99.5 Jetta TDI - Will not rev nicely over 3000rpm

Discussion in 'VW Mk4 Jetta, Golf, New Beetle, Passat TDI forum' started by Mavrick, Feb 15, 2012.

  1. Mavrick

    Mavrick Member

    Joined:
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    Car:
    1999.5 VW Jetta TDI
    Hello, new here. Lots of info, great site.

    Recently aquired a 99.5 jetta TDI wih 390k on it. Experiencing a few issues that i could use some ideas on. First of all, crank time is a little long, cold and hot - 5-6seconds. Haven't looked into this too much yet.

    More importantly, driveability has an issue. Low RPM idle-2400, is OK and pulls pretty well. Above 2500rpm or so, the engine just does not want to rev. Also makes vibration/noise when pushed to 3500rpm or more and really struggles to increase RPM. MAF value maxes out around 790 (a little low for WOT?), turbo boost matches spec within 100mbar, pump timing is within spec - advanced and around 80-90, intake is not clogged, no snow screen, new air filter, new fuel filter, fresh fuel.

    Recent repairs include turbo actuator, n75 valve (swapped EGR valve), air and fuel filters, timing belt.

    Im thinking of checking the in tank pickup for clogging next. Any other ideas? Ive never seen a plugged cat on a tdi, but on a gas car would result in similar issues.

    Thanks.
    Last edited by a moderator: Feb 15, 2012
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  2. Seatman

    Seatman Active Member

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    Car:
    2000 Mk4 Golf Estate 1.9tdi 174 bhp
    Location:
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    PP764's, turbo and mapping
    You could disconnect the downpipe from the turbo to rest the exhaust, I have seen the silencers just collapse internally before. Is there any difference with the maf unplugged? Are you saying too that the timing is up around 80 - 90? If so that's very advanced, the top line is around 70, I'd knock that back a bit.
  3. Mavrick

    Mavrick Member

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    Car:
    1999.5 VW Jetta TDI
    MAF unplugged is no change, similar if not the same power condition. Tried a MAF from a BEW car and same thing as well.

    The timing could have been 77-80, i forget the exact number but it was close to (but still under) the higher limit of the spec on my vag-com.
  4. Seatman

    Seatman Active Member

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    PP764's, turbo and mapping
    Yeh that's high for the ALH timing, ideally somewhere around the 65 mark unless you have bigger nozzles then aim for 70. I think the BEW maf might well be different even though it looks the same and if there's no change I'd suspect the maf.

    You can check the timing pics in here, you'll see how the top line works when you have the fuel at the right temp too.

    http://www.myturbodiesel.com/forum/...-new-beetle-golf-alh-engine-1998-2003-a-2976/

    Also if you look in here you'll see the mafs for the ALH and BEW have different part numbers.

    http://www.myturbodiesel.com/1000q/multi/maf-faq-tdi.htm
  5. Mavrick

    Mavrick Member

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    Car:
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    Problem was a clogged cat. Looks like somebody put a converter from a gas car in it, and it was full of soot.

    Power is much better, although short lived. On my road test home from work, i get no boost and limp mode - im guessing an overboost condition. I will deal wih this next week.
  6. Seatman

    Seatman Active Member

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    PP764's, turbo and mapping
    Cool, that's something anyway, did you knock the timing back at all yet?
    If you are overboosting check the vnt lever isn't sticking, you could try working it back and forth or maybe try something like WD40. Failing that I'd check the actuator.
  7. Mavrick

    Mavrick Member

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    Car:
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    Timing is sitting at 70, ill prob leave it there.. I cannot see gaining much by backing it off so little. Actuator is new, lever is free, intake is clear. N75 valve was faulty, so i switched it with the EGR solenoid, it could be sticky too.

    Turbo makes a funny squiggle noise when shifting or letting off the boost/throttle. I havnt heard this on any other TDIs before.
  8. Seatman

    Seatman Active Member

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    PP764's, turbo and mapping
    Usually cars with straight through exhausts make that sort of noise, as for the timing 70's ok, I thought you were saying it was over that which I don't think is good for the engine. It might be worth checking the faq for the actuator adjustment if it's not been set up yet.

    http://www.myturbodiesel.com/1000q/a4/VNT-wastegate-adjust.htm
  9. Mavrick

    Mavrick Member

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    Car:
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    This noise was made before i removed the cat as well. Ive worked on plenty of TDIs but have not heard this, hopefully its nothing bad!

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