Engine vibrates, runs rough
11-03-2020, 12:32 PM
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Engine vibrates, runs rough
91 4runner 3.0 auto
So on my way home from work my truck started acting weird, engine vibrating, exhaust fluttering, misfiring. Here's the symptoms
At idle, engine runs seemingly OK, maybe a little rpm fluctuation. The exhaust has a new fluttering sound.
While driving around town it seems to be mostly OK, occasional possible misfire and rpm fluctuation.
At highway speeds in highest gear is where it has issues.
With light throttling at about 2.5k rpm, the engine and whole truck starts to vibrate. The vibration gets worse until the throttle it pressed enough to downshift the trans. Once it downshifts and is at 3k and above rpm, it runs good.
If I let off the throttle, it'll hiccup and jerk a little but not enough to lose power. As soon as it goes back into high gear it starts hiccuping and vibrating with throttle again.
I have a couple CELs, I think its 42 and 43. They were there before this issue so I don't think they're related. I'm working on those as well.
Checked timing, about 13°. I haven't had a chance yet to check if the belt has jumped, which is what I suspect happened but not positive. Checked all vacuum lines, looks good. I was thinking of picking up some starting fluid to test for vacuum leaks a little more thoroughly.
So I obviously have some diagnostic work to do still but thought I'd see if someone can point me in the right direction
So on my way home from work my truck started acting weird, engine vibrating, exhaust fluttering, misfiring. Here's the symptoms
At idle, engine runs seemingly OK, maybe a little rpm fluctuation. The exhaust has a new fluttering sound.
While driving around town it seems to be mostly OK, occasional possible misfire and rpm fluctuation.
At highway speeds in highest gear is where it has issues.
With light throttling at about 2.5k rpm, the engine and whole truck starts to vibrate. The vibration gets worse until the throttle it pressed enough to downshift the trans. Once it downshifts and is at 3k and above rpm, it runs good.
If I let off the throttle, it'll hiccup and jerk a little but not enough to lose power. As soon as it goes back into high gear it starts hiccuping and vibrating with throttle again.
I have a couple CELs, I think its 42 and 43. They were there before this issue so I don't think they're related. I'm working on those as well.
Checked timing, about 13°. I haven't had a chance yet to check if the belt has jumped, which is what I suspect happened but not positive. Checked all vacuum lines, looks good. I was thinking of picking up some starting fluid to test for vacuum leaks a little more thoroughly.
So I obviously have some diagnostic work to do still but thought I'd see if someone can point me in the right direction
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