air intake missing "snow screen" plus a host of issues

Discussion in 'VW Mk4 Jetta, Golf, New Beetle, Passat TDI forum' started by blueskymine, Jun 1, 2012.

  1. blueskymine

    blueskymine Member

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    Car:
    2001 Jetta TDI
    I have a host of issues and tests to run so I'm not sure how many to bring up in one post. The car came with an aftermarket air intake so I found a TDI stock air intake that is now in place along with a new Mann filter. The airbox came with a MAF (as well as having the original MAF).

    I noticed, after reading the post about cleaning the snow screen, that I'm missing the snow screen. The snorkle is there, bolted to the fender, but the other end, opposite the airbox, there's a gap between the snorkle and the location that I determined channels the air into the box.

    Should I find this part before I test the MAF as outlined in the write up?

    I replaced the turbo actuator because the car came with a new one (the old one was deteriorated). I installed it, along with a new vacuum line, but still need to make sure it's adjusted properly via the write up I found for that.

    I have no "woosh" that I expected with a turbo. I have slow and steady power and constantly have people travelling behind me go around without patience when accelterating from a stop.

    VCDS shows actual boost not matching expected boost. I have a new N75 valve that I can install, but thought I should first make sure the acuator is adjusted properly.

    Also had a ton of oil (like 1/2 quart) in the intercooler - and from what I've read, it's normal to have some oil, but certainly not normal for the amount that came out. I replaced crankcase breather pipe and rubber grommet into valve cover, but not the actual valve before I discovered the oil.

    Today, after a fresh oil change and after driving about 200 miles, the oil level is down just below the low oil mark. Have not yet pulled the lower intercooler hose to see if any oil accumulated there, but I suspect that could be where the oil went.

    Right now, CEL is not on, but VCDS has found a recent code - P1556 Charge Pressure Control, negative deviation, intermittent.

    Sorry for bringing up so many different things in one post, but I know the system should work as a whole, and I'm sure there could be some issues that directly correlate and others that do not.

    Thanks for any input on where to start.
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  2. chittychittybangbang

    chittychittybangbang Administrator

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    2006 Jetta TDI
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    CT
    snowscreen is for keeping big stuff out of airbox and snow from soaking air filter. Won't affect power or make MAF fail since air filter is filtering everything downstream of it like the MAF. Not hurting anything unless it's clogged.

    yes, adjust actuator before messing with other turbo settings, I have a feeling it'll help a lot, esp since you have that code. adjustment is crucial to prop turbo function

    so how much oil was consumed in 200 mi? After changing oil, it does take some oil to circulate in filter housing and in engine so expect it to go down slightly. If it gets really bad and is going through the turbo you could be coming up to a runaway. see FAQ http://www.myturbodiesel.com/1000q/stop-runaway-diesel-engine-how-to.htm Maybe people are passing you because car has lots of smoke?
  3. blueskymine

    blueskymine Member

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    Thanks for the reply. Will work on actuator adjustment first - which will have to wait until Sunday and will post progress.
  4. blueskymine

    blueskymine Member

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    Car:
    2001 Jetta TDI
    Actuator does not move when the car is started. Disconnected the vacuum line from the N75 valve and brought it down the the ground level. Hooked up a mityvac and applied vacuum in increments and noticed the actuator moving in roughly the correct amount as per the parameters in the write up "how to diagnose, test, or replace the VNT turbo acturator".

    Removed the N75 valve, tested the resistance with a multimeter and it came up 16. something. Installed a different N75 valve (which is supposed to be a new and/or working unit) and replaced several vacuum lines. Tested it for resistance - similar to the first one. Removed EGR solenoid and tested for resistance. Again, similar numbers. Can you verify what the nuumber should read for a correctly working unit?

    I thought I could test for vacuum coming directly out of the N75 valve using a mityvac, but the needle did not move when I started the car. i hooked it up in replace of the vacuum line going to the actuator. Not sure if my thinking is correct on this.

    Hooked back up everthing with the "new" N75 valve, had someone start the car while I watched the actuator and no movement.

    Also looked for and found oil in intercooler (as I suspected I might) about a cup or more of oil by removing the lowest short rubber hose.

