Disco 2 Disco 2 4.0 V8 Hard Cold Start

Hello once again,

With the 82 Rangie stuff sorted last time, the time has come to take on the bloody world of electronics and sensors again. This time a friends 2000 Disco 2 4.0 V8. The vehicle from what he says has developed a very hard to start scenario when cold only. It will eventually crank into life (he said he applied the throttle too and had to crank it quite extensively - prayers out to the starter).

I have an OBDII scanner available (also had a T4 some time ago but that got sold) in order to plug it in, but its always nice hearing from the guys on here what could cause this. I did search the forum for cold start issues on V8s but most, if not all of them, are for the earlier 14CUX systems and on Disco 2s about TD5s.

I am thinking maybe Crank Sensor or Coolant Temp Sensor? Or could it be MAF ? Fuel pump i don't think so because he says that when he gets it running it stays on and also idles nicely. It also restarts normally when hot. That's something that i think might have me leaning towards a bad Coolant Temp Sensor as it might not provide sufficient fuel on start up when cold.

Things i know he has done is to replace the Lamda sensors as they were indeed bad.

Let me know what you think on this.

Cheers !!!

That is strange.
Is the battery fully charged?
Maybe the IAC valve needs to be cleaned out with brake cleaner. Easy to do.

Jim_P said:

Hello once again,

With the 82 Rangie stuff sorted last time, the time has come to take on the bloody world of electronics and sensors again. This time a friends 2000 Disco 2 4.0 V8. The vehicle from what he says has developed a very hard to start scenario when cold only. It will eventually crank into life (he said he applied the throttle too and had to crank it quite extensively - prayers out to the starter).

I have an OBDII scanner available (also had a T4 some time ago but that got sold) in order to plug it in, but its always nice hearing from the guys on here what could cause this. I did search the forum for cold start issues on V8s but most, if not all of them, are for the earlier 14CUX systems and on Disco 2s about TD5s.

I am thinking maybe Crank Sensor or Coolant Temp Sensor? Or could it be MAF ? Fuel pump i don't think so because he says that when he gets it running it stays on and also idles nicely. It also restarts normally when hot. That's something that i think might have me leaning towards a bad Coolant Temp Sensor as it might not provide sufficient fuel on start up when cold.

Things i know he has done is to replace the Lamda sensors as they were indeed bad.

Let me know what you think on this.

Cheers !!!

Click to expand...

Hopefully your friend isn't pumping the throttle when trying to start the engine.

As for the coolant temp sensor, as the coolant temperature rises, the resistance in the sensor decreases, as temperature decreases, the resistance in the sensor increases, so a test would be test the resistance or sensor when cold, info on the resistances of various EFI sensors should be it the workshop manual.
With the crank sensor, if the sensor or the wiring was iffy, and if engine is running it would misfire, or of course not start start in the first place.

Idle control valves have been known to stick but there aways other symptoms that would affect the engine running hot or cold, the D2s control valve isn't serviceable so repair is by replacement.

Other than that, it could be simply that the vacuum hoses to the control valve are partially blocked.