Welcome back from vacation!! I guess. So, my jag sat in the garage for over a week. I took it out last night to go get some healthy McD's, just a short drive maybe 5mls one way. Started fine, didn't give me a problem until I sat in the drive-thru. Once there, the idle was rough but worked its way out after I sat thru the drive-thru and left. Then the scary part..as I was driving home, I was climing a hill at 45mph, I pressed hard on the gas to get it to drop down in gears and the engine rev'd but nothing happened. Realizing this, I took my foot off the gas pedal and then gently applied. It resumed in the original gear, then did down shift normally after. I even stopped at the entrance of my neighboorhood, and gave it some extra, where it responded normally.

I have no lights or warnings. Anythoughts on what maintence, I should perform first? Both were a first with this car.

 

Always include your engine size and model year when asking for help.

Could be a partially-clogged fuel filter. Whatever debris may be in it had a chance to settle, congeal, and hamper consistent fuel delivery while the car was parked for a week. Of course, it could also be a one-time blip that won't return. I would put some more miles on the car and see if you experience the same issue.

Could also be a dirty mass air flow sensor or idle control valve, or even clogged fuel injectors. Right now, you just don't have enough consistent information for a proper diagnosis. Drive the car as you normally would over the next few days and report back....

 

I don't think S-Types have an idle control valve - they just use the (motorised) throttle

 

Yes. That is true.

 

Well, you were right. It's been out everyday since, and seems to be running much better. However, a significan't change happens with the a/c on. So, that would mean to me that it is a fuel line problem. I did see in another post that the 2000 S-types didn't have a sealed for life trans, and can be worked on at a local shop for a flush and fill. I thought I'd get a few maintenence things done at the local shop.

What do you think about this...other than the obvious oil change..

trans flush and fill
fuel line cleaner

 

Go back to what Jon89 said. If not changed, change the fuel filter as it's cheap and easy.

No harm in injector cleaner after that. (The lines shouldn't need cleaning, surely? We're not talking blood vessels and cholesterol.)

Make sure your a/c is fully charged (and not leaking - have it tested). Again, cheap. Don't use those top-up cans.

 

As mentioned earlier, I would recommend the cheap and easy things first. I would also clean out the MAF sensor and clean out the throttle body. Also, swap out the air filter. You can get cheap ones from:

Ken Karr
Motorcars, Ltd. 800 338 5238 x626
www.motorcarsltd.com

He also has a full range of other filters as well.

Mike

 

Update...
okay, oil, fuel filter, and air filter changed. Also, did a fuel injector service. Running better, but still not 100%. It has moments of rough idle and jerkiness. My next check is the A/C because the symptoms seem to be more frequent with that on. My question is would these symptons be present without the A/C acutall on?

 

Try plugs next? Since it is a 2000, that would be the next thing. I think the A/C connection is just placing the engine under load. But that's just a guess.

 

The 2000 year model would lead me to suggest pulling the coil boots and checking for oil. It sounds like a coil misfire which is VERY common. It has to misfire at a certain rate for the check engine light to come on. At your cars age and mileage I would plan to replace both the cam/valve cover gaskets and all 8 coils and all 8 plugs. Don't forget the plug well gaskets!! They should come with the other gaskets but be sure and check. I just consider this normal maintenance for any DOHC V-8 engine with a COP (Coil On Plug) ignition.

Remember you can use the Motorcraft DG-515 coils which are on EBay for about $160-$200 for all 8 coils. These are the same as what the Lincoln LS 3.9L engine uses.
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I had a similar problem with my 2k 4.0 and the problem was a misfire on 8. I replaced all coils and plugs and the car runs great again.