3vz92

I have just got a 92 Hilux with 3vz engine. I have a problem, when the engine is idle a little vibration is felt inside the cabine. Moreover, when I accelerate and run for a few minutes a hesitation is felt on low RPm ( below 3K). When I turn off and off the engine this hesitation disappear again for few minutes.
I have changed the fuel pump, air flow meter, distributor, air filter, fuel filter.

Can you please help. Me. In diagnosing this problem and what would be the cause for this hesitation which disappear immediately after restarting the engine....

1stgen88t4r

I've been tinkering with my 92 p/u with the 3vze and have similar issues. Yesterday my son and I narrowed it down to the fuel injectors. I had him pulling the plug wires one at a time to see if there was a change. No change on cyl 3 and slight change on 1 and 5. We'll be taking the intake off this weekend to run an ohm test on the injectors. We could barely hit 70mph on the highway with the pedal to the floor. We also have that vibration you mention. Good luck !!

COMTB

Do you have access to a timing light? If so see if your timing is pulsing at idle, that would lead me down the path of an ignition issue. Mine turned out to be a very worn timing belt causing my timing to jump a few degrees at idle.

Could also start pulling plug wires and see if there's no change for one of the cylinders.

Since it disappears with an engine turn off it could be related to being in open/closed loop in the ECU as well. Without more troubleshooting and information it's hard to narrow down.

3vz92

Thank you!
My next step is cleaning the Fuel injectors since some also advised to do so.
I will also check the plugs and their related wires.

If things didn't Inprove do you suggest it is an ECU problem! Can ECU be repaired or we need to replace it!!

COMTB

Net necessarily an ECU problem, it helps to start tracing some of these issues rather than just throwing money/parts at it.

It sounds like ignition/fuel related the FSM has some good tips for troubleshooting both (should be able to find one online). But cleaning things and doing a general tune up is never a bad idea (if it hasn't had a tune up in awhile).

You can check the cap/rotor for wear or corrosion, are all your electrical connections good? Grounds in good shape? Coolant temp sensor working? (ECU uses this signal to go from open to closed loop for the fuel) O2 sensors working?
Most of these things can be checked with a multi-meter and FSM

3vz92

I will try to look for FSM for the ignition part online. Hope I can find it.

I checked the rotor and the cap they are both functioning good. Will clean the injectors and look for the O2 and temperature sensor issue you have mentioned.
I tried previously to unplug the O2 sensor, but nothing changed. I don't know if this is the right way to check if it is functioning correctly since i don't know how to check them via a multimeter ( should I check for the resistance ohm in them?)

3vz92

hello, in order to check if my coolant temp sensor working is it sufficient to unplug it and check for any difference in the performance? or I need to buy and replace by a new one to know

3vz92

Today I cleaned the Fuel injectors, after cleaning them I also disconnected the TPS sensor and my truck ran perfectly. Can I continue driving it without the TPS connected!?
If unplugging the TPS solved my issue then I need to replace it? Is there any side effects on driving it without the TPS?

COMTB

There is a process to calibrate the TPS that might be worthwhile going through. You can do a ton of searches on this forum to see lots of TPS troubleshooting tips and instructions on calibration. It is not recommended to drive without the TPS for extended periods but it shouldn't damage the truck. It will just run on whatever maps are in the ECU rather than adjusting using the sensors on your truck, from my understanding.

3vz92

hello,

after i unplugged my tps, the hesitation in acceleration disappeared , but my rpm is high at idle...
thus, i replaced my tds, but also had the same problem again.. ( it sounds that the tps is not the problem in this case)
the weird things is that when i unplug the new tps the problem disappear again.
i tried to unplug the coolant temp sensor, but no improvement.
is there anything I need to check again you think !!
is there a way to check if the problem is with the ECU itself ?

COMTB

Did you adjust the TPS as per the FSM to verify it is providing the correct readings to the ECU?

3vz92

Actually I got a whole used ( throttle body + tps installed on it). I didn't adjust the tps since It came with the throttle body.
What I did is that I cleaned it and replace it with the one I have.

Should I readjust the tps although?

2ToyGuy

Could some of what you cleaned out of the TB have gotten into the TPS and be interfering with the contacts/wipers?

Just a thought.
Pat☺