Its That Dreaded Limp Home Again

[Seatdriver]

Hi,

 

I have posted on this forum before regarding my 03 Sharan overboosting and going into limp home. However I have recently observed the following and wondered what other peoples views are:

 

When the car is stone cold it will pull in every gear no problem even uphill. The revs get taken to 3000rpm(no choice im afraid as its a very long steep hill) and it NEVER cuts out regardles of how hard or how long you push it, it whatever gear.

When it is at full operating temp again I can start at the bottom of a very long steep hill and make it pull 4th gear from 30-60 and even use 5th at 60 keeping my foot hard down. The turbo whistles nicely (no odd sounds) and it NEVER cuts out.

 

Now if the car is run for 20 miles at 70mph, then left for 1.5 hours, then taken up a hill and carefully accelerated, the temp gauge showing 3/4 warm, it appears sometimes to fluff(hesitate) very very slightly and then off goes the power.

When I drive round town again at this temperature I will occasionally get a slight hesitation (not misfire) when accelerating. Its ony momentary and when lightly accelerating, when it begins to hesitate I can accelerate hard and car will accelerate away with no hesitation or fluffing whatsoever.

 

So this has be baffled, it may sound daft but the turbo appears to cut out when the engine is at a particular temperature(3/4 warm) and in all instances going uphill into a left hand turn (Shallow).

 

What to check,where to start!

 

Thanks

[sanjsanj]

don't know if you know this but, IIRC you can get out of limp mode by switching the engine off and restarting. Don't do this on the go though!

 

just a thought, if you have a trip computer, try monitoring the oil temperature.

 

out of interest, whereabouts is this stupid steep hill? scotland by any chance?

[chromedome]

If it's only when accelerating lightly it could be the throttle position sensor. The first segment could be worn, as that's used the most, and when you accelerate hard you pass over the worn bit.

[Seatdriver]

hi,

 

As to this steep hill, The Lake Distict! So yes Scotland Direction and yes I was aware of the switch off and on nonsense, v.dangerous having to carry out this on a busy motorway!

 

Regarding throttle position sensor, I wondered about this as the Sharan is now coming upto its 100,000mile and it must be worn.

 

Wonder if the loss of the throttle position under acceleration could cause the ECU to trip out the Turbo as it has in effect lost an important input into the system at a rather critical point.

 

Also wondered if the valve that is hidden away behind the heat shield that controls the amount of vaccuum delivered to the diaphragm that subsequently pulls on the turbo actuator hence moving the vanes could be worn and occasionally sticking (the valve not the vanes or linkage), it wouldnt take much and it must contain a stepper motor of sorts. After 100,000 miles it must be worn!

 

Penny for anyones thoughts.

[marinabrid]

have you had it on a vag com to see if there any faults, ours did a similar thing when warm, the fault was logged as the throttle position sensor. got a new pedal unit for Edited December 18, 2007 by motorcareman

[Rosie]

Hi

 

Try this as it worked for me on my old Gal.Buy some turbo aerosol cleaner from halfords,about