RUMBLE VIBRATION WHEN ACCELLERATING

A little help, maybe? My recently acquired '00 2x4 4runner v6 auto with 240k miles has developed a new vibration issue when accelerating. At low speed, under 30, it almost feels like a dead miss, smooths out between 30 and 55 or so, then comes back worse over 55 and up, as accelerating. Minor if any loss of power. But anytime its vibrating, if i let off the gas it stops. And the vibration is in the seat, not the steering wheel (so no front end suspension/tire prob, I think) and not in the brake pedal (so no brake probs either). No clunk when shifting into drive from park, but a bit of one when shifting from drive to reverse. Before buying I helped maintain this vehicle for the last 10 yrs, as in offered advice when probs cropped up, occassionally drove truck to help diagnose probs, and took to shop for probs when requested. The check engine light has been on for years (evap cannister, yeah, I know, on my list to get fixed, lol), but when this vibration is happening the ck engine light starts flashing on and off. I don't know that the rear end lube level was ever checked (at least I never specifically told the shop to do it, may have been ck'd as some regular inspection). Getting codes pulled this afternoon. Looking for options, opinions and best guesses. I'm betting drive shaft or rear end.

 

one thing I have noticed...as we drive our beloved 4runners, and rack up the miles...miles with the ongoing age, our vehicles start acting up..at times...like they have agendas of their own....LOL

 

RoxToy00, I would suspect U-Joints and then the drive shaft. You can also put a friend in the front on a test drive and then put them in the back to see if the shaking is worse in the rear which may indicate a rear differential problem. But because it stops when you let off the gas...I think it's U-Joints or drive shaft.

 

Update: worn rear universal replaced, changed rear end lube, then pulled codes: P0171 (system too lean), P0300 (random misfire), P0301, P0303, P0304 (misfire on indicated cylinder). So replaced fuel filter and discovered water in the gas (milky). Since I was down to 3/8 tank, filled up at Sunoco station I rarely use and dumped a can of gas dry (safe for injectors) in. Better. Then I cleaned the MAF (really dirty), cleared all codes, and went for a test drive. Still better, but still a slight vibration. Idle always good/smooth at approx 700rpm when warm, minimal vibration, only P0301 code returned, more power than as of late. I'm guessing a bad plug or wire or coil, but maybe a bad injector. No water in oil or bubbles in rad, no vacuum leak heard. Will pull plug and take a look, then swap wires and swap coils, clearing codes after each swap and going for a drive, seeing if miss migrates. This forum has been very helpful, still seeking opinions comments help.

 

Try removing and cleaning the throttle body it could help and couldn’t hurt. But it’s probably the plugs wires or a coil. Maybe an injector. Maybe try and check your fuel pressure.

Maybe the throttle position sensor. hope I helped a little bit.