passat starting problem

[billza1967]

hi all can anyone please help i have an 02 passat tdi 130 bhp its had a new turbo and cat a new cylinder head complete with cam valves injetion pumps etc cost 2500 from vw new airflow meter new coolant temp new ecu the problem is this, car starts and runs fine its only when its hot if i turn off the engine and try to restart it fires up for about 3 seconds then dies it does this about a dozen times then starts ,but when it starts theres no response from the accelerator for about 5 seconds i had an auto electrician look at it and he put a resistor in one of the wires coming from the coolant temp sensor this cures the starting problem only snag is it eats the fuel ,so i took it off if anyone can shed any light on the problem i would be most grateful there are no fault codes showing im really at the end of my tether ive spent over 4000 up to now vw say it could be the immobiliser which is built in to the instrument cluster which will cost another 350 but they havent been right about anything so far if it is the immobiliser why does the problem only occur when its hot thanks to all who read this
bill

[caldirun]

If its the immobilizer the yellow key symbol will be flashing and if you hold the key on full turn after a couple of seconds the engine will stop firing but will keep turning over. Sounds like fuel temp sensor is not working if the resistor cured the problem, check it with Vag Com.

[billza1967]

If its the immobilizer the yellow key symbol will be flashing and if you hold the key on full turn after a couple of seconds the engine will stop firing but will keep turning over. Sounds like fuel temp sensor is not working if the resistor cured the problem, check it with Vag Com.
hi mate thanks for the advice i changed the fuel temp sensor but its made no difference i had a new cylinder head fitted by vw and the problem started about 3 days after could it be some other sensor on the cylinder head or could the lambda sensor cause it ; or could it be the camshaft sensor its been on the computer and theres no fault codes it only happens when its hot im at my wits end i use the car to taxi and im terrified its going to cut out while im driving .it did cut out once while i was driving and it took about half an hour to get it goin again ;i got it started by moving the egr valve flap and turning the engine at the same time could it have anything to do with that when it does start it runs for about 5 seconds before i get any response from the accelerator

[billza1967]

hi mate thanks for the advice i changed the fuel temp sensor but its made no difference i had a new cylinder head fitted by vw and the problem started about 3 days after could it be some other sensor on the cylinder head or could the lambda sensor cause it ; or could it be the camshaft sensor its been on the computer and theres no fault codes it only happens when its hot im at my wits end i use the car to taxi and im terrified its going to cut out while im driving .it did cut out once while i was driving and it took about half an hour to get it goin again ;i got it started by moving the egr valve flap and turning the engine at the same time could it have anything to do with that when it does start it runs for about 5 seconds before i get any response from the acceleratorby the way mate although i still have the problem with hot starts it has made a difference to the overall running of the car it runs a lot smoother and quieter and it ticks over lovely it only cost 12 quid for the part so it was worth changing if i ever get to the bottom of this problem ill let you know cheers bill

[caldirun]

Hi Bill, look for something that activates when the engine is hot, I suspect a vacuum leak (pipe off or incorrectly placed or leaking diaphragm), the EGR can be disabled by removing the vacuum pipe and plugging the pipe, it is a mushroom valve though, not a flap valve as you suggest (puzzled as to how you moved the flap?). If resistor cured it could it be the device that is activated by the fuel temp sensor (maybe air intake flap valve, the resistor would not change and activate this!), I dont know enough to point you where, you could do with more response, come on guys!

[billza1967]

Hi Bill, look for something that activates when the engine is hot, I suspect a vacuum leak (pipe off or incorrectly placed or leaking diaphragm), the EGR can be disabled by removing the vacuum pipe and plugging the pipe, it is a mushroom valve though, not a flap valve as you suggest (puzzled as to how you moved the flap?). If resistor cured it could it be the device that is activated by the fuel temp sensor (maybe air intake flap valve, the resistor would not change and activate this!), I dont know enough to point you where, you could do with more response, come on guys!
hi mate i just assumed it was a flap inside the egr valve the other thing i think it might have something to do with the fuel pump inside the tank because when it doesnt start i cant hear the pump priming up but it works ok when the resistor is there i think your definately right about something the temp sensor is wired to could it be the accelerator because when it does eventually start i get no response from the accelerator for about 5 seconds ,then i can hear a sort of clickin sound like a relay or something then thats when the accelerator works,do you think it could be the fuel pump relay or could vw be right about the immobiliser i just doesnt make sense mate, puttin a resistor in cures it but makes it eat fuel taking it off makes it hard to start when hot ive now spent more on the car in the last four months than i actually paid for it lol thanks for tryin to help me out mate i really appreciate it i think ill try disabling the egr valve ill let you know what happens cheers bill

