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Holy Cow..Whats up w/ my ECU?

Okay, since the car is on jacks and not on the road yet I decided to pull the ECU to inspect the CAPS. Well what on earth am I dealing with here? Please expound !
 
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Barnes

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It done blowed up! /ubbthreads/images/graemlins/uhh.gif
 

mistaVR4

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Check your ISC coils, thats typically what an ECU looks like after the ISC goes bad. Don't put another ECU in there until you can verify the ISC is still good, I beleive your looking for 40 ohms. You might want to put a new one in there just to be sfae or you'll keep frying ECU's.
 
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Would you look at that, it's exactly what my ECU looks like (minus a few minor details). Indeed, my ISC was bad, and apparently it spikes the integrated circuit on the ECU which is the fifth spot from the edge. So now I'm replacing both my ECU and ISC, though someone mentioned that the car will run decently without the ISC connected even though that chip is toast.

The ISC pin readings are supposed to be between 28 and 33 ohms with the car cold. Mine were closer to 50, and two of the connections didn't even register a reading, so they must have been ruined.
 
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Why did the car drive fine with this much damage? Can this be fixed?
 
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3Diamond

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It idled fine as well? It could possibly be fixed, but youd need a donor ECU.
 

Yeah, when I first got the car in Feb. it had idle issues, but it was also missing the intercooler. I found a stock IC and after it was put on the idle issues I had basically went away. The car always felt underpowered to me, but hey, I had nothing to compare it to . If I remember, the car would idle barely high enough to keep running, then surge up and then back down and stay low (about 600rpm).
If I can save the board, do I need the donor to be from a 4G63T, or would any DSM ECU work for parts?
Anyone want to repair this for me?
 
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In the 1st pic,above the EPROM, it looks like that chip might be shot.Does it have an abnormal raised bump near the middle?
I had an ECU in my GSX go south and that chip bubbled right in the middle.Near impossible to replace that chip with its micro-sized leads.
Might have to send that barbequed box out to someone to check it out.
That sux

GL
 

Every Mitsu ECU I've seen from that era has a few of the M5269L chips in it. The chips ONLY affect the idle, so you probably wouldn't have noticed any other issues, unless the board damage/fire took out any adjacent components, which is rare.
I would remove your ISC and look for coolant damage. Very often the big O-ring-type seal leaks that seals the FAIV to the throttle body, and the coolant shorts out the ISC.
 

Thanks Jeff, I will checking that ISC, seems theres a consensus on that puppy. I'm heading to the Jyards today to see if I can find some donors. Anyone think this Barbecue pit can be cleaned up?
 
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holeshotmoe

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I cant read the p/n but those could be simple resistor networks that, if you can find a cross reference or ohm out a good one, are easy fixes and cheap. Even a common IC, if you can cross-reference it, is commonly a cheap fix. Also, looks like at least two cooked. If someone can get me the part numbers for all six of those (if they're different numbers) I'll try to look them up. I was once trying to fix a GM (olds) ECU and found that all of the individual components had GM-unique #s, even though the actual component was no different from one commonly available. And IMHO, no number = no cross-referencing = no cheap fix = must by new = BS. In short, forcing the owner to buy a new ecu vs. ordering two $1.50 replacements on the web. But (and a big BUT /ubbthreads/images/graemlins/ooo.gif) there is no guarantee that the visibly damaged components are the only thing wrong, e.g., chain reaction failures often occur. Get me some numbers and maybe a few of these ECUs can be salvaged. Also, whats the ID printed next to the component on the board? That's a clue to what the component is, e.g., R41 = Resistor #41, C27 = capacitor #27, Q15 = transistor (or IC) #15, etc...
 

holeshotmoe

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Oh crap, I see keydiver already put the number up, right? Have you tried to cross it up yet? **Edit** Also see this has been done before. Guess ya just have to find a source for them.
 
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I just got home from work an hour ago!
 
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stevep

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Quote:
Oh crap, Guess ya just have to find a source for them.

They are low saturation voltage drivers. New ones are impossible to find in the US so most of us recycle good ones from bad ECU's.

The ISC does do more than just manage idle. It's also emulates a dashpot to keep the engine from stalling when you close the throttle.
Anytime you read 0 ohms across one of the ISC windings you can count on the driver being blown. It's also common for IC105 to be blown when C106 leaks and shorts the ISC trace under it to +12.

Steve
 

3Diamond

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Why are low sats not available in US? Price? Regulations? As for the BBQ pit, i think you can go to electronics store and buy no residure electronics cleaner. As the name implies, its like a brake cleaner, but it leaves no residue that could short/damage something elese.
 

stevep

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Why are low sats not available in US? Price? Regulations?

The specific part is over 10 years old. It's pretty much obsolete and most of the stockpiles are located outside the US same as where most of the devices that used them were originally manufactured. You can order them but you have to make a large purchase, you can't just call Mouser or DigiKey.

Steve
 

Just an update...I found two ECUs as donors. I've got some help from a guy who makes his living wiring automation equipment, he'll replace the fried M5269Ls for me. He's also going to check the board closely for any other damage. This guy works for my dad, so I know he wants to do me right. Also, to my surprise, the CAPS were replaced before I got the car.
I have a new question, since a new ISC costs over $300.00, which is more than I have to spend on the car right now, whats your thoughts/experience with using a salvaged unit? I know on some , if not most, components, new is not only preferable, but necessary. Has anyone used an after market brand ISC? Thanks for all your input.
 
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There are guys on here that will sell you a rebuilt ISC for alot less. /ubbthreads/images/graemlins/wink.gif
The problem with the M5269L's, other than the fact they are old technology, is that most of this stuff is manufactured in Asia, so the chips are never stocked by American distributors. I can get them shipped here, but the minimum quantity is 1844 pieces! /ubbthreads/images/graemlins/shocked.gif
Be sure your friend understands that there is a conformal coating on both sides of the board, which needs removed with acetone around where you are going to be soldering/desoldering, otherwise it makes a real mess.
 
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