Texas91Runner

I had changed out my spark plugs (pre-gapped) and wires recently. Two of my wires were damaged from not being suspended properly and touching the manifold. After if burned, it started misfiring. I bought the exact same set of wires, and replaced the damage ones. It runs fine from a cold start, but after heating up, starts misfiring again.

This is a 1991 4runner 3.0 4x4 Auto

What is wrong?

abecedarian

pull the EFI fuse, or disconnect the battery, for a minute or two then go driving and see how it goes.

Texas91Runner

I actually had the battery disconnected for a while this weekend while changing my belts, and nothing changed... Any more possible solutions?

abecedarian

well...
I never trust pre-gapped plugs since the same plugs work on different engines and gaps may be different, so start there and make sure the plugs are gapped according to your engine's specs.
also, check the ignition coil resistance to make sure that the shorting wires didn't damage the primary windings in the coil.

Texas91Runner

Thanks.



I'll check it out this weekend and keep results and inquiries posted.

CHAUCH

Yeah.. I have the same type of problem with my 92 v6.. once she warms up .. it starts missing.... well probably misses the whole time just more noticable after the idle comes down.

The plugs were done by the last owner, and i just changed the wires .... with no results...

Texas91Runner

Anymore opinions?

TNRabbit

missing after warmup denotes a vacuum leak, usually. There are miles of vacuum hose on these engines and they're getting up in years, so cracked hoses are common.

Texas91Runner

Good point. I'll check my hoses tomorrow.

CHAUCH

any luck finding your leak?... When I pump my brakes the stumble gets alot worse and brings the rpm's down.

I have sprayed all visible vacuum lines...but I haven't been able to find anything yet

Texas91Runner

My apologies for taking a while to reply; I was out of town. I just replaced the majority of my vacuum lines (one of which I found to be torn) and I still get misfire. I feel it mainly at idle and after the engine heats up.



Any more options?
Any one?

Texas91Runner

I honestly can't feel the stumble while driving at all. In my case, I can feel and hear sudden bursts from the exhaust (mostly while idling), but when under the hood the engine doesn't appear to be much off pattern.



I would really like to know what's wrong. My runner never did this before the swap of the plugs and wires.. I'm most-likely going to check the resistance of the current coming from the distributor next if I can find my instrument. I'd probably suggest you guys doing the same.

CHAUCH

I haven't changed my vacuum lines out yet, but I can hear a very high pitched sound when the truck is idling I cant seem to find where its coming from.

I have changed my cap, rotor, plugs and wires. Mine is the same as yours, when sitting at idle, I notice the stumble as it mildly shakes the truck.

Does your idle decrease and get worse if you pump the brake quickly?

Mine seems to drop and get rougher when I do this.

Kiroshu

leaking booster.... get a new booster i promise that will stop

Kiroshu

check distributor for cracks and corrosions same with button try changin them they are only like 10-15 bucks..... check egr...and or vac lines to it..... fuel filter?

Hellvision251

I know im 4 years late. but im having the same type of problem. truck sounds good while warming up but at a warm idle you can hear it missing. I change the plugs, cap, and rotor it seemed to get a little bit better but not completely. I was reading on other threads and i think maybe a valve adjustment can fix this.?? any input?

Hellvision251

Okay. Sorry to post my problem on this tread but It seems my number 3 cylinder is the problem. Compression is only at 30 PSI, while all others are 175-180psi. Please help with any added info.