X300 AJ16 4.0 - Poor cold start

[BigCatXJS]

Hi All,
In the mornings, it takes around 5 or 6 secs to get my AJ16 to start-up. When it eventually does, it's quite a feeble pick-up, then she'll rev to about 1,100 rpm and then settle at a steady 750 / 800 rpm.

Warm / hot start - no issues; she fires-up just fine after about 1 sec of turning. So it's really a cold start issue. With both scenarios, once she's started then she runs and drives just fine.

I have tried Forte Specialist Injection cleaner - this didn't make any difference.

Any other ideas of what the issue might be and what can be done about it?

Any help / advice appreciated.

Thanks, Rich.

[ptjs1]

Rich,

Just some thoughts:

It could be either because it is cold or because it has been standing for some time. If it's the former, one might start looking at the sensor inputs, particularly the coolant sensor, which is cheap to replace. You might also look at cleaning the MAF sensor.

If it's the latter, you might start looking at whether the fuel pressure has dropped. You could get the pressure checked on both the flow and return sides of the fuel system.

Crankshaft sensors are often the cause of poor starting problems on AJ16s, but I don't think that would be limited to just cold starts.

I hope that helps. Good luck with sorting it.

Paul

[BigCatXJS]

Thanks - that helps. I have been tipped off about the coolant temperature sensor, so have ordered one up (along with temperature transmittor) from British parts - £20 the lot inc shipping. I hadn't considered the MAF sensor at all, so I'll look into that.

Cheers, Rich.

[robv12]

I'm tempted to suggest lack of fuel pressure here, the temp sensor usually dosen't affect cold start, but affects the running once the car is warmed up

lets us know how you get on

[BigCatXJS]

Thanks,
Changing the sensors hasn't made a difference, though replacing the thermostat has improved economy by 2 to 3 mpg :>)

I cleaned the MAF - no difference here either.

Fuel pressure - good point. I had a garage (Jag specialist) check it over - they could not find an issue, although I don't think they tried very hard as they were rushed with other jobs

So all out of ideas at the mo - although I will get the fuel pressure checked by another Jag Specialist soon.

Cheers, Rich.

[robv12]

Crank position sensor???

[BigCatXJS]

Crank sensor was on my list of things to consider, but the easy warm engine starts (less than 2 secs usually) I though might eliminate that.

Rich.