hey guys, just been reading up on some vr-4 forums and saw this thread

http://www.galantvr4.org/ubbthreads/showflat.php?Board=newbie&Number=34701&page=0&fpart=1

being a mitsubishi ill assume they carry a lot of similarities.

this is the text in the thread

"I wanted to stess the importance of replacing the capacitor in the ECU. The capacitors used are electrolytic capacitors which means they are acid based over a period of time and heat cycles they will expand to the point where they will become porous and will leak acid on the board. Know symptoms of this is random stalling, a fish like smell, injector(s) not working. I know there is more, maybe Jeff will be nice and chime in.

REPLACE YOUR CAPACITORS! or else you will be mad."

over time i have been having very similar issues such as the random fishy smell, stalled a couple of times and for the last couple of months its been feeling as if the engine isnt getting enough fuel when its cold. is there much truth to this considering a 92 tr magna? its EFI auto 4cyl if it helps

would the wreckers be a decent way to go to pick up an ECU to plug in or should i spend $200 to get one from ebay?

thanks, Alex

TAke your one out, crack it open and check for yourself.


FYI your car will not explode.

Try this guy http://www.autoelectronics.com.au/subpage3.html. Aparently he does ECU repairs for $250.00 ie: replaces capacitors.

Cheers

Well first of i would actually check your ECU before jumping to conclusions and wasting money. Open up the ECU and check the capacitors. If they are bulging at the top or bottom and they are rust coloured around the areas where they are buldging then yes your ECU has bad capacitors and needs to be repalced.

And i would find a replacement from a wreckers. I was down at my local upullit last weekend and auto 4 cyl 2nd gens are a dime a dozen.

ive replace plenty of 2g ecu's for this problem.... ecu emits smoke = no start
mostly 2g 4cyls but i have done 2 2g v6's 1 3g TE v6 and 1 mazda bravo (mitsi ecu)
on the 4's ive also noticed that 25% of the time it takes out the dizzy pickup too

but all in all i'd wait till it happens to sort it out... if at all... they dont burn over time... it happens very quickly and the fire never escapes the ecu(runs out of air)

well my worry is that if i dont have a running car then itll take me 2 hours to get to work instead of 30 minutes, and i drive late at night i.e. 11 or 12pm from work, so i cant afford to have it breaking down randomly.

will the leaking capacitors in the ECU come up as a fault on the MUT?

I don't think leaking capacitors will register a fault code. These aging capacitors are the same reason the TCU fails in First and Second Gen Magnas. I've done all kinds of capacitor replacements, be it on computers, televisions, power supplies and so forth, and it's really not a difficult job on these old Mitsubishi ECUs. They're not surface mount soldered, that is the capacitor leads go through the circuit board, so it's simply a case of melting the solder, removing the old capacitor, sliding the new one in and applying some fresh solder to the board.

I'm not sure just how many capacitors are inside these, but when I opened up a TR 2.6L Transaxle controller there was only 6 or 7 can electrolytics to note. Inside an ECU this number may vary, but I can't see there being hundreds of the damn things, and at a price of around 20c to 50c per capacitor from Jaycar, the repair cost shouldn't really be that high. Of course electricians will have a markup on the total repair cost, and that could vary quite a bit depending on who you ask.

Signs to look for, should you open up your old ECU/TCU to check is obviously bulging capacitors, or ones with discolouration around the top. However electrolytic capacitors can also leak from the base, and this can be identified by a slight discolouration of the circuit board below and around the capacitor. If you spot any of these, it's time to have those capacitors replaced.

Thankfully, once they've been recapped, they should last for a very long time. Perhaps even moreso now as capacitor manufacturing and designs have advanced over the last 20 years.

Finally, take note that none of these ECUs use components specific to automotive. These capacitors and boards are exactly the same as the kind you find inside your computer, inside your TV, etc. This gives you a bit more of an option to shop around with some general electronics repair stores instead of just focusing on auto electricians.

