Seat Leon FR TDI - bad starting

[moondustka]

Hi everyone, just after some other opinions if poss..

The car is as title, 56 plate - have owned it since 68,000 miles, now on 110,000. Early on during this mileage period, the car decided not to start very well and it's been the same ever since. No engine lights on, I did replace all glow plugs a while back also. It's just finally got very annoying.

It's marintlly worse in colder weather and very occasionally it takes a good 5 mins of intermittent cranking before it will cough, splutter and start. Sometimes you just need to keep the key turned as it goes to start to help it along a bit until it picks up its own momentum.

After some research I'm thinking this is either a clogged EGR valve or maybe a MAF sensor?

Anyone agree or have any other ideas? Was going to try EGR first.

 

[Frank]

Hook it up to OBDII and see what he makes of it?

If really forced to choose, then based on the poor starting in cold, I think I'd be looking more at the MAF side before the EGR. Do bear mind though, what I know about Seat Leon engines could be written on the head of a pin.

 

[moondustka]

Thanks Frank. Someone else has told me MAF sensor also - OBD says nothing, no codes. They only thing it had last time was an O2 sensor, which kept bringing the coil and DPF lights on. Never come on since.

I understand what a MAF does in the running of an engine but from the knowledge I have I don't know why it would affect starting?? Any idea?

 

[TGPlayer1]

EGR valves can cause bad starting if they get stuck open. Had a total mare with a Jag not starting and it was the EGR sticking open.

 

[moondustka]

[post]347338[/post] EGR valves can cause bad starting if they get stuck open. Had a total mare with a Jag not starting and it was the EGR sticking open.

Perhaps I'll try cleaning it - it's worse on some first starts than others.

Maybe try cleaning the EGR and get a new MAF as a matter of course.. I think it needs anoth cam belt this year also :roll: monies!

 

[Frank]

[post]347336[/post] I understand what a MAF does in the running of an engine but from the knowledge I have I don't know why it would affect starting?? Any idea?

As I understand it, if there is a fairly weak (or no) MAF signal then the ECU will instruct that no fuel will be injected so the engine does not start.

In addition, the ECU also uses the MAF signal to control the EGR system, so you can indeed have an EGR in the wrong position causing problems, but it's like that because the ECU told it to be like that based on incorrect MAF input. It's like a dog chasing its own tail, sort of thing.

All of that just boils down to is that they reckon check out the MAF before the EGR side. MAF-wise, you only have spray sensor wire with ContactCleaner (and unplug and do the connector as well) or replace options anyway, I think. I got lucky and spraying the sensor wire fixed mine.

In your own case, the lack of error codes is a puzzle and (I might be wrong on this next bit, this is complex stuff) wouldn't a MAF so far out as to mess up starting also cause more obvious MAF related problems when the car is running and I note that you didn't mention any? Still, the MAF doesn't take long to check out.

 

[moondustka]

Thanks for that Frank, that's a great help.

Well the only other issues I have are high idle at odd times, although I'm also told that can be part of the regen for DPF. But it also goes lumpy on idle sometimes. Sounds smooth but shakes the car slightly in an oscillating motion like I imagine an unbalanced flywheel or crank would.

I think I will try the MAF as you said and get a new one. I did find out that it's not unusual for my engine to be on its 2nd MAF by my mileage, and this one (from service history) is original.

Thanks again

 

[Anonymous]

possible glow plug wiring issue

 

[ArtfulHussy]

[post]347381[/post] Thanks for that Frank, that's a great help.

Well the only other issues I have are high idle at odd times, although I'm also told that can be part of the regen for DPF. But it also goes lumpy on idle sometimes. Sounds smooth but shakes the car slightly in an oscillating motion like I imagine an unbalanced flywheel or crank would.

I think I will try the MAF as you said and get a new one. I did find out that it's not unusual for my engine to be on its 2nd MAF by my mileage, and this one (from service history) is original.

Thanks again

This might sound daft but I had constant limp mode problems on my 3.0tdci sigma and also had the smooth but shaky idle you described here. I had the belt done and took the car for a run over 100miles cruising between 60-70mph. I have had a single limp mode or shake since. I understand on my car at least there's some kind of sensor that runs off the crank. Think it was something to do with dpf. I know little of diesel engines. It just surprised me that the problems seemed to go after the belt change and a blowout.

 

[tuonokid]

Hi Ben
What about water temp sensor?
Barry

 

[oilburner]

Is this still the Pumpe Duse engine? If so there was an issue on the 1.9 where the injector wiring frayed but as its inside the rocker cover its not immediately noticeable

 

[moondustka]

Thanks for the replies

I still haven't got around to actually doing anything. It's due a service, cambelt and water pump, MAF. It needs about £1000 :roll:

The wiring for the glow plugs is under the rocker cover as you say, I think the Germans have tried to be too clever here. It's even a nightmare just to get the rocker cover off. Whenever I touch this Leon, it makes me realise how easy I can get to everything on my Puma.. But I have re-designed half of it :lol:

 

[moondustka]

So, the car had its cambelt, water pump and a Bosch MAF sensor done in June.

Unfortunately, it still starts poorly. Maybe a blocked EGR valve? No dash lights either.