Good morning, everyone.

I need your help with a problem I've been having over the last few months with my 1996 Jaguar XJ6 3.2 X300.

In the morning, when the car is cold, it doesn't start well.

The starter motor turns for 2-3 seconds and the engine starts unevenly for a few moments.

Then it immediately settles down to about 800 rpm.

During the day, however, everything is fine. Perfect starts, no smoke, acceptable fuel consumption but slightly worse than a few months ago, normal performance.

To help you understand, I will tell you what I have already done:

battery just replaced, new air filter, new spark plugs as per Jaguar specifications, new fuel pressure regulator, air flow meter replaced last year with a used working one, oxygen sensors replaced in February, throttle body just cleaned, fuel filter replaced at 15,000 km, new crankshaft position sensor.

The only thing I have never touched are the injectors.

Could it be that dirty injectors can cause poor starting only when cold?

Thank you for your advice.

 

In the starting sequence the timing comes off the Camshaft position sensor and then eventually the crankshaft position sensor at a certain unknown revs

The CMPS sensor CEL is P0340 and the CKPS is P0335

The CMPS is more accurate as it sees each cylinder TDC as it has 6 targets of different window gap sizes , the CKPS only sees 1 as it's target comes around 2 times in a 4 cycle engine so which passing of the target is the TDC to fire # 1 as it takes a couple of changing of the pass choices ( is it the first come around or the try second for a start ) to get it correct

A good CMPS will read 600 ohms as a 3 wire hall effect sensor vs. 1300 ohms on the CKPS as a inductor sensor

The engine will start with the CMPS sensor connector removed only using the CKPS but takes more starter revolutions

Suggest clean CMPS connector as that is what I had

The CMPS is the hockey puck on engine top right fwd side with a small round window on it

You could be having a dragging injector with the cold and to be able to target that.....................................