Just my 0.02c.

thanks mate, thats a lot of really good easy to understand information.. might get a spare ecu from the wreckers and try soldering it myself

LOL your car will NOT explode :P

Electrolytic capacitors will deteriorate over time. I replace a lot of them in the the computers and equipment at work. I always replace them with higher quality ones and certain brands (i.e. we have shocking problems with Lelon branded ones). There was a 'recipe' stolen in Japan from one manufacturer and sold to others, only problem is that they didn't get all of it and hundreds of thousands of caps were made which leaked prematurely.

If anyone isn't confident, let me know and I am happy to do theirs for them.

Cheers
Pete

lol just to make it clear "Replace your ECU capacitors or your car will explode" is the name of the thread on the vr4 website which i posted from :P

damn, everyone who knows something about these things dont happen to live in melbourne lol

also if your ecu has an aftermarket sticker on it then it will be fixed
IIRC the ECU board is a multi-layer design so you want to make sure you can solder proficiently as you dont want a dry joint on one of the internal layers
also IIRC they are the 2 large caps in the centre of the board... signs of imminent failure are bulging case and or electrolyte seepage and or burnt board... also check engine lamp not illuminating soon after ignition is switched on

lol(at statement not poster) as for auto electricians having the knowledge to fix the internals of an ECU... yeah right!! i am an auto sparkie by trade(12 years) and i cant name any of my fellow tradies who have a higher proficiency in electronics.... not to say that there isnt any but the only reason i have is that electronics is a hobby of mine
just go to jaycar for the caps

Try this guy http://www.autoelectronics.com.au/subpage3.html. Aparently he does ECU repairs for $250.00 ie: replaces capacitors.

Cheers

my mechanic had EFI automative in perth replace the capacitors for $50. $250 is a bit steep.

express post your ECU and I can express post it back. Wont take that long :)

yeah we've had efi do some repairs for us too and i concur $$$$$

Yep, I agree with Cruiser. The circuit board in the ECU box is old style electronics (think 1970's transistor radio), all capacitors are hole mounted (ie easy to replace) and common types you will find at Dick Smith stores. Take out any that are bulging, and get replacements - the farad rating is on the capacitors, and you need to match those. Voltage rating for the caps should be the same or higher - the higher voltage ones are slightly bigger but there is plenty of room on the board. Capacitors are polarised with a + and - end, so draw a diagram of the circuit board where you took them from with the + and - sides marked.

Electrolytic caps are simply 2 layers of aluminium foil rolled up with paper between them, and soaked in oil. (NOT fish oil!!!!) Poor manufacturing or overvoltage can punch holes in the paper, leading to excess current flow, overheating of the capacitor, bulging and "bang" type failure. Other components can be damaged by the excess heat/current. So if they are bulging at the end, replace them!

Had my ECU, coil, power transistor and distributor checked by a local firm for $80 a few years ago (walked in with the bits)- turned out to be a dead coil, other bits were fine. (Off a TS 2.6L manual)

EDIT: EFI places probably recondition ECUs, you get a fully repaired and checked ECU, which is probably not the one you brought in. If you pay $250 for one, get a warranty in writing! Easy money for them if the only problem was some leaking caps!

I haven't looked into what you guys get for ECUs but pretty much everything Mitsubishi built between the mid 80's and 94 including transmission computers, and the digital AC displays and suspension computers used in the GTO/3000GT have problems with the capacitors leaking out the electrolyte past the seals where the leads enter the case.

I haven't seen any that fail the same way as computer VRM caps do. The cases don't bulge, the leak out the bottom and sometimes short.

I'm also starting to see more of the 95-98 4G63 ECUs with leaking caps. The first warning sign is corrosion/tarnish to the copper traces next to the lead and cracks in the waxy conformal coating around the capacitor as the electrolyte wicks under it.

Most of the "professional" rebuilders here in the states are hacks, strictly how fast can they move this ECU onto the fixed stack and if it fails later they will just send another, if it comes back, business model. Finding an owner with the tools and skill to do the job correctly and test the ECU in the car is much preferred. I get ECUs sent here from all over the world largely because reputation for quality work.

The caps that usually fail are the 47uF and 100uF caps in the power supply section. On ECU's I replace them all since they are getting old and I have no desire to see how long the "good" originals will last.

I'd suspect any first and second gen car at this point. The 3.0L SOHC and DOHC ECUs are likely the same as what we get and they are well known for leaking.