rsanders21

THe car is a 98 honda civic ex model all stock, and a new head was just installed. The idle seemed a little low so I started pulling plug wires to see if it made a difference on idle and see if I had a problem on any cylinder. When I pulled the number 2 plug wire the car dies and the coil is shot. When I swap the coil it starts again no problem. Any ideas what could cause the plug to short a coil?

Former User

Disconnecting a plug wire with the engine running is a well known way to blow the coil. Instead, unplug a fuel injector.

rsanders21

Disconnecting a fuel injector will tell me if I have a ignition issue?

Former User

No, the test will tell you if you have a dead cylinder.

Click the Spark link in my signature to learn how to check for spark at the plug without blowing the coil.

rsanders21

Thank you for the help.

rsanders21

OK read the article, my question i guess is this. THe idle seems low compression is 150 120 150 120 across and the idle control screw etc doesn't affect the idle. So by disconnecting the feul injector and no change in the motor would indicate a dead or problem cylinder? Thnak you for your time.

Former User

Yes.

Did you do the compression test as described at the compression link in my signature?

You appear to have two bad cylinders, but they are not dead.

rsanders21

I did the compression test exactly as described, is the low idle caused by the two lower compression cylinders themselves or a faulty injector or bad wire/ plug?

Sliced Beard

Low compression can cause a rough/erratic idle which is often lower than the computer tries to set it at.

Try putting a cap full of transmission fluid in each cylinder (via plug holes) and see if it temporarily smooths out.

rsanders21

Will do thanks for the help.