atx to mtx

TheRandom1 · Post by **TheRandom1** » Sat Mar 29, 2008 11:32 am

I have heard there is a way of using the stock ATX computer with a MTX car. How does the ATX computer keep track of whether the car is in gear?

cgneon · Post by **cgneon** » Sat Mar 29, 2008 1:52 pm

since the atx computer is not hooked up to the atx trans anymore -IIRC- it will think it is in nuetral, or park, making your rev limit max at 3500rpms

TheRandom1 · Post by **TheRandom1** » Sat Mar 29, 2008 1:54 pm

I know that part, but isn't there a way around that so I can still use my stock computer and make it think it's always in gear or something so I can still rev like I want to?

TNK · Post by **TNK** » Mon Apr 07, 2008 12:56 pm

*bump* for sean's ?, cuz i need the answer to this too....

Post by **occasional demons** » Tue Apr 08, 2008 11:47 am

The 3 speed ATX should be just a matter of using the park/neutral/saftey switch and setting it so the pcm thinks it's in gear, but don't know if another switch will need to be in the circuit to simulate neutral/park to get the starter to work, may have to tie it to the clutch switch somehow. A 4 speed ATX may be a bit more complicated.

TheRandom1 · Post by **TheRandom1** » Tue Apr 08, 2008 11:53 am

I know I have a 4spd, so that's what I'm mostly interested in. Tinkerbell, you have a 3 speed in yours or 4?

Post by **occasional demons** » Tue Apr 08, 2008 12:26 pm

The A604 will be a beast to simulate. The VSS signal I'm sure is different, and the TCM checks for proper ratios between input and output for each gear. The best way is to figure out what the needed links are between the TCM and PCM. And that would only work with pre NGC. I believe the TCM and PCM are intregated in one unit for NGC. You will prolly have to get a NGC MTX PCM to use the MTX. I don't think there would be any reasonable way to get around it, if everything is on one circuit board. Unless someone knows how to reprogram the PCM, if it is even possible.

TheRandom1 · Post by **TheRandom1** » Sun Apr 13, 2008 6:06 pm

Anybody else have an opinion?

TNK · Post by **TNK** » Sun Apr 20, 2008 5:18 pm

it was so easy to make my car run the 5 speed on the ATX PCM! i had a 3 speed, but all it took was removing the Torque Converter Clutch Solenoid from the transmission, plugging it back into the car and zip tying it out of the way, and wiring the reverse light switch from teh 5 speed car to the wiring on the skunk.... white to white, purple to purple, and black w/ yellow stripe grounded to the battery tray. after that was done, the car fired right off and runs like a champ! hope this helps some of you guys. (this was done ona 2000 ATX, using a tranny and parts from a 2000 MTX car)

patiofurnituregt · Post by **patiofurnituregt** » Sun Apr 20, 2008 5:55 pm

how does it run? I mean, the throttle maps feel right? does it have any problems between shifts or anything.

Im doing a swap and did the same wiring changes but also decided to pick up a MTX ECU, cuz I firgured it would be better suited for the 5 spd of course....but if the ATX maps work just fine then I'll return it and save the $150!

TheRandom1 · Post by **TheRandom1** » Sun Apr 20, 2008 5:57 pm

Only problem with shifting is the moron behind the wheel

patiofurnituregt · Post by **patiofurnituregt** » Sun Apr 20, 2008 6:10 pm

I meant that the computer doesnt falter in between quick heel-toes or if your WOT shifting, because before the atX computer would take like 2 seconds in between shifts soo

TNK · Post by **TNK** » Sun Apr 20, 2008 9:47 pm

nah. it works like a dream. i did some accidental WOT shifts cuz my gas pedal was getting hung up, and i have had no problems with shifting or anything.

sean, gofuckyourself. lol

TheRandom1 · Post by **TheRandom1** » Sun Apr 20, 2008 10:00 pm

Watch it, or that license plate will come out with some special sauce, Tinky!

TNK · Post by **TNK** » Sun Apr 20, 2008 10:41 pm

eeeeew

cbjones26 · Post by **cbjones26** » Wed Apr 30, 2008 5:00 pm

im planing on doing a atx> mtx swap soon i bought my gf a diff car (00 stratus) so my q's is should i just find a smashed neon an buy it as a donor? will a srt-4 tranny bolt up to 00 Plymouth neon is therea diff? in a non srt tranny? there is a lot of good info in this post i was wondering why it sounded like my car was gonna die when i tried to rev it N ( 3 speed auto) no tach (yet) looking to get a rt or srt speedo !! if anyone has done this tranny swap could they put up a how to with pics, being i will be doing this myself i live in upstate ny an there isnt any garages around that will do shit like this.!

