1UZ Engine Shutting off when temperature rises to half
11-10-13, 11:15 AM
#106
Forum Administrator
iTrader: (2)
Guys knock off the personal commentary or exit this thread (posts edited)
11-10-13, 11:32 AM
#107
Lexus Champion
I always advocate a systematic approach using the factory service manual and standard troubleshooting techniques some of which you mention. The only time I veer from systematic troubleshooting is when I recognize the symptoms immediately, due to pattern failure.
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Last edited by LScowboyLS; 01-04-14 at 05:41 AM.
12-07-13, 10:16 PM
#108
Pole Position
Thread Starter
I appreciate the assistance Im getting from everyone on this thread. I will reply to everyone's post / give feedback on advice provided as I arrive in TnT where this car is located, next week. As some of you may notice, Ive been MIA, but int'l work needed me.. Im taking Late Dec/ Jan to sort this baby out guys. Hope all is well and cmon guys buy sumn nice for your LS400 this Christmas ! lol
01-04-14, 01:44 AM
#109
Driver School Candidate
Join Date: Nov 2013
Location: UK
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Good day folks, after having executed a Diagnostic on my 1996 LS400 with a 1UZ-FE engine, no trouble codes are appearing.
FIRST START on a morning (engine is cold) --- The vehicle works beastly perfect in traffic and on highway. No smoke, no rough idling. Normal Idle at 900 RPM
After 20 minutes (when the engine is warm) ----The vehicle begins to rough idle. One big clump of black smoke when I floor it (Highway)
------------------------------------------------------------When in traffic, it rough idles and the RPM drops at or below 500RPM and during this time the Tach "hunts" until it reaches 500 RPM then drops and cuts off.. UNLESS while in traffic, I put the vehicle in Neutral and Accelerate\ REV till the Tachometer needle reaches at least the 2000RPM mark then I release the acceleration, only then the rough idle stops and idles normally again at 900RPM….and I work it like this “coasting” in traffic. However, if I drive in traffic accelerating between 1000 - 1900 RPM, the rough idle and shutting off would persist.
-------------------------------------------------------------When driving on highway (80 Kmph and more) which is above 2000 RPM on the Tachometer, the vehicle does not rough idle, it runs smooth. However, If I am driving slowly on the highway (approximately between the 1000- 1900 RPM) the rough idle and jerking would persist.
POINTS TO NOTE
Mileage-- 120, 000, and stopped there since,
The Speed-O-Meter has stopped working.
The temperature never reaches above half level, it’s always either half or below the half level.
I have changed the following;
all 8 injectors to new injectors 23250-50020
Oil
Engine Crankshaft Sensor changed to new DENSO 90919-05002
Fuel Filter inside of the fuel-tank to new 23300-50060
8 Spark Plugs changed to Platinum DENSO Spark Plugs
UPDATE : Parts changed after having taken the advice on this thread and other threads as at 1/11/2013 .
Engine Coolant Temperature Sensor
2 Ignition Coils
Fuel Pump inside of the Gas Tank
jumper wire or "direct" run from terminals 3 and 4 in the fuel pump relay
IACV serviced
Pre-Cat O2 Sensors changed
M.A.F meter changed
Nonetheless the problem still persists. Any assistance would be more than greatly appreciated.
FIRST START on a morning (engine is cold) --- The vehicle works beastly perfect in traffic and on highway. No smoke, no rough idling. Normal Idle at 900 RPM
After 20 minutes (when the engine is warm) ----The vehicle begins to rough idle. One big clump of black smoke when I floor it (Highway)
------------------------------------------------------------When in traffic, it rough idles and the RPM drops at or below 500RPM and during this time the Tach "hunts" until it reaches 500 RPM then drops and cuts off.. UNLESS while in traffic, I put the vehicle in Neutral and Accelerate\ REV till the Tachometer needle reaches at least the 2000RPM mark then I release the acceleration, only then the rough idle stops and idles normally again at 900RPM….and I work it like this “coasting” in traffic. However, if I drive in traffic accelerating between 1000 - 1900 RPM, the rough idle and shutting off would persist.
-------------------------------------------------------------When driving on highway (80 Kmph and more) which is above 2000 RPM on the Tachometer, the vehicle does not rough idle, it runs smooth. However, If I am driving slowly on the highway (approximately between the 1000- 1900 RPM) the rough idle and jerking would persist.
POINTS TO NOTE
Mileage-- 120, 000, and stopped there since,
The Speed-O-Meter has stopped working.
