ECU and other electrical issues
05-25-14, 03:32 PM
#92
Further info.
I do not believe the "new" ecu is why the car ran today for 40ish seconds.
I think that was a product of the car sitting for 3 months without anyone messing with it.
The "new" ecu in the car, the car now does as it did.
It throws no codes, but it only runs for a moment. Just as it did in the old youtube video I have.
1996 Lexus LS400 Issue - YouTube
I am somewhat at a loss, its dark out now, so I likely won't be messing with it anymore tonight, and maybe none morrow.
Any thoughts?
I do not believe the "new" ecu is why the car ran today for 40ish seconds.
I think that was a product of the car sitting for 3 months without anyone messing with it.
The "new" ecu in the car, the car now does as it did.
It throws no codes, but it only runs for a moment. Just as it did in the old youtube video I have.
1996 Lexus LS400 Issue - YouTube
I am somewhat at a loss, its dark out now, so I likely won't be messing with it anymore tonight, and maybe none morrow.
Any thoughts?
It ran for about 40 seconds.
It sounded like it should.
All the instrument panel lights were bright.
And then It died.
The Check light was blinking.
So I found my odbII reader.
Gave me 4 codes.
p300, p303, p304, p308
That seems to be some cylinders misfiring?
Some further googling suggests the firing order is 1-8-4-3-6-5-7-2.
The fact that I had a "random misfire' on 8,4,3. Makes me wonder if that is some sort of hint to what happened? Since those correspond to the firing order?
It sounded like it should.
All the instrument panel lights were bright.
And then It died.
The Check light was blinking.
So I found my odbII reader.
Gave me 4 codes.
p300, p303, p304, p308
That seems to be some cylinders misfiring?
Some further googling suggests the firing order is 1-8-4-3-6-5-7-2.
The fact that I had a "random misfire' on 8,4,3. Makes me wonder if that is some sort of hint to what happened? Since those correspond to the firing order?
what ours is doing is identical to yours. and i have replaced fuel pump new alternator there is pressure at the rail, there is spark, the ignitor and coils are all good, the compression is good all the plugs are good too. this sucks man! :/
any word on what it was?
Last edited by Cleanshots; 05-25-14 at 03:54 PM.
05-29-14, 05:40 PM
#93
guys please what was the solution or help me out so i can test more stuff. i just tried a good ecu and no change same thing. vroom. then turns off just like the video he posted.. BobSmith00 please tell me/us what the problem was so i can fix our ls400 its been down for 8 weeks man.
LScowboyLS, Yamae guys please PLEASE
LScowboyLS, Yamae guys please PLEASE
05-29-14, 06:08 PM
#94
hardly anyone reports back..which in turn wastes everyones time. so..everyone replaces or fixes their ecm's because every single thread is littered with a link to the ecm fix...tried to quell that long ago and now people are finding out first hand that its not a fix all...u don't start fixing ur car from the ecm back. I realize capacitors have a limited life..they all do including the ones in ur video card or motherboard..but unless a ripple test is done proving its bad..then ur rollin the dice.
05-29-14, 06:21 PM
#95
Moderator
There are many items that the ECU disables the fuel pump to work aiming not to damage the engine or to prevent the air pollution. The link below is one of the examples. This one was caused by the disconnected MAF sensor.
https://www.clublexus.com/forums/ls4...x-problem.html
https://www.clublexus.com/forums/ls4...x-problem.html
05-29-14, 06:59 PM
#96
thanks for responding guys! 
ok so things i have done..
test fuel pump,
run 12v straight to pump
replace pump
replace alternator
tried different maf
iacv is clean
ecu is the good one 50303 also tried another 50303 same thing
there is fuel to the rail, no injector pulse
ignitors fire the coils with the bypass test
there is one thing though.. there is a 4 wire plug next to the ecu with a brown wire a yellow and green and another color wire all just connect together in that little plug. they go ino the sheilded wires going into the ecu.. those 4 wires the insulation is like bubbled so to speak.. so the wire inside is just floating in a baloon of wire insulation..
im gonna test the cam sensors.. but there is NO CODES though. nothing. i tried a cheap scanner and a expensive snap-on one..
hardly anyone reports back..which in turn wastes everyones time. so..everyone replaces or fixes their ecm's because every single thread is littered with a link to the ecm fix...tried to quell that long ago and now people are finding out first hand that its not a fix all...u don't start fixing ur car from the ecm back. I realize capacitors have a limited life..they all do including the ones in ur video card or motherboard..but unless a ripple test is done proving its bad..then ur rollin the dice.
