P38 DSE Auto intermittent lack of power after vehicle has been hot

Hi All again,

Recently the P38 has intermittently losing power when it has got hot(up near the red) I have done datateks fan mod so have no viscous fitted. The fans come on fine and bring the temp back down when required.

The issue I’m having is more and more often I end with no power once it got up near the red. I know the ecu limits power one car is HOT and I can deal with this. Todays problem was temp had settled back to half way on guage but I lost power for a few miles intermittently which I believe could be a faulty or intermittently faulty ecu coolant stat.

Does that sound like a plausible explanation? I also think there is a coolant temp sensor on fip but I’m unsure of the symptoms of this.

Apart from this car drives well with recent water pump and upgraded radiator And uses no coolant.

Any one any ideas?

Many thanks,

Jacob

JT_spark said:

Hi All again,

Recently the P38 has intermittently losing power when it has got hot(up near the red) I have done datateks fan mod so have no viscous fitted. The fans come on fine and bring the temp back down when required.

The issue I’m having is more and more often I end with no power once it got up near the red. I know the ecu limits power one car is HOT and I can deal with this. Todays problem was temp had settled back to half way on guage but I lost power for a few miles intermittently which I believe could be a faulty or intermittently faulty ecu coolant stat.

Does that sound like a plausible explanation? I also think there is a coolant temp sensor on fip but I’m unsure of the symptoms of this.

Apart from this car drives well with recent water pump and upgraded radiator And uses no coolant.

Any one any ideas?

Many thanks,

Jacob

Click to expand...

If the stat is correctly set per the instructions, the temperature should never get near the red zone. If it does, the power will be reduced. The EDC coolant temperature sensor will not cause loss of power if it's faulty as far as I'm aware unless it is signalling over temperature. There is a fuel temperature sensor and a fuel heater but I doubt they will be the cause. It needs to go on diagnostics first to check for recorded fault codes and then look at the coolant sensor on live data.

Datatek said:

If the stat is correctly set per the instructions, the temperature should never get near the red zone. If it does, the power will be reduced. The EDC coolant temperature sensor will not cause loss of power if it's faulty as far as I'm aware unless it is signalling over temperature. There is a fuel temperature sensor and a fuel heater but I doubt they will be the cause. It needs to go on diagnostics first to check for recorded fault codes and then look at the coolant sensor on live data.

Click to expand...

Thanks Datatek, when I purchased the thermocouple for the fan mod I purchased one off eBay which wasn’t the best quality as it has a wide range of on off so if I set it maybe a bit to high to stop fans being on for to long. I’ll try cranking it down a bit (fans on more) and see if that helps. I’ve got a few code readers that can let me see live data not RR specific so I’ll see if they shed any light on the situation. Hope your well and thanks for the reply.

Jacob

JT_spark said:

Thanks Datatek, when I purchased the thermocouple for the fan mod I purchased one off eBay which wasn’t the best quality as it has a wide range of on off so if I set it maybe a bit to high to stop fans being on for to long. I’ll try cranking it down a bit (fans on more) and see if that helps. I’ve got a few code readers that can let me see live data not RR specific so I’ll see if they shed any light on the situation. Hope your well and thanks for the reply.

Jacob

Click to expand...

The fans should come on at 98C, if the stat is any good they should go off at between 90 & 92 C. I hope you removed the fan cowl to maximise airflow.
When set up correctly, the gauge should never get above the 12 o'clock position. If you are running up to the red zone, expect a cracked head.

Thanks I’ll recheck all of that, fan cowl has been previously removed, car generally sits at halfway on guage unless idling for a long time or doing lots of low speed work or I have foot down for a while up very long hills Mile or so in length. Don’t like the sound of the cracked head problem, I had heard about it. Best get it set up a bit better by the sounds of it!

Thanks again