V8 Misfire at idle

[gshadow325]

Oh, btw is there a remote starter in this vehicle?

 

[4RunnerV8]

No remote starter, but I'll check the wiring to the plugs. I'd love it to be something that simple. Would the engine temperature affect the wiring's capacity or ability to transmit voltage to the plugs?

 

[cloh09]

I was thinking the sane thing, but I think he means not clicked on referring to the connector at the coil pack at the spark plug

Yes that's what I meant. One of the wires coming out of the coil pack wasn't clicked securely in place. I couldn't think of the phrase "coil pack" and said distributor. Coil pack/distributor, same thing.

 

[4RunnerV8]

I should have figured. I checked the wire attachment to the coil packs - anywhere else I should check? Could a vacuum leak cause this? As far out as this seems, could a serpentine belt, long overdue for replacement as in 180K create enough stress on the electrical system to reduce the spark capacity when the engine is fully warmed up and at idle? I just want to try everything before replacing cats - I just don't think they are the culprit. Thanks, again, everyone for the help on this.

 

[cloh09]

Serpentine belt should have been replaced with the timing belt, water pump, etc. I don't have the knowledge on what it does, but but I think in general, they get swapped along with the other stuff. If you have paperwork on it, then maybe it wasn't replaced. You got me.

 

[4RunnerV8]

Thanks for the advice here. I'm taking it to a highly reputable independent mechanic in Durham, NC. He's confident he can figure it out, and doesn't think it's the cats either based on what I've told him. I'll suggest checking the fuel injector function, coil packs, and the O2 sensors that were installed last year. On the possibility of an incorrectly aligned timing belt - skipped tooth, etc) I'm assuming that would show up more often than at idle after full temp is reached. Acceleration and steady state driving is absolutely normal. Any other suggestions? I just want to focus on finding the problem rather than replacing everything on the car in hope of solving the problem.

 

[4RunnerV8]

Idle solved

The simplest and most obvious solution is usually the correct one. The original mechanic doing the o2 sensors installed a Bosch sensor on one side - no good. I don't know if it was the sensor, the fact that it wasn't Denso, or what - but replaced that sensor with a Toyota o2 sensor and the trouble is gone. A combination of highway and stop/go traffic on the way home from the garage and the truck ran as smooth as it used to - no stumbling, misfire, or anything at all. Let's hope it sticks. Thanks for all the advice on here.

 

[DiskDoctr]

A little late, but I was going to mention the upstream O2 sensors are WIDEBAND/AFR sensors, not the standard O2 sensors and are used to adjust your fuel ratio.

If you had standard O2 sensors in there, it would certainly cause troubles. Should have thrown a code, I'd think?