Turbo cutting out at around 60mph, have already checked MAf and Map Sensors

**Don_passat98** · 12-02-2008,12:59 AM

I have a passat and am having this problem. if i drive my car up to around 60mph the turbo cuts out and only starts working when engine is switched off and on again. Urban driving is not a problem as they is never any need to exceed 60mph but when i get on the motorway i have problems.

i changed the maf sensor with no success. i've also checked the map sensor , did this by disconnecting and tried driving the car , it had a lot less power which should indicated that it was working.

i plan to take the car to a garage at the end of the month but would like some pointers so i don't end up with a huge bill. I've heard of people being made to purchase new turbos and really don't want that. engine code is avn 1.9 tdi. i have tried reading extensively in other forums and tried all sorts with no success.

**Don_passat98** · 12-02-2008,01:06 AM

additional information.

You can actually hear and feel the turbo cut off as they is a loss of power. from my reading around i think the car is going in to limp mode , i've checked the turbo pipes for any leaks or splits and i cant find anything.

**angrydad** · 14-02-2008,07:45 PM

Have you checked the EGR valve? Simple way to do it is to pull the pipes off and see if the valve is full of gunk. If so, thats the likely cause of the problem.

The EGR (exhaust gas recycling) valve is located at the top of the engine at the left hand side. Unless you are proficient under the bonnet, I would recommend you get this checked at a garage who can service VWs

The turbo on my TDI 130 used to cut out if I accelerated at 6omph and would not come back on until I restarted the engine.....interesting whilst in the outside lane on the M4!!

Anyway, local VW specialist diagnosed the EGR valve, got one off eBay for 60 quid and it cured the fault immediately.

Hope this helps.

**kenney** · 14-02-2008,09:13 PM

Hi I think you will find your engine code is AFN however the charge pressure control solenoid valve -N75, is acommon fault on these engines

**Don_passat98** · 17-02-2008,08:13 PM

Thank you gentlemen i'll check the N95 valve and the egr valve and get back to you and give an update.

**bazzy20** · 01-03-2008,06:57 PM

i have the same problem with mine. i have the 1998 1.9 tdi 110bhp. at first the turbo wouldnt work at all but i changed the turbo pressure sensor costing nearly £90 and the turbo started to work but it hasnt worked properly because it cuts out after its been used for a while and also while speeding up for the motorway. i have had a diagnostic check done on it and it had no results. i checked for an air block and the filter was clear. i checked the hoses and replaced most of them and this still had no effect. ive tried disconnecting the air mass (thing) and there is still no change. can anyone help me out? could it be something to do with the fuel filter etc or any other fuel problem?
thanks Barry.

**ini** · 02-03-2008,12:16 AM

If you have renewed the MAF etc, a sticking VNT turbo mechanism is the most common cause of high gear limp mode.

The variable vane mechanism (internal wastegate) sticks 'open' and causes limp mode. (This is more prone to happen in higher gears when the revs are changing slowly)

Either a long journey (prolonged operating temperatures) or cleaning the turbocharger will stop it.

**danielintheuk** · 02-03-2008,09:17 PM

Hi mate

I have just had this problem with my passat, I thought I had checked all the easy stuff, but there was a hard to see vacuum pipe which I had missed . When I found it and plugged it in ...it solved the problem.

On the boost pipe ( solid pipe) which is parallel with the bulkhead ...there is a vacuum pipe which goes into this solid pipe, it is really hard to see , and therefore very easy to miss. I think its worth you having a look because if its not the problem you will have only wasted 5 minutes, and if it is the problem its a very easy fix.

Hope this helps.

Dan

**Don_passat98** · 04-03-2008,04:07 PM

cheers mate i'll have a look. does anyone by any chance know wot the n75 sensor does because i'd like to check that as well.

**ini** · 04-03-2008,05:53 PM

On your 110 car, it electronically manges the amount of vaccum applied to the turbo's VNT mechanism actuator.

The variable vanes are controlled by a mechanical rod & lever attached to a sprung diaphragm vac capsule.

This is in turn controlled by a variable vacuum regulated by the N75, which is electronically controlled by the ECU.

(in early 90bhp cars, the N75 manged the 'positive pressure' controlled external wastegate)