So it's been a long project but I think we are getting there or maybe that's wishfull thinking.

So ever since we purchased the truck she has had a low throttle bucking issue. It seems to be most noticeable in 1st gear at low speeds and partial throttle. Today I leaned out the VAFM back to stock (previous owner had it turned 7 clicks CW{rich}) and the bucking seems to have gotten worse but the truck is idling smoother and no longer smells like fuel. I have base timing turned back to 12 degrees with +4 built into the cams and running 92+ octane and at highway speeds the issue does not present itself. I am pretty sure the issue is throttle body related and could be TPS. Any advice is welcome.

1995 4Runner 3VZE 5 speed 4.56 gears
Rebuild 3VZE
crower cams/LCE valve springs
7MGE VAFM With 3" ISR
2.5 exhaust
and so on.

 

Have u got a lunchbox locker in the rear?

 

Not that I am aware of. It should be factory open diffs (for now)

 

The issue seems more dominate when the vehicle is cold at low speeds in first gear. It's best explained as a low speed miss or stumble.

 

It will stumble considerably at 0-10% throttle at low RPMs. It's more noticeable when cold but also does it when warm.

 

You can test the tps with a voltmeter to see if there are dead spots in the range. As well as check for smooth throttle plate movement.

 

Well we made a huge steep forward today. A friend had a extra manifold with throttle body attached and TPS. I swapped out the hole throttle body since it came off a running vehicle and sure enough the issue is gone. This throttle body had a toyota TPS sensor where the one that has been giving us problems was a cheap China made unit from rock auto that the old owner had installed.

 

Knock off sensors do not work well in Toyotas.

As much as I hate paying dealer prices or factory prices, they never let me down when trying to eliminate gremlins. Bosch or Denso o2 sensors, denso MAF sensors, NGK plugs, etc.