84 4Runner
Restless 'Runner
- Location
- Salt Lake City, UT
Does anyone know the specific symptoms of a burned valve?? My 22R has been having inconsistent problems for a few months now. Previously it would hesitate and misfire after warming up any time I tried to accelerate (especially up a hill). I replaced: spark plugs, spark plug wires, battery, coil, distributor cap and rotor, air filter, 02 sensor, and fuel pump.
After learning that it may be a problem with a burned valve, I did a compression test and found that my #4 cylinder had a VERY low compression, even relative to the rest (125, 125, 124, 95)! So I re-adjusted the valves and discovered that the #4 valve was improperly adjusted and was too tight. As far as I could see everything else looked great! This upped the compression in #4 to 112, which seems consitent with the wear #4 had when I rebuilt the head 3 years ago. I know it's not a ring because it doesn't smoke (except a little on starting) and the compression didn't change much when I put a little oil in the cylinder.
Now, however, the 4Runner is running VERY inconsitently. Sometimes it will run great, and other times it lugs like no other! Then on occasion it will missfire and hesitate for a brief second, and then run great again. The hesitation seems mostly to happen when I'm revved to about 3000-3500 rpm, but occasionally in lower rpm as well.
Does this sound like a burned valve??? Or does anyone have other possible ideas or experience? Thanks!!
After learning that it may be a problem with a burned valve, I did a compression test and found that my #4 cylinder had a VERY low compression, even relative to the rest (125, 125, 124, 95)! So I re-adjusted the valves and discovered that the #4 valve was improperly adjusted and was too tight. As far as I could see everything else looked great! This upped the compression in #4 to 112, which seems consitent with the wear #4 had when I rebuilt the head 3 years ago. I know it's not a ring because it doesn't smoke (except a little on starting) and the compression didn't change much when I put a little oil in the cylinder.
Now, however, the 4Runner is running VERY inconsitently. Sometimes it will run great, and other times it lugs like no other! Then on occasion it will missfire and hesitate for a brief second, and then run great again. The hesitation seems mostly to happen when I'm revved to about 3000-3500 rpm, but occasionally in lower rpm as well.
Does this sound like a burned valve??? Or does anyone have other possible ideas or experience? Thanks!!
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