1996 FZJ80 1FZ-FE Stumbles On Acceleration, Nearly Dies Then Fine (1 Viewer)

[Hornd]

Symptoms:
Go to accelerate and truck sputters and motor nearly dies, does this for about 5 seconds then it catches and drives fine like it never happened.
Makes some drive-train noise.
Totally Intermittent.
Seems to happen when cold and wet.
Truck Unresponsive to accelerator pedal.

EGR Wires are wrapped in Heat Tape
Changed Sock on Fuel Pickup after issue started.
Injectors refurbished about 1 yr ago after #6 died, issue did not occur till 2 weeks ago.
Plugs, Wires, Rotor changed about 2 yrs ago maybe 5K miles.

Vehicle is not a DD and I use it to mostly go far from home so until resolved will not be leaving town.

 

[Brandon98]

Check the electrical functon of the airflow sensor. Also, check the intake hose for cracks.

 

[diamondsbuy]

cold and wet has usually meant cap ,rotor and or plug wires for me, I know you said new cap, any way it might have gotten a crack? When I was a young idiot (instead of a old fool) I washed my motor in the winter .....not smart

 

[jfz80]

Did you just wrap harness by egr or open and inspect beforehand. I've seen some "looks good" bundles fail.

Also your symptoms seem similar to when I was tracking down a issue with my IAC and TPS bundles. Could be worth a look at those two sensors

 

[Hornd]

The Cap, Rotor, and Plugs are almost new.
The Intake Hose was removed, plugged one end, and held air when I blew on other end.

Will be ruling out the IAC and TPS.

Going to try cleaning the SMOG/EGR Ports in the Throttle Body.

Ordered a new throttle cable to rule that out. Tried cleaning, Tried lubing with cable and chain spray, still sticky.

 

[Golgo13]

vacuum lines are ok? maybe 1 slipped off?

 

[Hornd]

It's an itermittent issue so that pretty much rules out lines, but I think I will change them anyways when I pull the intake.
Really would like the whole EGR gone, but not sure about adding the resistor and what not.

 

[bicycleagent003]

Oxygen sensor - upstream fuel/air mixture. I had a somewhat similar issue and the sensor fixed it. After a year of trouble shooting and pulling my hair out. If you're on the original oxygen sensors, I would swap them out as PM. It's a 20 year old truck with 200K+ I'm guessing on the clock - I'd get new sensors on Amazon. The Densos are around $65 each.

 

[wlittleman]

I got the exact same problem. Wet and cold days would cause stumbling problems after driving a mile. I would have to park it for a few minutes, fire her up, and it drives fine. I never have the problem on hot or dry days.

I found an exposed wire in the harness, near the egr modulator that I suspected was shorting out on wet days, but after extensively insulating it, the problem still came back on certain wet and cold mornings. The problem wasn't as bad when I used to park inside the garage over night, but more that I park it outside, the frequency of the problem increases substantially.

 

[Hornd]

Throttle cable was loose.
Tightened it back up on motor and issue is resolved.
Ordered a new cable in the mean time before noticing it was lose.

 

[jonheld]

Throttle cable was loose.
Tightened it back up on motor and issue is resolved.
Ordered a new cable in the mean time before noticing it was lose.

How can a loose throttle cable cause the motor to, "sputters and motor nearly dies, does this for about 5 seconds then it catches and drives fine like it never happened."
This doesn't make sense to me.

 

[Hornd]

When accelerating it would stick and flood the motor.
My cable has most of the sheath gone and I tried cleaning it with carb cleaner and hanging it up to drain.
Then I tried cable and chain dry lube and then I ended up cleaning that out.
Then I ordered a new one.
Since I tightened the adjustment nut on the cable it has not done it.

 

[wlittleman]

I've been thinking of replacing my throttle cable. The throttle is really sticky, and the housing appears to be disintegrating. But, I don't see the correlating to the stunbling issues. Regardless, it's good to get feedback on what works, and what doesn't. Once it's later spring and summer here in northern California, this stumbling problem will go away.

 

[jonheld]

When accelerating it would stick and flood the motor.
My cable has most of the sheath gone and I tried cleaning it with carb cleaner and hanging it up to drain.
Then I tried cable and chain dry lube and then I ended up cleaning that out.
Then I ordered a new one.
Since I tightened the adjustment nut on the cable it has not done it.

An EFI engine can't flood. If the cable was sticking, then the throttle plate would stick with the cable. The engine would respond in kind, the same way if you pushed the pedal down or released it under normal circumstances. The throttle plate and TPS are connected.
I'm not trying to be difficult, just trying to understand.

 

[Freds]

IT"S FLOODED" haha
I LOVE THIS SITE. wire harness behind the valve cover, my 2 cent.

 

[Hornd]

Does the TPS feed a signal back to the ECU?
I was just giving the symptoms and trying to decipher cause/effect.

I know my Avalon has no cable so the gas pedal is just a sensor along with the gear changer, which is just a bunch of switches instead of cables and linkage.

 

[bonestock]

Bump. Experiencing this issue currently. Replaced fuel pump to no avail. Trying to look at the harness by the egr pipe for shorts and possibly change the fuel pump relay.

Open to tips.

Thanks!

 

[Landseer]

To add to all the advice above, I had vaguely similar symptoms - stumbling under hard acceleration. Ended up being the fuel pump relay, The 'high power' side of the relay was failing and when the ECM switched to the high fuel pressure mode under hard acceleration it would cut power to the fuel pump. The relay completely failed shortly thereafter and the truck wouldn't start. New relay fixed it.