TheRandom1 · Post by **TheRandom1** » Wed Apr 30, 2008 5:13 pm

It sounds like it's going to die because of the neutral rev limiter. Keeps you from blowing the motor by revving too high at the Moped next to you at a red light.

cbjones26 · Post by **cbjones26** » Thu May 01, 2008 4:54 am

lol...

patiofurnituregt · Post by **patiofurnituregt** » Sat May 03, 2008 2:54 am

The SRT tranny will bolt up no problem, and you will be able to use the lateral bending brace and the inspection sheild and dust cover from the SRT. You'll also need the SRT hydraulic clutch assembly and the trickiest part of the whole SRT tranny swap to the SOHC is that you will have to fabricate an intermediate shaft brace since their is no way to make the SRT one work. Easiest 5spd route would be to swap in a tranny from the sam year...be a lot less work, I did the SRT tranny swap and it wasnt a plug and play type swap..lol

GT Neon · Post by **GT Neon** » Tue May 06, 2008 10:23 pm

I am probably going to be doing a write up on this when I do the swap on my project. It will probably only be one way of several ways to do the swap but oh well.

jetas · Post by **jetas** » Sat May 10, 2008 1:49 pm

My ATX redlines in Park Neutral and Drive. Y does everyone elses stop at 3500

TNK · Post by **TNK** » Sat May 10, 2008 2:51 pm

mine limited at 3500 in park, neutral drive 1 and 2 were 6500.

Arro · Post by **Arro** » Mon Jan 05, 2009 2:23 am

bumpity bump, because searching threads over the past year didn't yield much... So for a 2000 do you have to get an MTX computer, or can you use the ATX one with a workaround? I noticed when you rev it in neutral it only revs to 3,500 like TNK says above here, and then in gear it goes all the way to 6,500. How is it that it knows that? Is there some kind of neutral sensor? It's not based on speed sensor, because I was on the freeway and decided to put it in neutral, and it only went to 3,500 while I was rolling at around 60 mph.

patiofurnituregt · Post by **patiofurnituregt** » Mon Jan 05, 2009 1:31 pm

It is a very simple wiring fix on the bay harness, only three wires, for the neutral safety switch. You can use the atx computer but you are better off to get the mtx computer in the long run.
(I will be selling my mtx computer in a few months when I do my SRT swap, if your interested.)

Arro · Post by **Arro** » Mon Jan 05, 2009 2:08 pm

Thanks for your help... what advantage does the MTX computer offer over the ATX? The 2000 year Neon transmission is not computer controlled.

If you can explain why the expense and hassle of reflashing my VIN to another PCM is worthwhile, yes I will be interested in buying yours when the time comes. It sounds like our timeframe is about the same. At the very least I may want to buy hour pedal assembly.. I am waiting to hear from someone if the pedals for the hydraulics (including the SRT4) are different or compatible with the 2000 year pedals.

Post by **occasional demons** » Mon Jan 05, 2009 2:28 pm

The advantage of the PCM is the higher redline limit. As far as VIN flashing, unless you have SKIM it isn't really necessary. It will plug and play. If you plan on selling it then it may be an issue. But to make it run it should work as is. I put an R/T PCM in my '01 with out doing anything but plugging it in. I even have a SKIM code, but it doesn't keep it from starting.

Arro · Post by **Arro** » Mon Jan 05, 2009 4:47 pm

I have SKIM for one thing... but let me ask something here about the redline. Do I really need more than 6,500? I take it that's the ATX's redline. What is the redline for the MTX PCM?

I'm wondering what the stock engine's powerband is... and at what point you're just spinning faster, and not making any more power.

patiofurnituregt · Post by **patiofurnituregt** » Mon Jan 05, 2009 10:59 pm

nevermind about the pcm I didn't realize yours was an 01 with skim, otherwise its just plug and play.

As far as MTX PCM over ATX. I assumed it had better fuel maps for an mtx, or atleast that it could handle quick heel/ toes and and aggressive gear changes. I thought I had also read somewhere a long time ago where someone used an ATX PCM but it crapped out on them after like 4 months, I never found out from the person why it did so I just decided to be safe (I don't see why it would mess up the ATX PCM, but eh).

If I am not mistaken rev limit is at ~6750rpm, I remember hitting it once and later checked my scangauge and it was somewhere there...and have read that else were.

Most stock engines stop making power ~5500rpm

Arro · Post by **Arro** » Tue Jan 06, 2009 12:38 am

Mine is not an 01, I have a 2000 SE car w/ ATX, and I definitely have SKIM.

But I don't think these engines make power in that range, so shifting higher than that is probably useless.... like you said, most of these Chrysler single cam engines run out of steam around 5,500.

I located a 2000 MTX, and I have the center console and shifter, just need the pedals, cables, and axles (and whatever other little stuff).

patiofurnituregt · Post by **patiofurnituregt** » Tue Jan 06, 2009 2:20 am

you forgot to mention a clutch and tranny mount, possibly inspection shield and starter (I know the SRT and ATX were different, just thought I would through that out their).

I don't recall but I believe can use a modular clutch, I think I remember hearing that only ~1st two years of 1gen's were non-modular but don't remember.

Also, the rev limit is the same for both ECU's.