Leon tdi cupra 150 arl engine - slow and reluctant start when cold - NOW FIXED!!!

[MJ]

Easy (and free!) way to see if the ASV is the cause - make sure it's open (look at position of operating arm), then take the vac pipe off and temporarily block it so the ASV can't be operated and jam shut when the engine shuts down next time. Just be very careful removing the vac pipe from the ASV, I'm told it's very very easy to break the plastic pipe nipple off.

Its been disconnected for 12 days now - no difference.

I've fitted a new valve for the top of the fuel filter - the other was stuck open but sadly this appears to have made no difference. I think that air is entering the system and allowing fuel to run back into the primary pump, the return pipe feeds directly into the primary pump this returned fuel is then pumped back into the system.

There just seems to be no fuel pressure there once the car has been stood for a while.

 

[MJ]

Well after a few hours in the workshop on saturday it looks like i have finally resolved my starting issue. Believe it or not (because i didnt) the fault was being caused by leaking injector seals!!!
I've worked on 100s maybe even 1000s of vag Pd engined cars and have come across many strange and intricate faults but i have never known one to have leaking injector seals.
I can and will put this down to using low quality fuel (ASDA's own "low sulphur diesel") because the car has ran without fail for the past 4 months whilst i've had it and the 2 years the previous owner had it using all different fuels.
I contacted a number of people with regards to this issue who all basiclly siad what i thought they were goin to say which was "If you use diesel which has a high level of detergent in it, this will eventually eat away at the injector seals - thus causing the problem you are having".

The repair itself was straight forward:
1.Remove the cam cover
2.Remove the rocker arms
3.Remove the injectors
4.Clean them and remove the old seals
5.Fit the new seals
6.Refit the removed items
7.Then test the car

Then leave it over 4 hours then try and start it, it now fires on the button just how it used to.

I have to thank a few people for the help i recieved with this problem, they are:

The members of this forum - who suggested many tests and procedures i could carry out
The members of uk-mkivs who pointed me in the right direction
And the nice chaps at feathers diesel in halifax

The peolpe who i would NOT like to thank are Seat technical due to there ignorant and arrogant attitude towards my vehicle and the fault in hand because they were both insulting and generally about as much use as boobs on a bull dog.

 

[devonutopia]

Kind of glad I read this thread and the last post especially. Whilst my car is off the road for a month+ I have removed the injector units and sent them away for bench testing at a Bosch specialist, United Diesel. I was getting occasional bad starting, no more than 4 seconds perhaps until it started, but worst of all, I was getting a small misfire between 1500rpm and 2500rpm when just slightly on the gas, but fine on WOT, which could also have been caused by leaky seals. I have now contacted United Diesel (who I hasten to add KNOW THEIR SHIZZLE when it comes to these injector units) to get them to check the seals, etc during the bench testing and if necessary renew anything worn out. Forgot to add, my injector units have also been fitted with Bosio Race 783 nozzles which could also be at fault perhaps.

 

[MJ]

It might be worth the cash to just replace them mate, i bought them through work (i got them at cost price and it they were still £13 per injector!) they come with all the rubber seals, the pluger for the top of the injector and the brass seal at the base of the injector, to be honest as i have stated i havent seen this before so i was really baffled by it. The car just litterally one day failled to start, then every time i left it for more than an hour it refused to go unless i let it turn over for about 15-20 seconds then it would begin to fire then eventually go.
I know yours i running really high power so it might just be worth a strip down and replacement seals because of the raised pressures.
What kind of fuel do you use?

 

[devonutopia]

I use any old fuel as the car was mapped on city diesel, so generally use that, or whichever is cheapest. 90% of the time I would say it is Tesco/Sainsburys diesel with added Millers, and the other 10% is Shell, perhaps a smattering of BP/Esso. I might switch to using only BP ultimate or Shell VPower diesel, but have always found the car more powerful and economical on supermarket stuff, with added Millers.

 

[MJ]

i was never one to jump on the band wagon when it concerned how powerful diesel was so i just used to run adsa low sulpher stuff with forte injector cleaner (no performance benifits and it still smoked its c*ck off), now on the otherhand i prefere to use v-power and run millers aswell.
I read a thread on here recently that v-power is the best performance diesel and has a much higher cetane level when compared to others, this with millers should mean much improved performance and driveability, however i've only done about 60miles but things do seem better.

 

[Andrewcupra TDI]

i seem to have the opposite to you , where its ok from standstill its when driven for a while ehrn hot , it wont restart , if i hold key on continuous it will fire

baffling me know

no codes which pi$$ me off more than anything

cheers

 

[MJ]

Yours could be something expanding when hot and allowing air in somewhere, do you have any visual leaks around the head i.e the fuel pump gasket?

 

[Andrewcupra TDI]

not that i can see will try and get another look

cheers

 

[Andrewcupra TDI]

notice my intank pump builds some heat up , if i fold seat and feel the top its quite warm , this normal

also when ever first start up it coughs and chucks out a cloud of blueish white smoke , after that first instance it doesnt smoke at all , ??