Kjj

Any body can advise how can get the capacitors easy way to my country..Oman
thanks,,,

VolumeToo

Hi Guys,

First of all, I will admit to not having read all 97 pages of this thread. So, if it's already been asked if this thread can be made sticky, I'll second that.

This is my current position: I have volunteered to inspect and (hopefully) repair a suspect ECU from an otherwise mint '92. The symptom is - I've been told - not starting, or one bank not firing (if that is possible). All other causes have been eliminated (so I am told). I only took this on because I cannot bear to see a car like this go to the scrapyard.

Interestingly, this ECU has only 8 caps. Part # is 89661-50160. Now, all the caps measure (in-circuit) under 3 Ohms at 100kHz, and many are about 0.5 Ohm. There is no sign of electrolyte leakage anywhere. I am planning to replace them anyway, which brings me onto the next point: Which to use?

Now, I know this has been covered extensively, but, unless I am mistaken, nobody has mentioned the Rubycon RX30 Series. They outperform every other capacitor I've seen, on every parameter: Impedance, ripple rating, temperature etc. Therefore I am looking to obtain these, or ZLG where the RX30 is not available. Of course, not knowing the function of each capacitor (coupling, decoupling, smoothing etc.) it's impossible to specify accordingly. So, if one series has an impedance only 0.01 Ohms higher than another, but double the ripple rating, then it's a no-brainer, right?

I already have the Rubycon datasheets printed out, and I am reasonably familiar with their various ranges - hence my preference for that brand. I've known Panasonic to leak electrolyte in storage, so I am somewhat put off by those. And the other premium brands? Well, there are only so many hours in a day!

The only tricky one is the 15u / 35, so for this I am planning to use 22u at 35 in ZLG.

Post 145 shows the datasheets for the original Nichicon PF Series. I'm amazed at how much impedance figures have improved, with the types I mention being up to ten times lower.

RS is also a good supplier to use in the UK.

Thoughts, please?

datarecvry

When i replace the 15uF capacitor I use the 50Volt version, rather than switch the capacitance.
In this thread, it has been said many times, you can go up in Voltage but not recommended to switch to a different capacitance.

ECU Repair
Sarasota Florida
Only using DigiKey components recommended by this thread
781-449-9990

VolumeToo

Not many manufacturers list 15uF, period. The only 15uF, 50V versions that I can get (from RS) are by Panasonic, which would not be my preferred choice for reasons that won't go into here. (Digi-Key often have MOQs of thousands PCS - including the caps that I wanted - so not much use to me.) There's a 15u 63V version in the Nichicon PW series, so let's take a look at the figures.

Z @ 100kHz @ 20c = 1.2 Ohms
Max ripple @ 105c = 160mA

Set against Rubycon ZLG (22uF 35V)

Z @ 100kHz @ 20c = 0.17 Ohms
Max ripple @ 105c = 480mA

Furthermore, capacitors like to be biased a fair way into their working voltage range. I have a vintage (40-year-old) Yamaha receiver that has caps operating right on their voltage limit. What you say about voltage rating is quite correct, but it's the heating effect of the ripple current that tends to destroy a capacitor in real life. And given that we don't know what that current is, it's best to err on the safe side.

Now, given a + 20% tolerance, a nominally 15uF capacitor could be as high as 18uF in practice. Just as a 22uF could be as low as 17.6uF.

It has also been said in this thread (and quite rightly so), not to choose by C value and voltage rating alone.

Update: I'm pleased to report that the repair was far more successful than I'd hoped, given that the original caps were - by "audio circuit standards" - OK. But new ZLG and RX30 versions brought the non-running car back to life, which - I am told - now goes like a rocket! (ESRs of new caps being up to 20 x better than the originals as found, and 10 x better than the originals' spec.) That, and re-making any solder joints that appeared microscopically fractured.

Another brand worth checking out is Elna, just for the record.

billydpowe

iTrader: (1)

for those of you in the DFW area, I bought 2 sets of Panasonic 95-97 capacitors for 2.62$ .
105c & low ESR at Tanner Electronics at 1100 Valwood Pkwy in Carrollton ph 972 242 8702.
all Japanese Panasonic caps shipped now are low ESR now, the lady said.
http://www.tannerelectronics.com/location.html

Louie7

OK, I recapped mine ('94 UCF10) and within a week and/or 100 miles driving time....
Solved ALL of the following symptoms that were making me stress and use bad language....

1. Hard starting
2. High Idle
3. Cutting out and missing
4. Overheating
5. CEL and TRAC light ON
6. Smell of un-burned fuel
7. OD switch not responding
8. Trac switch not responding
9. Low mileage (like 10mpg)
10. Poor acceleration
11. Fouled spark-plugs
12. Temp Gauge reading incorrectly

Here's some pics....

andiniku

And what about ECU 89661-24410 ? Where is this from? Or maybe it is already changed in my SC400...

gtoden1

I was reading cowboy's write up on how to replace ECU leaking capacitors, I have a 93 LS400 and ordered the capacitors he had mentioned.
I removed the ECU and opened the box first thing I noticed was the ECU doesn't look like the one he had posted a picture of, my ECU model is 89661- 50140, Maybe his was a different model?
So my problem is I think I'm not sure where these capacitors go. Does anyone have a picture or something that would show me where the different capacitors go? Any idea's?
Thanks:

andiniku

As far as i understand capacitors problem was related to this kind of ECU. And this is not like yours.

RA40

iTrader: (6)

This thread lists the ECU part#'s:
https://www.clublexus.com/forums/ls-...ica-yamae.html

Cowboy's ECU was from the 95-97 model year so the first gen will be a slightly different layout. Match the specs to the ones bought and replace the value with similar capacitor.

Were these the ones purchased?

spuds

Im starting to see murmurs this ecu business is a lot less of an issue on the 98-00 cars than on the earlier cars.Is this correct?

Legender

Spuds,
Not saying it can't happen on 1998 and up LS models, but if you look at the first post, it is much more common on the models 1997 and below. Very rare to happen on 1998 and above. Where you live and the climate are also huge factors in this. Our hotter, more humid areas seem to exacerbate the problem. Personally I've experienced this on my 95, but the 98,99 ad 2000 model LS's that are still running, with even more miles than the 95, have not shown any symptoms.

RA40

iTrader: (6)

Thanks Yamae for the correction.

Yamae

No, I have never informed you guys here that Toyota had changed the electrolytic capacitors in the 98+. Toyota/Denso had been kept using those QAS capacitors up to the end of UCF20/21 production. They have changed those to newer ones when UCF30/31 were started to manufacture. Read the thread again selecting what I have written and you'd know more.

What they have started to use for a 98-00 were ceramic capacitors of a new generation and newly designed processors. Those ceramic capacitors have bigger capacitance with the higher withstand voltage although the size is smaller. Newer processors were fabricated with the narrower design rule and the performance per watt was improved and this made it possible to work faster with less power. These two reduced the stress to those QAS capacitors.

We have to be still careful that the same series of QAS capacitors (PF) and (PR) were used for 98-00 models and they fail quicker than conventional ones. As far as I have experienced, the major initial problems among 98-00 were the strange AT shift problems. Changing those capacitors can fix the problem in most of the cases.

RA40

iTrader: (6)

Thanks Yamae.