92 Toyota Truck V-6 engine lacks power, 3.0L, help!

[froquejr]

hi;

I've had this 92 Toyota Pickup 156,XXX+ miles, orig. engine (XtraCab w/ V-6, 3.0 liter eng., 5 spd. trans, 2WD) for the past 6 years with no problems.
But recently, the truck lacks power, poor gas mileage, hesitates off-idle, very slow to accelerate, very noticeably on all driving speed, especially during high gears. Sometimes, it won't even get up to highway speed, and can't keep up with traffic....., sort of just "bogged" down under acceleration!, engine idles normal, sounds ok, does not run hot..., etc.

Truck has had these recent new parts installed/checked, repairs done; MAF, TPS, O2 sensor is orig., ECU orig., fuel pump original, but chk'd ok on PSI (40-58psi), catalytic converter new, exhaust is not plugged, cylinder heads rebuilt, (newly updated cyl.head gaskets installed), timing belt new, timing chk'd ok, injectors chk'd ok, fuel press.reg. new, all filters new, spark plugs, wires, cap & rotors new, ignition coil new, truck is all stock, compression 150+ on all cylinders, no "CHECK ENGINE" light ever came on, tried different fuel additives, tried different gas stations.....

I'm almost giving-up, if anybody has had this problem, or knows what may be wrong, any ideas, let me know please!!!, I don't want to throw any more $$$ on this old truck :-(

ALOHA!;
phil

[KimMG]

The only thing you didn't mention is valve lash. Did you check to see if the valves are adjusted properly?

[froquejr]

Originally Posted by froquejr

hi;

I've had this 92 Toyota Pickup 156,XXX+ miles, orig. engine (XtraCab w/ V-6, 3.0 liter eng., 5 spd. trans, 2WD) for the past 6 years with no problems.
But recently, the truck lacks power, poor gas mileage, hesitates off-idle, very slow to accelerate, very noticeably on all driving speed, especially during high gears. Sometimes, it won't even get up to highway speed, and can't keep up with traffic....., sort of just "bogged" down under acceleration!, engine idles normal, sounds ok, does not run hot..., etc.

Truck has had these recent new parts installed/checked, repairs done; MAF, TPS, O2 sensor is orig., ECU orig., fuel pump original, but chk'd ok on PSI (40-58psi), catalytic converter new, exhaust is not plugged, cylinder heads rebuilt, (newly updated cyl.head gaskets installed), timing belt new, timing chk'd ok, injectors chk'd ok, fuel press.reg. new, all filters new, spark plugs, wires, cap & rotors new, ignition coil new, truck is all stock, compression 150+ on all cylinders, no "CHECK ENGINE" light ever came on, tried different fuel additives, tried different gas stations.....

I'm almost giving-up, if anybody has had this problem, or knows what may be wrong, any ideas, let me know please!!!, I don't want to throw any more $$$ on this old truck :-(

ALOHA!;
phil

hi;

thanx for the reply, the valve clearance was supposed to be done at the machine shop where the heads were done, i think they did a poor job on the adjustment, there is audible sound of too much clearance on one or more of the valves...

i don't know if the valve clearance have a lot of effect on the power of the engine....., please let me know...

i priced the charges for valve adjustments on these engines, and it is not cheap..., i was told it needs to be shimmed, etc.....

thanx
fjr

[KimMG]

If the valves are not opening the motor can't breathe. What do the spark plugs look like? Is it running rich? How did you check the timing?

[KimMG]

Are the spark plug wires hooked up correctly?