My XJS V12 engine is losing power when hot. Not overheated. It happens randomly. And it lasts randomly. When pushing pedal something cuts off RPM below 1500. It goes up and down when pushing gas. Engine is still working, not switcing off. You can still drive with "jumping". You dont feel jumping when you don't push. And suddenly it works again!! It's very annoying. Is it a fuel problem or injection? Electronics?

 

Sounds like fuel pressure maybe? Better check that first I think...

 

Welcome to teh Forums.

Please do an Intro in the New members Area when the beast is sorted.

#1 for me is the CTS (Coolant Temp Sensor), located on the backside of the B bank thermostat housing. They are CHEAP, NOT Jag specific, and reek havoc.

#2 is the wiring to siad CTS, they break INSIDE the plug, under the rubber boot.

#3 is the TPS (Throttle Position Sensor), BUT it is rarely temp related issues with that sucker, it either works or it dont, Cold or Hot.

#4 is the Ignition Amp, the Black Box on the B bank Inlet manifold, also mentioned in that sticky.

#5 Ignition coil/s going AWOL when getting hot, very common now with age creeping in.

Have read of the sticky at the top of this section, OK its related to a NO runner, but easily able to skip items to what is happening to your engine.

Good luck.