Starting issues when hot.

[Seat Adam]

I seem to have a funny issue with my Leon Cupra TDI. It's an 04 plate. The other week I noticed it struggling to start when the engine is hot. The starter turns over for longer than normal. From cold it is fine. Usually turn the key and it starts straight away.
Anyway, I used it the other day and when I started the car it struggled when hot, then when it started the revs dropped and it cut out. Twice. Then it started the third time. It keeps doing it now when the engine is hot.

The car is due its 100,000 mile service which is now booked for 29th so that will eliminate fuel filter blockages. I put a green cotton air filter in in Feb. Spoke to a guy who used to work for Audi and Skoda, he told me engine temp sensor so I have gone and brought one from dealers. Only problem is is that I don't know where it is situated on my engine. Can anyone help?

I'm hoping to fit it this afternoon as long as it has cooled down enough and I don't break the clip that holds it in.

 

[Seat Adam]

Just had a look for the sensor, couldn't find it. Any Ideas?

 

[LEE69]

Coolant temp sensor gets my vote it's in the coolant pipe to the left of the lower engine cover on my LC, might be black or could be green.

 

[LEE69]

Use this guide if the same on yours
http://uk-mkivs.net/forums/t/147822.aspx

 

[Seat Adam]

A big thanks to LEE69 for that link. I searched loads on the web yesterday but didn't find anything as useful as that, so cheers buddy. I thought it was that when I had a quick look under the bonnet yesterday evening but wanted to make sure.
Anyway I have fitted the sensor this morning and need to just run the car and see what happens. I removed the old sensor which was a black one, part number 078919501C. Loads of Audi and VW forums saying these black ones are faulty so lets hope thats what my problem was. I'm sure I'll let you know.

 

[Seat Adam]

Well went out earlier for a nice long drive, got the car nice and hot. Went to start it and guess what, it struggled to start, cut out and then no start for a while like the immobiliser was cut in and not letting it start. After a while of waiting and trying again, got it to start, then drove home no problems. Turned it off on the drive and tried starting it again and it started but struggled.

What else could it be? It's really starting to annoy me now!!!

 

[Seat Adam]

Anyone?

 

[Seat Gooner]

i had something like this with my old golf mk4 tdi i was told its probably the fuel pump i dont know if this is correct

 

[Seat Adam]

Can't really see it being the pump itself as the car runs fine and starts fine when it's cold. It is going into Seat on saturday for its 100k service so I'll mention it to them to have a look. Have to keep an eye on it over this week.

Before I changed the engine temp sensor the engine management light wasn't on. If the sensor was faulty, would it have brought the EML on. If not could it not have stored a fault on the ECU which needs clearing? I'm hopefully putting a code reader on it tomorrow.

 

[Seat Adam]

Well checked it today with a scan tool and no faults found in ECU. I guess i'll have to resolve to Seat having a look when it goes in for its service on Saturday.

 

[Seat Adam]

Got my car back today from having the service done. It even got a free wash and vac, pitty the valeter missed most of the wheels, but hey, I prefer cleaning the car myself anyway.
The service guy put it on VAG.COM and guess what, a fault code. Not brought the dash light on though, so can't be too major. (I know the light works as it does light up every time ignition turned on, also worked when I had glow plug faults.) The code was 16725 P0341000 Cam shaft position sensor circ range/performance. So guess what, it's going back in on Friday now for the sensor to be changed and the fault erased. Will hopefully sort it. The sensor price is £63.24 +VAT and fitting is £35.20 +VAT.

 

[Seat Adam]

Well, been to Seat today, had the sensor changed. The mechanic was little annoyed as I got it hot before I got there hoping it would struggle to start, which it didn't!, and he burnt his hand a few times. Anyway, they checked again, fault still there, changed the sensor, cleared the code and took for a test drive. Seems to be working fine now. I drove it home, turned it off. Started it again straight away and no problem. Hopefully this has now cured the fault, otherwise it has to be crankshaft sensor, so i've been told by an ex Renault mechanic.
So, hopefully all ok.

 

[LEE69]

Fingers crossed.

 

[Seat Adam]

Drove it around today, been fine, went to the petrol station, filled up with diesel. Payed, got in the car, went to start it and nothing. Wouldn't even attempt to start. No noise from engine, relays or anything. Couldn't even hear the pump in the fuel tank.
Pushed it out of the way (with the help of a nice guy with a Kia, asking if i'd put unleaded in it), kept trying, opened the bonnet and waited about 15mins. All of a sudden, started it up. Guess i'll have to get it back to Seat for more checks and more money!

 

[LEE69]

Fuel pump relay?

 

[Seat Adam]

Well the car went back into Seat today. I told them to run it for over an hour then try to see if they could find the fault. Sure enough, it wouldn't start for them, not even turn over. (About time, it's not just me!)

They wiggled the wiring to the starter motor and got it to start. They then took battery and tray out and found a wire broken, and a wire on the starter loose! Don't know how. Anyway, they replaced the wire and made a new connection and I got charged £107.78, £88 labour. Drove it for about an hour so far, got home, trialled it and started straight away no issues. Hopefully all sorted now. Third time lucky!

 

[LEE69]

Let's hope that is the end

 

[Seat Adam]

I hope so, it's cost me about £300 to £400 so far! More testing to follow shortly.

 

[Farlos]

So what's the longer-term verdict mate? Problem still solved?

I'm currently having exactly the same problem on my 2003 petrol Cupra - starts first time every time when it's cold, but after a long journey it sometimes takes four or five turns of the starter motor, or sometimes doesn't work at all! Similar to you - had to get a push away from a petrol pump on Wednesday and then wait for a while before it would start again!!

 

[Andrewcupra TDI]

i too have this problem, still not resolved

if i hold the key fully on when starting it does fire up (you sound like a learner driver ringing the starter motor too long