Intermittent cutting out/loss of power (1 Viewer)

[iansplatinum]

***EDIT: for anyone reading this thread, the below snippet from the FSM is WRONG. It has a typo. See later posts for more info. The rest of this post has been left unaltered for posterity, but I misdiagnosed my VAF as being faulty when in reality the FSM is erroneous********



May have just made a breakthrough:

It reads about 1700-1800 ohms when fully open. Both measurements are out of spec.
Doesn't explain the intermittent absolute loss of power, but might explain lower than expected mpg (11-12 average)

 

[sogafarm]

May have just made a breakthrough:

View attachment 2781165


It reads about 1700-1800 ohms when fully open. Both measurements are out of spec.
Doesn't explain the intermittent absolute loss of power, but might explain lower than expected mpg (11-12 average)

Try a loaner from a working LC to see if that's the problem. If the afm is faulty, it will not run properly.

 

[Irish Reiver]

Is your metre calibrated?

 

[iansplatinum]

Is your metre calibrated?

apparently not. Is there a way to recalibrate?

 

[Irish Reiver]

apparently not. Is there a way to recalibrate?

Typically you send it to shop that do the adjustment and issue the cert. Alternatively you could get your hands on a couple resistors- 600ohm and 1200ohm (or something close) then measure those with your metre. If the metre shows a reading within the tolerance band of the resistors then you know it is fairly accurate.

 

[iansplatinum]

Typically you send it to shop that do the adjustment and issue the cert. Alternatively you could get your hands on a couple resistors- 600ohm and 1200ohm (or something close) then measure those with your metre. If the metre shows a reading within the tolerance band of the resistors then you know it is fairly accurate.

I thought you meant my air flow meter. The ohm meter is pretty accurate, I tested my throttle position sensors and both came back within spec, although I haven't calibrated it... The temperature ohm readings on the VAF came back dead on, so by this logic, either the thermometer in the VAF and my ohm meter are wrong, or the VAF air flow readings are wrong. Either way this points to a fault in the VAF.

 

[sogafarm]

There is this guy who refurbishes AFM's.

88-94 Land Cruiser VAFM REPAIR SERVICE

forum.ih8mud.com

 

[iansplatinum]

There is this guy who refurbishes AFM's.

88-94 Land Cruiser VAFM REPAIR SERVICE

forum.ih8mud.com

Yeah probably will go to him.

For anyone else who might stumble upon this thread, here are the things I am replacing:

EFI relay (toyota)
Fuel pump & sock (denso)
Fuel Pump Relay (toyota)
Main Relay (denso)
Fuel pressure regulator (toyota)
Air tube (toyota)

I am also sending my VAF to be rebuilt.
Will likely send injectors to be cleaned/flowed.
Buying used spares of igniter and fuel pump resistor.

If I don't reply to this thread again, assume one of these things fixed it. If it does not, I'll be back.

 

[iansplatinum]

May have just made a breakthrough:

View attachment 2781165


It reads about 1700-1800 ohms when fully open. Both measurements are out of spec.
Doesn't explain the intermittent absolute loss of power, but might explain lower than expected mpg (11-12 average)

All, for anyone reading this thread, THE FSM IS WRONG, IT HAS A TYPO.
It shows the rightmost two pins as being E2 & VS. This is incorrect. It should be the second and third from the right.

Now I just sent my perfectly good VAF to south carolina for rebuild for no reason.
And I chewed out the repair guy saying he needs to go look at the FSM, when in reality the FSM is wrong.

Thanks Toyota

Attached is the corrected version.

 

[jonheld]

FWIW, the EWD is correct.

 

[Landcresha]

I've really tried my best to figure this one out, but I'd appreciate some opinions.

05/1993 FZJ80, 270k miles

Symptom:

When driving on the highway, the vehicle will randomly "cut-out". By this, I mean a noticeable loss in power and throttle response is suddenly observed. If I am driving at 70 mph, the vehicle will lurch forward as if I took my entire foot off the pedal. The engine will become unresponsive to throttle pedal input, unless the input is very slight. I can usually feather the pedal to limp the car to a nearby exit or the shoulder of the road. There does not seem to be correlation, and nothing in particular seems to fix it. I just cycle the computer on/off a few times, open the hood and take various connectors off/on, and it usually fixes itself until it does it again. No CEL, no dash indicators. When on the shoulder of the road, I have put the vehicle in 'Park' and have still observed a struggling engine. Pressing the throttle in 'Park' produced a bumpy rev that struggled to get above 2k rpm. But then, as if by magic, it will heal itself and act completely normal again until it randomly happens again. Could be 15 minutes later, an hour later, or a month later.

My assumptions:
I assume this must be electrical in nature, as a severe mechanical issue would not self-heal. I have driven the car about 3000-5000 miles since this issue first started happening.

I assume the issue is unrelated to the transmission, since I was able to observe the behavior in Park.

Parts Installed (all toyota brand unless otherwise noted):
Good used ECU from '94 FZJ80 (60221 variant)
Good used transmission computer
Plugs, Wires, Cap, Rotor, Ignition Coil.
Fuel Filter
Throttle Position Sensor
Vacuum Lines
New O2 Sensors (denso)
New Fusible Link

Relevant Services/Tests Performed:
PAIR system removed
EGR vacuum lines blocked off (no EGR sensor on early 93 models to jumper)
Tested Vacuum at warm idle- 20mmHg with a little bit of flutter, not concerning amount though
Cleaned throttle body
Cleaned NSS barrel connector
Cleaned O2 sensor connectors
Inspected intake hose for cracks (wrapped in even more tape to be cautious)
Transmission #1 Solenoids
Checked Harness by EGR pipe, no visible damage. Was wrapped in woven fiberglass by previous owner.


Next step for me is to replace fuel pump, EFI relay, Fuel pump relay, and ignitor.
I have to take this vehicle to Colorado in less than a month and need it to not cut out on the side of a mountain.

Mud, anybody got any clues? I feel like I have done all the basic "it's probably the..." maintenance, and now I'm still left with some obscure random intermittent issue that I absolutely cannot figure out or even hope to diagnose.

 

[bicycleagent003]

I would not hesitate to replace the fuel pump if I were planning to keep the truck for a while, and if it were original or not Denso. It's a 2 job, maybe even one a half. Just my two cents.

 

[TurbodreamZ]

Did you ever solve this?

 

[iansplatinum]

Did you ever solve this?

Yes, I'm about 90% sure it was the fuel pump. I replaced it with a new Aisan OE pump and new strainer, hose, etc
There were some other minor parts I replaced at the same time (FPR & some misc electrical stuff) but my gut tells me it was the pump.
The factory strainer design seems to have been updated slightly to reduce collapse or clogging. I can't remember the details but I remember them being slightly different. So IDK if the pump was faulty and just starting to give out, or if the strainer was collapsing and choking the flow under certain conditions.

I noticed also after replacing the pump and FPR that the 1FZ was able to rev much higher. I think I never saw it touch 4k rpm prior, now it'll almost touch 5k. Sounds tortured when doing so but that's just cause it's old.

304k miles on the rig now, so about 34k since I replaced the fuel pump. Issue has not come back since.