nigelhenry

Hi guys,

Have spent a couple of hours searching and reading for ideas and symptoms seem to vary so I thought i'd throw my issue out there for comment.

Own an 03TT. 60000 miles and good service history, last major service at Porsche just a few thou miles ago (so, plugs changed)

Driving today, during quite hard acceleration at around 5000rpm the engine seemed to bog down and the rpm rate of increase significantly declined.

It just seemed to struggle. It kindly felt like a non turbo engine but the boost stayed good at 0.8-1.0 throughout.

Did a few runs to look at it.
From a dead start it did better, most runs up to about 120mph seemed normal but from around 40mph and hitting it hard the problem occurred.

FYI- In Dubai, probably around 100degrees temp outside.

Ideas?

Cheers.

Macster

No CEL I take it. So that sort of eliminates coils and plugs.

Still, I have to wonder if there's any connection between the service and the symptom. Last thing touched and all that.

Boost seems high.

Is the engine/DME stock?

For a stock Turbo the max. boost is nominally 0.7 bar though under some conditions -- my experience is at higher elevations -- it can reach and hold 0.8 bar even 0.9 bar. I've never seen 1.0 bar but I have never had the car over 9K feet in elevation.

Thus to my mind to see those high of boost numbers is kind of odd.

With that high boost I wonder if the DME wasn't dialing back timing to prevent the engine from detonating its brains out?

Just a guess.

Anyhow, reads like air flow is ok, and spark is (probably) ok (which I kind of covered above).

That leaves fuel.

You fill up at a strange/different gas station last time? You sure the gasoline is fresh? Right octane grade?

When was the last time the fuel filter was changed?

And since the car is new to you how about the engine air filter?

nigelhenry

Hi Macster, thanks for the reply.

There could be a correlation with the service but it's done 3000mls since with no problem.

It's always boosted high, it was first owned by some rich sheikh here and it's got something done to the engine, I enquired about that at the Porsche dealer when I bought it. So as far I know that it ok too.

I was thinking Maf sensor or fuel too. Last tank of gas was at the usual gas station and generally here the fuel is excellent and high octane. But it's possible it's crap.

Fuel filter is a good thought and the air filter looks good and I assume was replaced at the service at porsche.

What do you think about Maf?

Macster

The MAF gets blamed for a lot of engine trouble, and sometimes it is to blame, that the MAF is to blame here, well, I'm not yet convinced. The evidence is way too thin.

A poor man's MAF test is to disconnect the MAF at the harness, clear the error codes to reset (among other things) the long term fuel trims to their defaults then drive the car as you would and see if the symptom/behavior appears.

Say it does not.

Then reconnect the MAF, clear the error codes as before, then drive the car again and see if the symptom/behavior appears.

I'm hesitant to recommend this poor man's MAF test for you because the car may not, probably does not, not have a stock DME program and a stock engine.

Thus I worry if the modified program can deal with the proper fueling with the MAF out of the picture.

3000 miles since the engine was touched and before the symptoms appeared? Sort of lets the engine work off the hook, but not entirely.

You did mention the rather high ambient air temperature. I'm unfamiliar with the climate where you are but has the previous 3K miles been covered in milder weather conditions, specifically during cooler temperatures? If so my thinking is the engine with its mods and the likely custom DME are unable to cope with the high ambient temperature.

Before you do anything else it might be worth it to check that all the coils are connected to their respective plugs securely and that the connection of each coil at wiring harness are all good too.

While the behavior seems at odds with a boost leak, the techs tell me a common problem one that has to be considered when working on these engines is the intake hoses can get a bit of a loose piece at their end. This end is slipped over the connector and secured but the loose piece gets bent/folded back and the hose connection is not 100% pressure tight.

Trouble is if this has happened this is hard/impossible to detect without resorting to some static pressure test of the intake system.

Each at risk hose connection has to have the hose removed and then reinstalled. If the hose's end is too bad -- tech's call -- it should be replaced. The hoses must seal and hold against the boost pressure which in the case of a modified engine and custom DME are higher than stock.

Also, while you mentioned plugs were changed 3K miles ago I hope the coils were given a thorough inspection and deemed ok to reuse? Some places are quite conscientious and would advise you even if you didn't specifically ask the coils be checked for signs of needed replacing but some places might not be that conscientious.

