My truck has run great until I went for a smog check. The dude adjusted my timing before running the test. When I left, it ran like absolute crap.

I checked the timing and it was at 10btdc, I put it closer to 12-14 and it seemed to run better. No pinging at all. After a few min, was back to low power (i mean 75 mph top speed). I did a tuneup, fuel filter, cap/rotor, plugs, airfilter and it helped a little bit, the cap was due, but not too bad. This helped a tiny bit, but still rough acceleration, as if the engine was working hard and accelerating with the e-brake on or something. When I had it apart to do the plugs, I noticed the TB really dirty, dumped half a can of TB cleaner into it, made the idle much smoother and no more hesitation. Runs MUCH better now, but there is still a hint of power loss, again, like i'm driving it around with e-brake partially pulled, and it is inconsistent, sometimes its fine and sometimes feels wierd. Is there some emissions device that could be retarding the timing or something? Bad knock sensor? I have no idea at this point. Its 80% back to normal but still lacking. No check engine lights ever. Ideas?

 

well it could be, just maybe a bad 02 sensor, causing rich condition, but you might check the TPS and see if it is working well. You cant get good timing with they are bad,

 

still having this problem. It runs much MUCH better now, but now and then has this intermittent slight power loss. I put 89 gas in and it seemed to run a little better. Sometimes I hit the gas and have full power, other times I push the pedal and feel the engine strain but not accelerate too much, seems like when it does this, the farther I push the pedal the less pull from the engine, and if I back off its a bit better. Is this still a timing thing? Does it retard under acceleration? Why only sometimes? I don't think its pinging but I could be wrong. I'm still idling differently now and then too. when warm, i can turn it off and start it and it will idle at 1k. sometimes when driving (warm) and I pull up to a stoplight, it will idle at 1500. no rhyme or reason, and only these two rpm's. no check engine lights ever. currently the timing reads 14btdc. if I set it alocer to 10-12, the idle drops and it runs with less power.

 

yes, I would check the 02 sensors
I just bought a 95 4runner, and I have noticed it acts the same way: sluggish at times and gets up and goes at others. I recently replaced the spark plugs, and the check engine light is on after doing that.

One question...I'm installing downey headers on my 4runner, and having a shop install a dual exhaust system for me. Should I have the 02 sensors replaced while I'm at it or keep the old one(s)?