Frustrated with MTX swap

[redshoman]

I am in the middle of an ATX to MTX swap. I have a great 93ATX and started making it into a MTX. Got a 95 doner (really rough) and removed almost everything.. so I though. The trans is all gone through and cleaned and sealed and painted up. I stripped the 3.2 down to heads and block, put on 3.0 timing, oil pump, accessory brakets and comonants, rear exhaust manafold, oilpan, inner engine harness( one in lifter valley), outer engin harness (one with PCM and RRCM conncetors) PCM and RRCM. So engine and trans are done, good MTX subframe on its way. I have searched and searched but still have a few questions.

What list of parts or componants do I need to swap or get for the A/C to work correctly? My 95 MTX donor has most everything rotted so the existing parts on that car are useless.. In my good car I already have condencer, evaporator and pump. Im guessing accumulater and bracket, and return line for the 95, but does anyone have part numbers?

On top of using the 95MTX engine harness's, PCM and RRCM... do I also need to swap over the entire front clip harness? the one that even runs into headlamp and washer pumps??? The question stems from the A/C.. 93 had no high pressure switch.. 95 did... I know I can omit it (jump it) but I would like to do this correctly.

GRRRR... very aggravated.. maybe just at this moment... I have the donor in one spot.. now coverd in snow.. and the recepient in the shop, might just be because I can't look at them both together... but a little hot under the coller due to lack of definte answers....

If I sound like a raving lunatic im sorry... but the internet is a great vent... thanks

 

[sperold]

You can buy the AC lines that run along the inner fender, but that is it. The 94, 95 MTX lines are different from the automatic cars. I had great difficulty getting the cluster of AC lines that bolt to the compressor, and had to get them used on this forum (which worked out fine). Lots of people delete the AC system, so put out a post, they are out there. Lots of places claim they can fab them up for you if you send them the old stuff. Forget it and buy the used originals.

 

[rubydist]

You need the mtx a/c lines. Are you going to use the R134a system from the 95? The high pressure switch is normally closed, and opens when the pressure is too high, so you just need to jumper that connector (you just lose the failsafe for overpressure.) But if you have used the 93 mtx wiring, then there is no connector there, so nothing to worry about.

The dash wiring is different from atx to mtx. You have 3 choices:
1. You can choose to keep the atx pcm and ignore the egr-related CEL (or install the egr) or
2. you can swap the dash wiring along with the front body harness and the engine harness to mtx, or
3. you can rewire the huge connector under the airbox to convert it from atx to mtx.

Part of that decision is related to if you want to use the atx cruise control (which is more functional) or if you want to use the mtx cruise.

Also be aware that the windshield wiper motor is wired different on a 93 than 94/95, so if you swap wiring harnesses around, you need the wiper motor that goes with that vintage of harness.

And, just to be clear, you didn't say that you put the mtx water pump on - you need that too as the pulley location is different.

Read this again, if you haven't lately:
http://www.shoforum.com/showthread.php?t=95183

 

[redshoman]

I am going to use the Engine, trans, Engine harness, CCRM, And PCM from a 95MTX in a 93 ATX... so The rrcm and pcm will be looking for a high pressure cut off switch.. so I can use the 92/93MTX lines and accumulator if i just jump the high pressure switch. Or I can use the 95MTX style lines and use the switch as it was intended too. Correct???

As far as anymore of the wireing goes.. I was reading, and hoping that I could just swap pins in the c100 connector, under the air box. I even still have the female end of the plug so that I dont have to grind off any tabs.

I did want to use the ATX cruze control.. I hadden't completly researched the wiring, but it has it's own harness off shoot from the ATX front clip wire harness, thats I was keeping in the car.

I was hoping to use the the 93 ATX wiper motor with the body harness, so I did know about that. Same idea as the A/C.. keeping it simple

I did swap the water pump, and the coolant tube.

After the motor, trans, subframe swap.. I was hoping to keep it as simple as possable.. I thought I would be simpler to seperate the driveline from the body. Than swap the pins in the 100 connector and ignore the clutch pedal possion switch... thank you for the data... any more would be great

 

[rubydist]

I don't know if you can use the atx cruise control setup w/ the mtx pcm - you will need to do some wire harness work to see if that is possible.

