Technical Non starter on first crank of engine

[GiantHogweed]

I have a Ducato 2.8jtd 244 . Prior to having new cam belt fitted and new clutch it would start first time every time. Since it has come back it will not start on first crank of engine, switch off , second crank starts no problem, runs and drives ok. Returned to garage and they say it is air temp sensor fault ?
Diagnostics show air temp at 40+ actual air temp 10c.
I am a little sceptical about diagnosis as they cannot find the sensor to check it.
Any thoughts please.

Thanks

 

[Anthony489]

Hi

The anomolous reading suggests the intake air temperature sensor (IAT sensor) or its wiring is faulty, or it has lost its power supply. The IAT sensor will normally sit somewhere in the side of the intake air pipework upstream of the turbo, and will have a small 2 pin connector. Given the recent work, I suggest you look for damaged/disconnected wiring as this may have happened by accident. It's possible the sensor just happened to fail at the same time, but rather unlikely. Also, check the fuses in the engine bay fuse box, especially Fuse 11 which supplies a number of the less critical engine management components.

I assume it still cranks at normal speed ? If not, check the engine and starter motor earth return wiring which might have been disconnected/reconnected when the gearbox was removed.

Finally, the diesel high pressure pump is driven from the cambelt and its timing is critical.

 

[GiantHogweed]

Hi, thank you for your diagnosis with my problem. I will work through those and let you know the outcome.

Thanks

Roger

 

[Anthony489]

Addition - the HP pump timing is only critical if you have mechanical injection, i.e. not the later type using an ECU and electronic injectors

 

[Communicator]

There are several versions of the 2.8jtd engine. The version without EGR seems to be the most common in the UK. So probably the OP's vehicle will be without EGR, flame starter, and UFI (green????) filter.

This version uses a combined Manifold Air Pressure & Temperature Sensor, K044 in diagrams. There is no Mass Air Flow, or Debometer. K044 is fitted to the inlet manifold, towards the vehicle RHS near the tming belt.

It is possible that the sensor connector (4 pin) may have been disturbed when the timing belt was replaced, as it is quite close to the RHS engine mounting.

 

[Communicator]

In the penultimate line of my post above, for Debometer, please read Debimeter.

The attached diagram from eLearn, showing the position of the absolute pressure sensor is far from ideal, but may be of some use.