JoShmo

Took my '95 Celsior on a road trip to my duty location which is 260 miles away.
When I was cruising at speeds of around 70-100mph for extended periods of time (45-60 mins) and I would come to a junction or exit, the engine would shutoff. I initially thought it was the cruise control module since the previous owner had it replaced to remove the speed limiter on it, but I tested it out by driving high speed/extended time without the cruise control on and it would still stall.
I noticed that when I come to these junctions or exits the tachometer wants to plummet to 0, and I mean PLUMMET. I tried giving it gas to prevent this from happening which would help not stall the car, but it can only help so much before I have to come to a complete stop and the car ends up stalling anyways.
Can anyone send me in any direction to get this fixed?

timmy0tool

iTrader: (7)

i suspect the car is idling too low then just stalls. low idle plagues these cars!

start with the simple things like cleaning the MAF sensor and checking for vacuum leaks. then i would check the idle air control valve. use this link for more help:
https://planetsoarer.com/IAC/iac.htm

Yamae

This is just for you to search.

JoShmo

Oh wow thanks! That is my exact problem.

Yamae

You are welcome. The stalling issue is a known problem among all 95 models for JDM, USDM and others. In case of a USDM, the firmware update or the ECU replacement was done by dealers but as far as I know, JDM 95s were not so. The best way to avoid the problem would be to do what Dutchy had done.

JoShmo

I've looked all over ebay and can't find a 89661-50380 ECM! Is that the only compatible ECM replacement? The closest I can find is -50340, -50341. Would it just be better to get my existing ECM rebuilt?

Yamae

The rebuilding is nothing to do with the halt problem. The original firmware is not designed well enough to prevent the idling RPM goes too low. In case of a 95 Celsior, to use an ECU 89661-50380 is the only way to go. There sometimes appear an ECU 89661-50380 on the Yahoo Auction Japan and I can find 2 today below. There are some bidders who bid for foreigners and asking them to bid is the way to try.
https://page.auctions.yahoo.co.jp/jp...on/e1035868688
https://page.auctions.yahoo.co.jp/jp...on/p1035882075

JoShmo

It says I was able to win the bid on one of the ECMs!
Also, I just drove 130 miles for about 1 hour of driving and I didn't stall when I came to a stop... I left my Cruise Control Module unplugged before I left for my trip. Another 120 miles to go and I will see if I don't stall again.

Yamae

Several owners had the throttle body cleaned and the halt issue was rather improved but not complete. Many of them replaced the ECU installing 89661-50380 and there was no more halt problem. That's the reason why I recommend to use a newer ECU 89661-50380. There may be a way to fix the problem cleaning everything including the IACV, intake manifolds, surge tank and intake valves in addition to the throttle body. But no one around me did that much and I can't say it with a confidence.

Nuro

Excuse me Yamae sensei,

If two SMD aluminum electrolytic capacitors have the same specs except the rated ripple current, is the higher is better for ECU car application?

Yamae

Our Celsior/LS400 don't use any SMD aluminum electrolytic capacitors for the ECU and I haven't tried to use them. Generally speaking, Lower ESR capacitors endure the higher ripple current. But there are many other factors and I can't say any definite answer without knowing the detail of the ECU circuit. Another important issue is the oscillation problem due to the phase rotation and the gain vs frequency response of the error amplifier used at the voltage regulator in the ECU.

Nuro

Thank you for your reply. Could you tell just buy looking at this picture? This is not mine. Mine is still working good.

Yamae

Judging from the location and the voltage of the capacitor 220uF/35V, it is used for the 12V input voltage line together with a tantalum capacitor and a ceramic capacitor in parallel. The high frequency ripple current must be handled mostly by those last 2 capacitors and you don't need to worry about the selection of a 220uF/35V capacitor too much. I don't find any switching regulator which usually uses an inductor. I'd say a low ESR capacitor is not very much needed in this application.

JoShmo

Another 260 miles down and I didn't stall/halt with the cruise control module unplugged! Regardless, I am still going to replace the old ECU with the -50380

95celsiorg

I had to replace the IACV on mine. I tried the ECU rebuild, cleaned throttle body and MAF sensor to no avail. IACV fixed the issue temporarily. Currently i have a fix another user engineered I can post that thread if you’re interested. Ymmv.