Turbo And Maf Problem?

[TeamGreen]

Hi everyone, my 98 Sharan 1.9 TDI AFN engine has got the usual overboost problem which I'm working my way through with just the vaccum hose to the ecu to replace and a good dose of Millers as a first attempt at the limp mode. I have been trying to avoid going into limp mode by keeping the revs below about 2500 revs but there is just no power. I've tried it with the MAF both connected and disconnected with not a lot of difference between the two. I know from everyone elses posts that this points to the MAF having failed, it was last replaced 5 years ago, but as the engine warms up it does improve a bit so I was wondering if there is a temp sensor that might have failed leading to the ECU running at incorrect settings?

 

Thanks in adavance.

[TeamGreen]

Update.

 

Having struggled with no power for a while I noticed that if the car had been stood for an hour or so after getting up to temp the low down power was greatly improved so I changed the coolant temp sensor as I believe that if it's giving false readings then the fueling will be way off. This seems to have sorted out the low down power prob as even from stone cold, -5 air temp, there is plenty of power.

 

I now need to change the ecu vaccum hose as there is a hissing behind the dash / footwell area and whilst I can trace the hose from the footwell to the ecu and also along the bulkhead but where it drops down in the engine bay to pass into the car I loose sight of it. Can anyone tell me what I need to remove in the engine bay to change this so I can stop the overboost?

 

Cheers.

[westytwo]

Update.

 

Having struggled with no power for a while I noticed that if the car had been stood for an hour or so after getting up to temp the low down power was greatly improved so I changed the coolant temp sensor as I believe that if it's giving false readings then the fueling will be way off. This seems to have sorted out the low down power prob as even from stone cold, -5 air temp, there is plenty of power.

 

I now need to change the ecu vaccum hose as there is a hissing behind the dash / footwell area and whilst I can trace the hose from the footwell to the ecu and also along the bulkhead but where it drops down in the engine bay to pass into the car I loose sight of it. Can anyone tell me what I need to remove in the engine bay to change this so I can stop the overboost?

 

Cheers.

 

The pipe runs along the bulkhead from left to right as you stand at the front of the car. Remove your scuttle plate (the big plastic thing that spans the width of the engine bay and goes under the wiper mechanism) there should be 3 10mm bolts holding it in place 1 on the left, 1 on the right and 1 in the middle. You wont believe how much more access this gives you. The pipe comes off the bulkhead to the front of the engine onto a solid plastic pipe (black) which drops down onto your turbo intercooler. There will also be a sensor attached to this plastic hose with a wire coming off it so you should be able to identify it. Hope that helps and hope that cures your problem, it did not help on mine but its worth trying.

[zorgman]

if yo have hiss at dash the ecu is begind clocks chances are its not connected but also theres a vac pipe goes to the heater speed switch for air recirculate. inside the ecu is a small link pipe that connects to the map sensor, this goes all gooey soft and the vac can suck it in and it clags together so stopping the vacuem getting in.

i changed every pipe on mine used 15foot of pipe to find out about ecu internal pipe had gone

[TeamGreen]

Thanks guy's,

 

here's hoping for a dry weekend and permission to have a look but then again it's Mothers Day weekend so that might be an issue.

 

Will let you all know how things turn out re the hoses.

[love_dem_galaxies]

Best of luck with the hiss-I fixed mine but still have the scars. Whowever designed the ecu housing must have been a sadist! You will not beable to see the screws but they ahave a security pin in the center and are torx or hex. You woll also have to remove the big ecu plug, there is a plate at the back that unscrews that stops the locking mechanism sliding. Fixing the ecu once its out is dead easy. Good luck! Srry bout spelling, im using my mobile. Mark

[westytwo]

Best of luck with the hiss-I fixed mine but still have the scars. Whowever designed the ecu housing must have been a sadist! You will not beable to see the screws but they ahave a security pin in the center and are torx or hex. You woll also have to remove the big ecu plug, there is a plate at the back that unscrews that stops the locking mechanism sliding. Fixing the ecu once its out is dead easy. Good luck! Srry bout spelling, im using my mobile. Mark

 

 

Hi Mark,

 

Did you have to remove your dash to get the ECU out? I have replaced all hoses to including the 1 to the ECU but not the internal 1 inside the ECU. It looked like a hell of a job to remove the ECU! How is the ECU fixed to the car is it bolted? Replacing the hose to the ECU was a mission lol! ,but i reckon that might to cure my problem my symptoms are the very similar to yours.

[westytwo]

if yo have hiss at dash the ecu is begind clocks chances are its not connected but also theres a vac pipe goes to the heater speed switch for air recirculate. inside the ecu is a small link pipe that connects to the map sensor, this goes all gooey soft and the vac can suck it in and it clags together so stopping the vacuem getting in.

i changed every pipe on mine used 15foot of pipe to find out about ecu internal pipe had gone

 

 

Hi, did that cure your problem when you replaced the internal hose???

[ncb]

Is this vac pipe to the ecu just for the non-pd tdi's or do the 2000 on Pd-Tdi's have them too?

 

I have a 2002 115bhp Sharan Pd-Tdi and when I accelerate at about over 3000 revs I can also hear a hissing from the dashboard area, seems like it comes from behind the glovebox area. I am getting the same limp mode problems after pushing the car especially uphill.

[zorgman]

yes fixed my problem on car but a sod to get ecu out but well worth it, month later got limp mode again ripped turbo out and gave it agood clean with oven cleaner cars never flackered since