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Discussion Starter · #1 ·
Well a DSM friend of mines is suggesting that I changed out the capacitors in my ECU because that they may leak out acid due to old age and destroy the board or do other things such as mess up idle or other ECU functions, I was wondering what all y'alls think about this? aight peace
 

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err

the capacitors in electronics don't have acid. Depending on the Dielectric material it has (can be Air, Teflon, plastic etc). There is no liquids in electronic capacitors.

Acid?? where did he get this information? You should tell him that the acid also release the magic smoke inside the capacitors. Once the magic smoke is release it can not be put back in and must be replaced :)
 
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What is an Electrolytic Capacitor?
A capacitor is generally used in an electronic circuit to filter out unwanted signals. The electrolytic capacitors in the DSM ECU are used to filter the power supply. An automobile is an extremely hostile place for electronics. The output of the alternator isn't all that pretty to begin with. Couple that with the spark plug high voltage firing, the radiator fans, the interior fan, turn signals going on and off... the +12VDC main power line gets a lot of crud on it.
Which capacitor to choose? There are a lot of different types out there - some large, some small, some really accurate, some "cleaner" for low noise applications, etc. For power supply filtering, electrolytics are almost always used. Power supplies generally require a large capacitor to absorb spikes and dips. You can't afford not to have a steady power supply line inside of a computer - the microcontroller might act erratically or reboot. Electrolytics are chosen because they provide a lot of filtering for their small size. They are also very cheap
The Problem
Electrolytic capacitors do have a downside, though. They tend to leak with age when exposed to heat and many power cycles. The electrolyte that leaks out is very harmful to PC boards. It can actually eat the copper traces, eventually making a short on the board. When that happens, the ECU will either stop working altogether or act very erratically. As the capacitor leaks, it will also lose its filtering properties, allowing possibly harmful spikes into the ECU.
Signs of Impending Doom
Luckily, there are usually some warning signs that your ECU is on its way out.

A rapid clicking or chattering from under the dash. Usually accompanied with the engine stalling or losing power during the noise. This is the microcontroller going into reset over and over and over again due to a bad power supply. Every time it resets, it will turn the fuel pump relay on and off. This could also be a bad fuel pump relay, but not usually.
An usual smell that seems to come from the center console. Especially if it smells like rotten seafood. Consider that it could also be your heater fan motor, unless accompanied with a power loss or stalling.
Your car is older than seven years and sees a lot of extreme temperature transitions.
 

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Moderator, l337 M0d3r4t0r
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Wouldn't it be cheaper to replace the whole ecu for a used one if by chance it did leak out?.
 

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errr hello

one more damn time. Capacitors contain a DIELECTRIC inside which is not a LIQUID!!!! Electrolyte is in a DAMN BATTERY!!!! :p

a liquid has a tendency to pass electrical charge MUCH easier than a non-conductive solid. Hence the use of teflon, plastic and sandwiched in between a metal film.

And btw

From http://www.justradios.com/captips.html
Electrolytic capacitors are often referred to a "filter capacitors". Electrolytic capacitors help to convert (filter) AC (alternating current) power into the DC (direct current) voltage that your radio tubes need to operate.

A capacitor does not get hot enough to melt teflon or any other dielectric. So please go google dielectrics. And LEARN what a capacitor really is :rolleyes:


geezes where the hell do people get this crap from?
 

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SF in my veins... sigh
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http://www.careyholzman.com/caps/images/busted_caps_3.jpg

It can happen... but it is more often related to defective capaitors than to age.

Edit: Enjoy the carnage...

http://www.careyholzman.com/caps/gallery.htm

This is from a page re: a class action suit against motherboard manufacturers. I haven't ever heard of this being a "common" problem in ECU's but eh.. it could happen I suppose. Not enough risk to worry about.... or risk futzing your ECU by going in with a soldering iron.

Edit 2: more info on leakin caps...

http://www.google.ca/search?q=capacitors+leaking&ie=UTF-8&oe=UTF-8&hl=en&btnG=Google+Search&meta=
 
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ZaZZn said:
Wouldn't it be cheaper to replace the whole ecu for a used one if by chance it did leak out?.
nope, the cost of caps are pennies on the dollar compared to a used ecu. unless u can get a used ecu for less than 50 bucks
 

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Actually a electrolitic capacitor does contain electrolyte. The leaking electrolitic capacitors is a problem on some first gen. DSM's and can be a problem on other cars that have ECU's with electrolitic capacitors. When electrolitic capacitors are exposed to temperature changes they can leak electrolyte onto the circuit board over time, damaging copper traces on the circuit board. With that said, I have not heard of many other cars having that problem.
 

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Discussion Starter · #15 ·
drjonez said:
word. some caps have "acid" in them.

and no, MKIIIs do not have the stupid DSM problems. totally diff car, totally diff manufacturer....
Thanks Jonez, I was telling him that the whole time, supras don't have problems like DSM's do... aight peace
 

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MRSUPRA said:
The leaking electrolitic capacitors is a problem on some first gen. DSM's and can be a problem on other cars that have ECU's with electrolitic capacitors.
The only other cars that have that problem are some cars that used Mitsubishi ECU's (which would include some Mitsu-engined Chryslers, and some Mazdas). They used capacitors with too low of a temperature rating. My brother had trouble with some glue used by Isuzu in his old Impulse. It ate through the circuitboards and killed his digital dash, trip computer, and ECU. It was quite a mess. I've never had a problem with any of my Toyota ECUs, though.
 

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Only worth doing on a DSM because ALL of their POS ECUs did this, and a working unit is in high demand. No issue on any Toyota, and used ECUs are a dime a dozen anyway.
 

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Uhh Figgie your WRONG and electrolitic and Dialectric capacitors are two totaly diffrent animals

Dielectric caps are commanly made out of many things... ceramic,teflon, etc etc... they are usualy NON polar

Electrolitic caps are diffrent.. usually in a metal can they are basicaly made out of long strips of a paper type material and foil that are wound into a big coil then chemicals are added (the electrolitic material hence the name) which the paper absorbes and are stuffed into the can and sealed.... they are usualy polar(makes an interesting toy when hooked up backwards :) KABOOOM and I do mean KABOOOM!! so dont do it) And like was stated they have a habit of leaking after use and time........

Luckily our ECU's contain no electrolitic caps so we have no worries about it llike the early dsm crowed does...



figgie said:
errr hello

one more damn time. Capacitors contain a DIELECTRIC inside which is not a LIQUID!!!! Electrolyte is in a DAMN BATTERY!!!! :p

a liquid has a tendency to pass electrical charge MUCH easier than a non-conductive solid. Hence the use of teflon, plastic and sandwiched in between a metal film.

And btw




A capacitor does not get hot enough to melt teflon or any other dielectric. So please go google dielectrics. And LEARN what a capacitor really is :rolleyes:


geezes where the hell do people get this crap from?
 
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LOL, you guys don't have enough things to fix on our cars already, that now you're making up problems that don't even exist in our case?

If it ain't broke..........

:)
 
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