98 tdi turbo/wastegate problems

[Rbgjetta]

I replaced the wastegate bypass regulator with no difference in performance. I ordered a vag-com from Ross-tech today so that I can better diagnos the problem. I'll let you know what I find out.

[Rbgjetta]

I recieved a cable from Ross-tech. I deleted the fault codes and they didn't return. Yet, the car is still underpowered. With the help of my daughter, we went on a test run while measuring Maf and intake manifold pressure. During max acceleration, the specified Maf reached 850mg/str while the actual only reached 495 mg/str. The intakes manifold pressure at 450 my/str reached 1500 mbar. I know there is no exhaust restriction. So, if anyone has any ideas, I could use your help.

[Seatman]

Sounds like the maf might be bad but I'm not 100% sure, I think it can also be caused by the egr valve. Have a look in the faq at the low power and also there's another link somewhere about other things that can cause limp mode. I know it's not limp mode but it might give some idea of things to look at.

[Rbgjetta]

If it's the egr, that would mean it might be stuck open bleeding exhaust off the turbo. Is there a chart that would show me what the intake manifold pressure should be? The highest I could get it was about 1520 mbar. Does that sound low?

[Seatman]

Now that's something I don't know lol but someone else might.

[chittychittybangbang]

don't think there's any charts but if you hold the mouse over the measuring block a tip box will appear. I forget if the bar is absolute or just above atmos. since 1 bar is standard pressure at sea level.

[Rbgjetta]

So, today I rented a borrowed a vacuum pump from Autozone and tested the Egr valve which worked perfect. It even held when I left pressure on it. I did notice allot of oil residue in the intake pipe and manifold. Is this normal? My next option is to replace the Maf and see what happens. I'll let you know. Thanks for all the info.

[Rbgjetta]

So, a friend of mine has a new MAF sensor which we tried whisks it did not help. I unplugged the intercooler and pressure tested it. It was fine. I still have the problem of a low MAF reading which has to mean there is a restriction in the system. I have replaced everything on the exhaust side of the turbo and checked every thing on the intake side of the turbo. Which leads me to think it's the turbo. I have noticed a film of oil on the piping from the turbo to the intercooler and back to the intake manifold. Does anyone have a good test for a turbo?

[Seatman]

The film of oil is normal, it comes from the ccv (crank case breather)

[rexhooligan]

Hi, sorry to butt in, but I am also having an issue with low/no boost. VNT moves freely, replaced vnt actuator(was bad, had rust/dirt falling out of "weep hole"), vacuum hoses and egr solenoid. Also new air filter(stock) and fuel filter. Was running great then on way home from work, maybe 10-12 miles ,get off highway and start off from stop and no boost. Swapped the vacuum solenoids and ran great for a couple of days. Now same no boost after trip home. I was using my buddy's generic code reader and had maf numbers up but didn't know what I was looking for. Do I need to vagcom to see the actual vs spec numbers? I also noted before the solenoid swap that it didn't matter if engine warm or cold for no boost. Where should I go with this? I'm leaning towards maf but seems like it wouldn't be an on off thing but a gradual loss. Thanks