nuclearfishin

This is getting to be an old topic but I'm going crazy trying to figure out why my car is running so slow. Here's the pertinent info:

- car ran great earlier this year and I've made no changes since.
- just got the car back from getting checked for boost leak and it's tight as a button at 22 psi.
- Tires are not spinning at launch.
- during launch, it looks like the overboost function is not spooling as high as it used to--not sure if this is a cause or a result.
- idle at cold start up fluctuates for about 2-3 minutes between 700-1000. Once engine is warm it's rock steady at 800. I'm thinking this could be a maf issue, but once the engine is warm would it really cause that much of a power loss?
- power loss is around 1.5 secs in the quarter mile, significant for the upgrades and tune I'm running.

Any ideas from you guys would be greatly appreciated. Thanks!

DJ23

When was the last time the plugs were changed? You also may want to check the coils as well. You are also right to check the MAF. Also what octane are you running? Race gas?

Hope this gets you started.

Jay

nuclearfishin

Plugs and coils were all changed last summer when I had the coolant leak fixed. I'm running 93 octane, same as earlier in the year when I was running 11.0 flat. Now I'm barely running 12.4's.

808c2s

Can you log a run? Is your timing retarded?

elite1

Clutch slippage? Logs would be great to see if you have them! It sounds like you are chasing the same ghost I was last year. I don't really want to ask this but,

-How many miles are on your car?
-What oil viscosity are you running?
-Earlier in the season, you ran better but, do you think ambient air temps / Humidity may reflect on this change?
- what air filter is installed?

Maybe your racing adrenalin is fading with comfort?

(Avatar) Have you tried racing on Saturday night? Just kidding!

jcnesq

I'm having plugs changed soon, have some cut-out at higher revs, think that may be it. (32K miles, fvd tune.)

nuclearfishin

All good questions. I just ordered a durametric hoping that might provide some useful data. No clutch slippage as car is a tip, but I do notice significant less boost while brake boosting on launch, then boost goes way up after the first 200-300 feet. Car just turned 40,000 miles, has a bmc air filter, about one year old. Oil is motul, whatever dealer used, 0w40? Ambient temps have actually been cooler lately at night. I tried running on Thursday and saturday, no difference from friday...

AudiOn19s

Despite the air not being horribly hot it's been really crap air for making power with all of the humidity lately.

Doesn't explain THAT much performance loss though. Wish I had better ideas... the obvious stuff has already been mentioned.

nuclearfishin

Still waiting for my pentalobe set in the mail so I can clean the MAF sensors. I'll report back if it makes a difference. If not it's back to Wright Motorsport to troubleshoot the problem.

Forcedbird

Have you done a compression test?

I am new to the porsche scene, but does having a tune disable the OBDII CEL functionality?

Forcedbird

Haha this had me cracking up!!

Fishey

This the car that was at P3 autokrafte? If so I know when I looked at the car I did a smoke test and found a vacation line off the FPR, which was checked and looked fine. So it was reinstalled with a ziptie (T&b) and I found a loose boost hose at the IPD plenum. I fixed that but suggested factory clamps as the wider aftermarket clamps used didn't fit as nicely. I did check it to 22psi at that point. I got busy with another car when the clamps showed up and a different tech did the replacement. However, he is completely competent so I doubt anything went wrong with that small change. You still having problems?

nuclearfishin

CEL functionality is not disabled, although I do have the cel from the rear O2 censors disabled.

I haven't had a compression test done and hope it's not anything related to that. I really think it's a sensor/programming issue because the car will make tons of full power, just not consistently, especially during launch. From 1/8 to 1/4 mile, it's pulling the same as always gaining approx. 26 mph, but that first 1/8th is slow, on launch, at 60', 1000', etc.

Fishey

So, is this somehow not the same car? If so that is simply amazing.

nuclearfishin

Yes, it's been to P3 and I have no complaints or doubts that there's no longer a boost leak, but it's still down on power by about 1.5 sec in the quarter mile, and rpms still fluctuate +/- 300 until the engine is warm. I feel bad that I've brought it in 3 times for this issue and don't want to be that PITA customer. If you just drove the car you'd never know, but I keep such good records with my timeslips that I can definitely tell when it's not running 100%. The reason I mention taking it to Wright Motorsport is because they installed the tune and I've been talking with the folks at GIAC and am wondering if it was a software thing. My durametric arrives today, hopefully with the pentalobe socket so I can see if the MAF is the cause. If not, I give up.