Question: : I have a '98 ford escort zx2 with a 5-speed transmission. I was stopped at a stop sign the other when my car started to buck and jerks. Ever since then it won't idle unless you give it gas.

It starts up fine but if you don't give it gas right away it just shuts off when it gets to 0 rpm's. Do you know what the problem could be and how much it would cost to get it fixed?

Answer:

It sounds like your Ford might have a vacuum leak. Vacuum leaks affect idle mostly. This would cause the engine to run lean and that would make it buck and jerk when sitting at idle. When you give the car gas a vacuum leak would not affect this normal driving.

One way to check is to spray brake cleaner around the engine when it's running. But be very careful. It is very flammable so you need to stay away from any sort of ignition, like spark plug wires, spark plugs or ignition coils. If the spray gets to the point where the vacuum leak is you will notice a surge in the engine idle. Check for any vacuum leaks before you do anything.The next step would be to scan the computer for codes to see if there are any stored in the computer. These codes give an indication as to where the problem might be. You could have a MAP sensor code, mass airflow sensor code or any number of other issues.

Another possibility is carbon buildup in the throttle body. Take the aircleaner ductwork off the engine throttle and look inside. Rub your finger around to see if it comes out full of soot. If it does you'll need to clean it out real well. Carbon in the throttle will also affect idle on your Ford Escort.