Hello,

I have a 98 4runner, 3.4l V6, 191k miles.

My truck started running really rough, and the CE light came on. It was a cylinder 4 misfire.

Spark plugs and wires are 20k miles old. But I started by swapping out that plug, cleaning MAF, changing air filter, and ran fuel injector cleaner through the tank. No change. I also checked the wires, but they looked fine to me. They are fairly new.

Then I swapped coil swaps around, but the misfire remained on cylinder 4. I was down to the fuel injector.

Yesterday I swapped the fuel injector, changed valve cover gaskets, cleaned throttle body, IAC, and intake manifold. At first it seemed to run fine. No misfire. Although in park or neutral, it was idling at 1700 rpm. I assume this is because I cleaned throttle body, and need to add a washer in between the throttle linkage.

But today, the CE light came on again, and it started misfiring. Same cylinder. It seems to run better, but it's sluggish. And it only misfires while in gear. In park or neutral, it doesn't misfire, just revs up real high.

Any ideas?

 

Could this be a head gasket issue???

 

My next step would be to do a compression test. See if that cylinder is losing compression somehow, either via a valvetrain issue or stuck rings/headgasket...

 

I'm having this identical problem right now. Just completed compression test today and it looks like the mechanic will have to tear the motor apart :/

p1300 igniter circuit
cyl 3
cyl 4
multiple cyl misfire

looking at the motor from the front.... compression test came back as

195 210
180 210
200 125

So cyl 3 and 2 numbers are low. What does this tell us? I hope the mechanic i met is wrong about me having to spend 3k to fix this.

could it be the computer, electrical? or something else other than the motor?


- babied 4runner 1998 limited 161k miles