[billza1967]

hi mate i just assumed it was a flap inside the egr valve the other thing i think it might have something to do with the fuel pump inside the tank because when it doesnt start i cant hear the pump priming up but it works ok when the resistor is there i think your definately right about something the temp sensor is wired to could it be the accelerator because when it does eventually start i get no response from the accelerator for about 5 seconds ,then i can hear a sort of clickin sound like a relay or something then thats when the accelerator works,do you think it could be the fuel pump relay or could vw be right about the immobiliser i just doesnt make sense mate, puttin a resistor in cures it but makes it eat fuel taking it off makes it hard to start when hot ive now spent more on the car in the last four months than i actually paid for it lol thanks for tryin to help me out mate i really appreciate it i think ill try disabling the egr valve ill let you know what happens cheers billhello mate i disabled the egr valve done what you said it now starts everytime i cant thank you enough i know this might sound daft but does that mean the egr valve is knackered or by blanking that tube have i made a stronger vaccum also what will happen if i leave it disabled either way im just over the moon your a lifesaver :beerchug:cheers mate

[billza1967]

hello mate i disabled the egr valve done what you said it now starts everytime i cant thank you enough i know this might sound daft but does that mean the egr valve is knackered or by blanking that tube have i made a stronger vaccum also what will happen if i leave it disabled either way im just over the moon your a lifesaver :beerchug:cheers matehello mate the car starts up every time the only thing is when it starts i get no response from the accelerator for about 3 or 4 seconds have you any idea what would cause that it only happens when its hot cheers bill

[caldirun]

Could be the EGR system does not work untill the engine is hot, there is a valve in the line which directs the vacuum to the EGR diaphragm, if the diaphragm is leaking that would exhaust your vacuum and could cause no end of problems.
Put a short length of pipe on the nipple of the EGR and suck then put your tongue in the hole it should hold it there untill you pull it away (cheap vacuum tester!), or it could be a split vacuum line or the change over valve itself (test them the same way). Ive read lots of posts about disabling the EGR, the yanks swear by it, stops the oily gunk frying in the inlet manifold, I did mine with VagCom but I suspect it has reduced my MPG figures, I have to test this theory. No idea about the throttle lag when hot, sorry, unless its a shuffled pipe when they fitted your cylinder head.

[billza1967]

Could be the EGR system does not work untill the engine is hot, there is a valve in the line which directs the vacuum to the EGR diaphragm, if the diaphragm is leaking that would exhaust your vacuum and could cause no end of problems.
Put a short length of pipe on the nipple of the EGR and suck then put your tongue in the hole it should hold it there untill you pull it away (cheap vacuum tester!), or it could be a split vacuum line or the change over valve itself (test them the same way). Ive read lots of posts about disabling the EGR, the yanks swear by it, stops the oily gunk frying in the inlet manifold, I did mine with VagCom but I suspect it has reduced my MPG figures, I have to test this theory. No idea about the throttle lag when hot, sorry, unless its a shuffled pipe when they fitted your cylinder head.hello mate back again its started acting itsef again it worked fo a while never mind i think were on the right track i noticed the vaccum was very weak from the pipe what would cause that and also ive been driving the car hard its temp is fully up and the heaters are red hot but the coolant in the expansion tank is cold is that normal? sorry for bein a pain cheers bill

[caldirun]

Sounds like an airlock in the cylinder head, probably not bled properly, or non functional thermostat.

[billza1967]

Sounds like an airlock in the cylinder head, probably not bled properly, or non functional thermostat.
thanks mate ill look into it and thank you youve been a great help cheers bill

[caldirun]

[quote=billza1967;122598]hello mate

[Freebaggin]

Hi all,
I have Petrol V6 2.8l, 2002 auto that has the same problem. More so when the ambient temperature is hot, but only after the engine has been stopped when at operating temp, then restarted ~5-15min later when heat soak has occured. A right PITA!

[Freebaggin]

Guys, all solved with replacement of Water Temp sensor. Had a malfunction and was replaced. All credit to mechanic I go to, German Auto in Edwardstown, Adelaide, SA.