96 SL1 w/ MP7 TRANS??? PLZ HELP!!! SWAP PCM FROM DOHC???? SWAP BOARDS???

[randyshear]

Hello, I have a few questions, but first I'll give you all the specs I have on this car: 1996 Saturn SL1, 209K, 1.9L SOHC, MP7 trans. I just bought a 96 SL1 3 days ago for $200. I bought it with a cracked block. I since pulled the motor (I pulled it from the top), and replaced it with another 1.9L SOHC. Runs perfectly, but upon driving, I noticed I have 1st and occasionally 2nd, and reverse only. Very irratic shifts. Of course my SES light is on, and I am getting codes P0732, P0733, and P0734. So I look at the tranny, and the ID code is MP7!!! Can u imagine how MAD I am at the guy who sold it 2 me!!! I would have bought it anyway, and swapped a motor / tranny combo, and been done with it! Now the motor cost me $75, and a tranny will cost me $65, so I'm still getting a great deal here, my problem is I don't want to swap the tranny, after spending 2 days on the motor. I really am not equiped to do a cradel drop, and was wanting to know, if I pull a PCM from a DOHC saturn, will it work with my SOHC engine? If not, can I seperate the PCM & pull the board that controls the tranny, and shift points / gear ratio (they are connected by ribbon cables soldered on board) and solder the tranny board from a DOHC to my SOHC ECM?? Anyone ever done this?? I know this sounds crazy, but I'd rather swap tranny control boards than trannys, I'm sure you would too if it's possible, rather than swap a tranny.. LOL.. Anyway, if it's not possible, then I may just part her out. I'm just really disappointed, and ready to give up. I will say this: This is my first Saturn, and i've never worked on one before. This car is one of the easiest automobiles I've ever worked on, and I love Saturns now! This board is great, and you all seem to be very helpful, and I love your site!! Hope someone can help me out. Thanks, Randy

[dlczrx]

All I can tell you is the PCM's are year specific. Look for the last post by uzzy, which is down a page right now.

[randyshear]

Thank you for that info. I have another question... If it is not possible to swap boards, or PCMs, then would it be easier to pull the motor, and replace it with a DOHC and the matching PCM, then just bolt it up to my MP7?? For more info, I pulled the motor from a 1995 S-series.. Can't remember if it was an SC1 or 2... It is a SOHC though. Had 2 doors, that's all I can remember.. I had to change a few sensors over from my dead 96 motor... I am also getting a EGR code... P1406... Anyway, all I want is to make my little car go... Any help would be GREATLY appreciated. I've been reading threads, and posts for about 6 hours now... It doesn't look good for this Saturn.... Please help me save her!!! It's a beautiful car!

[Geronimo]

You can take the engine with transmission buy pulling the powertrain by the hood.
http://www.differentracing.com/tech_...dohc_swap.html

[eljefino]

try a dohc computer, the ign and fuel timing will be off a bit but it'll still run okay, say the people that've done it.

If you mercilessly flog that sohc though you'll float the valves at 6k on account of the higher rev limiter before it'll upshift... but hey... it'll move.

dlczrx is right about this year being year specific. Last year of the original fuel pump, first of OBD-II.

Are you keeping this thing or going to resell it?

If you have $10 and a little time you can have this puter shpped to your door.

[randyshear]

You guys have been really helpful so far, thank you. I plan to keep this car, it was going to be a Christmas present for my wife. I hate to pull the motor, or tranny, since I already did it, and cut my hands and arms up, it was a painful experience... But if I have to I will. I can get a DOHC puter, but does it have to be 1996, 95-96? What year range am I looking for?? I assume it has to be 1996 on the money because OBDII started in 96, and since 97 started a new fuel pump it would have to be a 1996 PCM... Am I correct?? I don't know the term "flog" the SOHC... Is that like running it hard?? Full throttle?? I'm not trying to race it, I just need to drive it. We have 3 kids, and all we have is an old 76 Chevy PU... We need this car. Obviousely we don't have tons of money, or I would have just bought a running saturn.. What is floating the valves??? Is that like blowing them up?? I will drive it easy, as long as I'm easy on it will she be ok? Anyway, I'll prob take you up on the computer if you have one that'll work. Does the wiring harness have 2 be changed as well??? Thanks, and I appreciate any and all help I can get from you guys.. Also, what about pulling a valve body, and actuators from an MP6, and putting them in my MP7??? Isn't that the same tranny, with differant resistance actuators?? Just curiouse, and trying my best to get this car going, the easiest and most comprehensive way possible. big thanks to you all for trying to help us out.. -Randy

[eljefino]

the issue with your trannies is the ratios for 3rd and 4th are different between dohcs and sohcs, so when the computer goes for 3rd, it sees a wrong ratio, figures it's slipping, slams back into 2nd, and probably throws a trouble code, lighting the check engine light too. You would have to completely gut the tranny to change the gears out to fix this.

Standard shift trannies have none of these issues and are fairly easy swaps to automatic cars too.

[madpogue]

The DOHC PCM will "understand" that tranny better, yes, but I gotta wonder what it would do with the SOHC cluster. Speedo and tach readings might be all wrong.

