Yamae

The ECU 89661-50380 is programmed to have a bit higher idle rpm compared with 89661-50240/-50241.

I knew several JDM Celsior owners who replaced the ECU from 89661-50240/-50241 to 89661-50380 and most of them were happy with the result. Some of them were mentioning that the engine and the transmission performances were also improved as Dutchy experienced. On the other hand some others mentioned that there were almost no change except the stall-free and the idle rpm.

Probably one of the reasons why so was related to aged capacitors and another reason might be the newer program. I am curious to know what happens on Dutchy's Celsior when capacitors are changed soon. He already has experienced several changes and I wonder those are related to capacitors in his old ECU or the new ECU which has not been used for sometime and the capacitors are not so bad.

I used to analyze ROMs for German cars and made modified ROMs. Some of those Porsches that have my ROM are still running around here. I have tried to do the same with Toyota cars but they weren't that easy. The only thing I could succeed was to fix failed ECUs.

LScowboyLS

yamae - do you happen to know the difference in my 89661-50303 and the current ECU being sold by the dealership for my 96 which is 89661-50304

Yamae

I don't know the detail of 96 USM. The only thing I can guess is that -50304 might be a minor improvement version of -50303. Toyota does not inform the contents to any and in order to know the difference, you need to crack the contents. As far as I know, nobody has ever succeeded to do them. Generally speaking, only +1 increment is just a minor change such as a small bug fix or a performance / smog / gas-mileage improvements and etc.

When something serious is found, a TSB is released and a re-programing or an ECU change is done. The ECU's ID in a case like this is not a simple incremental figures.

Dutchy

So maby this idle is normal with this ecm is what you are saying? I only can think that the engine-oil pressure is too low with 400 rpm, but maby im wrong.

LScowboyLS

no, 400 rpm is not normal, should be around 750

yamae was trying to say that you need to disconnect the negative battery terminal for a few minutes and then drive the car for a while so that the ECU can re-learn your driving habits and the new vehicle it is mounted in. - You may find that the idle problem will fix itself after this learning process - you can hold the idle up to 750 with your foot on accelerator to help the ECU relearn!

if the idle does not improve after a day or two, I would either go ahead and do the capacitors or else check the Idle Air Control Valve as per the Factory Service Manual

Dutchy

The air control valve is OK im sure of that. With the old ECU it did 550-600 RPM ( and thats fine i think ) Some other guy i know here in NL his LS400 did the same idle. I will disconnect the - terminal again today and try some things out ! thanks

LScowboyLS

OMG - just realized my Sencore LC53 capacitor tester itself needs new capacitors - it's like the Matrix or Inception!

or maybe just the end of the Mayan calendar?

LScowboyLS

recommended capacitor 100uF - 35V Rubycon ZLH 35ZLH100MEFC6.3X11 is currently on backorder

a great substitute is 100uF - 50V Panasonic FR EEU-FR1H101

adrenelin5

Here are pic's from a virgin!!!

wfseward96

Need advice from ECM experts. Did this procedure after ordering the suggested/prefered caps for my 96. And opon reinstall she wont start. I did appropriate checks on connections, fuses and such. I pulled the ECM and rechecked my solder work and even checked continuity on the board traces and all was good. Is there something I have missed? Seems to be dead as door nail.

(One interesting note, the unit in the car is a remanufactued Denso. I inherited the car and have no record of service to refer to. This remanufactured unit had the old style caps so I forged ahead with recap.)

As a plan B I found a rebuilt ECM (exact model number) for reasonable price and will probably get that to get me back on the road and sort out the other module later. What will I have to do to the replacement ECM to get it up to snuff with my car?

I have only had the car a month and I really love driving it. I was a BMW snob before spending time in this car. I did learn alot working on my Bimmer and leaned on the forums for knowledge and now im here in need again with a whole new learning curve.

wfseward96

Well I'll be danged it works now!
After pounding away at this for 10 hours my girlfriend made me stop and eat dinner and take a break.
After dinner, on a lark I decided to try a sequence of remotely locking the car, then opening the drivers side with the key. Then I put the key in ignition and waited 10 seconds or so and the turned it to ACC. i was amazed to see the check engine light, then cranked it and it stated! Now I don't know If the ECM just need time to mind meld with the car, or I got lucky on the secret handshake routine. I'm back on the road again (well after putting the glovebox complex back together).

LScowboyLS

the ECU has to re-learn - many different deep "open heart surgery" operations that my Lexus has gone through, had a rough first 1-5 minutes upon initial startup, then everything became as smooth as silk!

sam12345

iTrader: (1)

How is that. Is this different than a 98 gs400? Because on my 98 as soon as ai put the new computer in it ran perfect.

LScowboyLS

It depends a lot on how confused your computer was before the repair - in my case, the ECU had deteriorated so badly that it was all messed up in its "learned" settings, and with the new caps, it had to do some relearning - now in the case of a computer replacement with one that was already operating perfectly, say out of a different vehicle, it could run fine immediately, because its internal adjustments are not way off initially.

PureDrifter

iTrader: (10)

it shouldn't matter, once the ECU has sat long enough that the power in the caps has dissipated, especially when the caps have been replaced, all learned habits are reset to baseline. If there's still a problem then it's likely that either the ECU is still damaged, or (more likely) something else (ignition, fuel, etc.) is the root cause.