91 3.0 ECU found another

[Law Dog]

Bought a 91 D50 4X4 3.0 not running it was suggested the AIC stuck on these trucks and fried the ECU it came with 2 that were toast one was fubar the other I sent in for repair. It came back but the fuel pump would run as long as the battery was hooked up key on or off sent it back came back the same way they refunded my money I just lost the cost of shipping.

Seen one on EBay for $250 scooped it up and it worked so the truck is useable but it idles high at start up and won’t start after a short trip until it cools off but around the home place it’s fine. Those issues could be a lot of things but without a working backup it’s hard to dump a lot of money into it not knowing if I can find one when I need it. Some places want $700 to $1,100 for a working one then no clue if the components are any good or not.

Found one on eBay last week they wanted $570 bucks for it I did a buy it now for $250 and got it. LOL So if and when it gets here I have some decisions to make rebuild one or both as down time is not a problem. I’ll test the new one for function and see if anything changes performance wise. I think the place in TX charged $250 to rebuild it I talked to another place yesterday that was clueless they kept asking for the part number that I kept giving them and then the vin number and still were lost they wanted $750 to rebuild my ECU.

Do they just change out the components and return the units do they test them in any way if they tested them you would think that fuel pump issue would have been caught the last time. It seems everyone and their uncle thinks they can rebuild these ECUs but that’s not my experience so far. Even the local auto repair shop says one of his guys can do it is it that simple?

[Chargerx3]

I don't think they test the circuits. They would only test that their new surface mounts function and have continuity. Welcome to the running v6 club.

[Law Dog]

They always claim they don’t need to be reprogrammed when you get them back but I’m guessing they don’t get into that part of it with what they do mostly circuit changers it sounds like. I don’t see how they could have that kind of data and so many people think they can do it. I’m just afraid if they mess up I’m out a couple working ECUs and totally screwed then.

[Chargerx3]

They will not have the ability to program. They will just remove surface mounts like resistors and capacitors and replace with the equivalent.

[Law Dog]

So in reality any electronics guy could do it for way less if the components are not a crazy price. One guy in TX will redo a ECU for $250 these not being fried should be a cake walk for the guy I’m hoping.

[Chargerx3]

Depends on the depth of the damage. Typically its surface mount capacitors that leak out and then disrupt or damage the copper contacts on the board. Those connections are difficult to repair. I've seen a lot of sloppy fixes to those over time. However you may get lucky and its just a simple replacement. I've done a few myself but im no pro. They price you high just in case there are some challenges along the way.

[Law Dog]

New ECU came today tested it right away it’s definitely better than the one I have in it now. The idle dropped to normal levels and it restarted when warm both 2 issues the old one was having.

Neighbor has a machine shop he said I can send them both in and reprogram the old one with the new one. I’m getting that contact info later today just not sure if theres issues that are not that noticeable say like timing issues. I’ll see what the tech has to say on Monday. Will mess with it more tomorrow it was getting pretty hot idling that’s a new issue but it was too hot to mess with now.

[Law Dog]

Added some antifreeze and started it up then took it for a drive then let it idle it stayed within the normal heat range.

[Chargerx3]

Nobody can reprogram your ECU's. Nobody has that old technology and Mitsubishi never released it. They will only inspect and replace bad surface mount connectors.

[Law Dog]

That’s what I figured the one ECU is good I just don’t trust the leaking issue and no telling if others things are off that you can’t see/hear but the check engine light does not come on with that one. I’ll be curious what the high idle, warm start, check engine one will do after the rebuild? I’ll have 2 ECUs off my 90 V6 to send in also both untested.

At least this guy is honest and not crazy on his prices if he can’t fix it them I will get a refund.

[Law Dog]

Opened the 2 91 ECUs both looked very clean no corrosion on either boards. I looked at the 90 board it has a quarter size spot of flaking on the board guessing that’s some leakage I found. I have another 90 ECU coming today I’ll look that over when it gets here the box is trashed but I have another cover box I can use for it if the boards any good. A good box is necessary to fit in that tight spot it goes into it’s kind of a pain.

Will end up holding onto the good working 91 ECU for now and sending in the one with the issues for repairs, then I’ll send in the 90 ECU that looks the cleanest of the 2 for starters. I need one good one for the 90 to get it running before I get too deep into it. I can always sell the rebuilt ECUs down the road if it comes to that.

[Law Dog]

The other 90 ECU arrived the board looked clean except for one component looks suspect a little “fuzzy” but not impacting the board itself just off color a bit. Now to figure out what ones I’m going to send in or hold back. They are good property if they work I might just get them all rebuilt I could sell them off later.

[Chargerx3]

Glad things look good. Here is where the capacitors go bad on 3000gt's. Our boards are not too dissimilar.