[eljefino]

Probably be a matter of percent off on the cluster. PCM will say "drive needle with 50% voltage to 50% position" which will be 55 on a sohc but 65 on a dohc for example. Same with tach.

You run into a situation that's like lying... you have to keep introducing new lies to cover the previous ones...

[madpogue]

Oh, and if/when you sell the car, you get to check that special little box on the title transfer that says something like "There's no way on God's green earth to know for sure how many miles are really on this car....".

[randyshear]

Yeah that's true.. But if I can fix it, I have no intentions of selling it any time soon. I can drive it being a lil off, until a few months or so when I feel froggy enough to replace the transmission. Anyway, I guess in the morning I'm off to Pull-A-Part for a 1996 DOHC PCM... Any cars you sugguest pulling one from? Any SC2, or SL2 I guess??? I'll post my results tomorrow! -Randy

[madpogue]

Or SW2. But DON'T get one off a 5-speed (you'll be in even a bigger world o'hurt).

Edit - you have salvage yards open on Sunday? Geez, ours close at noon on SATURDAY - forget Sunday. I'm envious.

[eljefino]

Don't throw away your old computer-- if you go to either the proper sohc auto or a 5 speed it'll be handy. The auto computer will throw a code for "missing trans" with a 5 speed but function otherwise.

[randyshear]

Yeah our Pull-It yard is open 7 days a week. From 8:30A-4:45P M-S, and 12P-4:45P Sun! Isn't it great! I love it. Well in 3 hrs they open, and I'll get a 1996 DOHC Auto PCM, and I'll cross my fingers. I was hopeing to hear from someone who may have done this and get their results, but no such luck. Maybe this thread will help someone else with my problem. (Although I hope there aren't very many SOHCs with MP7s in them....) I can understand prople not knowing the diff, but heck this is my 1st Saturn to ever work on, but even I traced it to the wrong tranny, and there was salvage yard wrighting all over it and the torq. So I'm more upset with the yard who sold this person a tranny for a DOHC.. A yard should know the diff, and all the tranny says is "Saturn 95-02", on it. So obviousely they have no clue that just because a part LOOKS the same, doesn't mean it is the same.. DUH!! It belonged to a lady in Ft. Worth it's whole life, and I have tech sheets for EVERY service since day 1! (It's a long sheet) She sold it in 2005, and I guess in 1 year the poor car got butchered! The block was cracked all over it, has the wrong tranny.. I mean someone went to town on this thing... It's a Frankenstein car... SOHC, MP7, w/ DOHC PCM... LOL.. Anyway, I'll save this old Saturn... Bring her back to life, and hopefully start buying Saturns at auction now.. I really like them, and this is a great site if I run in to trouble. Oh and I spent like 6 hours doing research on here, (B4 I posted a thread) and I noticed a large number of people who get help, and then disappear, without posting their results. You can assume it must have worked, since they didn't return, but it's kinda rude to leave people hanging... So I WILL post my results, not just leave everyone hanging in the air...

[randyshear]

Well no results to post I'm afraid. My Pull-It yard has none left. All the PCMs were gone!! Must B a hot item.. So I pulled a MP6 tranny, and almost got my MP7 out. I'm attempting to drop half the cradle, just on the tranny side. I think it'll work. I'm going to pull the pinch bolt off the rack, and loosen the pass side cradle bolts 1/2 way, then use a jack to support the driver side, and drop the bolts.. Should be enough clearance to pull the MP7 out. I got the axle out, strut pulled, hub out of the way, all wires off, and dog bone off, and the tranny mount off. I need to pull the trans to motor bolts, fly wheel to torq bolts, and lower the cradle... So hope it works!!! Let you know tomorrow, should b finished with the MP6 install by then! Thanks again!

[randyshear]

Just an update: I have removed the MP7!! YAY!! My 1st cradle drop went well!! Now I'll pick up my MP6 in the morning, and get my baby on the road again! BTW, I had no hoist, I used 3 floor jacks, and ALOT of patience!! Took about 4 hours. I'll post more when I get it running, or when I run into another problem.

[eljefino]

Cool. Hope you can get a hundred or two $ on craigslist or something for the surplus trans.

[randyshear]

I wish... I have 2 use it as a core, I am so broke.... Waste of a good tranny.. Anyone want a good MP7 for $40?? That's my core fee....

[randyshear]

Well the results are in.. After fighting with the tranny install, it is complete. She runs, and drives like a top. I am getting some tranny fluid leaking from the base of the dipstick, is there supposed 2 b a gasket there??? There wasn't one... Also, all error codes are gone, and it seems to shift to 3rd pretty quick.. Smooth shifting, but lack of power.. After reading threads here, I guess that is normal for these cars. Thanks 4 all your help guys! Saturn rules...

[madpogue]

Originally Posted by randyshear

.. Smooth shifting, but lack of power..

Yuh, it's an SOHC with an automatic geared for economy. The only thing that would make it slower would be the old 85hp TBI from a couple years earlier. (Oh that, or a 50lb fake "wing" on the trunk lid.)

I've never worked on an automatic, but my gut tells me there should be a gasket on the dipstick seal. Do you still have the old tranny? Answer may be there.