[Vwdiesel] Limp Mode Frustration

Sun Mar 4 17:41:45 PST 2012

I doubt you can blow the vnt clean by driving, I think it is more
about freeing the vnt's movement by working the mechanism (by
driving).

The amount of rod movement is small enough that I wouldn't trust a
judgment "by feel" to really say much.  Also, it depends on "where" in
the range of movement it is moving. If you follow me.  If it can only
move from +1 to +5 and can't move into the minus range, that could be
an issue. It could be that the actuator rod length adjustment is off
on the jetta as well.

On 3/4/12, Dave Cook <davevw at yahoo.com> wrote:
> Couple new details:
>
> I swapped the MAP sensor from my working '02 Golf into the Jetta.
>
> The Jetta continued to go into limp, and the Golf did not.  So I guess this
> would say the MAP Sensor is ok.
>
> Also, I compared the feel of the actuator between the two cars.  They
> feel the same to me.  I did note that the Jetta's actuator did seem to
> very slowly lose some vacuum while the Golf didn't, but it was so slow I
>  figured that either 1) it might be a small leak between a hose and the
> gauge or 2) it was small enough that the computer/N75 could be able to
> compensate.
>
> Maybe I'm wrong on that.
>
> Any other ideas?
>
> Dave Cook
>
>
> ________________________________
>  From: Dave Cook <davevw at yahoo.com>
> To: VW Diesel Group <vwdiesel at vwfans.com>
> Sent: Sunday, March 4, 2012 3:49 PM
> Subject: Re: [Vwdiesel] Limp Mode Frustration
>
> More thoughts/questions from a response I just put up on TDI club.
>
>
> I have pulled a vacuum on the line from the N75 and felt the rod move.
>
> To add details from what others have asked:
>
> The intake manifold was cleaned when I had the head apart.
>
> I also checked that the rod moved at that time on the turbo.
>
> Head was off because it was pushing exhaust gasses into the coolant.
>
> And a couple questions:
>
> I have heard of people having success blowing the vanes clean by driving
> it hard.  Is this at all effective if it is in limp mode and the turbo
> is shut down by the computer?  Do I need to keep restarting it to clear
> limp mode (briefly...) or can I keep driving it hard to try to blow it
> clean even though it is limping?
>
> Also, if the vanes are stuck from crud, will the actuator rod move?  I was
> under the impression it wouldn't.
>
> Dave Cook
>
>
> ________________________________
> From: Dave Cook <davevw at yahoo.com>
> To: VW Diesel Group <vwdiesel at vwfans.com>
> Sent: Sunday, March 4, 2012 3:33 PM
> Subject: Re: [Vwdiesel] Limp Mode Frustration
>
> I did clean the manifold, and it didn't have a very thick layer anyway.
>
>
> I can reach down and move the actuator rod, and when I had the head off I
> also checked and it seemed to move appropriately then too.  I do intend to
> set it side by side to my Golf and see if they feel similar.  But it does
> move, and I can attest that no one has tried adjusting anything since before
> when it drove well.
>
>
> Dave Cook
>
>
> ________________________________
> From: "dieseltdi at verizon.net" <dieseltdi at verizon.net>
> To: Dave Cook <davevw at yahoo.com>
> Cc: vw fans <vwdiesel at vwfans.com>
> Sent: Saturday, March 3, 2012 10:04 PM
> Subject: Re: [Vwdiesel] Limp Mode Frustration
>
> Just off the top of my head, it sounds like the VNT vanes are stuck causing
> an over pressure situation.  If the vanes are stuck they can't modulate the
> boost pressure.  Another possibility could be a really clogged intake
> manifold.  When you fixed the other stuff, did you remove and clean the
> intake?  I also had this problem when I installed the hoses on the N75
> wrong.  You might want to closely look at that also.  Just a few things off
> the top of my head.  I will kick it around a bit more and think about it to
> see if anything else comes to mind.  Hayden
>
> On Mar 3, 2012, at 9:43 PM, Dave Cook wrote:
>
>> This is a friend's '01 Jetta TDI.  Keeps going into limp mode, sometimes
>> with a check engine light, sometimes without.  Has been this way for a
>> long time.
>>
>> Last spring, I replaced all the vacuum lines while replacing the head
>> gasket, timing belt, and a few other bits in hopes of fixing this.  Also
>> replaced the N75 at that time.
>>
>> Still goes in limp, and does it more often than not at this point.
>>
>> I decided to try some more troubleshooting today.  In doing some
>> driving, I found that the ECU would show two different codes after going
>> "limp".
>>
>> They were:
>>
>> 16618 - Boost Pressure Regulation
>>             P0234 -
>> 35-00 - Limit Exceeded (Overboost Condition)
>> 16492 - Manifold / Barometric Pressure Sensor (G71) / (F96)
>>             P0108 -
>> 35-00 - Signal too High
>>
>> They were showing up sort of alternatively, maybe a couple times one of
>> them and a couple times the other.  Or a couple one, then the other,
>> then back to the one.
>>
>> Once, both popped up at the same time.
>>
>> I was romping on it going up hills during this testing.  It only took a
>> couple seconds of heavy acceleration to cause limp to come up after
>> having shut down the car and clearing the codes.
>>
>> I then pulled the MAP sensor from the intercooler.  I noted a oily
>> coating on it, so I cleaned it off with air flow sensor cleaner.  No
>> change on reinstallation.
>>
>> I'm thinking the problem might be the MAP sensor, but my friend doesn't
>> want to throw money at the car hoping something fixes it.
>>
>> Any other thoughts?
>>
>> Dave Cook
>> _______________________________________________
>> Vwdiesel mailing list
>> Vwdiesel at vwfans.com
>> http://www.audifans.com/mailman/listinfo/vwdiesel
>
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