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Discussion Starter #1
Hey guys I've been having a problem with my 3000gt base model for about 2 months and I've run out of options. I could really use someone in the Lehigh or Florida in general to let me throw my ecu in and see if it works right
 

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Can’t help since I’m no where near Florida and not sure where The Lehigh is, guessing somewhere in Florida. But may be able to help with some friendly suggestions.

First you should list year of your car as that is critical concerning ECU’s, also MDxxxxxx number on cover of yours would confirm if theirs is same as yours. Depending on year of you’re 3000gt base could be either a SOHC or DOHC engine.

Wish you luck and hope these tips might help you get a response soon.
 

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Discussion Starter #3
Sorry was at work and in a rush. The year is 1994. I know the first gens had a problem with capacitors. I've opened mine and seen slight wear it appears in one of the 3. It is a DOHC
 

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If it’s not a California spec car it probably has a MD192591 ECU with build set E2T35694.

Yeah.. First gens are noted for capacitor problem, but the 2 nd gens are starting to be same as it has to do with age and cycles on ECU. Unfortunately can’t tell by looking at them as some fail looking perfect, while others show leakage or completely burn up. You’re doing right thing trying to find a known good running test vehicle near by.

Might include some of you’re symptoms, sometimes there is a clue there that someone might recognize. I’ve had to replace capacitors in my ‘93’s ECU, TCU and TACH all failed over about 4-5 year period.
 

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All year model ECUs need new capacitors, they wear out due to age and usage.

Take to any electronic repair shop and have them replace those electrolytic capacitors.
 

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Discussion Starter #6
Ita non California no egr. The tach is very weird I'll start the car sometimes runs smooth for a second sometimes it runs smooth enough to drive to the store. A weird thing I've noticed is the car will start to die off misfire and even backfire while its freaking out. If I give it gas and tey to hold it around 2000-2500 it will slowly drop speed and will die after it reachsabout 20mph. I've replaced crank and cam sensors and the cel still has only those two codes. The tach also doesnt always read correctly. After the engine has killed itself the rmp will bounce for a second d or two after the engine killed itself
 

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.....A weird thing I've noticed is the car will start to die off misfire and even backfire while its freaking out.....
That is one of the common symptoms of beginning capacitor failure in a ECU. You're at point capacitors need replacing anyway, which doesn't have to be an expensive situation, you can buy capacitor set from 3sx for like $10 and have someone with board component replacement experience replace them or as BlackStealth indicated take it to electronic repair shop.

The tach also doesnt always read correctly.
You're tach symptom is same as how mine started before it finally quit working. Replaced the two capacitors in that and cured it, those two capacitors looked like brand new but failed.

Just to be clear PTU controls tach signal so could be that, but most times it's capacitors in tach.
 

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Discussion Starter #8
I replaced the ptu along with a complete tune up when I first got the car. Only about 2000 miles ago. So I seriously dont think it's the ptu. I had a issue with a badly rusty fuel filter. Changed it and my injectors got a rebuild from 3sx and the car starts alot better but doesnt consistantly run still. Was thinking of pulling the fuel assembly to see if its blocked off by rust in the tank. I've also read the iac(know mitsu calls it something else) can cause the ecu to go out. Anyway to test it to make sure it's good before I go putting in a new ecu to have it die on me? And if the capacitors are the reason. Wont their be damage to the circuit board? I'm not real tech savvy I'm more of a gear head. I love Mitsubishi I had 2 3rd gen eclipses before the 3000gt and I can say when they run they run good. But when they dont run it's such a pain in the ass. Thanks for all the input been going crazy trying to get it back on the road.
 

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...... I've also read the iac(know mitsu calls it something else) can cause the ecu to go out. Anyway to test it to make sure it's good before I go putting in a new ecu to have it die on me? ......
Yes and it can be done without removing it from throttle body. Simply unplug harness connector and take following ohm readings:
ISC or IAC.jpg
1) Meter black lead on pin 2, red lead to pin 1 and then pin 3.
Should read ~ 30 ohms at both pins 1 and 3.

2) Meter black lead on pin 5, red lead to pin 4 and then pin 6.
Should read ~ 30 ohms at both pins 4 and 6.

Note: If your IAC is black instead of tan top like one pictured, readings should be ~ 40 ohms.

....And if the capacitors are the reason. Wont their be damage to the circuit board?....
Most of the time circuit board is not damaged, but some are if capacitor actually burns-up which is obvious when viewed. One did exactly that in my TCU which caused bad smell inside car at time, I knew something electrical burnt but didn’t know what it was until later when I realize a shift problem with auto-trans. But even that one just needed small trace repair.
 

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Most of the time circuit board is not damaged, but some are if capacitor actually burns-up which is obvious when viewed. One did exactly that in my TCU which caused bad smell inside car at time, I knew something electrical burnt but didn’t know what it was until later when I realize a shift problem with auto-trans. But even that one just needed small trace repair.
I would like to mention that the electrolyte that leaks out is corrosive and, if left in contact with the board long enough, will cause damage.
 

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Discussion Starter #11
Thank you guys for the input. I've been working on it for so long with no clear direction on what it could be and let's face it one symptom is the same for 3 problems lol. I'm ready to get this car running again so I'll pull the ecu and send pictures so someone can tell me if the circuit board is damaged. I'll have to wait till after work to do it tho I'll let you guys know then. Thanks again
 

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if you upload high res, close up pics of the areas around the caps I can tell you if I see anything. In complete honesty if you suspect a problem it's best to have it inspected in person by someone who knows what to look for, pictures only go so far.
 

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Discussion Starter #13
Sorry it's been a few days since I've been on, been busy for the last little bit. I replaced the iac just to be safe and nothing really changed. Be posting in a week or two once I've got some cash to replace the ecu. Stay tuned and for everyone in the future once the car is running i will be posting what fixed it lmao
 

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You never really indicated what # ECU you had, are you even sure it’s right one for your car? You indicated 3 capacitors earlier, when I look at pictures of the one I expect to be in your car, I see 4 capacitors. :unsure:
 

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Discussion Starter #15
Honestly I'm not sure. I got the car kinda as a barn find. Guy had it sitting in his shed for the longest time because it was his brothers. Something happened and the car came into his possession. He wasnt sure what was done to the car and it looks like aside from big rims and a radio nothing was done to it. Everything I've pulled to replace has been old enough to be OEM. Just pulled the ecu and on the blue Mitsubishi sticker the two numbers are. MD192591. E2T35694
 

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....... Just pulled the ecu and on the blue Mitsubishi sticker the two numbers are. MD192591. E2T35694
OK… That should be correct as I indicated in post #4, just confused by you saying one of three in your #3 post.
 

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Discussion Starter #18
The 3 capacitor reference was going off of what I've been told and how their is 3 particular ones that like to go out if you look at pictures I definitely have 4 along with some kind of weird build up by one of the capacitor
 

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Yeah… those are original capacitors and C104 has been leaking. There doesn’t appear to be any major board damage and area around C104 other than what can be cleaned with alcohol.Those are mostly what goes wrong with ECU’s, the other components are usually OK especially in your model year. Keep in mind that what I said previously, they can be replaced at minimal cost without replacing the whole unit, but that’s up to whatever you feel comfortable with.
 

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........what I've been told and how their is 3 particular ones that like to go out......
Little bad info there…. All those older “barrel” capacitors tend to go bad over years, maybe just not at same time.
 
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