jguillory

My 95SE w/ 133k has developed a serious miss. I would best describe it as a "bump" that usually starts only after the car is warmed up. Under acceleration, the car is usually fine; but at idle, you can feel the "bump" and notice a momentary drop in the RPM; also if the lights are on, you can notice a brief dimming when the engine misses. But it never dies; just idles roughly.

I assumed it would be a coil problem, or maybe a fuel injector. Didn't have a CEL, until I checked and sure enough the bulb was burned out! Anyway, I got codes for the KS and the coolant temp sensor. I replaced the coolant sensor ($25 part ~ 1 hr. DIY), and that code went away. But the "bump" is still there, and the KS code still registers (although of course it doesn't set the CEL).

Since there are no other codes, I have a new KS on the way. But could the KS really cause this problem? Has anybody else experienced it? I guess the sensor could be messed up somehow to send weird spark timing to the ECU?

If the new KS doesn't fix the problem, I don't know what else to do. Any suggestions?

mansurxk

iTrader: (14)

coil packs dont necessarily throw codes until there completely dead. you might want to remove a coil and put it back in and see if you notice the one that causes you change in condition. or borrow someone elses 4th gen and swap the coils and see if it solves it. the KS wouldnt cause a miss, most people dont even notice it on their 5speed if it were bad. what plugs are you using? ngk? if not then that could be a cause of the problem. and also as you suggested it could be a bad injector.

jguillory

I thought it could be a coil problem. I'm using NGK coppers (the most recent set only has about 10k on them - I checked them last week and didn't notice any fouling). Any other ideas on how to diagnose without having to get a new/borrowed coil pack? When you suggest removing a coild and putting it back in, do you mean putting it in a different cyl? Tried that between the 1 and 3 cylinders and didn't notice any difference...

Armani

I am willing to bet that it is indeed one of your coils going bad. As previously stated, bad coil WILL NEVER throw a code, UNLESS it is deteriorated to a point where it causes a SEVERE cylinder misfire.

jguillory

Well, I have checked all of my coils for resistance, and all of them were exactly the same. But the results seemed different than other posts I've read. Here are the results for all the coils:

+pin1, -pin2 = 25 ohms
-pin1, +pin2 = infinite resistance
+pin1, -pin3 = 60 ohms

The Haynes manual states that resistance between +1, -2 should be INFINITE. Does this mean that ALL of my coils are bad?

The probes on my multimeter wouldn't reach all the way down in the spark plug boot to check that one. Is there a way to remove the boot to get to it?

I really appreciate any suggestions!

mansurxk

iTrader: (14)

when i said remove it, i meant remove one at a time to see if you sense a change in firing. if 1 coil pack is bad, and you remove one thats nto bad, itll misfire badly. you keep doing it til you remvoe one and thers no change in misfire. thatll be the bad coil pack most probably. you only posted results for 3 coil packs, what about the other 3?

jguillory

all 6 coils had the same readings as above.

mansurxk

iTrader: (14)

your going to need to swap packs with someone, it might be intermittently failing. resistance check isnt the best way to check them, thats what alot of orgers had to say anyway.