No, my car doesn't experience a stumble.

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0==WW==0
"…axles of evil…" - george w. bush

 

I went through a similar thing. I purchased my car used with a little over 50K on it, and had no issues at first. I'm at about 65k now, and it's doing a very similar thing as yours is.

I only experience the problem around 3K RPM in 4th and 5th gear when I'm above 50% throttle. I've found that when I back off to less than this, I also experience a stronger acceleration. This seems to indicate a boost or fuel problem of some sort...my feeling is that since there is not problem at or below 3rd gear, it wouldn't be an ignition issue. For the same reason, I'd think it could rule fuel out as well, but I'm not sure. I have an appointment tomorrow to troubleshoot, so I'll let you know what i find.

 

Interesting info. Sounds like we are experiencing the same problem. Let me know what you find out.

I think that the issue maybe the same in 1st and 2nd, but because the acceleration is so much quicker in those two gears, it is not as noticable.

Where are you going to troubleshoot DJ Catchem?

 

If there is a problem with the ignition, it is more likely to show up under acceleration in the higher gears. Higher gears = more load on engine under acceleration.

--
0==WW==0
"…axles of evil…" - george w. bush

 

We're going to take a look at the ignition to be safe, and the turbo and connections. I'm not leaving the dealer with the car until I have a reason, if not a solution in place. I think it's safe to rule out fuel delivery at this point, and I'm still leaning toward an issue with the turbo, because of the way the power in my car is "pulsing" at that point in throttle, but I'm open for anything at this point.

We'll see...

 

Update - I'm waiting to hear the results of a hydrotest on the intercooler, of all things. More to come...

 

I didnt finish reading all of the responses to this thread, so I apologize if I am repeating anyone.....

I had a similar problem with my car.....I had horrible accelleration, BAD LAG, and my turbo sounded like it had a broken fin inside it rattling around (I could hear it, and when the turbo was cold still I could put my hand on it and actually FEEL something "knocking" inside it.....

I took it to the dealership and explained my problems to them, they took out my turbo, inspected all parts of it internally and found nothing wrong....but it still had the problem....so they looked deeper into the car (all stock at the time) and ended up finding the cat in my UP PIPE had totally melted itself into one huge chunk of metal, nearly completely blocking off my exhaust flow, which was causing sooooo much backpressure that the engine would barely want to run at any speed/gear sel. above idle. They replaced the up pipe (under warranty) and I felt like I was driving a totally different car, all the power/ throttle response was restored.

In the months leading up to this problem I had gotten a few CELs that the dealership could not explain....after they found/fixed this prob. I havent gotten anymore CELs...its been about 6 months now.

I dont know if this is the same issue, but I would definitely check out any CATS that you have on your car for internal damage (ex. melted catalyst) before tearing apart your turbo.

good luck

-Ted

 

GotBoost? -

Thanks for the reply - i would look where you are looking except I have no pre turbo cat, just a catless uppipe from vishnu.

DJ Catchem - Let me know what happens at the dealership!!!!

 

It appears that GotBoost? may be on to something. I just off the phone with the dealer, and he went through the engine and management top to bottom. The turbo system seemed to check out just fine, although the first thing that was checked was the intercooler for a leak (hydrotest). Ignition seemed to be fine, and boost was particularly solid. Which brought us to exhaust.

The first cat in the exhaust was *really* clogged, from what he says. Judging by the diagnostics he ran, under heavy flow (at WOT in higher gears...) the backpressure would spike and choke things off big-time. I guess that seals it...I know what my next mod is. No way i'm paying for a stock cat. Turbo-back it is.

You might take a look into your other cats as a good starting point.

 

DJ Catchem - which cat was clogged? The pre-turbo cat or post turbo cats?

Let me know man! I am getting excited here!!!

 

The post-turbo cat is clogged up like you wouldn't believe. When the car comes under heavy throttle, the exhaust can't expel quick enough to keep up, and the bogging occurs. It's actually causing so much back pressure that, when at wide-open throttle and full boost, the turbo is pushing a *consistant* 24.5 psi! No wonder I had to replace that coil...

Gotta love that! Looks like it's time for an uppipe and turbo-back...

 

I have scheduled my car to be checked out tomorrow at my local dealership. They are actually pretty supportive, he said they would check it all out and let me know. I will post again with any findings.

Chris

 

Dealership denied service today. Major bummer! The service guy thought that he could install new cats for me and we would just move on, however - the parts where over $1000 plus labor so his boss put the nix on the fix.

I now have to wait until the end of January to have the factory rep ride in my car. I will update again at that point if I do not find a fix for the issue sooner.

The dealer recommended running a fuel system/catalyst cleaner through one tank of gas and see what happens. Any thoughts on additives?

 

I got the same response...Center pipe plus cats plus labor...well over a grand.

However...

Aftermarket turbo-back is closer to 800. THat fixes the problem, and puts a great power mod in place as well. How can I resist?

I'd look into a turbo-back. Even if you're still under warranty, you have mods already, so you'll get denied either way. Kill two birds with one stone.

 

My only "hesitation" with putting on the turbo back right now is if my problem is not a plugged up cat or ruined cat. I would hate to put on a sweet exhaust system, still have the problem, and then really get denied warranty because my car is so NOT stock. If I remember right, the onus is on the dealership to prove that my aftermarket part is the cause of the problem. We will see what happens in the near future.