Last week a local muffler shop did some welding on my rig and right away electronics on my truck started acting up. After some exhaustive trouble shooting it is time to face the fact the 'my little ECM' will never be the same again <img src="/forums/images/graemlins/frown.gif" alt="" /> And so now I have to go and find me a new controler, but while I'm at it I wanted to know if any of you guys are running some of the after market computers in your 3.4 modified Troopers, mine is a 91' auto and seeing how I have to get a new module I thought may as well see if there is anything out there that would do better job than stock parts mainly in the area of fuel economy. My 3.4 engine has enough power so that's no longer an issue.
So feel free ya'all to let me know what what's the 'word of the wise' on Trooper ECM replacement subject.

If you are up for a serious electronics project, check out www.megasquirt.info I saw this referenced in one of Houlster's threads and it looks like a lot of fun. Once built, you can tune your engine using more prarmeters than your stock ECM ever could, plus you get a live picture of what's going on.

If not AC Delco makes remanufactured ones for about $175. I'm running one. You could also go to a yard and get one for less. I don't know of any other performance ones.

What made you change your ECM, I mean was there an obvious problem with it. Right now my ECM seems to be getting all correct inputs but it has a hard time determining right course of action based on all the inputs. Another thing is that internal ECM fault is difficult to track down or even get it to show as an internal failure on a scanner.

I hooked up an aftermarket tach to the wrong side of my coil and fried my ECM somehow. If I had known that was the problem I would have got a new used ECM at a yard, but I threw in the towel and had a mechanic diagnose the problem. They said a new aftermarket one was like 150, so I just said do it.

I would not start replacing ECMs until you know exactly what's wrong, seems like you don't know for sure but you just have a feeling.

I've had exhaust shops weld on my truck a number of times and no problems.

Although, I have also gone through 4 computers. When I bought the truck it had a 92 Astrovan ECM in it. Then before I knew anything about engines, I had a mechanic replace my oil pan. He pulled the motor, replaced the pan, but when he put everything back together it wouldn't start. He said my ECM was bad and charged me $80 for a used one. That was a 92 Rodeo ECM.

I fried that as mentioned above, and now I run the aftermarket refurbished one.

You are right about the fact that I'm not 100% sure about this ECM affair but I checked all other sensores and they are all doing exactlly what they're supposed to as per service manual and Snap-on scanner. Plus I noticed yesterday that computer became really sensitive to even most moderate electrical spikes, like when I turn my bush lights on, the hole thing just goes nuts for about a second or so lighting up all of the dashboard lights. I was looking inside the ECM couple days ago, by the looks of things that thing appears to be mostly an analog unit with rows of diodes and transistors. If one of those semi-condustors is fried and only mulfuncitons when it heats up I could be chasing this problem forever and not find the specific fault. That's what leads me to a conclusion that it's ECM it self. As for welding things on your car or truck every manual tells you to disconnect negative bat. terminal first regardless of the type of work. It's true that it happens rearly but things like ECMs and such are extremely sensitive to any kind of a static charge, when some dude goes to Town with a MIG or worse yet an ARC and doesn't have a good ground on the clamp the sky is the limit as to what can get toasted, that elecrical arc will find its ground somewhere. On my truck it was an instant response to 'little welding' the thing went from running flawless to instant bag of crap. This whole experience leaves me a firm belief that yet again a little preventive measure would go a long way in ensuring a happy ending. I guess I'll have to chuck this one up to what I refer to as character building experiences in life.

So you are just supposed to disconnect your negative when welding to protect your ECM? So is protecing your ECM just making sure it is not powered when you weld on the truck? I suppose that would help but wouldn't it be safer just to disconnect the ECM? I thought disconnecting the negative cable was to prevent you from getting electrocuted rather than actually protecting the ECM. I have been to a few exhaust shops where they are working on 5 trucks at a time but never seen any techs disconnecting electrical equipment. Not sure since I've never heard of this, but I don't know much about welding safely either.

If your engine does weird things when you add another load on the alt/battery, like turning on aux lights, I would check your battery to see if you have 12v. Also ground wires if any are loose. Lastly, the alt itself. Not sure about that, but i've read bad alts can produce strange behavior and random dash lights when they go bad.

I'd just hate to see you start throwing money at computers if it wasn't it. These ECMs are definetly sensitive to electronic discharge, I agree, but they aren't very complicated, all the fuel maps are stored on one simple chip.

Yeah disconnecting the ECM it self is the ultimate in prevention of accidents like mine. Trying to convince an average auto shop about it is another story. The guy that did the work on my truck said it him self that it's something they never do because customers get upset when their clock is flashing 12:00 and all radio station pre-sets are gone but the alternative is rather costly.

Sometimes the shortsightedness of car mechanics floors me, but that's a topic for whole separate discussion.
Bottom line is that computer it self will cost me little in comparison to many hours of scanner trouble shooting, and hey if it doesn't fix the problem I can always return it and know at that point that whatever is giving me the headache will be small potatoes.
And hey if that doesn't drain enough time out of my day I have another project in the form of my rear diff. which just started acting strange couple days ago, it has over 200K on it and all that new found power and engine torque must have put a final nail in it and it starts to look like a re-build time. This truck just keeps on giving... <img src="/forums/images/graemlins/nana.gif" alt="" />

But what would life be without chalanges right?

Oh another thing I was going to ad was that those who suffered and literally got burnt by the welding arc will know right away what I'm talking about. Friend of mine had a computer on his Ford smoked right up by a welder, I mean a whole row of pins on ECM plug had electric arc burns on them.

But I wanted to ask you about how you like your Rancho 9000s, my brother in law wants a set for his Jeep TJ for christmas and I was wondering how are they performing being that they're adjustable and all.

I would like your opinion on this subject <img src="/forums/images/graemlins/pfft.gif" alt="" />

My truck is shot suspension-wise, needs lots of new bushings and new balljoints. I am constantly adjusting the ride hieght which also effects ride quality more than the shocks do. I need to replace rear shackle bushings that are already toast after 1 year.

It is an old truck that has never ridden well, so I think spending the 250+ on shocks was a big mistake, I would not know if they were good or not because there are always so many other variables (items to fix). If your truck is maxed in the front, it is also important to mention shocks don't do a whole lot since most of the down travel is already used up. My point is the shocks themeslves could be great but my money should have been spent elsewhere.

As far as adjustability is concerned, it got old after a few weeks, I couldn't even tell you what setting they are on now. Not putting down the shocks, they just weren't a good value for MY application.