OKSTANCE

im sure someone has brought this up through the vast amounts of pages
how do we pick them out from digikey other than just selecting say 10uf @50v with 105 op temp
and make sure they are one of the brands suggested? are there more options that can help downsize the search instead of ordering them from several different website as your specific links take you to?
im looking through all of the 10uf@50v-105 degree and there are still SO many sizes and other variables =0

ALSO listed on page 3 i would would need these for my ucf11 (93)
Qty. 2 of 10μF - 50v
Qty. 2 of 15μF - 35v
Qty. 1 of 47μF - 63v
Qty. 2 of 100μF - 10v
Qty. 1 of 220μF - 16v

but the links on the first page dont have these links with the matching voltages

example - page 1 lists links for 47uf are 35v and 50v YET above tells me to get 63v so that just kinda confused me why the links voltages are different
also im doing my shopping on alliedelec.com

edit: found these but only lets me order 5 at a time lol
http://www.alliedelec.com/search/pro...x?SKU=70068438

OriginalLS

I just purchased a1990 LS400 with 61K miles on it in May and had no problems. When it became hot with summer I began experiencing sudden loss of power/deceleration, staying in idle regardless of pressing the accelerator, and sluggish acceleration. I pulled codes and found nothing. I bought a used ECM for a 92 and it seemed to fix problem. Now notice same problems with new ECM when driving in hot weather. Do Capacitors fail to function more when heated? I have bought new caps LSCowboy/Yamae suggested from Divinely, will use to replace old ones. How long should I expect new caps to last?

OriginalLS

meant "Digikey" but computer changed it to "Divinely".

Yamae

As I have told people here, you should not expect for used ECUs of the same/near age which still have old capacitors. I'd say, "Multiply 5 or 6." 20 years old PF (M) capacitors are at least equal to 100 years old of humans. Some 100 years old people are still OK, but many are not. The climate affects, but don't expect it too much. As aged people are not good at both too cold and too hot conditions, those capacitors are the same.

Simply replace those aged capacitors before the liquid damages the board. You don't need to worry about the lifespan of those recommended capacitors because those will be lasting more than the remaining life of your car. You will be amazed at how the car runs good compared with even before you have noticed any problem.

usoff89

iTrader: (2)

Yamae, I ordered the CORRECT caps from Digikey for the ripple test. I'll be doing the test again just to verify the ECU.

I'm pretty much out of ideas as far as solving my issue with the car. I've tested the AFM, TPS, IAC, and also made sure everything is getting the correct amount of voltage and grounds. Everything is coming back to the ECU.

I've ruled out my issue being on the output side (fuel/ignition). With the AFM unplugged, it idles rough (lean) but drives nice with plenty of power. With it plugged in the car idles perfect, but boggs down on WOT. If you slowly press the throttle to the floor it will rev out all the way.

OriginalLS

Yamae,
Thank you! I will replace them today!

python

iTrader: (4)

the ripple test thread needs to be stickied or in the faq section

Yamae

I also am wondering why your car behaves that way.

One simple question to you, usoff89. Is your AFM once cleaned using any liquid or is it totally new? As far as I hear from people, an incorrectly cleaned AFM causes the problem that the car runs better without it. But you wrote that you were getting the correct amount of voltage, and your AFM must be OK. Would it possible for you to inform me the reading voltage and the rpm curve of your AFM?

Is there any one who owns the same generation of your LS400 near at you and can you ask the person to allow to use his/her car's AFM temporarily? This may distinguish the problem quickly.

Regarding the ripple test, you have to be careful not to pick up ignition pluses as an EMI (ElectroMagnetic Interfere). When the cables of the multimeter are close to ignition cables, you will have an EMI and the value you get will be bigger. It would be better to use a twisted pair cable for the multimeter. If it's not available, just twist the black and the white leads to the multimeter as much as possible to minimize the EMI and measure the ripple voltage.

RA40

iTrader: (6)

The ripple test is in the FAQ. Might label it additionally as the "ripple test" but it is listed as "How to check the ECU without removing it from car".

usoff89

iTrader: (2)

I've never cleaned the AFM. When testing the AFM for voltage, I'm getting 5v in and it has a solid ground. The signal wire reads about 2.8-2.9v. I've realized though, that the signal is read in hertz. The voltage doesn't fluctuate at all when you rev the motor. BUT if I switch the meter to hertz, I get a reading. It reads lower at an idle and then as you move the throttle the reading climbs. IMO, this tells me the AFM is working properly. There is a nice 93-94 LS in my neighborhood. I might try and ask them, but I don't know them.

My caps from digikey should be in today or tomorrow. I'll check back soon.

python

iTrader: (4)

ahh.thanks man

usoff89

iTrader: (2)

Well..... My new caps came in from digikey (.47uf). I was attempting to check the AC voltage when I noticed there wasn't even a pin connector in the service port????? For the pin OP1, its not there.....

Here's a couple pictures.

Yamae

I understand that some early US models don't have the terminal OP1. In that case try to check the ripple voltage at the coolant temp sensor which has 2 wires. Check the AC voltage between those 2 lines inserting 0.47uF film capacitor in series without worrying the polarity of wires. Anther idea is to measure the ripple at the 5V line at the MAF. In this case, the reading ripple voltage is a bit higher.

Regarding the MAF, the ECU has a default mode. When the MAF sensor is not connected, the ECU works in accordance with the internal data table compensating it by signals from O2 sensors, the vacuum sensor, the water/air temperature sensors and others. This often shows better results compared with a bad MAF sensor connected.

usoff89

iTrader: (2)

Yamae, mine is a 93 just for the record. Is that considered a early model?

I'' check the ripple voltage sometime this week. Thanks

mm88

1.) Thanks for your response & the resources that you posted above. I dont think ill be using polymer capacitors after reading those articles & doing more research about LDO. So the ECU uses a LDO regulator, is that correct? do you know which IC it uses? The articles that you posted above were very interesting & I wanted to take a look at the datasheet for the LDO that the ECU uses to see what the "tunnel of death" or range for the ESR/CSR is.

2.) I plan to reorder the recommended capacitors for my model tomorrow. hopefully i will get them by friday. when i do, I'll be sure to measure the ones that i replace.

3.) I dont think that i will be using polymer capacitors. I believe i would need an oscilloscope to measure the phase margin if i went that route.

I did have another unrelated question. I tried using the ECU checking procedure stickied on the front page to check the ripple (https://www.clublexus.com/forums/ls4...-by-yamae.html) but it doesnt look like there are any contacts in port OP1 on my car.

Thanks again for your time.