extended crank time when hot

Hi, I’m a Newby to the forum. I purchased a 2004 Jetta TDI GLS 5 sp. with 73,000 miles last June. I have a small complaint that I have not seen listed on the forum. (I’ve been a member since my purchase.) My complaint is, the cranking time is less than one second when cold. When hot the crank time is 2-3+ seconds. I followed a thread that I saw on the forum to a web site sponsored by VW to familiarize mechanics with the PD engine. One of the features of the PD engine is a “Quick Start” feature. This is accomplished by using the camshaft position sensor and the crankshaft speed sensor to determine the relative position of each cyl. piston to the compression stroke so that the appropriate injector electro valve may be energized thereby starting the engine. Should the cam shaft sensor fail, the engine will continue to run/ (start ?) using the crank shaft speed sensor alone to determine the appropriate piston position, however if the crankshaft speed sensor fails the engine will fail to start/run. Because the engine always starts & runs fine, it appears to me that I may have a partial camshaft sensor failure or restriction of signal to the ECM only when heat is present. I have seen no codes on the dash display. I am going to apply Stabalant 22 to the cam sensor connector and see if that helps. If anyone has any information on this issue, I would sure appreciate it.
Rmorton102

If you have VAG-COM, or can get to one,
Check the cam timing, by reading field 4 of block 4. Verify it is close to zero. While the spec is -3 to +3, starting can get harder at -1.5 and below.
You can also get the last start data, in a log of group 5, which will check the cam synchronization, among other things.
Group 4 log, would also tell when the fuel injection is starting.
A common problem with hard starting is a bad temperature sensor, so checking that the fuel, coolant and Inlet air temperature sensors read the same by checking them at ambient conditions after a nights cooling with group 7 of VAG-COM might be worth doing.

DanG

Thanks for the info. I will be changing the TB soon. Will be going to one of the trusted shops. They will have a VAG-COM to due the required tests.

Thanks again
rmorton102

Have you had the battery load-tested and confirmed that it meets OE specs? There are very few aftermarket batteries that meet the specs - and even fewer that can be had for a better deal that the dealership, usually. Battery failure is commonly temperature-sensitive, and not in the way you think. Just a general tip - start with the basics.

Fred

And if anyone says "Red Top" to him, I may throw something at you.

There have been a lot of threads in the past concerning 'slow/no start when warm'. Sometimes these are timing issues, sometimes battery, sometimes the starter.

I agree you should check the cam timing through vagcom. If it gets slightly retarded you can have these same issues.