'94 Jeep Cherokee Tuning

[sev80]

that would be great. the version i posted should be able to be burned back to a chip. however, i would suggest you read your chip and send it to me so i can take a look at it and compare to the one i already did to see what, if any differences, there may be.

All around good news today. I got my jeep back from the shop. Plugged in the ECU I just socketed and it fired right up! Looks like the SBEC-II is alive and well!

I also got my rom burner in the mail today. It's old school and uses a parallel port. Luckily I have a cache of old computers and got it working and dumped the eprom file from the ecu I socketed.

This is for a 94 Grand Cherokee A/T 4.0L with Federal emissions. The ECU part number was 56028310 and the date code is 10/07/93

Here is the file:

https://www.dropbox.com/s/hps77grxq5...38310.BIN?dl=0

[wowzer]

well, the good news is that it is almost identical to the 781 code, bad news is that it is off just enough to require it's own code and table base even though the cals both ID as 94 cals. hopefully will be as simple as just changing addresses. it will be interesting to determine what the new tables/code are.

[sev80]

I did a file compare with the 781 code last night and noticed that in some places the file is identical to 781 and a few places it's not, so hopefully it's easy to find!

Thanks for taking a look. Im getting very excited. I ordered a 2 27SF512 chips from Moates! I might also pick up a USB based burner as I was reading the Willern ones can fry the chips if you dont configure them right.

Im so curious what would hapepn if i burn the 781 code onto this ecu and try to run it.

[wowzer]

here is the latest attempt. there are 2 tables having to do with the ptu that give invalid results. don't know if i have the table type wrong or what. if someone can point me to where the rev and speed limiters are i'ld appreciate it.

[A_ Kelley]

Rev limit is 5k, speed limit is already in the cal I posted. The rev limiter I didn't look too hard for as the 4.0 didn't need to be spun much over 5k. Self disassembly occurs around 6500 rpm if I remember right. Addresses are org'd statically. All the tables in mine reference the actual variables fed to the lookup functions. I spent probably fifteen to twenty hours on it over about a week. I got my flash chips yesterday, but as Rob pointed out, I got the wrong ones but I'll make a adapter for it. Actually thinking of making a SRAM board so I can flash it in about a tenth of a second. (USB interface to it with a dedicated micro, actually could buffer two chips and do a live reflash)

[wowzer]

Rev limit is 5k, speed limit is already in the cal I posted. The rev limiter I didn't look too hard for as the 4.0 didn't need to be spun much over 5k. Self disassembly occurs around 6500 rpm if I remember right. Addresses are org'd statically. All the tables in mine reference the actual variables fed to the lookup functions. I spent probably fifteen to twenty hours on it over about a week. I got my flash chips yesterday, but as Rob pointed out, I got the wrong ones but I'll make a adapter for it. Actually thinking of making a SRAM board so I can flash it in about a tenth of a second. (USB interface to it with a dedicated micro, actually could buffer two chips and do a live reflash)

would you point out the specific table or code addresses where these 2 limiters are. thanks.

[A_ Kelley]

I will once I charge my laptop. If you look at the tpl file I posted, you'll find it along with the address. I don't remember if I bothered with finding the Rev limiter or not.

Cruise max speed is at 0x8900, min @ 0x8901. Didn't look for Rev limiter.

[wowzer]

I will once I charge my laptop. If you look at the tpl file I posted, you'll find it along with the address. I don't remember if I bothered with finding the Rev limiter or not.

Cruise max speed is at 0x8900, min @ 0x8901. Didn't look for Rev limiter.

ya, i've already identified those in the cal. i've found a value in the code that seems to reference 6000 rpm. however, that seems kinda high for a jeep. i've seem some videos that seem to imply it is closer to 5250. i'll look at the code again for the mph.

[A_ Kelley]

Once I set up the bench setup, I'll Rev it to 5-6k and see what happens, if it's fuel cut or spark cut.

[sev80]

are you building a sbec II simulator?

[A_ Kelley]

Why not? I've got the harness, extra ecms, and technology to make the sensors appear there... Best way I've ever found to test anything in any situation, duplicate it.

[sev80]

Why not? I've got the harness, extra ecms, and technology to make the sensors appear there... Best way I've ever found to test anything in any situation, duplicate it.

That is really impressive!

[wowzer]

Why not? I've got the harness, extra ecms, and technology to make the sensors appear there... Best way I've ever found to test anything in any situation, duplicate it.

i'ld love one also!!! i've used risen's smecstim for years and actually contacted him recently regarding the sbec stuff. it's invaluable to be able to run the cals on the bench and analyze data. lmk. in fact maybe you/risen could get together to make this happen, since he has done 90% of the ground work already. i think he just needed to rework the sequential injection stuff and some other timing issues. also would need it to run both 4,6,and 8 cyl ecus :-) !!!!!!

[ShelGame]

Once I set up the bench setup, I'll Rev it to 5-6k and see what happens, if it's fuel cut or spark cut.

I can all but guarantee it's a fuel cut. I have never seen a spark cut in any stock Chrysler system.

[wowzer]

instead of posting up new files i'm just going to use this link below and keep the most current zip file there. i probably won't be doing much work on it for a while at this point (but who knows). there's LOTS to be figured out yet

https://dl.dropboxusercontent.com/u/.../jeep1_781.zip

[sev80]

my 27sf512's should be arriving today. Should I try burning and running these cals on my grand cherokee? Any chance it might damage the PCM since its for a different truck?

[Force Fed Mopar]

Should be fine.

[sev80]

So I started my own, separate thread for my dumb questions, as to not clutter up this thread anymore. Here it is:

http://www.turbo-mopar.com/forums/sh...74#post1122074

Wowzer, have a few questions for you there for when you got some time!


Long story short. My original 310 bin wouldnt work. I compiled wowzer's cal and it worked. on a 94 grand cherokee with auto.

[vprtech]

Something that might be of some interest, the table type "Fixed X 9 Byte" I have not seen in any of the Magnum V8/V6/Viper cals, however they do appear to be the same table type and shape as what you would find in a Renix ecu used on the pre-SBEC2 Jeeps. My assumption is that the calibration department over at JTE on Plymouth decided to port over some of the code and lookup tables from the Renix ecu's to save on development time and cost. Just a guess, but interesting to think about.

[sev80]

Gents, (wowzer and A_Kelly), where did you source the 781 cal? Im wondering if it is really from a gulf states emissions ecu or if MPtune is compiling and putting something in there to say that. I want to pop the cal back in my truck and drive it around more, it felt more peppy but I didnt push it last time I tried.

I wonder how much there is a difference between california emissions, Federal Emissions, 50 state emissions and Gulf states emissions (I have all the PCMs for each of these.)

The original SBEC II in my 94 ZJ is cal emissions, the 381 cal is Federal emissions, the 95+ cal is 50 state emissions and the 781 cal is "gulf states" emissions.