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1997 Toyota 4Runner Randomly Stalling

Hi, I have a 1997 Toyota 4Runner SR5, 6 cylinder with 188,000 miles. I love my car, it’s treated me well over the years. About 2 months ago it started stalling at stop lights, etc. Basically, any time I came to a stop and it was idling while in gear. I start it right back up and when my foot’s on the gas, it doesn’t stall. After 10 times or so I learned that if I took it out of gear the RPMs went up a little and it didn’t stall. About 2 weeks later the “check engine” like went on so I figured, now it’s time to take it somewhere. So I took it to a mechanic that I’ve been to before and trusted (here in San Francisco) and he said, “oh… it’s probably just an idle adjustment” so I think, great, no big deal.

After a few days he said wasn’t the idle and that after testing he found that all 6 cylinders were randomly misfiring. So he needed to change the spark plugs cause they were down to a bare nub. I figured, ok, it’s about time anyway. He said it could also be the ignitor?, he didn’t sound 100% positive, but told me there’s probably something wrong with it since it’s pretty old too and that’s all he could think of. So he changed all 6 spark plugs and the ingintor and the engine light was still on. It was stalling less frequently, but still randomly stalling. He then said he was going to have his Toyota specialist friend look at it. His friend couldn’t figure out what was wrong either. Then he sent to to the Toyota dealer, they checked everything they could think of, but couldn’t diagnose the real cause either. Apparently they even checked the “Dynamic Balancer”? I’m not even sure my car has one of those. They might as well have told me it needed a new agonculator (totally made up word) for all I knew. So they had my car for 3 weeks and finally I said, enough is enough, these guys can’t figure it out. After 3 weeks of hearing how much money they spent on other people to figure out it, I finally said, let’s stop the bleeding. The car still runs and doesn’t stall that much. The last thing they tried was 2 series of a fuel injection flush (decarbonize)? So they did that with not a whole lot of improvement. They also managed to run all the gas out of my car and by the time I picked it up, the fuel light was on and I took it immediately to a gas station. No joke, they burned about 1/2 tank of gas and didn’t refill it.

After 3 weeks and $1000, they come up with “we don’t know what’s wrong, but use Premium gas and it might fix itself”. In the end they told me they were down to only one misfire, cylider #4. Also, the “check engine” light is still on. Since I’ve gotten it back it hasn’t stalled, so there’s an improvement. But I’m no closer to figuring out what’s wrong that’s keeping the check engine light on. Needless to say, I’m not taking it back to these guys. Fool me once shame on you, fool me twice shame on me.

Any suggestions? I greatly appreciate the help. Everything else works great and I’m willing to put the money into to keep it going as long as it’s the right thing.


Good Lord, where should I begin…

Firstly, you need an actual technician that can do diagnostics. There are numerous reasons why an engine might misfire, and you have codes stored in the ECU that might lead the way to the root cause(s). The reason I used the plural is there’s probably more than one contributor. If the plugs were all worn to the nubs, the engine has clearly been neglected.

Possibilities on a vehicle this age include sticking injectors, bad sparkplug wires (this is a distributor based system), worn out rotor and/or distributor cap, a flakey idle air controller, and more. Any competent technician can resolve this, if he’s willing…dealers often don’t want to mess with aging vehicles. Their shop costs are high, and aging vehicles often have multiple problems.

Try starting by having the fault codes read at a parts store (many will do so free) and post them here.

And, for the record, you do have a “harmonic balancer”, often called a “harmonic damper” or “vibration damper”. It’s at the front of every engine’s crankshaft and “dampens” rotational pulses (rotational vibrations) caused by the constant pushes from the ignition explosions.

Everyone also has an “agonculator”, but nobody has ever found out what it is…:slight_smile:

@Sterg…you almost got it right. This is straight from the “Urban Dictionary.” Gonculator…
mystical device in automobiles which processes goncules for the gonculatory process; an inherently important component of the internal combustion engine. The gonculator is a fairly inexpensive part and is labor intensive and costly to install. I would assume the rest of the definition would have something to do with “boat payments” or the like.

Start simple, is there a gas filter that is replaceable? If so has it ever been replaced?

I would hope they replaced the ignition coils. Also, this could be a bad coolant temp sensor, MAF sensor, fuel pressure or injector #4. Valve clearance/Timing and or burnt valve. Of course compression and a leaky head gasket would cause your code. I would throw intake leak in for good measure. You need a good tech and I would check “mechanic File” at the top of the page and find one in your area.

If memory serves, this buggy uses a single coil. And Knfenimore has cited some excellent possibilities…especially that coil.

Any halfarse decent tech with an ignition analyzer can find a bad coil (or any of the other ignition related possibilities) in no time. Your chore is to find a halfarse decent tech.

Thanks all! This at least gives me something to go on. And thanks for the advice to have fault codes read, I really didn’t know they could do that. I know there could be multiple issues going on and I know I’ll have to find a talented tech who can do some good diagnostics. Thanks for all the help!

I’ll definitely check on the gas filter. That could be an easy win. Even if it’s not the sole cause it can’t hurt and won’t cost much.

You should no longer used “trusted” and the name of this “mechanic” in the same sentence. Did he at least give you a list of the tests they did and what the results were? This isn’t rocket surgery…

Good replies all but, as “the same mountainbike” said in the first reply, get the fault codes at a local auto parts store and go from there. Whether it’s free or not it’ll be great info and info is what you resolve your stall problem.

Try a new OEM iac valve. Make sure the coolant hoses going to it are free flowing as well.