2.5 V6 Hot (cold engine) starting issues

[S4_dan]

Hi guys,

done a quick search and nothing with coming back I can relate to really.

Problem I have is the car will start fine first thing in the morning. But when I come to leave work 8 hours later and the car has been basking in the sun all day it cranks and cranks and cranks before firing and plume of smoke from exhaust. I can then drive a few miles, switch off and go back 10mins later and it will start fine again even when engine up to normal operating temp.

What is causing the 'cold' engine sat in sunshine to take so long to fire up?

There are no DTC's relating to anything. ~Timing is within spec according to VCDS. Stumped with this one!

Cheers,

Dan

 

[frankc]

You're not the only one suffering this issue Dan, I have the same problem with my BDH V6. Tried a new CTS, checked for leaks, checked timing last summer and I'm sure it's in spec. It was fine over the winter but now the sun's out it's playing up again.

Only thing I can add is if the coil light goes straight out on turning the key then you can guarantee it will crank over for an age, if it stays on a touch longer then it seems to fire fine. Might just be inconsequential.

Frank

 

[abyrne153]

There was a recent post regarding starting problems on a 2.5 TDI which was finally traced to a faulty egr valve. As these are fully mechanical on the a series engines they often don't show up fault codes. You could try and blank it off if not already done and see if that helps. This type of problem could also indicate the start of injection pump failure.

 

[S4_dan]

Cheers guys,

Hopefully not the fuel pump. Can't afford to replace that until Christmas at the earliest. In the service history there is a receipt for lift needle sensor been replaced in the fuel pump.

I have the same issue with the glow plug light as above. Does anyone know which sensor it is that tells the ecu how long to apply the glow plugs for?

Even if I turn the ignition on and off a few times each time waiting for the glow light to go out, it doesn't make a difference.

She started at the first crank this morning just like she always should.

 

[frankc]

Pretty sure it's the CTS that determines the use of the plugs and dynamic timing adjustments, though I've read that in the event of the engine not starting using the info from the CTS then it will fall back on data from the fuel temp sensor & needle lift sensor amongst others. For this reason I'm wondering if I may have an intermittent open circuit somewhere in the. CTS wiring?

I was under the impression the needle lift sensor (G80) is part of injector number 3 O/S bank at the rear. You should see a wire coming out from the top of it.

Frank

 

[dublin]

Any updates on this one? I have the same engine and the same problem.

 

[Jimmy TDI]

I had a similar experience on a 1.9pd Bora that ended up being a CTS that wasn't throwing up any faults. It's a totally different engine, but this might be worth a try.

Next time it does it try disconnecting the electrical plug from the CTS, then try to start it. If it starts this is a good indication it's the CTS, or even dirty pins in the plug that you can check while it's unplugged.

If it's unplugged the ecu automatically sets the car into cold start mode, so it should start first time whatever the weather.

 

[AudiLeon]

Have you checked your leak off pipes?

 

[frankc]

Leak off pipes on mine are all new, some of them replaced multiple times to cure weeping. Gonna take a closer look at the CTS and wiring when time permits.