There are many items that the ECU disables the fuel pump to work aiming not to damage the engine or to prevent the air pollution. The link below is one of the examples. This one was caused by the disconnected MAF sensor.
https://www.clublexus.com/forums/ls4...x-problem.html
https://www.clublexus.com/forums/ls4...x-problem.html
test fuel pump,
run 12v straight to pump
replace pump
replace alternator
tried different maf
iacv is clean
ecu is the good one 50303 also tried another 50303 same thing
there is fuel to the rail, no injector pulse
ignitors fire the coils with the bypass test
there is one thing though.. there is a 4 wire plug next to the ecu with a brown wire a yellow and green and another color wire all just connect together in that little plug. they go ino the sheilded wires going into the ecu.. those 4 wires the insulation is like bubbled so to speak.. so the wire inside is just floating in a baloon of wire insulation..
im gonna test the cam sensors.. but there is NO CODES though. nothing. i tried a cheap scanner and a expensive snap-on one..
Last edited by Cleanshots; 05-29-14 at 07:10 PM.
05-29-14, 09:36 PM
#98
Similar symptoms in this video. An air leak threw off the mixture leading to immediate stall.
http://www.youtube.com/watch?v=w2tLU...share&index=32
http://www.youtube.com/watch?v=w2tLU...share&index=32
cam and crank sensors are good..
05-29-14, 09:55 PM
#99
Moderator
there is fuel to the rail, no injector pulse
ignitors fire the coils with the bypass test
there is one thing though.. there is a 4 wire plug next to the ecu with a brown wire a yellow and green and another color wire all just connect together in that little plug. they go ino the sheilded wires going into the ecu.. those 4 wires the insulation is like bubbled so to speak.. so the wire inside is just floating in a baloon of wire insulation..
ignitors fire the coils with the bypass test
there is one thing though.. there is a 4 wire plug next to the ecu with a brown wire a yellow and green and another color wire all just connect together in that little plug. they go ino the sheilded wires going into the ecu.. those 4 wires the insulation is like bubbled so to speak.. so the wire inside is just floating in a baloon of wire insulation..
How did you check injector pulses?
Did you observe the actual waveform?
Regarding the shield wires, they just surround the center wires to avoid the electromagnetic interferences. As long as all 4 are connected to the ground line of the ECU with a low resistance, you don't need to worry about.
06-01-14, 09:19 AM
#100
just pulse i checked for the injectors.
its not the cam sensors or the crank sensor. there are no codes in the ecu and wont throw one either but any time i unplug something it throws a code so its working properly.. it has to be something simple and stupid that's causing the problem i just don't know what it is..
its not the cam sensors or the crank sensor. there are no codes in the ecu and wont throw one either but any time i unplug something it throws a code so its working properly.. it has to be something simple and stupid that's causing the problem i just don't know what it is..
06-01-14, 08:54 PM
#101
Moderator
Let me confirm. Do you mean that you felt the pulse by your ears as sounds or some mechanical vibrations by your hand touching it?
The ECU is checking the continuity of the coil for injectors but it can't check clogged injectors.
It would be best if you could use an oscilloscope and check pulses at injectors and ignitors.
Clogged injectors can't be checked directory by the ECU but that will cause other problems such as a too big air to fuel ratio.
The ECU is checking the continuity of the coil for injectors but it can't check clogged injectors.
It would be best if you could use an oscilloscope and check pulses at injectors and ignitors.
Clogged injectors can't be checked directory by the ECU but that will cause other problems such as a too big air to fuel ratio.
11-10-15, 04:33 PM
#102
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No end result, BobSmith?
I can't believe I read most of these posts and the original poster doesn't appreciate people's input and TIME and in the end does NOT report what the problem was. What an ungrateful person....geez, Louise! 
11-11-15, 01:02 PM
#103
With this problem the first thing I would check is to make sure there is voltage from the ignition switch after the start position is released. And from reading through this every thing else was tested, except what I just mentioned.
12-26-16, 02:41 PM
#104
Driver School Candidate
Update:
So I just got my car back from the shop (tiresplus) and looks like everything is okay. I only drive it from the shop to home so I didn't have enough time to really test it out. I have a warranty on the alternator, a manufacture warranty, so I can get it replaced if anything else. Plus my battery is also changed 
so my car should have some life for a while. Will update after a week. Considering buying a voltmeter to occasionally check the current of the battery to check if the alter is completely charging the battery up. Thanks all!
so my car should have some life for a while. Will update after a week. Considering buying a voltmeter to occasionally check the current of the battery to check if the alter is completely charging the battery up. Thanks all!
12-26-16, 02:45 PM
#105
Driver School Candidate
I am a bit naive to electrical systems in a car let alone cars for that matter. Mind explaining why?
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