cold start problems

[cypher007]

ive had cold start problems for a while now. here's what ive done so far:

1) vagcom said the temp sensor was nacked, so replaced it.
2) replaced all glow plugs.
3) fitted BMC cotton panel filter.
4) run on shell regular, though did run some millers through it a while back.

any ideas? when it does finally start it puts out some smoke for a second or so.

 

[oldman]

glow plug harness is next, not easy but doable. based on experience and the 300 other threads on cold start issues.

vag-com give anything new? since replace & cleared the error log for temp sensor.

 

[cypher007]

ok

nope. someone said a while back it could be the glow plug relay. if its the harness where do i check, can i test with a meter at various points?

 

[oldman]

not sure if can be checked, but do recall it being mentioned on a thread as possible, so may be worth a quick search.
changed myself and i have no idea and all is good.

do not think it can be checked per se

 

[cypher007]

ahh

when you say changed, do you mean the rubber spark plug type connector rail, which seem to have a connector on one end?

 

[oldman]

yes that thing.
mine is 4wire newer jobbie and gooes along enginer under battery and air filter box to a plug behind there.
noy sure on yours though.

there is a thread called glow plug harness which links to the guide i used

 

[cheshire cat]

ive had cold start problems for a while now. here's what ive done so far:

1) vagcom said the temp sensor was nacked, so replaced it.
2) replaced all glow plugs.
3) fitted BMC cotton panel filter.
4) run on shell regular, though did run some millers through it a while back.

any ideas? when it does finally start it puts out some smoke for a second or so.

which sensor, there is one in the pump for the fuel also

 

[cypher007]

err

its the one in the collant hose intersection, it was the dodgy black version that failed, and i installed a green version.

 

[cypher007]

yes that thing.
mine is 4wire newer jobbie and gooes along enginer under battery and air filter box to a plug behind there.
noy sure on yours though.

there is a thread called glow plug harness which links to the guide i used

where does it break then? i think mine has a connector on the end of the rubber rail.

 

[oldman]

depends i think on engine
mine, thick black thing that to the right as you look at engine joined a bundle of cables and this was all taped together and went through some trunking under battery & airbox up towards the pollen filter location.
had a 4pin plug on it.
easy thing, cut cables at each and re-plug covering up.
i followed the guide noted in previous thread mentioned above;
http://www.seatcupra.net/forums/showpost.php?p=2338839&postcount=13

 

[cypher007]

update

ok ive had a meter on the last glow plug and if i manually hold the glow plug relay in i get about 10v, which sounds good. the trouble is the glow plug relay has 3v on one side and 11.9v on the other side of the coil, im assuming this is the ecu using a low voltage of 8v accross the coil to detect if the relay is ok. so when the ecu calls for the glow plugs it just drops the 3v to 0v.

so my next question is at what temp does the ecu use the glow plugs? is there an afterglow system on these cars? why does the car still take maybe two attempts too start in the morning even if the ambient is maybe 17c. should i try some injector cleaner?

 

[ChrisGTL]

ok ive had a meter on the last glow plug and if i manually hold the glow plug relay in i get about 10v, which sounds good. the trouble is the glow plug relay has 3v on one side and 11.9v on the other side of the coil, im assuming this is the ecu using a low voltage of 8v accross the coil to detect if the relay is ok. so when the ecu calls for the glow plugs it just drops the 3v to 0v.

so my next question is at what temp does the ecu use the glow plugs? is there an afterglow system on these cars? why does the car still take maybe two attempts too start in the morning even if the ambient is maybe 17c. should i try some injector cleaner?

I do believe there is an afterglow system. I had some literature on it, but can't find it right now.

Not sure if this is anygood for you?

http://forums.tdiclub.com/showpost.php?p=1156568&postcount=1

 

[cypher007]

ta

i had a look but it seems its for cars that still wont start with the glow plugs on, so there extending the glow time. i think my problem might be dripping injectors, as when it does start theres a cloud of grey/white smoke, almost as if its burning off unburnt fuel.