    I began to read up on how to look for boost or vacuum leak check thinking since there seems to be no vacuum from N75, perhaps there's a reason.

    At this point, I'm not sure if I should continue to drive the car during my 110 mile commute.

    Just to re-cap - car has about 300,000 miles with little to no past maintenance history. I've changed the oil with Castrol Edge 5W40 and used a Mann oil filter. Replaced fuel filter with Bosch, reinstalled OEM airbox with a new Mann filter. I did do the MAF redline test, and the car could easily make it to the redline. My last fuel economy MPG check came up around 53 MPG.

    Thanks for any input!
  5. chittychittybangbang

    chittychittybangbang Administrator

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    If someone revs the engine, does the vac gauge hooked up to n75 move? not sure what resistance is.

    a cup or more of oil in the intercooler is more than I would like to see...if it's not coming from the crank case vent hose it's coming from the turbo. Esp since that was in only 200 miles.
  6. blueskymine

    blueskymine Member

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    2001 Jetta TDI
    I was checking the ohms with a multi-meter (resistance). There is no vacuum at N75, not even a little with increase in revs.

    I discovered the clamp on the larger diameter black hose coming from the vacuum pump was loose. I replaced the clamp but the metal tube coming out of the vacuum pump that the hose / clamp attaches to swivels and by monitoring the vacuum from the 3mm (?) line that goes to the first T ( the line that comes out just at the check valve just before heading to the brake booster), I can see fluctuation in the amount of vacuum just by twisting the metal tube. I assume this metal part is not supposed to be moving and my guess is, by the time the vacuum is supposed to reach the N75 valve, there's not much left.

    Does this indiacate a need to replace the vacuum pump? or is it normal for it to twist.

    I'll do some more digging with checking vacuum levels at different locations as the lines start to T off.

    If I haven't had any vacuum and VNT actuator movement while driving due to this issue, wouldn't that prevent me from highway speed (65 with cruise control, no problem) and/or would this be the root cause of so much oil ending up in the intercooler?

    Thanks for your feedback and assistance.
  7. chittychittybangbang

    chittychittybangbang Administrator

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    can't remember if it's normal for it to twist but I dont think so. Should not cause loss in vac. Shouldn't be related to oil loss but fix 1 thing at a time and see what happens.
  8. blueskymine

    blueskymine Member

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    Thanks, will post progress as it happens.
  9. blueskymine

    blueskymine Member

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    some success

    After deciding that the main vacuum line out of the vacuum pump is suspect of leaking some vacuum, I used some high temp RTV silicone around the metal outlet tube to make it less wobbly and hopefully maintain better or correct vacuum to the rest of the components.

    Hooking all of the vacuum lines back up the way they should still did not produce any vacuum (at idle) to the N75 valve, but I made a little progress, measuring vacuum with mightyvac with the engine running, I think there's a leak before the vacuum reaches N75.

    Then, after more research, decided to bypass everything and hooked up the main (small) vacuum line (just before brake booster) directly to N75 and drove the car and actually felt and had real acceleration for the first time since driving the car. I consider this quite a break through. VCDS confirmed specified boost and actual boost nearly matched - instead of before where actual boost would decrease instead of increase with higher RPMs.

    Now, to figure out where the vacuum leak is - somewhere between the "main" vacuum line mentioned above and N75 valve for turbo actuator.

    I know there are several T and Y connections. Has anyone had these fail? Is it also possible to have the other valves leak (anti shudder - I think N239) or N18 (EGR) as opposed to actual failure (electrical). I have no other VCDS error codes except for intermittent charge pressure control.

    The anti shudder valve is not secure to the car. I'm not sure where it's supposed to be, but the person before me used a zip tie to keep it from moving too far.

    Also, if, for some reason, the EGR is not functioning the way it should, can that cause a lack of vacuum at N75? It seemed to hold vacuum when I connected a mighty vac to it.

    I also tested the vacuum storage container - I applied vacuum to it and the vacuum did not appear to leak out.

    Once the car is back on track to working correctly, I'll take the time to make sure the actuator is adjusted correctly.