The temperature never reaches above half level, it’s always either half or below the half level.
I have changed the following;
all 8 injectors to new injectors 23250-50020
Oil
Engine Crankshaft Sensor changed to new DENSO 90919-05002
Fuel Filter inside of the fuel-tank to new 23300-50060
8 Spark Plugs changed to Platinum DENSO Spark Plugs
UPDATE : Parts changed after having taken the advice on this thread and other threads as at 1/11/2013 .
Engine Coolant Temperature Sensor
2 Ignition Coils
Fuel Pump inside of the Gas Tank
jumper wire or "direct" run from terminals 3 and 4 in the fuel pump relay
IACV serviced
Pre-Cat O2 Sensors changed
M.A.F meter changed
Nonetheless the problem still persists. Any assistance would be more than greatly appreciated.
01-09-14, 11:16 AM
#111
Pole Position
Thread Starter
Thanks for your assistance Shanjam. But rick1987 is correct, I changed my Engine Crankshaft Sensor, but still the problem persisted. My question now is therefore whether or not these 1UZ's carry 1 or 2 Engine Crank Sensors ?
Members,
Thus far, I have tried another ECU that came off another 1996 LEXUS LS400 with the same 1 UZ-FE Engine, but as seen in the pictures below the serial numbers with this ECU I bought (pic 2 ) and my original ECU (pic 1) are slightly different.
PIC 1 - MY ORIGINAL ECU - 89661-50240
PIC 2 - ECU I BOUGHT - 89661-50302
What happened when I plugged this purchased ECU in ?
1) Engine check Light appeared
2) I distinctly noticed the engine fan performing with significantly more power as compared to when working with my original ECU.
However, I sensed the smell of something burning. The scent was not coming from the ECU Compartment. I am unsure where this scent came from, and before I had any chance to run this vehicle till the temperature rose to half I cowardly shut the vehicle off, pull the main fuse, then unplugged the Purchased ECU.
I simply re-installed my original ECU, the engine check light disappeared and the Engine fan speed was back to how I usually know it to be (spinning with much less speed and power as compared to the purchased ECU).
Members, please bare in mind that the problem being experienced (See Post # 1) only arises when the Temperature is at Half Level
Members,
Thus far, I have tried another ECU that came off another 1996 LEXUS LS400 with the same 1 UZ-FE Engine, but as seen in the pictures below the serial numbers with this ECU I bought (pic 2 ) and my original ECU (pic 1) are slightly different.
PIC 1 - MY ORIGINAL ECU - 89661-50240
PIC 2 - ECU I BOUGHT - 89661-50302
What happened when I plugged this purchased ECU in ?
1) Engine check Light appeared
2) I distinctly noticed the engine fan performing with significantly more power as compared to when working with my original ECU.
However, I sensed the smell of something burning. The scent was not coming from the ECU Compartment. I am unsure where this scent came from, and before I had any chance to run this vehicle till the temperature rose to half I cowardly shut the vehicle off, pull the main fuse, then unplugged the Purchased ECU.
I simply re-installed my original ECU, the engine check light disappeared and the Engine fan speed was back to how I usually know it to be (spinning with much less speed and power as compared to the purchased ECU).
Members, please bare in mind that the problem being experienced (See Post # 1) only arises when the Temperature is at Half Level
01-09-14, 11:38 AM
#112
Lexus Champion
the LS400 has only 1 crank sensor, and 2 cam sensors
89661-50302 is a correct number for 96 LS400 for export to USA, although 89661-50303 and 89661-50304 have newer firmware.
89661-50240 is a '95 JDM Toyota Celsior ECU number, is your car a Celsior or an LS400?
PS - both of these ECU's are among the most common of all for failing ECU capacitors
89661-50302 is a correct number for 96 LS400 for export to USA, although 89661-50303 and 89661-50304 have newer firmware.
89661-50240 is a '95 JDM Toyota Celsior ECU number, is your car a Celsior or an LS400?
PS - both of these ECU's are among the most common of all for failing ECU capacitors
Last edited by LScowboyLS; 01-09-14 at 11:46 AM.
01-10-14, 05:16 AM
#113
Pole Position
Thread Starter
My Car is a JDM Celsior.. But to keep things into perspective, lets not stray from the fact that its the same 1UZ-FE Engine, where the ECU I purchased (PIC 2) is causing my fan to perform significantly better, and thereby has the potential to cool my engine better than my original ECU (PIC 1) . Seeing that my problem is a temperature problem ( when the engine is heated to half temp), should I take the chance to plug in this Purchased ECU and run the vehicle to see whether or not the engine is cooling better and thereby solve my half temp shutting off problem ?
