Misfire Issue Options

[PaukST]

So, about 3 weeks ago my 94 ST started getting a misfire. Initially, it was only under mid-heavy load, like going up a hill at relatively low revs. I replaced the spark plugs and it got better for a few days, then went back to the occasional misfire. However, a few days ago it suddenly got way worse. I pulled up to a stoplight, but when I went to take off, it would barely go. It's nearly undrivable. It's pretty much a constant misfire now. It seems to be cylinder #2. It tries to die if i pull a spark plug wire/unplug an injector from 1, 3, or 4, but nothing changes when i unplug either from cylinder #2.

I had changed out my spark plugs and wires probably less than a year ago. I rebuilt this engine June of last year, and have had a VERY slight miss with this engine all along. I assumed it was due to the ever-worsening crack in my exhaust manifold (located closest to the cylinder #2 exhaust port).
So:
---Rebuilt 18 months ago
---Replaced spark plugs about 2 weeks ago, the old ones weren't broken or particularly noteworthy
---Replaced spark plug wires within past year
---Switched over the injectors from my other 7A-FE thinking one may have been clogged, no change

Anyone have any ideas? Advance tells me they can't check the CEL code on anything pre-96.

Second edit to add that I replaced my distributor cap/rotor around the same time as my spark plug wires. I took the dist cap off today and cleaned up the contacts, they looked fairly bad again. Unfortunately that changed nothing.

This post has been edited by PaukST: Dec 12, 2013 - 6:15 PM

[Smaay]

spark plug wires should have very low resistance. ohms is the measurement of resistance. you want that to be very low so that voltage will travel at its best.

[czwalga]

spark plug wires should have very low resistance. ohms is the measurement of resistance. you want that to be very low so that voltage will travel at its best.

Not necessarily true. Low resistance provides a ton of EMI interference at those voltage ranges. Most OEM spark plug wires have very high resistances per foot.


EMI can have negative effects on your ECU/Gauges etc. Also most 'low resistance' spark plug wires are made with spiral wire instead of solid core wiring. In transmission lines, the majority of the power flows through the outer most portion of the wire; so if you have stranded wire its actually hindering the transmission.

This post has been edited by czwalga: Dec 16, 2013 - 2:14 PM