Plug damage/misfire or kick

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J

jgranthevagrant

10 Year
Joined
Sep 11, 2012
Threads
66
Messages
816
Location
Rossland, B.C.
Ok, I will try the Mudders. Truck is a 1990 DLX. 330 000 ks. Gas, 22re, Canada.
about 250000 ks on this motor. Has been running very well, but has just started having this little misfire or slight hesitation, about 4 times in 100 or so ks. I am commuting to work in stop and go, and then often up to the ski hills after work. No real off-road in the winter.

I pulled the plugs 2 days ago to have a look, and the number 2 plug is severely damaged. Electrode is not really there. Quite a bit of black deposits, but looks more dry than wet. Engine not blowing any blue, or burning much oil. Compression and power seem good.

I put in new plugs, and still had some occurrences of the little kick, or very brief hesitation. I pulled the number 2 plug again tonight, and it already has some little deposits on it. I will try to attach a picture.

This is obviously a symptom of another problem, but which one? Valve guides leaking oil into the number 2 combustion chamber? Timing off slightly?

It is snowing here right now, and I do not have access to a garage, so I'm hoping to get through winter before anything major.
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That's a preignition symptom, maybe overheating engine, incorrect timing. If those things check good try using high octane and see if that helps. Otherwise you will have some serious engine damage quick. If it burning away a steel electrode it is going to damage the cylinder.
 
Ok, I'm back. I ordered a new TPS from Toyota. Old one was clearly shot. Installed, tested it, and set it up with the multimeter. Re-checked timing, which now is accurate. Runs and idles as good as ever, but the little kick or misfire or hesitation is still there. Sometimes 3-4 times in an hour of running time, sometimes not at all for 3 hours. I'm running out of ideas, but I hope I can limp until spring.
 
Did you check the injectors and valves as Scott suggested?
 
I listened to the injectors with a scope. They make a regular click noise. Of course, that doesn't mean they work, but that is what the FSM says is normal. I checked the valves in November, and reset a few slightly. Nothing seems unusual. Sounds good, and idles almost perfectly. If I make to spring, I will take apart the whole intake side, and send the injectors for cleaning. Again, I have to make it til March or April because I don't have a garage or a second vehicle.
 
Hmmm. I now notice that the stumble/kick/hesitation is much more prevalent when it's raining, and that it exactly coincides with my wiper motor action. The tach bumps down with the wiper startup as well. So now I think it is electrical. I will check all the connections. Maybe something interfering with the coil or igniter? Too much load on the alternator?
 
How old are the plug wires? I'd pull the injector and check to see how it sprays.
 
Plug wires are pretty new. 3 - 6 months old. Kick/hesitation definitely occurs when lights, fan, stereo, wipers etc are on at the same time. Haven't had time to really look at it yet, because I'm leaving for work in the dark, and coming home in the dark.
 
Back again. Running with most accessories on in the rain seemed to trigger the misfire or kick much more often, so I investigated charging and ignition wiring. found a broken ground? wire that comes up from the alternator harness to attach near the PS pump. Dash voltmeter now reads about 2 volts more than before, and does not fluctuate. No sign of the misfire/kick, after about 4 days of commuting and some back and forth to the mountains. Averaging about 120 ks per day. someone will explain the how much effect one little ground wire has? It was broken inside the connector, so hard to find. Pulled on it accidentally.
 
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