TCarideo

I recently purchased a 2004 Porsche TT with 12,500 miles on it--now 15,000--and took it up to the track for the first time this weekend. The car has a software upgrade and has been lowered, so even though it wasn't disclosed to me, I'm 95% sure the car was tracked before.

The track I was on has 10 turns, lots of braking and acceleration/deceleration, and after six 20-30 minute runs (about 80 laps), the car started hesitating as though it was running out of fuel, and kicking out fault codes, one of which was for a bad MAF sensor.

Is it unusual for this part to go with so few miles on the car? (My long-time shop, which runs cars in the race class, pulled the part out and cleaned it, but the fault code, after being cleared, only returned and the hesitation and loss of power continued.) Is it possible that the software upgrade, which added a little more horsepower, could be a contributing factor-shortening its life?

Finally, I've been able to find corresponding parts ranging all the way from $35 to $795 OEM, with a fair number in the $200 range, including a Bosch @$277, which is described as the OEM part w/o the Porsche markup. Why such a huge spread, which would suggest a significant difference in quality and performance? Or not?

Kevinmacd

What fault codes are you getting

TCarideo

Thanks for responding to my post. Here are the fault codes:

P0234 turbocharger/supercharger overboost
P0102 Mass or volume air flow A circuit low input,

Then two of this one. . .but it's probably not related:

X2P1133 WO DTC definition found, see service manual.

Macster

P1133 has two failure modes. Too much fuel or not enough.

Here is a bit of info on the too much fuel condition:

Oxygen Sensing Adaptation, Lower Load Range, Bank 2 - Below Limit
Diagnosis conditions
• Oxygen sensing system active
• Time elapsed after engine start-up: 250 to 350 seconds (USA)
• Time elapsed after engine start-up: 302 to 402 seconds (RoW)
• Engine temperature greater than 60 °C
Possible fault cause
♦ Incorrect signal from MAF sensor
♦ Fuel pressure too high
♦ Fuel injector leaking

And here's a bit of info on the not enough fuel condition:

Oxygen Sensing Adaptation, Lower Load Range, Bank 2 - Above Limit
Diagnosis conditions
• Oxygen sensing system active
• Time elapsed after engine start-up: 250 to 350 seconds (USA)
• Time elapsed after engine start-up: 302 to 402 seconds (RoW)
• Engine temperature greater than 60 °C
Possible fault cause
♦ Incorrect signal from MAF sensor
♦ Intake air system leaking
♦ Fuel pressure too low
♦ Volume supply of fuel pump too low
♦ Fuel injectors fouled


If I had to guess I'd say MAF. The MAF sees considerable heat when the Turbo engine is working hard and this can shorten the life of the MAF. If the car was tracked before you bought it who knows how many track miles the MAF saw?

"02996ttx50

definitely. tuned cars have a far greater tendency to "fry" maf's than "stock" particularly if the car has been pegged/bounced of the rev limiter at redline. it exceeds the voltage ( iirc? ) that they are ordinarily capable of handling.

as long as you purchase from a reputable vendor ( though i source mine on eBay ) a new bosch maf ( part ending in 124.00 ) in the yellow box w/ bosch logos with the brown wax paper you'll be fine. just make sure it's bosch, and "new", regardless of what you end up paying. i sourced a brand new bosch a few months ago for $150.00 w/ free shipping.

if you track the car or regularly drive it to its limits, you'll find you may go thru spark plugs and mafs at a somewhat faster rate than if you just drive around "normally". some owners never need to replace maf's. I've gone through several, but again, pegging the limiter ( my tune's raised it to 7200rpm ) can "fry" them, as mentioned. also, the 986 boxter maf is the same part with a different part number, so be aware of that when shopping/comparing. here's one for 200$ new http://www.ebay.com/itm/Porsche-911-...ZY0R-S&vxp=mtr

32krazy!

you have a large boost leak

TCarideo

I've been a Rennlist member for a long time, and have learned a great deal over the years, but this is my first time starting a thread. I'd like to thank all of you for the information you've provided! I really appreciate it. I can tell you that throughout my maiden voyage at the track with this car (I've been a DE guy since 1999), I was very careful to keep the revs from red-lining, but now that I think about it, 02996ttx50, I felt the car hit the rev limiter at least once, (maybe twice?) in that last run: Right. Before. The. MAF. Failed. Game, set and match; if nothing else, that was the straw that broke the camel's back.

Thank you, also Macster, for the technical data and the initial prognosis, and also 02996ttx50 for the information on the part I should buy. Wow. Thanks again, guys.

Third-Reef

10 turn track, was it Laguna? Just got back from there with my mildly tuned x50. Must say i hit the rev limiter about 5 to 8 times and she still runs smooth. 3 hour commute with her tomorrow at 4 am and then back tomorrow night in 105 deg heat. These are awsome cars, very broad capabilities. Change those plugs if you haven't.

powdrhound

I don't get this blowing of the MAF deal. I have a 7500 redline and frequently see 7700-7800 on data. Just about every shift is at redline. In 7 years of tracking the car I've never had any MAF issues whatsoever, knock on wood.

jeanmarcboilard

Do a pressure test to check for leaks. Most MAF codes are related to air leaks.

Carlo_Carrera

Pressure test before doing anything.

Macster

I hear what you are saying and I can't argue with you. While I don't track either of my cars my luck with MAF's has been good. 156K+ miles on the MAF in my Turbo and around 200K miles on the original MAF in my Boxster.

(Pretty good but not perfect: Some years ago I mis-diagnosed what proved to be an oil filler tube cap leak as a bad MAF. After I replaced the Boxster's original MAF with a new one and then when the error codes reappeared replaced the cap I left the new MAF in service. However, after around 100K miles the replacement MAF went bad. I had saved the old MAF and reinstalled it and the symptoms went away and have remained absent for roughly 100K miles. Very recently though the CEL has been coming on once in a while and the error codes suggest a MAF. I'm still in the investigative stage not having decided just yet to replace the MAF.)

Back to the OP's car: I focused on the P1133 error code but the other codes deserve to be factored into the diagnosis as well and I was amiss in not doing so.

While I am willing to leave my "guess" as the problem being the MAF stand I would add and this is a repeat of what Carlos said -- but it bears repeating -- and that would be to check for any boost leaks first.

This boost leak check doesn't cost much -- other than some time -- while a new MAF is a rather expensive component.

jeanmarcboilard

I have 2 perfectly good MAFs sitting in my garage from misdiagnosis before I starting performing pressure tests.

pfbz

15K miles or not, it's still a 14 year old car.

As mentioned, good chance it's a boost leak or vacuum line. Rubber deteriorates, clamps loosen, higher boost can loosen a line... If you don't have a boost pressure test setup, I'd start with a careful and thorough visual inspection with a flashlight and inspection mirror of all the lines you can get a look at. Won't catch many (most?) leaks, but maybe you'll get lucky (then order a boost test kit!)

Search for markski's boost test thread and video for some of the common points of failure.

I also think it's a low probability that it is a maf, but it's one of the easier parts to swap if you don't mind paying the $ for the part.

Couple of follow up questions:

"02996ttx50

pretty much everyone knows that hot wire mafs fail for two reasons:

contamination.
excessive voltage.

i neglected ( or did i? lol..) to mention also that your symptoms mimic failed plugs, and burnt spark plugs are common and more frequent on a tuned car than on stock. "breaking up" is coils and/or plugs, more often than not.

that said, you could have a failing maf and plugs and if you don't know whats been swapped recently or since you took possession of the car? i'd swap them them ALL, incl a new maf. gl w it!