    Thanks and I hope someone can benefit from the dialogue.
  10. djantzen

    djantzen New Member

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    Thanks I didn't know that either!
  11. vtamb81

    vtamb81 New Member

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    Car:
    2000 Jetta TDI GLS
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    Charlottesville, VA
    BlySkyMine, did you find that your problem was a vacuum leak somewhere in the system? I have almost the identical issues with my 2000 TDI right now and am still working through troubleshooting it.
  12. blueskymine

    blueskymine Member

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    I never really figured out where the leak came from. It seemed like perhaps the anti shudder valve was not operating correctly. I had everything taken apart (which is dangerous, because it's pretty easy to forget what hose goes where), but I applied 12 volts to the anti shudder valve and heard the solenoid valve click, which may have dislodged it from being stuck, but I'm not sure. Once everything was put back together, I had enough vacuum to allow the turbo actuator to operated properly. I adjusted it, and the turbo worked ever since. There was only one or two times when it seemed the car slipped back into limp mode, but after shutting the car down and re-starting it, it seemed to correct itself. So it's hard for me to say where the pinpoint of the trouble was. It could have been multiple problem spots.

    I just sold the car late last week with 358K on the odometer, so I'm afraid I can't look at it for verification, if needed. I would measure the amount of vacuum you have right from the source (the vacuum pump) just to be sure you have enough at the source.
  13. UhOh

    UhOh Member

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    spah likes this.
  14. spah

    spah Member

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    Thanks for the link, my pump nipple is slightly loose (doesn't jiggle, but I can rotate it by hand) - nice to see that others have this issue and use rtv to seal it, that's now on the to-do list.
  15. vtamb81

    vtamb81 New Member

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    Car:
    2000 Jetta TDI GLS
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    Thanks for the replies everyone. So we worked on the car again yesterday. This time we went through the vacuum system systematically looking for leaks.
    • we tested the large line coming directly from the vacuum pump, as well as the lines all the way to the N75 and both had a vacuum between 28-30 hg...what i've read indicates that anything over 25 is normal.
    • We also tested the vacuum line at the end of the system feeding the VNT actuator and it had a vacuum of 18. My buddy has an '02 TDI with working turbo and his VNT vacuum line read exactly the same at 18hg.
    • the turbo visually appears to be new as stated by the seller after a failure of the old turbo.
    We're pretty sure at this point that its not a vacuum leak. We observed the VNT acctuator rod while reving the engine in nuetral and could see no noticeable difference between my TDI and my buddies. The acctuator rod starts to move at 6 and completes its movement at 18...which again seems about right from what we've read.

    When test driving from a fresh engine start, it appears that we get some boost (1-2.5 PSI) but then the engine goes into limp mode. FYI, we have seen no difference when swapping the N75 from my buddies functioning TDI.

    So we're slowly chipping away at possible causes, right now we're thinking its could be:
    1. actuator rod adjustment causing turbo vanes to be out of whack. the psi for the rod movement is correct, but the actual visible rod length is almost 2cm compared to my buddies which is significantly smaller.
    2. boost leak in the system somewhere. the intercooler is a little banged up and leaks oil. we tried spraying it with soapy water to see if there was any air escaping but saw nothing. last week we tapped and drained the intercooler and plugged it with a screw. after about 250 miles of driving this week we drained it again and got 3-4 more ounces out....not sure whats normal.
    Really want to figure this out instead of bringing to the dealer.
  16. UhOh

    UhOh Member

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    "last week we tapped and drained the intercooler and plugged it with a screw. after about 250 miles of driving this week we drained it again and got 3-4 more ounces out....not sure whats normal"

    I'd have to say NO. That is, if you're pretty certain that you got most everything out with the first drain you shouldn't be accumulating that volume of oil in such a short period of time: I don't even think that 3-4 oz per 5k would be good, but others might suggest that that amount would be reasonable.

    "the intercooler is a little banged up and leaks oil"

    Fix stuff that needs fixing first! Otherwise you could be chasing your tail.

    BTW - It's hard to keep track of what you did as it's intermixed with blueskymine's thread here. No idea whether you've checked the MAF.

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