Tdi Keeps Cutting Out

[98 TDI 90]

Hi folks, I really hope someone out there has a clue on this one. I'm now on first name terms with the nice AA man.

I have a 1998 TDI 90 bhp that has done 99k miles. Up until recently it's been reliable and economic (great fun too).

For the last six months it has been cutting out, no tell tale signs to warn you, just dead. This usually happens right at the worst possible point. The thing just goes dead as if I'd turned the engine off myself. It usually won't start straight away but after a few minutes it's fine, as if nothing had happened.

This is intermittent too, from 3 days to a month and a half between occurences. Fuses are all fine and the fault doesn't register anything on any fault code reader. I've had a new MAF fitted, hoses replaced, tried new keys, the list is endless.

Other than this the car runs well, is economical, doesn't smoke too much for a 99k car and I don't want to have to bin it. The trouble is that you never know quite when it'll let you down.

If anyone has any ideas then please contact me, all efforts greatfully recieved.

 

[CraigW]

Try the idle control valve or whatever it is. When the car is running idle this switch is on to keep it at the correct runs at idle speed. Sometimes when you start moving this doesnt switch off to let the car run at the correct engine speed for gear etc.

My mate has this problem with his 206. It starts alright and idles fine. As soon as you start moving it starts stuttering and wanting to stall and its because this switch doesnt switch over.

 

[98 TDI 90]

Thanks Cruiser87 I'll give it a go and let you know the outcome. Someone else has recommended a relay, number 109 I think.

 

[sssstew]

yep exactly what i was thinking as i was reading your thread, have a look to see what you have, the older grey style ones were a problem with overheating and cutting the system, swap out for the newer black one. check yours.

 

[98 TDI 90]

Latest update.
Thanks to sssstew for his post.

I've fitted a new relay 109 (new vw one is grey-old seat one was black), sourced from a VW dealer as none of the local Seat dealers kept it in stock. No further cut outs yet but time will tell. I'm going to assume it's fixed after two months of driving without it happening again. Wish me luck!

Relay 109 apparently controls the fuel pump, so the VW dealer told me, in case any of you were wondering. When I removed the old black 109 relay it was bloomin' hot. The new grey one seems to be running cooler so far.

The idea about an idle control valve seems to have led me to (yet another - getting used to them with this problem) dead end. My specialist VW/SEAT/AUDI/SKODA garage advise me that those valves are strictly a petrol only thing. Any thoughts on that anyone?

Another suggestion given to me by the VW dealer was a wire broken between the ECU and the fuel pump (apparently common on some Leons). I'm praying that's not the cause as I don't fancy chasing that one down myself, or paying the bill for the auto electrician to do it.

Hey ho, just keeping everything crossed for no more cut outs for now. Keep the ideas coming in though guys, every little helps!

 

[sssstew]

ah seems like i got my colours the wrong way round. anyway glad it sorted (well seems to be) hope it stays ok. The 109 relay is classed as the main power relay so i think it does more than just the fuel pump.

idle control valve - yep petrol only.

 

[CraigW]

idle control valve - yep petrol only.

I wasnt to sure if they were only on petrol cars or not. Thats why i suggested it because i wasnt to sure.

 

[98 TDI 90]

Success!

Well folks, that good ol' relay 109 seems to have fixed the problem good and proper. No more cutting out and the fuel economy seems to have improved a bit too. Result!

Thanks to everyone who offered advice and assistance. Even wrong ideas helped me to weedle out the seemingly endless list of possibilities that my garage came up with when I first mentioned the problem to them. So thank you to you all.

 

[sssstew]

nice one, glad it sorted, thanks for letting us know.