awx poor starting

[Damrob]

Any help would be appreciated,my awx 1.9 started to become difficult to start wether hot or cold,had it fault code read and two faults appeared. The coolant sensor and the engine mount,both parts were replaced with genuine items,the car is no better. The glow plug light only comes on for one second hot or cold? is that right?.the other thing is when the coolant sensor disconnected the car starts fine it maybe in limp mode?
any help would be great,cheers

[dan.taylor.1]

I take it you have the codes cleared after replacing the parts, and the sensor was a genuine VAG part yeah?

Dan

[Damrob]

yes both VAG parts, it was not an Audi dealer that fitted the parts but said there were no fault codes after he,d cleared them.

[nevo]

Might be worth getting a start with jump leads from a decent battery,your cranking speed may be low and not injecting enough diesel,by disconnecting the temp sensor you're codding the ecu into thinking the engine is stone cold.

[Damrob]

I will try anything, anything else you think of please let me know.
cheers

[Columbo]

You need a new tandem fuel pump. When the engine is cold reach round under the fuel pump (back of the head nearest the bulkhead) feel for diesel. If you find diesel then the pump is leaking air when off and it's having to prime it's self by cranking a while.
Not too hard to replace, the part number is 038145209 X where x needs to be the highest you can find which uses the metal type gasket.
Got mine off ebay and used a new audi gasket. Think mine was off a crashed B7 1.9 tdi which i got for £20.

[Damrob]

Thankyou for the info Columbo will have a look tomorrow,doesn,t smell diesely but it sounds possible.Id love to sort it i like the car,its my 3rd a4 and i have never had any serious problems with any of them.

[nevo]

The tandem will cause starting problems, but you said unplugging the temp sensor makes it start ok!Another quick one to eliminate is try starting it with your lights on,dodgey light switch can cause problems.

[Damrob]

The tandem will cause starting problems, but you said unplugging the temp sensor makes it start ok!Another quick one to eliminate is try starting it with your lights on,dodgey light switch can cause problems.

Thats right it does but right now i will check any ideas anybody has got. Thankyou for info i will try the lights in the morning,fingers crossed

[Damrob]

Managed to get a look at the tandem pump,i cant see any damp areas on the pump its self.Took the pipes off the fuel filter and i cant see any oil in the diesel. There is some oil leaking around the tandem pump but it looks like its coming from the rocker gasket. Tried starting with lights on it didnt change the poor starting,worth a try

[Columbo]

Are you sure it was oil? Did it smell of diesel? Check the coolant pipe that runs under the tandem pump. If it feels swollen or soft that could be a sign it's had diesel dripping on it for a while and will need replacing.
When i replaced my tandem i found diesel had made the pipe ballon out and wouldn't had been long until it would have burst.

When you first turn the key do you hear the rear fuel lift pump priming for a second or two? Stick your head in the boot and get some one to turn the ignition on but not crank.

Do you know when the last itme the fuel filter was replaced? Whet mileage are you at? My pump let go at around 120K miles.

[Damrob]

I am going to have a good look and clean on Saturday,there is no obvious diesel smell on the oily residue. I cant hear any pump noises,but when i had the pipes off the fuel filter i tried the ignition and fuel came out of the pipe immediately. I presume that means the lift pump is working. i will listen for the pump tomorrow.
The fuel filter has not been replaced for a while. It has done 142k miles.

Is your car an awx engine code, may not be related but how long do your glow plug lights stay on for mine only comes on for 1 second
thanks for your help.

[frankc]

With modern direct injection diesel engines the heater plugs are not really required until it gets very cold - last winter my a4 was starting first turn down to about -15.

As suggested above, the most likely culprits will be air leaks or incorrect timing.

[dan.taylor.1]

To be honest modern diesel glow plug lights are there to tell you theyre working, or rather that they have turned on, the duration of the heat is determined by the ecu from engine temp sensors, as obviously when its hot after a run and you go to restart it it wont need heat, but on a cold morning itll leave them on for a bit to assist fuel atomisation.

But that does depend on engine etc.

Dan

[nevo]

With respect guys I think your barking up the wrong tree with the leak or timing,if she starts ok with the temp sensor disconnected it cant be either of those.

[Damrob]

Thankyou for your help and interest,i am going to spend tomorrow going through your ideas and suggestions. One thing i can,t get my head around,is why its not coming up with fault codes.
My limited understand is it has to be a leak air/fuel or a mechanical problem,if no codes are flagged up.

In some of your comments it doesnt sound like the glow plugs are an issue,i didnt think so because of the poor warm starting but just had to check.

would a damaged ecu come up with a fault code?

thanks for the help

[Damrob]

Changing the battery didnt improve things. The tandem pump is leaking oil down the block,but its definatley engine oil. The internals most be worn because there is engine oil in the servo pipe,wether this will be anything to do with the poor starting i dont know.

Columbo did you have oil in your servo pipes? i might bite the bullet and fit a second hand one and see if it does anything

[Columbo]

Yes, my A4 is an AWX.
I think your pump is leaking at the gasket so a new gasket one might sort that out. You can get a bit of oil in the vacuum line but should only be a residue not loads. I should leave it be for now and get the starting problem sorted first.
I think Nevo is right, the pump is not the starting problem in your case. It's deff an electrical problem. Are you sure it's the coolant sensor that you disconect and it's fine? The one at the back under the tandem pump. If this was duff then it should give a fault, but they can still be faulty and not register as open circuit etc. What are you using to scan for faults? If you have a pc scanner like vagcom you can check the actual temps of the sensors.
When it is running is it running smooth or lumpy?

[Damrob]

Its a snap on code reader,and its the sensor below the tandem pump i have disconnected. Car runs well and feels smooth. I never have noticed before and i dont know wether its normally but it has a really deep induction noise but when you have a fault you start listening to everything.

I have seen the vagcom on ebay, around £20 for a disc and cable is that all its if so i will order one

[Damrob]

after getting worse at starting and stalling all the time,its finally sorted. The cambelt had slipped. According to the garage it had slipped 2 teeth on the crank and 5 on the cam. so extremely lucky. The tensioner had seized.
Thanks for the suggestions my work horse is back to form