1999 UZJ100 Intermittently Drops Dead (1 Viewer)

[truggier]

Hi Everyone,
I've been dealing with a frustrating problem for the last six months or so. Intermittently, our 1999 UZJ100 (152K miles) drops dead. One instant we're at full power, the next the tach drops to zero. My wife drives it, and it's potentially dangerous - I'd hate to be making a left turn and have it do this. I haven't been able to establish any sort of pattern. Mostly it drives fine, and the problem pops up here and there. The problem has intensified to the point where it can't be driven three times in the past six months:
1) The first time, a buddy and I poked around at this and that, but in the end all we really did was clean some ground cables. The problem went away for a bit.
2) The second time, I brought in into a shop, where it actually died while they had it hooked up to a diagnostics machine. They didn't get much out of that - when they returned it, it did not have the problem for a while, but they said they had just cleaned some fuse box contacts.
3) The third time, I cleaned the mass air flow sensor, checked the snorkle for leaks, cleaned the throttle body, and replaced the air filter. The problem went away for a while, but now it's starting to crop up again.

I tried a different (paid) forum for this...here is my original post, the answer I received, and then my reply:
ORIGNAL POST
------------
99 Toyota Land Cruiser 155k miles Car intermittently drops dead, either while moving or at idle. If moving we usually have to stop it, put it in park, and start it. It usually restarts easily but sometimes it's hard to start. When moving fast (+55 mph) sometimes you can pump the gas pedal and restart it while still moving, without turning the ignition key. We took it to a local shop. It died with the code analyzer on it, but they were not able to determine anything useful from this. They returned it after 'cleaning some relays'. For a few weeks the problem didn't return-and now suddenly it is worse than ever. History: We've lost 3 cylinder coils in the past 2 years - 2 of them were on cylinder 8. The 2nd time we lost one on cylinder 8, it wasn't a new coil-the old coils had been rotated. A few years ago we had intermittent starting problems. We'd park it and when trying to restart it wouldn't start. The engine turned but didn't catch. Cleaning fuse contacts solved the problem.

Optional Information:
Year: 1999
Make: Toyota
Model: Land Cruiser
Engine: V8
Already Tried:
Cleaning fuse box relays, ground cable connections. This seems to make things better for a time, then the problem returns worse than ever.

TECHNICIAN REPLY
----------------
You could have a bad mass air flow sensor. Or the snorkel from the mass air flow sensor to the throttle body could be ripped. Both are very common and can cause you vehicle to loose power along with many other drive ability issues. First look for cracks or rips or anywhere air can enter the engine that is not accounted for by the mass air flow sensor. Next comes the Mass Air Flow (MAF) sensor. This is a very important sensor input to the computer. It uses a hot wire sensing element to measure the amount of air entering the engine. The MAF sensor then outputs an analog voltage signal to the PCM proportional to the intake air mass. The PCM calculates the required fuel injector pulse width in order to provide the desired air/fuel ratio. If the sensor is bad than this air/fuel ratio will be off causing severe performance issues. In extreme cases, I have seen these two problems cause a no start condition. This input can also be used in determining transmission Electronic Pressure Control, shift and torque converter clutch scheduling. The check engine light may even pop on if the sensor is bad, the snorkel is ripped or a tube has fallen off. This will result in a lean condition.

MY REPLY
--------
Hi...I'm pretty certain that the MAF or snorkle is not the problem. There has never been a case where the engine has run lean - it just is full power one instant, and then dead the next instant. I was driving it the other day, and watched the tachometer fall from 2500 to zero as it died. We were traveling about 40 mph on a slight downgrade, and it restarted itself while we were still moving, without having to pull over and crank the engine. Between the engine dying and the restart, the check engine and battery lights flashed briefly. This happened again several seconds later, and then it hasn't done it again since then, even though we've driven it another 50 miles or so.


Any ideas? This issue is driving me crazy...

 

[bamachem]

Gotta get back to basics :: 3 Requirements for Combustion

• Air
• Spark
• Fuel

Start with Air. If the MAF sensor were bad you would probably throw a CEL. If there is a problem with the MAF sensor, then it might show up intermittently, but I would doubt it. If there were a vacuum leak that was intermittent, it shouldn't make it stall out completely unless it was a problem with the main intake tube to the throttle body and you sucked in so much air that you get beyond the bounds of the air/fuel combustable ratios. In other words, it should be obvious...

Spark. Interesting that you've had 3 coil packs go bad, and two of them were on #8. If you lost spark on one cyl, you'll loose power, but it won't stall. If you loose power on two, you might stall under the right conditions. I doubt this is the case because it would either take an ECU issue (not likely) or a dual-mode failure of two packs at once, which is HIGHLY unlikely without some sort of voltage surge or other impending issue as the root cause.

