cylinder not firing - how do I find it.
 

I have a cylinder that is not firing. I know this because the car is running rough and it seems as though fuel is running right to the exhaust because I leave a trail of white smoke behind. This originaly happened just now and then, now it is constant. The car is in the garage until I fix the problem. Any ideas on how to find out which one is not firing?
Tom

Spray some light oil on the headers pipes were they exit the heads. It should be obvious which one is cold.

Or, pull one plug wire at a time until you find one that makes no difference in the way the car runs. Use a heavy glove so you don't get a jolt!

EDIT: oops SoCal beat me to it.

Thanks guys I'll give that a try.
Tom

If you prefer not getting zapped you could back off each banjo fitting leading to an injector at the fuel distributor with a 12mm box end wrench.

This will cause a slight fuel leak at the fuel distributor but not a significant problem.

Cheers,

Joe

no, once you start the car, spray regular water on the headers. the dead cylinder will not immediately steam the water. work sorta fast, because the heat will travel to the dead cyl from the good ones and mask everything. disconnecting plugs works but the water is do friggen easy, why bother.

After a short run time ( one or two min ) rub the exhaust stack with a crayon or the edge of a credit card. Crayon melts around 140*F while the credit card melts around 350*F. All should melt at the same rate, if not that is the bad one.

old time motorcycle guy showed me that trick. best mechanic in the world. he got shot in a drive by in oakland, while gassing up. i pass his tip on, in his honor.
cliff

I had a bad injector once and I tried disabling one cylinder at a time to find the bad one. It was far from obvious. I was surprised how subtle the difference was.
-Chris

No doubt. Sometimes you have 1 1/2 cyinders out. That's real fun. I like the water idea. That would even show a weak one.

Yikes!:eek: Gasoline?!!:eek:

You could take the plugs out and look and see which one is wet, if it is an ign. problem. If it is a fuel problem then that won't work.

I also wouldn't crack the banjo bolts. That would disturbe the sealing rings possibly
Dean

similar thought, but just wet your finger and see which pipes dont sizzle when you quickly touch it with your finger. Always works for me.

Well,
I went the route of taking out each plug. They were all grey in color except for #2, it was black as coal. I check the resistance of the plug wire and it measured the same as the rest. I put in a new plug and it runs much better but still rough. I feel I have a fuel delivery problem which caused the plug to foul.

Injector leaking?

If it's ignition related you can simply snap an induction fired timing light on to each wire, one at a time.

If it isn't sparking you won't get s strobe flash. If it is firing cortrectly you will get the light to flash.
Onliest problem here is if the wire is grounding and arcing through something besides the spark plug you will still get a signal.

sam, i did that once, and i got flashing from the timing light. but the badness was the plug. water bottle, you dont even need to jack the car up. set the water bottle on "stream".