freegard

I have a 94 LS 400 that purs at idle, it is clearly firing on all 8. So, that rules out a coil. And if I gradually accelerate I can take the RPMs up to 4500 with no problems, nice and smooth.
If I back off the gas when she dies she comes right back to life instantly. She does not die until she hits 2000RPM and I have her floored. (I do not have to have her floored; I almost never drive that way.
But if I am trying to pass someone on the freeway I push the pedal a little harder than normal and she dies instantly, I let up and she comes right back to life. These are not catalytic converter symptoms. It is something different; something I have never before experienced.

I replaced the temp sensor to ECU this afternoon; that fix changed nothing.
Sometimes it hunts for idle, this is why I changed the coolant temp sensor. It has new plugs, wires,
and a whole slew of other parts are new under the hood. The throttle body is dirty, yes; I have only
owned the car for 17K miles; it has 250K on it. I have all the reciepts since the car was new.

The ECU has never been worked on. I am thinking that those capacitors in there are
causing these issues. Thos polarized electrolytics of inferoir temp and grade that cause issues with the instrument cluster in vehicles from 90 to 95. I replaced 10 of them and the instrument cluster is fine. I am wondering if this is the ECU caps doing this. My median fuel mileage is 15 to 16MPG. It should be much higher than that--20 or so.

53bel

had the same problem its the caps in the ecu i posted pics of the ones for our car but have someone really know how to soder well do this not just ok but well cause its tight in there and when taken them off dont yank them off cause the ribbon can and will go with it deff 2-3 person job to be safe https://www.clublexus.com/forums/ls4...pacitor-3.html

freegard

And another thing: I can smell that telltale electrical overheating odor in the cabin. I bet I have
a chared 202 resistor that I have seen in other posts.
I am embarrassed to say this but I cannot get that panel under the dash, the lower most one, off.
I went to three wrecking yards today to look at one that had been removed. I saw no bolt or screw fasterners, only snaps, but I cannot get the thing unsnapped, and there is that floor light
in the bottom to contend with. I tried to reach up and pull the wires off of it but could not get to them.
This is absurd. It has always been the most difficult thing for me to do. Remove the trim and panels
in a vehicle. It is the ONLY area of tearing a vehicle down that I have not even begun to master.
I have asked repeatedly for someone to help me with this, but all I get is: Remove panel, remove side panel and lift carpet, and there is the ECU.
HELP!!!

freegard

I found it in a 2006 post from Georgia; a diagram. Even though it is midnight
I had to run to the car and give it a shot. Forty-five seconds later the panel is
unscathed and warming up in the bedroom with me.
So, tomorrow is the big day, 8 caps coming out and 8 new ones goin' in, oh yeah!

53bel

remember to be careful with those ribbons when you open it and use a very fine tip low heat soder.

freegard

Roger on that; okay got two of the capacitors from dgi key. The 15 microfarad 35 volt ones and just finished soldering them in. Actually they are 63v because NO ONE seems to carry 35v and though the esteemed Japanese ECU engineer did not cover what series these caps should be I picked the PS series. Hope that is good!!!
I read on Lextreme that they are the first choice, PM the second choice, PW third, and H series the fourth choice.
Unfortunately, the 15uf 63v low ESR rated caps from digikey are H series; but manufacturer is Nichicon after all--some consolation there.This is why I went with Mouser for the other six; Digi key did not have any PS series.

ANYWAY:
One of them that I removed had leaked considerably. I did not realize it until I cleaned up the area and a tremendous amount of powder like residue where the negative side enters the board had to be cleaned away before I applied the soldering iron. Another thing that I noticed is that the negative leads of the new ones did not want to penetrate the circuit board; just the way it worked out probably. The stainles steel sewing
needles that I used to ream the holes while the solder was fluid kept on adhering to the solder; that is what I get fror buy them at the dollar store.

HEY!!!! Why am I seeing a lot of "WARNING THIS SITE WILL DAMAGE YOUR COMPUTER" on google?
regarding ClubLexus; what is that about?

Anway, the other six capacitors did not show up today LIKE THEY WERE SUPPOSED TO from Mouser electronics.
So, I will put the ECU on a nightstand beside the bed; and grab these new slotted and drilled front discs and ceramic pads and go get rid of that Damn steering shimmy and come back to the ECU on Sunday. Stay tuned.

LScowboyLS

yes, the esteemed Japanese engineer as well as myself have specified at least 10 times each which series the capacitors should be.

To quote Master Yamae:



forget what you read on Lextreme, and please reread my original leaking capacittor thread - all of it, because if you don't use the right type of capacitors, you are just wasting your time! - I also give soldering and desoldering and other tips, read all 5 pages!

PS - you need to replace ALL of the aluminum electrolytic capacitors, not just the visibly leaking ones, there are between 6 and 10 of them, depending on the year of your LS400

freegard

Okay got it; did it; took it for a spin and every problem is gone.
The check engine light is gone for the first time since I owned the car.
It no longer hunts for idle and responds on hard acceleration like a detuned
formla one car.

I apologize to the esteemed Japanese ECU engineer.

Obviously I failed to see where he spoke about series.

Of those I installed 1 is an H series, 6 are PS series, and one of the 100uf 10v I received
from Mouser was crushed so I ran down to Frys Electronics and picked up a "VHT100M25"
(100uf 25v series VHT), installed that--there were eight in my particular ECU.



I am on the West side of the Cascade mountain range in the Seattle area where the
climate year around ismoderated by the Pacific ocean, never extreme, cold or hot.

Will these I chose be okay? They seem to have worked fine on initial test drive.
The car screams through the gears, no quitting at 2K RPMs anymore.

I bet I see that 20MPG finally.

freegard

Cowboy, get down on your knees when you speak of Japanese master where you belong. ha ha ha.