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Discussion Starter #1
Well, things are looking bad in mn12-land. Car was running great and then I parked it at work the opposite direction I usually face. Went to fire it up to hit the hardware store and it was running rough and surging heavily. I haven't drove it in 2 weeks until today.

Black smoke from the tailpipe leaves black marks on the ground. It finally threw rich codes for both banks. I have looked at data with the scanner and all looks normal except the o2s sometimes stay pretty high. Stfts are negative. I've seen them as low as -25.

I have tried unplugging the maf, draining all my gas and refilling, fuel pressure is 35 with vac to fpr. Finally, I unhooked the o2s today to no avail. I have also put a noid light in my injector plug and it flashes, not on constant. My old 94 hung injectors once, it's not the exact same. Any ideas? Would love to hear someone else's insights. Thanks in advance.
 

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If you have a spare eec, you might try it; they've been failing a lot.

The only thing I can think of otherwise is a failed maf, or something stuffed in the air filter.
 

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I was afraid it could be an eec since everything else looks basically ok. Weird that I just replaced it a few months ago with a used one. Had to show Sct a receipt and mail off my xcal to unlock it so I could flash the new one.

I suppose I could temporarily install one with one of my j chips and see if it'll run better. Is there a preferable code to get? I have had nothing but mbe2 and mbe3. I was thinking newer revision= better part. Maybe that's not true.
 

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If you're using a tune, the catch code doesn't matter.

Did you try unplugging the maf, and see if it straightened up? the MAF is pretty easy to check for gross fails. :)
 

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Yes, I already unhooked it. I didn't try driving it, but the symptoms were still there at idle. I guess I will go ahead and order a couple of used eecs to hang onto. I hope there's not something wrong with my car causing all these different eec failures.
 

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The one I have has obvious soldering issues that failed over time.

There was a batch of these, because they run these bu the hundred or thousand.

Mine looks like the reflow oven was about 5-10 degrees too low, lol.

There's an eighth of an inch of conformal coating over the whole thing, which takes about a gallon of cleaner to remove, so it could be refluxed, and ran thru a reflow oven, which would probably fix the problem.

The real drag there, is that the reflow process will probably totally erase the flash memory, rendering it useless.

My understanding is that even with a tune, we are only changing small amounts of the total programming; if we CAN rewrite the entire address space, then this would fix a dead eec.

I guess Jerry or possibly KDanner are the only ones who could answer this question.

I was amazed to find after extensive testing, that this type of flash memory can be refurbed by heating it to 160 degrees c for an hour, then you could reprogram it another million times. :)
Totally erases it, but it's not worn out anymore.

Our flash never gets rewritten, that could be part of the problem, IDK.

I do know that rewriting the failed one I have didn't help.


EDIT: Reading over the other sites, it seems, like every ******* thing else I've dinked with this weekend, it has bad caps. :)

Those are fairly easy to replace, I'll see what it needs, and order some.

I need some more for this old motherboard I'm working on; It still has a shorted 5V rail, and it's pissing me off, lol.

I found another MB I forgot I had, So I got it working at 5am this morning, but that doesn't get the other one off the hook, lol.
 

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That's crazy about heat renewing the memory. I had no idea. I may try to tap on the computer in the next day or two and see if the symptoms change. If so, maybe it can be repaired.
 

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I had the exact same problem with my 97 Cougar that I bought in 2011. The owner couldn't figure it out but it would puff out black smoke like crazy. Turned out to be the ECM. I replaced it and the car ran perfect after that.
 

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Well, I haven’t posted any updates because there haven’t been many. This website is atrociously slow on my phone and it’s a chore to spend time on the pc, so I never even visit much anymore. It’s been crazy busy at work. Anyway, back to the black smoke problem.

I got a used pcm and installed it. Unplugged the maf since it’s not tuned for the lmaf. At first I thought it was slightly better, but it’s not. Hooking up maf does t make difference. I haven’t went through the trouble of returning the old pcm to stock so I can flash the new one. I’m afraid it’s not going to make a difference.

A couple of weeks ago I started to drive it to the shop. It fell on its face so bad I couldn’t accelerate, so I backed it the whole block back to the driveway and it’s still sitting. I really hate this because I now have it lowered with brand new suspension all around and can’t even enjoy it.

Do you guys have any suggestions before I take this to the shop and take a fresh look at it?
 
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