Hacking/tuning the jeep ecm

[EagleMark]

I think it would be easier to repin what you have to a GM weatherproof under hood ECM. Then tune it...

[JeepsAndGuns]

About the only gm ecm/pcm I think I would swap to, would be the 1220411. Its sequencial, has great aftermarket support, and can run a 6cyl. But its just so freaking expensive to tune. It would also require harness mods, and probably a couple diffrent sensors, and a crank trigger wheel/pickup fabed for it, cause the jeep one would not work. It would be really hard to hack up the factory untouched harness in my jeep (that I have had for a long time, and has always been my baby) If I modded the stock ecm, then thats the only thing modded. If it didnt work, or work out, I could just swap back to the original ecm and be done.

So lets "pretend", for now, swapping to a diffrent ecm/pcm is not a option. I would like to keep the discussion on "is it possiable" I pulled the top cover back off the spare ecm I have, and looked through the gel with a flashlight, and its a 27c256 eprom in it, with the little picture of texas on it, also has a sticker covering the window and a bunch of numbers on it. There is a setting in the moates prom I/O for that chip. So I'm thinking it could be read? The jeep ecm's also have a 7 diget number on them, with the last 3 being twice the size of the first 4. The spare one I have is from a 93 cherokee automatic (my wrangler is a 93 5 speed) I had read the cherokee is supposed to have a "better" timing table. All I noticed was slightly less torque, so I swapped back to my original one.
The first 4 digets are the same on both, so I would assume this would translate into a ecm service number (if we want to think of it like that) and the last 3 digets are whats diffrent. So I would assume thats gonna translate into a BCC or the tune on the chip.

I just want to make sure, that beyond any reasonable doubt, that the jeep ecm is absoultely postatively not hackable/tuneable before I even start to think of swapping to a diffrent/gm pcm. I dont mind chip bruning, and I just LOVE emulation/real time tuning. And emulation is just so expensive to do with the 411.

[cmaje72]

I looked into this a couple years ago when I thought a mopar 5.2 or 5.9 swap might be good into my cherokee. I did not come up with anything except that you needed special hardware to program the PCM's and startup costs were in the $3000 range. So basically unless you were doing it on a shop level where the hardware and software would pay for itself its not DIY friendly. I did not find anyone disassembling the chips either...

[EagleMark]

That's going to be a major project. Since it's such a popular vehicle if it were possable I think it would have been done. What are guys doing when they build an engine for that vehicle?

There's an easier way to make changes to ECM for what's needed to tune the engine after you build it. PiggyBack tuners. They get wired into existing harness and make changes needed in signals to tune the new engine. I have used the Perfect Power products for vehicles such as yours with great results.
http://www.perfectpower.com/index.ph...&id=5&Itemid=7

[JeepsAndGuns]

I bet anything it has been done, but like said by cmaje72, its probably been on a shop level where they make/have lots of money and hire someone fulltime to do nothing but hack/tune the ecm.
My guess why it hasnt been done on a wider scale is because it (appears to be) a eprom based ecm, not flash based. The eprom is sodered to the motherboard and then its all encased into the waterproof gel. Its not like the gm computers where you simply take two screws out and can uber easaly remove the chip, read, hack, tune, and reinstall it. I think thats why it has been done so much and easaly on the gm ecm's. And the ford the same way, so many out there, I'm sure the mustang builders pretty much demanded a way to tune the ford computers. So a way was found. The jeep ecm on the other hand is gonna take a little more work to get to the chip. I would have no problem doing this, I however am nowhere near smart enough to read the code and do all that magic to where it can be displayed in a tunerpro format where I can understand it.

Anyone have a lead on any other forums I could join, or people to email to get in touch with someone smart enough to do said work?

[EagleMark]

I'm telling you the piggy back tuners are what guys use in cases like this. I have personally used several from Perfect Power. They will do everything we do here with GM stuff. They also work with all the GM ECMs instead of doing the chips. They also have capabilities for tuning nitrous, turbo and superchargers. Once you find out how much they cost and the ease of installation and use compared to re-inventing the wheel you will believe me.

But if anyone would know if your Jeep ECM could be done would be Westers Garage.
http://westersgarage.eidnet.org/index2.html

As far as someone to hire to disassemble a chip, write an XDF and ADX look for Traxion or Cal Editor on:
http://www.monodax.com/forums/forums.php

[1project2many]

Imagine you want to get more power from an engine but you have no idea how it works. You don't have books, you don't have the 'net, and you don't have someone else to ask. You don't know what a cam is, you've never heard of compression ratio, and the word piston has never been spoken near you. You have some tools but they may or may not fit the engine and they may or may not work together to disassemble the engine. You know someone somewhere has modified their engine so you have faith it can be done, but you have no idea what it took them to do it. All you know is if someone did their engine, then they or you should be able to modify yours. Doesn't seem like an easy job, does it?

Making a definition file and coming up with a disassembly is a huge undertaking. Around 2001 Lyndon Wester actually hired a guy to work full time on disassembling GM code for him because it takes so much effort and time to get it done. And that's with a known processor and known examples of code from similar computers. Working with an unknown ecm can take even longer. If it were simply a matter fo finding someone and handing over cash, everything would have been hacked a long time ago. What stops these efforts is the sheer time it takes to work out the details.

You can probably read the eprom in your ecm. But what you'll get won't look like anything you recognize. Will it be code? Or calibration data? Or both? You'll need to pass it throught a disassembler to know that. And in order to know what disassembler to use you'll want to know the type of processor used in the ecm. And then the disassembler may choke multiple times forcing you to make manual modifications and restart the process.

If the ecm is a chrysler design similar to some of the cars and trucks there are a few places to go. Like the GM stuff, you'd better be prepared to do some research first.
http://www.omniglht.com/cal.html
http://www.omniglht.com/sbec.html
http://www.turbo-mopar.com/forums/fo...?36-EFI-Tuning
http://www.turbo-mopar.com/forums/kn...BEC-Tuning-FAQ

I wish you guys would stop thinking everything needs to be SFI. The 86-87 GN is sfi and it uses an older "C3" ecm. But the Syclone is batch fire and can do everything the GN does.