[david.snelly67]

Hi Fellow Touareg owners,
I need some help diagnosing my current starting problem. Most of the time my car will start, but occasionally it will crank for about 2 seconds and then stops cranking for no apparent reason. I have replaced the battery and the fuel filter, but so far this hasn't made a difference. There are no warning lights when the problem occurs, and the speed of the cranking is normal, but it just won't crank for more than 2 seconds. I can then go for another week with normal starting, and then it will suddenly just stop cranking properly.
I have noticed that when the engine is starting from cold, it doesn't seem to have the problem. The problem seems to occur generally when the engine is still warm.
Has anyone had a similar problem, and what was the solution?
Regards
Dave

 

[gazaflash]

Plug in VCDS and read any codes.
Not a proper connection at the starter? Could be when it’s cold there is enough contact on the wire to starter and it starts. When hot, metal expands and possibly the resistance increases and there is no continuity.
Remove positive wire to starter and sandpaper both ends, add a dielectric grease and reconnect

 

[david.snelly67]

Plug in VCDS and read any codes.
Not a proper connection at the starter? Could be when it’s cold there is enough contact on the wire to starter and it starts. When hot, metal expands and possibly the resistance increases and there is no continuity.
Remove positive wire to starter and sandpaper both ends, add a dielectric grease and reconnect

Hi thank you so much for your input. We have plugged in VCDS and when the cranking problem is happening nearly everything is showing codes, but when it starts normally no codes are showing. I can certainly try your suggestion with the positive to the starter, as I have nothing to lose, because we have no other possible solution at this stage.

 

[rgh0]

Sounds like high voltage drop during cranking affecting a lot of modules preventing starting. Could be bad battery or bad connections

 

[SaVAGeSoot]

As per above. Voltage drop test the starting circuit.

 

[JimJ]

Most of the time my car will start, but occasionally it will crank for about 2 seconds and then stops cranking for no apparent reason.

I have a similar problem.
If you immediately repeat an attempt to start, does it crank and start?

 

[david.snelly67]

Sounds like high voltage drop during cranking affecting a lot of modules preventing starting. Could be bad battery or bad connections

Thanks. I have replaced the battery, and also had the new battery tested the other day, and it is still testing as very good.

 

[david.snelly67]

I have a similar problem.
If you immediately repeat an attempt to start, does it crank and start?

Not usually, but give it a couple of hours and it will be fine.

 

[SaVAGeSoot]

 

[rgh0]

I would measure the voltage at the postive terminal under the hood when cranking to see what it is when it does not start and if different when it does start.

 

[david.snelly67]

I would measure the voltage at the postive terminal under the hood when cranking to see what it is when it does not start and if different when it does start.

Thanks, I am willing to try anything at this stage, as I am not getting anywhere in diagnosing the problem. Even my mechanic has come up with a blank, as it hasn't faulted since I dropped the car to him a week ago.

 

[dragline1570]

Presuming it is a 7L TDI
Classic failed engine speed sensor G28
Generally, doesn't throw a VCDS fault.
LHS lower of engine sensing on the torque converter.
Fails to start when hot but allows to start when cool.


replace with a Bosch sensor # 0 261 210 261

Bosch Crankshaft Position Sensor 0261210261 fits Audi Q7 4LB 3.0 TDI quattro | eBay

cheers
Drag

 

[david.snelly67]

Presuming it is a 7L TDI
Classic failed engine speed sensor G28
Generally, doesn't throw a VCDS fault.
LHS lower of engine sensing on the torque converter.
Fails to start when hot but allows to start when cool.


replace with a Bosch sensor # 0 261 210 261

Bosch Crankshaft Position Sensor 0261210261 fits Audi Q7 4LB 3.0 TDI quattro | eBay

cheers
Drag

Hi Drag, thank you so much for your input to my problem. It is a 2007 3 litre V6 Diesel TDI. Is replacing the crankshaft sensor a big job or is it easily accessible? It definitely sounds like a worthwhile solution to try.
Regards
Dave

 

[dragline1570]

The replacement of the sensor is pretty easy to replace even easier if you have small hands.
It is located just behind the joint between the bellhousing and the engine block about 8 o'clock and the LH engine mount as per attached.
Have a look at the sensor link and the photo of the sensor and look under the car to find it.
Just need a set of torx keys and a hook and pick set for the elect plug.

