94-3.4

my car has been running poorly and i thought it was plug wire related so last night i put a new set of wires on and it ran the same. The car feels like its missing on multiple cylinders at idle so we started pulling plug wires and to our surprise it ran the exact same with any one plug wire removed. So i stuck 4 different wires next to a bolt and started the car, each time we did this you could see the spark arcing to the bolt on a constisten basis for about 4 seconds that it would stop and then start again. So i am not gettinga constant spark which is why i am having a low rpm missfire. With that said i am guessing its the optispark which i replaced 2 months ago Can anyone clarify this for me? Thanks

BlownF1

My bet is weak coil...it sparks a few times after building up enough energy, then goes away for awhile...fairly common failure.

P.S. I'm assuming you changed the coil wire when you did the plug wires...if not, check it for white powder in the boot.

BlownF1

Ohh, and checking spark by grounding/arcing to a bolt can be very misleading...get a cheapo $5 spark tester at any parts store and ensure the spark is able to jump the appropriate sized gap. It's over 1/2" or so on a 4th gen if memory serves me...

94-3.4

I did not change the coil wire but i will now. What does white powder mean if i find any? Thanks for the info!

BlownF1

Ohh, that's a definite "must do" on these cars. It's VERY common for white powder to accumulate in the coil wire boot and corrode the connection. Not sure where it comes from myself (arcing?), but it's been a known fact for years and is the first thing to check/change when having ignition problems...start there and hopefully it's as simple as that!

94-3.4

Well i replaced the coil wire and the coil and it runs exactly the same. Any other suggestions? Some other simptoms are noisy rockers, low vacuum as well. Thanks

BlownF1

Bummer... I'd try the spark tester next to confirm whether you're really getting strong consistent spark at each cylinder...

When you did the OPTI, was it a full new OEM one or rebuild kit, etc.?

Hyperspeed97z28

Double/Triple Check your wires.... When you check the coil wire.. It should have ZERO resistence?

94-3.4

How can i check for resistance? Will this show anything on the other plug wires as well?