YotaMitch

Is there a way I can test my ECU? I have a 93' I recently purchased and it is having a lot of the symptoms as described in the original post. Poor idle, very sluggish acceleration, no communicated with OBD ports, running very rich. I want to be sure this is my issue before I send away my ECU (for over a month I can assume) and fInd out I was having another issue. The car has been stored every winter and sat for about 2 months before I came to buy it so I can only assume the capacitors may need replacing. As well I'm in Ontario, Canada...does anyone know the best and least expensive place I can send it away to be repaired?

Thanks!

Biddles

iTrader: (2)

How long does it take for the ECU to readjust after rebuilding it and reinstalling? I thought I read 30 minutes, but can't find where I saw that now.

Yamae

The Japanese document I have says, "Needs a number of drive cycles to relearn".
It doesn't say any about the time.

Yamae

A 93 is old enough to replace those QAS capacitors. 22 years are long enough to damage them. It is sometimes too late to repair because copper traces and parts around are badly damaged. As I write often, we must know that the liquid QAS becomes very strong alkali when aged and leaks out. Regular electrolytic capacitors are just drying out and there's no leak but QAS ones are not that simple.

When you can't find anyone to do, why don't you try it yourself after the good practising. Sooner the better to do.

erroldo

Here is the deal: even if your 93 somewhat works, it's a matter of time before the evnironment start to claim the capacitors. I would say, first get the list LSCowBoy published and change all of them. either as a diy or farm it out. That will remove any symptoms related to those caps. who knows, nothing may change, but you rule them out. You also just add another 10 yrs before they fail.
Then you can start working the mechanical issues that may be causing those symptoms. Some of them may just disappear before you get to root causing them. Let's face it, the ECU takes input sensor values and control the many output voltages/currents to dc motors, distributors, fuel injection, etc to make for a smooth run. So once you remove the ECU as a source of errors, then you may want to start root causing the adjustments/sensor inputs to the system.

erroldo

I just replace the 3 caps in the 94 instrument cluster with high temp NTE electrolytic(all 50v) purchased from Fry's Electronics. Took 30 mins to desolder and reattach them. Put in the cluster and turn her on. She lighted right up!! feels good. Fuel gauge now showing correct tank level.

The DigiKey ones for the ECU was ordered Fri and waiting their arrival.
Only had a Weller solder with a pointed tip and a small screwdriver, so I detached the trace for the lower 1uf cap. It was connected but lifted from the board, so grab sone silicone-II and cover the whole cap with it. That should prevent and vibration detachment. Need to invest in a proper solder station for the ECU undertaking. I could farm it out but that removes the fun of saying I restored the 94 LS400 myself. This community has been so helpful to me. Thanks to all of you who posts your issues and how you solve them. I even got a 91 LS400 to pass emissions after someone posted that the EGR pipe cracked and caused failure. For me, this is a new found hobby. Think I will make one of these LS 400 into my daily driver and park my newer vehicle.

YotaMitch

I'm not really understanding what your saying, sorry, I'm in the automotive trade myself but when it comes to electronics I'm lost. As far as doing the repair myself it's out of the question, I've never taken on a task like that and I'd rather have it done by someone who know what there doing. I plan to remove the ecu tonight after work. Is there any pictures I could send you to tell wether my capacitors have leaked or not? And if I was going to buy a new ecu, where would be the best place to buy one from?

Thanks

YotaMitch

Makes sense. Do you know the best place to buy a new or refurbished ecu from?

89OLDMAX

I just recapped my 1990 ls400 I have owned since 2000. It has 270,000 miles and seemed to be running fine. The computer number was 89661-50010 and it did not have the Nichicon QAS PF[m] capacitors. After recapping the original capacitors in it there definitely is more power and the transmission is much more responsive. Even though the capacitors in this particular computer do not seem to leak their effectiveness must degrade over time slowly and you do not notice the gradual performance loss. I can't imagine that the engine performance now and transmission operation were any better than when new, that's how well it runs.

Yamae

As far as I was informed, the QAS capacitors for auto-mobiles use were not released when the LS400 design was started. The very early production of LS400 was started using non QAS capacitors. But this caused problems at very low temperature places. At that time, QAS capacitors were already available and Toyota have decided to switch and use those.

QAS capacitors show good characteristics even at -35 degrees C or below. The countermeasure has been quite successful for a decade+. But now there are lots of different problems loosing the capacitance, increasing the ESR and some leaking the liquid badly damaging around.

