Starting issues

[WinDrop]

New summer, same issues. Worst this time then last summers. Guessing because it's lot hotter...

So every summer I have this issue with car not starting properly.
This only happens when it's HOT outside and the engine is COLD. (E.g. Sitting in a drive for the night or not being driven for a day or two)
So not hold engine start problem, not cold engine start problem (As it's starts in the winter) but cold engine start during hot weather (It's weird right?)

I can barely start the engine second time after cranking it for about 10 seconds during both attempts.
It doesn't feel slow, battery isn't dead.
It sounds healthy, but looks like there isn't enough fuel injected.
When it eventually starts, it gives quite a bit of smoke out of the exhaust.

I have genuine VCDS hex-Can so can do my own scans and engine is not returning a single error so obviously it thinks that everything is absolutely fine.
Could anybody point me in the right direction here? Perhaps any live data I could check when starting the car? Any sensors etc? Specific values?

Car is VW Passat 2.0TDI 2007

[niall campbell]

Engine Coolant Temp sender unit is the old favourite to change

Also ALWAYS wait for the glow plug light to go out, all year round

It is my belief, that the VAG group suffers from this. Jump in the car, switch on the ignition, put your seat belt on and then start the car . Its like a self check the car does and it doesn't like missing this out...………………………………… in my head anyway


You could also check the fuel temp sensor unit as well, some cars the Coolant & Fuel sensors are the same. Go to VW or Trade Part Specialists TPS for a genuine one. They should have a green ring round them,

As a short term fix, disconnect the engine coolant temp sender unit to see if it helps, this puts the car to default setting of winter time and extra fuel and see if this helps

[WinDrop]

Engine Coolant Temp sender unit is the old favourite to change

Also ALWAYS wait for the glow plug light to go out, all year round

It is my belief, that the VAG group suffers from this. Jump in the car, switch on the ignition, put your seat belt on and then start the car . Its like a self check the car does and it doesn't like missing this out...………………………………… in my head anyway


You could also check the fuel temp sensor unit as well, some cars the Coolant & Fuel sensors are the same. Go to VW or Trade Part Specialists TPS for a genuine one. They should have a green ring round them,

As a short term fix, disconnect the engine coolant temp sender unit to see if it helps, this puts the car to default setting of winter time and extra fuel and see if this helps

Thanks Niall.

Yeah, I always wait for the glow plug light to go off. Sometimes when car doesn't start (I can kind of know it after 2-3 seconds of cranking that I'll have to repeat the process couple of times) I even insert key couple of times letting glow plug light to turn off just to make sure that they are fine.
Do that during winter as well as summer.

Thanks for the pointers regarding sensor. I can't believe they will be expensive. Probs looking at around £20-£30 mark right? If that doesn't help I'll look into Fuel temp sensor next.
Now just to find out where they are under the bonnet lolz :)

I'll let you know if I run into any issues once it's replaced.

[niall campbell]

if I park my car on a slope, forward or rear facing, then I have a slight air leak in my car when it is starting, which I hear for 2 to 3 seconds whilst starting. Parking on level ground and she starts no problem. I can live with it as I know what it is, just not ripping the car to bits to find it

If your car had the same starting problems all the year round, then its likely a join or seal leaking to an injector leaking

Let us know how you get on

[Crasher]

For this test the battery must be fully charged so after an overnight soak charge if possible. Disable the engine from starting by disconnecting the head wiring harness. Open VCDS in engine 01 and select measuring blocks and find the rpm. Now crank the engine over and keep cranking, don’t let go of the key. VCDS will drop out initially and then take a few seconds to re-establish coms with the ECU and then when coms comes back, you need to view what the rpm is; it MUST exceed 280rpm for a clean start. I keep going for about 30 seconds to get a good idea of the average starter rpm. After the test, don’t forget to reconnect the head harness and clear the codes you will have generated.

[WinDrop]

For this test the battery must be fully charged so after an overnight soak charge if possible. Disable the engine from starting by disconnecting the head wiring harness. Open VCDS in engine 01 and select measuring blocks and find the rpm. Now crank the engine over and keep cranking, don’t let go of the key. VCDS will drop out initially and then take a few seconds to re-establish coms with the ECU and then when coms comes back, you need to view what the rpm is; it MUST exceed 280rpm for a clean start. I keep going for about 30 seconds to get a good idea of the average starter rpm. After the test, don’t forget to reconnect the head harness and clear the codes you will have generated.

Hey bud. I have no doubt in your knowledge of cars so sorry for this blunt question.
When I have this issue and I try to start it, it throws some sort of oil pup error stating to stop the engine. Think it might be oil pressure or something. (Surely because oil pump isn't running) I think this happens after around 10 seconds of cranking.
If I do it for 30 seconds, isn't it going to cause harm to the engine?

[WinDrop]

if I park my car on a slope, forward or rear facing, then I have a slight air leak in my car when it is starting, which I hear for 2 to 3 seconds whilst starting. Parking on level ground and she starts no problem. I can live with it as I know what it is, just not ripping the car to bits to find it

If your car had the same starting problems all the year round, then its likely a join or seal leaking to an injector leaking

Let us know how you get on
Nah, not that mate :) only getting issues during hot weather and car has always been parked on a nice straight road.
Maybe few degrees here and there but nothing more than that.

[Rob69]

[The oil pressure stop engine warning always comes up after extended cranking period, you will still have oil pressure and the oil pump will be running, QUOTE=WinDrop;1089016]Hey bud. I have no doubt in your knowledge of cars so sorry for this blunt question.
When I have this issue and I try to start it, it throws some sort of oil pup error stating to stop the engine. Think it might be oil pressure or something. (Surely because oil pump isn't running) I think this happens after around 10 seconds of cranking.
If I do it for 30 seconds, isn't it going to cause harm to the engine?[/QUOTE]

[Crasher]

When I have this issue and I try to start it, it throws some sort of oil pup error stating to stop the engine

Don’t worry about this, they do this because of the daft and useless oil pressure warning system VAG now use.