John Evans

Sudden loss of power; as though you were running out of fuel. Problems have occurred after extended operation (1-3 hours). Once, the transmission shifted up and down erratically. Once, the traction control shut off at start up and the associated dash light flashed for an hour and a half until we stopped to eat, then quit upon restarting. Both ignition coils replaced, MAF sensor cleaned, no improvement. My question: what companies may be recommended for ECM repair, and how to make certain that the caps are replaced with the aforementioned replacements. Thanks for all the help, the information available in these forums is very enlightening.

Rmmccarthy

Hello all I am very grateful for your site I recently acquired a 92 LS 400 for 350$ it needed a starter some vacum lines and I need to knock the ugly off but otherwise it runs great.... for a couple minutes then shuts off like I turned the key it will restart sometimes it fights me ( have to work the throttle) but I can get it going I was thinking fuel but the dampner screw is flush or better and I had a voltmeter on pump and it had just shy of 10 volts on it constant when it died. I attempted getting codes but no check engine light would flash only the O/D light like there were no codes for the tranny, the check engine never lights up. so I am leaning towards the ECU I pulled it and it LOOKS ok at first glance I haven't conducted continuity tests on any traces or anything but from what I've read this seems to be the culprit. I am hoping one of you with more experience will tell me I am on the right track or that I am crazy and stop either way your help is appreciated. this is such an amazing place to share information I will post some pics of my find when I get her on the road in the next day or so.


thanks
Rick

dicer

Continuity on traces? I don't think I would apply 9 volts to the circuit board to do that.
You can check for the ripple, ask Yamae.

Rmmccarthy

true dicer thanks... I went to a local store and bought some supplies but as the thread states umpteen times they didn't carry or even know for that matter what low ESR was soooo they are definitely not my guys. I am ordering tonight I figure with the age of the vehicle it is a repair that should be done regardless I believe it will fix my issue at least let me read codes if it doesn't solve it completely. I am still searching for a wiring diagram or assembly diagram of the ecu so I can locate each cap and verify physically. is it in here somewhere have I overlooked it I am going cross-eyed at this point.


Thanks again

Rmmccarthy

ok follow up I ordered the right caps and swapped them couldn't hurt I figure I also did plugs and a fuel filter and I ran the bypass for fuel pump resistor and the car runs beautifully when cold it seems like when it warms up and goes into closed loop it dies. Like I turned the key it doesn't stumble or sputter just shuts off I cant get codes when I use a jumper to do so the trans flashes like no codes but the check engine light doesn't ( it never lights up) I would really appreciate some thoughts on this I need this car any and all input greatly appreciated
thank You]
Rick

Rmmccarthy

ok another follow up the check engine light wasn't coming on because of the bulb the codes I get are 14 ignition 1 and 24 intake air temp.... I believe this is correct. I tested the igniter it tested bad but the car runs so good when cold before closed loop is this only used then? any and all input appreciated
Thanks again
Rick

dicer

https://www.clublexus.com/forums/ls-...n-running.html

This seems to be a common problem with these cars. I have one that I am slowly dealing with, I've been under the weather for a bit so progress has been slow. I had a gut feeling it was not related to the ecu, because of how good it acts when cold. I did get the air meter code and like the one fellow says, I will replace it with another, at the cost for new that will not happen so it will be another used one. And if you solve the problem please let us know. There are a few others with that problem as well.

Rmmccarthy

will do should be this week do you know about the igniter and open closed loop?

dicer

The only thing I can think of that would be different is there is a program to run the engine when in open loop. In closed loop then it takes in sensor information to control things. Mine just started doing it out of the blue for no reason.

dicer

Did you jumper the correct terminals, sounds like you didn't, and did the ones for the transmission.

Rmmccarthy

I found the reason for no check engine was a bulb(infuriating stupid) codes were 14, 24 i acquired another maf and that seemed to fix. Code 24. Now it still runs well but when it warms up it cuts out and I did igniter test my belief is when the coil gets hot it opens and boom no more vroom vroom as long as code 14 is drivers side coil is this correct I may also be dealing with a broken wire bad connection etc as always any and all input greatly appreciated.
Thanks
Rick

Rmmccarthy

ok quick question on the 92 the igniters are 123 and I was able to locate some from a 94 the 201 igniters I notices a small difference on the connector but nothing I cant overcome if they are electrically the same which they appear to be does anyone know for sure before I waste more time I am currently under the impression that a wire or a igniter or??? is opening when it warms up causing it to shut off I do appreciate any help I will continue to update with findings
Thank you
Rick

Rmmccarthy

ok I replaced coil and it ran great for way longer then it has I belive I am now looking for a broken wire or ground very strange

89OLDMAX

Rmmccarthy, I have a 95 SC400 and 94 LS400 that were setting code 24 air intake sensor. I used an old Nissan trick of adding an extra ground to the Maf sensor ground wire. This would help poorly running nissans of the 1990's vintage. On the lexus maf connector the wire all the way to the right is the ground wire when looking from the back of the connector. Splice into that wire a couple of inches behind the connector and add a #12 gauge wire and run it to the 10mm mounting bolt for the maf as a grounding point. This solved the code 24 for both of my cars.

dicer

Why ? Did you check the ground terminal in the connector for continuity to ground ?
And thanks for the tip.

Something must have happened to the ground point that the connector ground wire goes to???
What do you think Yamae?