wont start when engine is warm??

[dalef1992]

been doing this for a while on the girlfriends car 1.4E 16v 2001 on a Y reg ... had it to a mechanic changed map sensor and come back unfixed :/ so im having a tamper with it and think i may have narrowed it down hear goes.


When the car engine is cold it starts first turn of the key no faults idles perfect and then drives spot on temp gauge rises as it should up to 90'C and the car continues to drive ok..... until you turn it off and go in a shop for example come back and it wont start until cooled down to like 70'C. It turns over the engine will judder and idle rough then cut out maybe some times it will idle around 500 and sometimes around 1500 :/ (iv got a video but not sure how to upload it) also if you try to rev it whilst idling rough it cuts it out.


iv cleaned the plugs up and they spark fine

coil pack seems fine and sparks on every lead

cleaned air box out and pipes out

EGR seems ok and has has vacuum when you take the little pipe off.

The only things i can think of is....

1) temp/coolant sensor but the gauge works and no fault on the dash

2) throttle body needs cleaning ( but would this effect when cold starting also if i remove to clean it needs realigning or programming ? )

3) EGR needs a clean out


let me know what you think and if you need the video put your email up i will link it to you if i dont figure out how to upload it


P.S its no central locking but does have a sigma alarm what i dont think even works could it be a fault with this ?

[Defcon5]

Someone else has had this problem, have a search.

The CTS has two outputs, one to the dash and one to the ECU. Allegedly the one to the ECU can be incorrect and the one to the dash fine, so for the sake of 25 quid and a cup of water you may as well change it

[dalef1992]

that's exactly what I thought mate and luckily it's only £11 inc vat from euro car parts ordered it erlia and it's instock for 8 in the morning I always use them for parts and never had a problem so I trust there quality and vw wasn't open today and the girlfriend is inpatient and won't wait afew days so she is settling for a non genuine part :-D will still do the same job

[jon_273]

Is it not something like the fuel temp sensor that causes this (if the 1.4 has such a sensor that is). Definitely read about this problem before on here so have a good search, using google will probably help.

[dalef1992]

I'm unsure about that I think it's just the coolant on the 1.4 I've just done a quick search and can't find nothing I came across about the map sensor but I've already changed that so it's not that either I'm just goin to try this coolant sensor tomorrow and hope it work if not it's only a low cost. :-D

[sharpelupo]

I had this problem on my 1.4 sport changed my coolant sensor and fixed it, best to get genuine senor tho rather then a cheap copy that could easily go wrong

[dalef1992]

I went and got the sensor this morning at 7:30 and quite a cold morning the car got to full temp 90*c after a miles or two and ran fine and started first time ... but just to add I cleaned out the EGR lastnight with WD40 and a thin brush wasnt that mucky but the valve could have been sticking.... we didn't turn the car off this morning incase we got stuck at the shop.. cut a long story short when we got home with the sensor turned the car off (was warmed up) and it started straight back up waited abit temp lowered to around 70*c on the gauge and started back up first try and again after that :-/ puzzled so we waited until it's now sunny just been out for half hour around 15miles and it's starting straight back up first time could the EGR have been the problem as I have not yet fitted the coolant temperature sensor.....

[dalef1992]

update in the fix.....may help others :-D

been afew days now and I seem to have fixed the car.

I cleaned the EGR out With WD40 and the car runs spot on no problem starting when warm must have been the valve jammed shut and engine pressure build up or something :-\ not fitted the coolant temp sensor so it can go back as I no longer need it.