If you use the atx front body wire harness, you will need to do some wiring work on that too, since some of the a/c items are positioned in different locations, the wiring is different.

The rest of your plan sounds good!

 

[gmail]

you dont need to change A/C lines.

wiring can be done real easy.. keep the atx wiring and modify the shift selector.

i just skimmed threw the thread so if i missed something sorry.
if you want to use the mtx be prepaired to replace the interior wiring, underhood etc
its not just plug and play it all needs changed!

 

[rubydist]

You do need to change the a/c lines, I know this from experience.

 

[redshoman]

Yea, I just started fitting the old mtx lines, I know that with the motor/trans/subframe from mtx the accumulator needs to be moved to the front of the engine compartment, I also calmed downa bit from when I wrote the original post and started matching up the mtx wiring harness with the ATX front body harness... I would say 85% matched up, the rest is just wire chasing and repinning.. I even took a minute and cut off the old harness part of the mtx high pressure a/c switch and figured out how to make it correct...

Rubydist... I am defintaly appreciative of your advice, how did you do your atx to mtx comvert? What combo of wireing and mounts did you use?

 

[Eric VerValin]

When I did mine, I had a 92 so it was a little different, but not far off. In the end it was faster for me to pull the dash harness from the donor and do that instead of splicing all that crap.

Body harness, engine harness, dash harness all from the donor, cruise and wiper motor went as well. (I think the wiper thing was a 92 and earlier tho so you may not have that issue.

Now if something messes up I don't have to say... well I wonder if one of those splices are loose.

Good luck either way.. I know exactally how much fun your having. Just be glad your not swapping your exhaust, suspension, gas tank, seats... lol

 

[redshoman]

LOL... thanks for the support... luckly the interior is freeken flawless.. but the suspension is comprised as a big box of new fun goodies right now. mwah ha ha ha. There is nothing wrong with the stock currant one... just want to get it running and correct before I start to change the rest...

 

[rubydist]

I used all the atx wiring, and just ignored the check engine light. Eventually, I just pulled it from the cluster.

fyi, the cel will light due to the lack of egr, after a few minutes of the engine being at operating temp.

 

[Eric VerValin]

Thats why you use the real harness. How do you guys pull codes on a car without a CEL? Dosen't make much sence to me.

 

[rubydist]

Easy, like you are supposed to do anyway.

You jumper the connector under the hood, and you connect the 'self test out' pin to a 12v light and to the + on the battery. (see details on shotimes.com) The light flashes just like the cel does and you count it the same way. fyi, that is what happens if you use one of the 'diagnostic tools' to check the codes, only the tools typically have an audible indicator too, so counting is easier.

 

[pwrshft99]

so, if you dont care about CEL, you can swap an MTX into an ATX car without changing any wiring ?

 

[rubydist]

so, if you dont care about CEL, you can swap an MTX into an ATX car without changing any wiring ?

Read through the thread I have linked in post #3.

 

[redshoman]

I don't think the CEL will light up do to egr using the method that I am. Because I am using the MTX engine harness, PCM, and CCRM, and deleting the EGR... It wont even know that the car ever had it...

 

[Eric VerValin]

Well thats what I used on mine. Every thing came off my non-Cali emmission XJ2. But if the car is used to seeing that EGR, I don't see how it could just ignore it. Plus you would never know it if something was off a little. I know mine was a little different because I used stuff from the 92 which was kind of special in itself, but for me I wanted to have everything "correct".


And if that 95 didn't have an EGR, then your right it wouldn't have a clue. Every SHO i've had didn't have an EGR. I won't have that crap. lol "Let's dump hot exhaust into the intake, right after I installed a CAI. Never did like the idea of EGR's. EGR's were the main reason for the GM LIM failure on those 3100's.

 

[rubydist]

Only CA mtx cars had egr. If the pcm is from a non-egr car, then it will not expect to see an egr and all will be well exactly as redshoman has planned