Hi all:

'99 XK8 here with 99,500 miles.

Recently, I had several occurrences of the following. When starting the car cold in the morning, it struggles to start and runs roughly for the first minute or so. After the first start of the day, it starts and runs normally for the rest of the day. Car is in northern California so the ambient temperature is above 40 F.

Here are a few other things I've observed. When trying to start the car when these symptoms show up, I find depressing the gas pedal helps to get it going. When the car get going and runs roughly, it smooths out and stays that way if I briefly increase the RPMs to 3000 or so. And, as I said above, this happens at the first start of the day and then things are normal for the rest of the day.

BTW: I replaced the air pipe yesterday because the old one had a leak at the baffles. No sure if this is relevant or not.

Looking for some suggestions as to where the problem might lie. There are no codes being thrown to point me in the right direction.

Thanks

Thom

 

Connect you scan tool and see what your coolant temperature and intake air temperature read at cold start (overnight). If they vary substantially lower than ambient, they can cause a rich start condition. High readings can cause a lean condition and make cold starts hard to achieve. My guess is the CTS.

 

Makes sense...the ex (retired) Jaguar mechanic, who works from time to time on the car, suggested the leaking air pipe was causing the car to run lean. Maybe this is the cause. I'll try to remember to scan coolant and air temp in the morning before and after starting and report back. I'm also wondering if the computer system adjusted the fuel mix given the leaking pipe and whether it needs to relearn the air fuel balance.

 

+1 to the above.

Well I’m a big fan of zero dollar fixes, so here’s a few other things to try.

1. Check the PCV breather pipe that goes into the air tunnel. It’s just been worked on. Mine had a crack on the connection on the cam cover which closed after the Engine warmed up.

2. Clean the MAF sensor. There’s an exposed bulb which monitors air temperature.

 

+1 to all the above

Then when hot, i.e. the problem's gone, look at fuel trims to see if there may be an air leak (which the car can't know if cold so fuels on the basis there isn't any leak).

 

Nothing insightful to report this morning. Car started normally. The outside air temperature was 53F and intake air temperature was 54F. Unfortunately, it took me awhile to find the coolant temperature on the scan tool and by the time I did it had increased from 'cold'. Will try again tomorrow morning before and just after starting.

 

4782-----

Since it's a 99, things are quite old under the hood, so check the oil filler cap rubber seal, then the "O" ring on the oil dip stick. Replace if bad or missing. Solves a lot of problems if these two items are bad or missing.

Cheers:
Chuck

 

Closing out this thread for now....

I haven't been able to replicate the rough start problem since it occurred for the first time. I've tried to follow the suggestions others provided, but everything looks normal for now. If ot happens again, perhaps I'll be able to figure it out then. Thanks for the advice


Thom

 

Sure sounds like you solved your problem when replacing the pipe with holes in it.
Well done.