3.4 Cyl misfire

[wvjeepers]

Toyota newb, been dealing with Jeeps all my life.

Wife has a 02 SR5 with the 3.4, I was getting a cyl 1 misfire. Checked the injector with my mechanics stethoscope, and could tell it wasn't working. Replaced the injector, firing correctly (by ear), cleared the code, drove it around the block, CEL again. Cyl 1 misfire again.Swapped the coil from 1 to 3, cleared the codes, now im getting cyl 3 misfire code. Im assuming the coil is bad.
My question is, can one side of the coil go bad? each coil runs 2 cylenders, but I'm just getting misfire on one of them. Is there something else I'm missing?

 

[hambob]

Maybe the coil is good but the boot or wire is bad? Good luck

 

[Dirtyfingers]

If it sounds like a lawn mower it's a spark plug. Is its a small rumble it's the wires. At least that's how I diagnosed mine. I'd replace wires and plugs.

 

[wvjeepers]

I didn't move the plug when I moved the coil, but the misfire followed the coil. Hadn't thought of the boot being bad, but there was condensation/light rust coke red dirt on the boot when I pulled it. Can the boot be replaced by itself without replacing the entire coil? I'm a cheapskate lol.

 

[FROGrunner]

Most likely then a coil.. There's no way to cheap skate that other then to get a used one..

 

[TheDurk]

Toyota newb, been dealing with Jeeps all my life.

Wife has a 02 SR5 with the 3.4, I was getting a cyl 1 misfire. Checked the injector with my mechanics stethoscope, and could tell it wasn't working. Replaced the injector, firing correctly (by ear), cleared the code, drove it around the block, CEL again. Cyl 1 misfire again.Swapped the coil from 1 to 3, cleared the codes, now im getting cyl 3 misfire code. Im assuming the coil is bad.
My question is, can one side of the coil go bad? each coil runs 2 cylenders, but I'm just getting misfire on one of them. Is there something else I'm missing?

Sure. If there is a short at the boot AROUND the plug, #4 (the other in the pair) will keep firing (common fail mode). If there is an open circuit, both will die. If the fail is in the primary, both will die, but that is very rare, as the primary is relatively few turns of heavier gauge wires. Out of my you know-what, but I'd say grounds on high-voltage are more common than opens. Look carefully at the coil boot. NAPA sells just the boot, although I am not sure if Toyota does.

 

[TheDurk]

Toyota newb, been dealing with Jeeps all my life.

Wife has a 02 SR5 with the 3.4, I was getting a cyl 1 misfire. Checked the injector with my mechanics stethoscope, and could tell it wasn't working. Replaced the injector, firing correctly (by ear), cleared the code, drove it around the block, CEL again. Cyl 1 misfire again.Swapped the coil from 1 to 3, cleared the codes, now im getting cyl 3 misfire code. Im assuming the coil is bad.
My question is, can one side of the coil go bad? each coil runs 2 cylenders, but I'm just getting misfire on one of them. Is there something else I'm missing?

Sure. If there is a short in the secondary at the boot AROUND the plug or in the plug itself, #4 (the other in the pair) will keep firing. If there is an open circuit, both will die. Out of my you know-what, but I'd say grounds on high-voltage are more common than opens.

Look carefully at the coil boot. NAPA sells just the boots; I am not sure if Toyota does.

 

[M-Piers97]

I didn't move the plug when I moved the coil, but the misfire followed the coil. Hadn't thought of the boot being bad, but there was condensation/light rust coke red dirt on the boot when I pulled it. Can the boot be replaced by itself without replacing the entire coil? I'm a cheapskate lol.

Yep, the boot pops right of the coil. You could try cleaning the contact points on the coil to see if it makes a difference.
Hang in there, i know first hand that finding/dealing with misfires sucks

 

[wvjeepers]

went out and pulled the coil, cleaned it, but didnt notice any defects. wrapped the boot in a layer of electrical tape. No cel so far, seems to run good (other than a exhaust leak and heat shield ratteling). If this fixes it for good, I'll grab a boot later this week. Thanks everyone.