Fuel. Have you checked fuel pressure? Could be an intermittent problem with the Fuel Pump or power supply to it. I would start here by cleaning the contacts on the relay and at the wiring harness connector at the top of the tank (access is under the driver-side middle-row seats under the carpet).

I think the most likely point of failure might be the Fuel Pump since a failure or start/stop/start condition would not throw a CEL, fuel pressure would drop out, and then might pick back up once connection to either power or ground was re-established, as you have described.

I think much less-likely scenarios are a bad MAF sensor or a bad ECU.

I seriously doubt you have a major intermittent vacuum leak, voltage spikes, or 2 more bad coil packs going bad at the same time with no other symptoms or issues.

Best of luck. Please make sure to post up what you find and if you can fix it.

 

[sleeoffroad]

I would pull the fuel pump and inspect it. You might have a loose contact on the pump, or the pump is starting to fail.

We had a truck with 300k miles that we could not figure out. It would drive fine for days, then you park it, get back in and it would not start. You leave it for some time and it would start.

Sometimes these trucks flood themselves if you drive a very short distance ( like 200 yards or so), turn them of and restart.

If it does that, floor the gas, keep it floored and restart. However I do not believe this is the case with you. I believe you are loosing fuel.

 

[steenh]

Probably a super long shot, but I had a similar issue with a previous 99 a few years ago with 90k miles. Would run fine, then completely die (with a little shudder seconds before). Would start back up fine. Happened twice and we were driving to vacation at the time so we left it at a dealership and rented a car. It took them 5 days to get the problem to repeat with the diagnostics hooked up... technician drove it to and from work for the week. Turned out to be a bad cam sensor.

 

[bamachem]

Probably a super long shot, but I had a similar issue with a previous 99 a few years ago with 90k miles. Would run fine, then completely die (with a little shudder seconds before). Would start back up fine. Happened twice and we were driving to vacation at the time so we left it at a dealership and rented a car. It took them 5 days to get the problem to repeat with the diagnostics hooked up... technician drove it to and from work for the week. Turned out to be a bad cam sensor.

And no CEL? Wow.

 

[steenh]

And no CEL? Wow.

Nope, nothing. They'd never seen that before either at the dealership and I've never seen anyone post up that issue over the years... definitely a longshot but figured I'd share what I have.

 

[boonacka]

I had the same issue with my '01 last year. it would stall at stop lights and such.. pretty scary. i ended up just cleaning the MAF and the carb really well, ran BG44k through the fuel system and all is well so far.

 

[Cj80cruiser]

Hi Everyone,
I've been dealing with a frustrating problem for the last six months or so. Intermittently, our 1999 UZJ100 (152K miles) drops dead. One instant we're at full power, the next the tach drops to zero. My wife drives it, and it's potentially dangerous - I'd hate to be making a left turn and have it do this. I haven't been able to establish any sort of pattern. Mostly it drives fine, and the problem pops up here and there. The problem has intensified to the point where it can't be driven three times in the past six months:
1) The first time, a buddy and I poked around at this and that, but in the end all we really did was clean some ground cables. The problem went away for a bit.
2) The second time, I brought in into a shop, where it actually died while they had it hooked up to a diagnostics machine. They didn't get much out of that - when they returned it, it did not have the problem for a while, but they said they had just cleaned some fuse box contacts.
3) The third time, I cleaned the mass air flow sensor, checked the snorkle for leaks, cleaned the throttle body, and replaced the air filter. The problem went away for a while, but now it's starting to crop up again.

I tried a different (paid) forum for this...here is my original post, the answer I received, and then my reply:
ORIGNAL POST
------------
99 Toyota Land Cruiser 155k miles Car intermittently drops dead, either while moving or at idle. If moving we usually have to stop it, put it in park, and start it. It usually restarts easily but sometimes it's hard to start. When moving fast (+55 mph) sometimes you can pump the gas pedal and restart it while still moving, without turning the ignition key. We took it to a local shop. It died with the code analyzer on it, but they were not able to determine anything useful from this. They returned it after 'cleaning some relays'. For a few weeks the problem didn't return-and now suddenly it is worse than ever. History: We've lost 3 cylinder coils in the past 2 years - 2 of them were on cylinder 8. The 2nd time we lost one on cylinder 8, it wasn't a new coil-the old coils had been rotated. A few years ago we had intermittent starting problems. We'd park it and when trying to restart it wouldn't start. The engine turned but didn't catch. Cleaning fuse contacts solved the problem.

Optional Information:
Year: 1999
Make: Toyota
Model: Land Cruiser
Engine: V8
Already Tried:
Cleaning fuse box relays, ground cable connections. This seems to make things better for a time, then the problem returns worse than ever.



Any ideas? This issue is driving me crazy...

I had a truck that did this also...thought it was the fuel filter or fuel pump so I changed both out. Wasn't the case. Went on to change out everything I could think of and took it to a dependable shop about 4 times before they said it must be the ECU. Musta been cause never had any more trouble after that.