P.S
PIC 1 - My Original ECU has been re-manufactured with all caps changed
PIC 2 - The purchased ECU came off a working 1996 LS400
P.S
PIC 1 - My Original ECU has been re-manufactured with all caps changed
PIC 2 - The purchased ECU came off a working 1996 LS400
01-10-14, 11:49 AM
#114
Lexus Champion
for me to properly advise on this, I need high resolution photos of the insides of both ECU's - I have no ideal if the capacitors inside are even the correct ones, or if they are leaking, if they are of a known defective series or if some Beavis "rebuilt" it or what.
Yamae could better advise than I could on whether using an LS400 ECU on a Celsior is a good plan. - I am no Celsior expert!
Yamae could better advise than I could on whether using an LS400 ECU on a Celsior is a good plan. - I am no Celsior expert!
01-10-14, 10:14 PM
#115
I don't know much about the ls vs celsior but I would be careful running the LS ecu in your car if it's jdm.
Reason being Japan and US models have different emissions and probably different systems for emissions.
I highly doubt the US market ecu will plug and play with the jdm vehicle.
I'm sure others that know for sure will chime in but I will be careful.
Reason being Japan and US models have different emissions and probably different systems for emissions.
I highly doubt the US market ecu will plug and play with the jdm vehicle.
I'm sure others that know for sure will chime in but I will be careful.
01-11-14, 07:39 PM
#116
Moderator
The biggest difference is the cooling fan control. A JDM has a hydraulic fan, on the other hand, a USM has an electric fan. Other than this, the emission control is different. There are some others but I don't remember the detail.
The best ECU choice for a 95 JDM would be 89661-50380 for UCF20 08/96-07/97. A 95 has a engine stall problem when the intake line is badly clogged.
The best ECU choice for a 95 JDM would be 89661-50380 for UCF20 08/96-07/97. A 95 has a engine stall problem when the intake line is badly clogged.
01-12-14, 05:31 PM
#117
Pole Position
Thread Starter
Thanks Yamae.
How can I diagnose whether or not the only fan in my car (the engine hydraulic fan) is cooling my engine like it is supposed to be ? For example, when first start for the day ( the engine is cold) the engine is running, I can literally stop this fan with my hand. Fifteen (15) minutes later (the engine is warm--half temperature) the hydraulic fan gains momentum and surges for 10 seconds then trips off, then a couple minutes later it gains momentum and surges for 10 seconds then trips of again. However, I can still literally stop this fan with my hand.
Is this how a JDM CELSIOR hydraulic fan is supposed to work ?
i.e 1--The fact that it gains momentum for ONLY 10 seconds then trips off and then on after some time.
i.e 2--- The fact that I can stop this fan so easily, because the fan is spinning too freely.
This essentially leads me to the concern whether or not, does my 1996 JDM CELSIOR has a separate COOLING FAN COMPUTER ECU ?
How can I diagnose whether or not the only fan in my car (the engine hydraulic fan) is cooling my engine like it is supposed to be ? For example, when first start for the day ( the engine is cold) the engine is running, I can literally stop this fan with my hand. Fifteen (15) minutes later (the engine is warm--half temperature) the hydraulic fan gains momentum and surges for 10 seconds then trips off, then a couple minutes later it gains momentum and surges for 10 seconds then trips of again. However, I can still literally stop this fan with my hand.
Is this how a JDM CELSIOR hydraulic fan is supposed to work ?
i.e 1--The fact that it gains momentum for ONLY 10 seconds then trips off and then on after some time.
i.e 2--- The fact that I can stop this fan so easily, because the fan is spinning too freely.
This essentially leads me to the concern whether or not, does my 1996 JDM CELSIOR has a separate COOLING FAN COMPUTER ECU ?
01-12-14, 05:56 PM
#118
Lexus Champion
just get the correct ECU that your JDM Celsior is supposed to have (I would get the updated part number that Yamae mentioned) and then have the 18 year old worn out caps replaced in that ECU with the rare correct caps listed here, and then you should be all good! 
01-12-14, 06:23 PM
#119
Pole Position
Thread Starter
01-12-14, 07:04 PM
#120
Lexus Champion
if you want to use the LS400 version ECU, you will likely have to change to electric fan set-up