With the presence of a some engine mods and probably a custome DME program comes the issue of not only the plugs (and coils!) suffering accelerated degradation but also the O2 sensors. The Turbo uses wide band sensors to help improve the accuracy of the fueling. In a stock engine these can last a long time (my experience anyhow) but in a modified engine their useful lifetime may be rather short.

The odds are the gasoline is ok. I thought you might have filled up at some out of the way station but if the gas station you used is busy, and offers quality gasoline, bad gasoline is unlikely.

I did mention the fuel filter. Be sure you know this is good.

Sorry, I have nothing concrete. With a CEL and error codes sometimes (sometimes) what's wrong is easier to deduce. You have no engine telemetry to review/analyze, no real time capture of ignition advance, short/long term fuel trims, etc, that might point a finger at something.

But with just the one symptom to go on...

32krazy!

clutch is going south

nigelhenry

Great info and it's really appreciated.

I've been travelling and get home tmw and will see how it drives. I might have a poke around at the things you suggested and if nothing is obvious I'll refer it to the tech here in Dubai.

Thanks very much and I'll report when I get to the bottom of it.

Nigel.

P.s it's a tip.

turbo4 me

I am not sure why Macster thinks your car doesn't have a stock DME program, but he's certainly entitled to his opinion.

My car was exhibiting similar symptoms and I replaced plugs, coilpacks, and fuel filter without fixing the problem. I even tested the MAF using a meter (there is a DIY on that) and it tested fine. I was about to give up and take it to the shop when I found this "poor man's" MAF test on another website. Needless to say, driving the car with it unplugged it ran like a rocket so I bought a new MAF and have had no problems since. If I had done this first I would not have needlessly changed plugs and coilpacks.
So invest 5 minutes and you can either fix the problem or eliminate one very likely cause.

PS you will have some alarms lights but it won't hurt the car.

nigelhenry

Thanks Turbo.

I dont know enough to comment on the details of engine upgrades, I appreciate the expertise on this forum though.
I'll may know what was done to the engine, but knowing the 'need for speed' in this part of the world, anything is possible, although the engine comaprtment appears stock.
Which would lead me to conclude some intervention with the engine managment software as a possiblity.
Time will tell and hopefully I can learn something about what was done out of this.

Cheers, Nigel.

Macster

Because the OP posted this:

"It's always boosted high, it was first owned by some rich sheikh here and it's got something done to the engine, I enquired about that at the Porsche dealer when I bought it."

Based on my experience I could accept a stock engine boosting 0.8 bar, even 0.9 bar (at elevation) but to 1.0 bar and consistently? That reads like there's been a tune applied to the engine controller, probably to go along with whatever the rich oil sheikh (is there any other kind?) had done to the engine.

The poor man's MAF test I touched upon but I'm reluctant to suggest the OP use this with (possibly) a modified engine and custom tune applied. I'm not sure how well these custom tunes handle no MAF.

But the MAF could be the cause of the problem, that's for sure.

nigelhenry

Hi guys,

An update to the power loss my TT was suffering. Took it to a the local (non-dealer) Porsche specialist. Took it for a spin and they thought it was likely to be coils.
Had a good look over it and discovered one of the hoses on the fuel pump was perished. New pump, problem gone.
Have seen the same defect on this forum too.

Thanks for the posters, appreciate the feedback, TT is going great again!.

wross996tt

I've had that hose rupture three times. Finally I had the tech. (at a dealership) replace it with a high pressure hose...custom and I have had no issues since.

nigelhenry

Apparently the latest version of the pump dispenses with the part of the hose that is subject to failing.

Macster

First time I've seen that. Usually a jet siphon hose fails and the engine acts up, stalls, fails to run at around half a tank gasoline.

jpflip

Keep the pump and replace that hose. Common problem and different ways to fix it..... Note: the loop hose is now modified with a stronger materiel by Porsche ....

http://www.6speedonline.com/forums/9...-pictures.html

http://www.6speedonline.com/forums/9...fuel-pump.html


http://www.6speedonline.com/forums/9...fuel-pump.html

http://www.6speedonline.com/forums/9...ally-dove.html

http://www.6speedonline.com/forums/9...el-line-2.html

Kevin

The condition of the nylon tubing is suspect. New they are light beige.. The older the nylon gets the chances that the nylon hose splits goes up.