Author Topic: Turbo issues! (Read 4478 times)

dtech · « **on:** November 05, 2007, 11:48:08 pm »

I own a mk3 gl tdi and just recently i have experienced problems with the turbo!
I get seroius lack of power intermittantly! I have noticed it tends to lose full power when at full running temp.
Following that, the minute i pull over and restart it is fine and have full power and boost again!
Please help as this is becoming very irritating!
Appreciate your replies
Dtech

windex · « **Reply #1 on:** November 06, 2007, 06:27:22 am »

dtech,

If you suspect the turbo as your cause, I would hook a boost gauge up to the engine and see if your lack of power correlates to a lack of boost pressure. Also, you can remove the intake pipe from the turbo (passenger side, one hose clamp) and inspect the inside of the housing for scoring and check the shaft play.

Do you hear any screeching or loud whining noises when the turbo is operating?

dtech · « **Reply #2 on:** November 06, 2007, 08:29:01 am »

I havn't heard any strange noises! Thats why i think it could be an electrical fault.

Maybe mapth sensor?

jtanguay · « **Reply #3 on:** November 06, 2007, 10:01:11 am »

do you get a CEL when it happens? almost sounds as if your car is going into 'limp' mode?

Quantum TD · « **Reply #4 on:** November 06, 2007, 08:07:03 pm »

Pull the lower intercooler tube and look for oil build-up. Also check the turbo for shaft play. If there is no major oil-buildup in the intercooler hose, and no shaft play, then I'd say either your N75 valve is bad, or the MAF is done.

These two parts are relatively cheap (at least a whole lot cheaper than a new turbo). The N75 runs about $75-100 and you can upgrade to different ones for more boost. The MAF runs about $75 at the dealer.

You can check the N75 valve. It's that little square box on the passenger side of the engine bay. It should have 3 hoses coming out of it, and a single plug with 2 wires. Your Bentley manual should outline how to test the N75 with a simple Multi-tester (I bought one at harbor Freight tools for $3: works great).

I think that you can test the MAF in the same way.

I'm betting it's the N-75 valve. It electronically controls the boost by allowing the waste-gate to open under high pressure. Under normal conditions, the N75 keeps the waste-gaste shut by creating vacuum to hold it closed. When it goes bad, there is no vacuum created and the wastegate simply opens up and lets all the boost blow out.

If you've done regular oil changes, use synthetic oil, and the car has under 200,000 miles, I'd say your turbo is fine. Look to those 2 main things (MAF and N75) after you rule out a bad turbo.

dtech · « **Reply #5 on:** November 06, 2007, 11:54:26 pm »

Thankyou so much! Very helpful.

I will check those two main things first.

Will post again when i find out what it is!

Cheers