Regards
Drag

 

[SaVAGeSoot]

It definitely sounds like a worthwhile solution to try.

If that's the culprit, it's not guess work to flush it out... look at the RPM and\or ideally log them when in a no start condition. If you don't have RPM signal, then it's confirmed.

 

[david.snelly67]

The replacement of the sensor is pretty easy to replace even easier if you have small hands.
It is located just behind the joint between the bellhousing and the engine block about 8 o'clock and the LH engine mount as per attached.
Have a look at the sensor link and the photo of the sensor and look under the car to find it.
Just need a set of torx keys and a hook and pick set for the elect plug.

Regards
Drag

Thanks Drag, that is really helpful information. I will order a new sensor and let you know how it goes
Regards
Dave

 

[david.snelly67]

If that's the culprit, it's not guess work to flush it out... look at the RPM and\or ideally log them when in a no start condition. If you don't have RPM signal, then it's confirmed.

Thanks for your help. I will look at the RPM's and see what it shows
Regards Dave

 

[ddimon74]

Hi Fellow Touareg owners,
I need some help diagnosing my current starting problem. Most of the time my car will start, but occasionally it will crank for about 2 seconds and then stops cranking for no apparent reason. I have replaced the battery and the fuel filter, but so far this hasn't made a difference. There are no warning lights when the problem occurs, and the speed of the cranking is normal, but it just won't crank for more than 2 seconds. I can then go for another week with normal starting, and then it will suddenly just stop cranking properly.
I have noticed that when the engine is starting from cold, it doesn't seem to have the problem. The problem seems to occur generally when the engine is still warm.
Has anyone had a similar problem, and what was the solution?
Regards
Dave

Hi Fellow Touareg owners,
I need some help diagnosing my current starting problem. Most of the time my car will start, but occasionally it will crank for about 2 seconds and then stops cranking for no apparent reason. I have replaced the battery and the fuel filter, but so far this hasn't made a difference. There are no warning lights when the problem occurs, and the speed of the crank

Hi Fellow Touareg owners,
I need some help diagnosing my current starting problem. Most of the time my car will start, but occasionally it will crank for about 2 seconds and then stops cranking for no apparent reason. I have replaced the battery and the fuel filter, but so far this hasn't made a difference. There are no warning lights when the problem occurs, and the speed of the cranking is normal, but it just won't crank for more than 2 seconds. I can then go for another week with normal starting, and then it will suddenly just stop cranking properly.
I have noticed that when the engine is starting from cold, it doesn't seem to have the problem. The problem seems to occur generally when the engine is still warm.
Has anyone had a similar problem, and what was the solution?
Regards
Dave

Hello, this is a typical malfunction of a 3.0 liter diesel. Diagnostics, as a rule, will not show an error. Replacing the crankshaft position sensor solves the problem, here is its part number Bosch 0261210261.One hundred percent that this is a problem in it, the symptoms of the car's behavior were the same as yours. After the replacement, everything went away

 

[david.snelly67]

Hello, this is a typical malfunction of a 3.0 liter diesel. Diagnostics, as a rule, will not show an error. Replacing the crankshaft position sensor solves the problem, here is its part number Bosch 0261210261.One hundred percent that this is a problem in it, the symptoms of the car's behavior were the same as yours. After the replacement, everything went away

Thank you so much for your input. I have now ordered the new sensor and will fit it next week....I will let you know what the outcome is. Everyone on the forum has been so helpful.....thank you.