Car, 1990 Supra Turbo, idles rough at low rpm so I thought timing might be out so I hooked up the timing light on number 1 plug wire and the timing light started acting erratic. Looking at the rpm and watching the light it was all over the place so I put it on number six plug wire and operated just fine. Rpm showed about 900 rpm. Checked 2 through 5 and showed about 900 rpm. Numbr 1 bounces from 0 to 700 and when I say zero I mean no blinking light. Looked at plugs and number one looked like it was fuel fouled. Has anyone ever had this problem with a misfiring cylinder? Not sure how the coil packs get info to fire. Any help would be appreciated.

How many miles on the car? How do the other plugs look?

If the timing is eratic as in jumping from 5-20, you need to short terminals "T" and "E1" in the diagnostic terminal. This will put the car in diagnostic mode and hold the timing steady at 10 BTDC.

If you're getting a miss, first make sure the coil pack ground is good (its problematic on 7M-GTEs). Make sure the plug wires are tight and secure on the coils and plugs. If that doesn't help and it has been a while since you've changed them, replace the plugs and wires. If #1 is still missing, I'd suspect a leaky injector...

If you are doing it right, the ignition wire is bad. It is showing the voltage spiking extra high from the resistance. If you say the others dont do it. It will move a little on its own.

Cylinder #1 plug was bad. I changed all the plugs out to Autolite Coppers and no more problems. Thanks for all the help.


Mike