As many people were reporting here, the replacement made them happy getting the better engine running, better gas mileage, smooth AT shift and others. Some people were able to say good-bye to unsolved strange multiple problems. I always say that it's almost a must to replace those capacitors, if you want to keep your car running good and long.

PardonPS

Hey, so... I've been looking through the thread pages and I cannot seem to find anyone who posted about the capacitors of a 97 Camry. My ECU number is 89661-06361 just in-case anyone wants to point me in the right direction! Thanks!

KBH2

PPS, don't take this the wrong way, but this fix, if you are going to do it yourself requires self starting, and a can do attitude.

The safest thing to do is pull the ECU out and see exactly what caps are currently installed. That's what I did for my Son's 92 LS400. I ordered all of the caps from Digi Key.

I haven't replaced the caps yet, but after reading the first couple of pages of this thread I am clear on the important procedures to follow.

Again, I don't know your skill level, my whole point is to be a sounding board and make sure you are ready to take responsibility, if you choose to take this on for yourself. If the above makes sense then you won't have any problems that you can't overcome.

Best of luck.

erroldo

I have 2 LS as project cars. 19 I had since 1993 and had been in 3 fender benders, all repaired. Never had any electrical issues in 20+yrs. However power reduced. 94 i bought a month ago for 450$ with the engine dismantled and in boxes. Put it back together. My first time working on an engine. I am not a mechanic. Had several issues after it started. dead instrument panel. dead lcd. Found info here and replaced lcd and caps. Now panel lights up and temp lcd is as new. Car now drives but rough. waiting on ecu caps from digikey. once replaced I may have fixed everything i found and have a 94ls400 for less than 900% invested. very clean interior and exterior.
My reason for mentioning is, this was my first time for this project on a car, ever. I have been changing the oil, timing belt, brakes and starter on the 91 but nothing electrical. All the info I obtained on google.
The caps just have 2 leads dipped in solder. A good solder iron will melt the solder and allow the lead to be removed. Just be careful. Then u just have to cut the leads if the new caps and apply a little flux a little solder and reattach. If you cut the leads about 1/2" longer than the old leads, it makes ataching them easier. Since we are not dealing with gigahertz here, the extra length of the leads won't attenuate the signals. Based on what Yamae said, these caps are just filters(low pass) for smoothing pout ripple voltages(voltage cannot spike across a capacitor, current can and reverse for inductors). So, if you cannot find anyone cheap enough to do it and savings is important to you, be courageous and dot it. Get an old board with caps from some old electronic, stereo or computer and just try to remove one of those caps with a solder iron and reattach one as practice. Get a magnifying glass if your sight is getting blurry to do the solder. It is easier than it sounds. You will just be using small parts in tight spaces. Heck, I am 50 now and did it.( though I mentally feel like 25). Noticed my eye were straining and got a 4$ magnifying glass from walmart. When I replace the LCD for the heater display, 2 segments did not light up. I just remove it again, took my multimeter and checked for continuity. I had 2 bad connection out of 40 leads. Heated those pads and got a solid joint. Now she displays as new. I must disclose, I have an MSEE but I am not a technician, so while I know how the discrete parts work(caps, res, inrductors, transmission lines, frequency responses, static effect) I never actually fix finished circuits. So there was a lot of learning for all your experiences on the LS400 posted here. Hopefully this post will give you some courage to DIY! It's fulfilling to know you get your car running again with your own hands. That's mainly why I do this. Now I will give the 94 ls400 to my 16yr son. He just won't know it cost less than a grand and a lot of hours.

89OLDMAX

What is the expected service life of the new replacement capacitors that you recommend. I notice some are physically much smaller, will that effect their useful life. thanks for the response.

89OLDMAX

This might help a little. I replaced the capacitors in a 1991 camry v6 automatic. Computer #89661-32571 it had non QAS PF{M} capacitors. The capacitors had markings of KMC on them. The capacitors were four 10uf 50volt, one 15uf 35volt , one 100uf 10volt, and one 220uf 10volt. Replacement for these capacitors are all posted at the beginning of this thread. The capacitors in this computer are pretty easy to replace none are seriously boxed in. For me so far replacing Toyota capacitors in ecu's the capacitor values are the same as the lexus capacitors listed in this thread.
This 1991 camry also had the engine coolant temperature sender changed at the same time. The car ran ok but had a high idle with or without the AC on. The transmission had down shifted on its own a couple times in extreme cold weather for no reason and developed a stacked shift for 2nd to third and immediately then 3rd to 4th under moderate acceleration at the slightest let off of throttle at the top of 2nd. Idle is now good, the transmission shifts properly and the engine runs better also.