 

[landylover21]

Just a thought but have you had the exhaust system looked at or replaced lately? I remember I had a stalling problem where my 98 100 just randomly died on the road, when I started it, the throttle was very choppy (was in limp-home-mode - wasn't electronically controlled but cable-controlled during that time) and it turned out that the original exhaust had collapsed inside the muffler and that was restricting the exhaust flow.

My .02.

 

[scooterp7]

I had a similar problem. Check the wiring connector going to the fuel pump. It is under the rocker panel at the drivers rear door. Mine was coroded and causing an intermittant killing of power to fuel pump. YMMV.

Scott

 

[truggier]

Thank you everyone for the suggestions. There are definitely some things brought up I had never thought of before and will likely go through them one by one until I find out what the issue was. When I do I'll update the thread accordingly.

 

[truggier]

I'm sorry to say that I'm done with this Cruiser. Things I have replaced to try and solve this problem:

+ Mass Air Flow sensor
+ Cam sensor
+ Crank sensor
+ EFI Main Relay
+ ECM (that's right, the main engine computer)
+ Fuel pump
+ Timing belt

And still the @#$#%Q$@ thing drops dead on us. Full power one instant, tach is dead the next. No choppy throttle or loss of power, just instantly dead.

No shop can figure this out because it happens so intermittently - I've brought it to four different places, including the Toyota dealership.

No corroded wires that we can see, it is an Arizona car.

All the electric items in the cabin still work if we don't touch the key when it drops dead, so it is not an ignition key cylinder issue.

Starts right back up sometimes, hard to start back up other times.

Sometimes if it is still moving it restarts itself without touching the key. We know it went dead though because the steering and brakes get stiff and tach goes to zero.

 

[jwagner]

may sound dumb/simplistic and im sure everyone else knows way better than me but... a loose alternator connection or bad alternator? bet its something simple.

- i know you said the accsesorys still work but you could have enough juice to run them and not the engine.

 

[1loudLX]

but no APPS or TPS?

 

[Yotato]

It sure does sound like the APPS/TPS issue.... Simple fix...

 

[truggier]

but no APPS or TPS?

Thanks for the suggestion.

TPS = Throttle Position Sensor?
APPS = ?

(I guess I haven't given up entirely yet).

 

[lndcruz]

Don't these trucks have immobilizers? Wonder if its something wrong with the key or immobilizer.

Friends lexus would do this occasionally and it turned out to be the immobilizer in the key.

 

[jwagner]

Accelerator Pedal Position Sensor.
-tps is on the engine side of the throttle cable, while apps is on the pedal side.

-ive had both go, and both shut off the truck but also set off all the bells and whistles.....

-good idea with the key...maybe only happens w/ the wifes key? if not maybe whatever sensor picks up the key. do you get the blinking key light?

 

[truggier]

Accelerator Pedal Position Sensor.
-tps is on the engine side of the throttle cable, while apps is on the pedal side.

-ive had both go, and both shut off the truck but also set off all the bells and whistles.....

-good idea with the key...maybe only happens w/ the wifes key? if not maybe whatever sensor picks up the key. do you get the blinking key light?

Thanks for the help.

When you say 'all the bells and whistles', what do you mean? When this happens to us, no indicator lights flash, and after a number of seconds the battery light comes on.

Not sure about the blinking key light - this always happens to my wife, not me. Refresh my memory about the blinking key light? Where do you see it?

Asked my wife to use a different key (one we had newly keyed with the new ECM) to see if that makes a difference. Thanks for the suggestion. I think we may have tried this in the past but can't quite recall.

 

[jwagner]

Thanks for the help.

When you say 'all the bells and whistles', what do you mean? When this happens to us, no indicator lights flash, and after a number of seconds the battery light comes on.

Not sure about the blinking key light - this always happens to my wife, not me. Refresh my memory about the blinking key light? Where do you see it?

Asked my wife to use a different key (one we had newly keyed with the new ECM) to see if that makes a difference. Thanks for the suggestion. I think we may have tried this in the past but can't quite recall.

-both times my dash looked like a christmas tree. all the warning lights come on. and iirc the a-trac light stayed on even after re-starting and limping to the dealer. went out when fixed.

-the key light is by the clock, but i cant speak to its specific function. i think it indicates that a correctly program key has been inserted. check for threads on lost keys or ask an expert. i would start by using the new key as you know its correct. again not sure on how its "sensed" but if whatever senses the key is on the fritz (loose ground?) it would cause an issue. in the 2000 fsm it looks like there is a "transponder key coil" and "transponder key amplifier" integrated with the key ignition.

-if it happens again try to note the voltage. still cant help but feel like its something simple like an alt connection or alt itself. but the immobilizer system is also a good guess.