounds like Turbo/EGR related issues. You might be on track with that waist gait talk...there might be some black smoke instead if someone were behind you long enough to report back

Edited January 28, 2009 by ohberlin

[Chuck Jones]

WROSS: I'm running the Beru.....just changed out plugs at 30K and didn't see all the hullabaloo about going to the Bosch until after we did the install...and I wasn't going to go back under there to swap out again. I'm getting a steady 1.1-1.2 at WOT even with the Beru plugs and dont' have any hiccups.

One thing I did that made a BIG difference was to go with ARD's suggestion and do the wastegate upgrade. That moved me into a higher category right off the bat and I've been very satisfied since then. I've said it before....but for the money, the wastegate upgrade is the single best and cheapest mod you can do. Just to be clear...I'm talking TT X50 here.

[jackchung]

Hello Chuck. What is the wastegate upgrade that you are talking about? Are you getting 1.1 to 1.2 bar without a aftermarket chip on just X50 package? Just a wastegate upgrade? Thank you for the comments.

[wross996TT]

Chuck...glad to hear your beru's are working OK for now...they are known to be troublesome, even Porsche does not use them on the TT. Jack, Chuck got the UMW wastegate kit. His car has been flashed, but the wastegate kit (essentially stronger springs) helps to maintain the boost as the gates don't open prematurely. This is a great mod, but may (will) not fix your issues.

Edited January 28, 2009 by wross996TT

[Chuck Jones]

Jack: WROSS explained it precisely. Nothing more I can add, except that if you opt to do the wastegate upgrade, it's not something that's an easy task....you have to cut apart the wastegate cans, install the new springs and make sure the diaphram is centered right with no pinched edges....then you need to adjust the wastegates so that they open at the same time. Some guys do it by the millimeter measurement from the end of the rod to the back of the lock nut.....but a more precise methodology is to measure the psi at which they open and adjust them to open at the same psi. ARD did a DIY on this subject along with pictures, but he also used a home-built pressure gauge to ensure accuracy of each side....actually it's pretty well done....but if you're not mechanically inclined....use your VISA!!

Edited January 30, 2009 by Chuck Jones

[jackchung]

Still living with the issue. My Porsche dealer cannot seem to find what is wrong with it.

[wross996TT]

Still living with the issue. My Porsche dealer cannot seem to find what is wrong with it.

I can't remember everything that has been discussed, but it could simply be the programming not set-up for altitude. I know mine was modified a couple of times until it was right. I also know that I am near the limit of fuel with my current set-up at altitude....perhaps I should move to sea level....NAH!!!

[jackchung]

Just an update. I went in to the dealer again for another issue, grinding noise as I am turning the steering wheel, only on warmer days. They replaced the strut bearings last week thinking it was the issue but the noise was there as I drove off the dealer. Under further inspection, it is looking to be the ball joint. Good thing I have extended warranty. When I was there yesterday for the inspection, I did talk with the shop foreman about the boost issue. He and I went for a ride and he felt it right away. He thinks it is a fuel or spark issue from FVD chip. He is willing to switch out the ECU with a stock one just to see if it is the programming. He said a lot of aftermarket programming ignores certain codes and actually stop looking at certain perameters like pre-ignition. His first suggestion was to lose the Beru plugs. He said it was junk and he would not put it in his own car! He said his hands are tied at the dealer because it is stock OEM part for Porsche. He has to put it in cars for that reason. He suggested putting the cooler bosch plugs. I will do that sometime next week and see if it helps. Thanks wross996TT for the heads up on the plugs!

[ard.]

I really think you want to look at the coil packs... you can get cracks in the potting that causes funny issues at higher rpms. I don't think this will necessarily show any codes.

If you are reverting to the Bosch, this should cost you no more than $0 for labor.

A