Engine almost stalls at stoplights

By Doug McAllister

Q. After starting out and driving several miles in my 2000 Type S Jaguar, there is an almost imperceptible miss of the engine. It is mild and very intermittent. The "check engine" light doesn't come on. It seems to be worse when I'm idling at a stoplight in gear as opposed to in neutral. I had the car in for a brake job recently and had my mechanic look at it. He said it didn't leave a code on the computer.

My question is whether I have to wait until the engine pukes and I need a tow to the shop before the problem manifests itself, or is there a way of finding the problem without the help from the computer before engine failure.

A. If your Jaguar had a full-blown misfire, it would set a misfire code. It seems you might be dealing with a little bit of an idle quality issue.

You might try having your technician perform an air-induction cleaning. This is where you fog the engine with a good cleaner, which cleans all the byproducts of combustion out of the intake, cleaning the valves and the top of the pistons. You could also add a can of fuel injector cleaner to the gas tank, as well, to clean the fuel injector nozzles, too.

The other thing that he might want to check is to be sure you don't have a weak motor mount giving you excessive vibration and the feeling of engine roughness. An exhaust pipe rubbing the car somewhere could also give the same sensation.

I hope this helps and you get to the bottom of this issue.

• Douglas Automotive is at 417 W. Main St., Barrington; 123 Virginia Road, Crystal Lake; and 416 Northwest Hwy., Fox River Grove. For information, visit douglasautomotive.com. Send questions to underthehood@dailyherald.com.