91-94 ecu swap into my 90

[remofzero]

hey guys...need some help here...

i have a 90 gs-turbo 5spd fwd and my ecu has leaky caps like no tomorrow, i get about 5mpg and it runs so rich i smoke all the time. so tonight i talked to my buddy and he sells me a ecu out of a i think 92 talon tsi- he told me my tach wont work but everything else will with the 6 and 14 pin swap. so i paid him the money and off i went with the ecu. so i printed up the pin set up and when i went to switch them, well ill be damned if they werent switched already as far as i could tell. it said pin 6 was green and white and 14 was green ---but pin 6 was green and white and 14 was green already! now i couldnt idle for the life of me with the old ecu so i just slid this in and now the car starts and dont die it actually idles. i have no tach but o well untill i find a 90 ecu.

movin on is where the issue comes into play.....now that i have this in i can rev the car without the skipping and smoke as long as im not in gear- no smoke no skip, but i put the car in gear and when i go to give it gas it dies kinda and then goes ...almost like a auto ecu into a 5spd (already did that one dont work ) but if i rev it high then let out my clutch it goes fine....what is the issue? like if i put it in gear and bearely touch the gas it revs up and down up and down...like it dont know what to do with itself...what is my issue? any ideas guys??? please help ### this is my daily driver and i dont know what to do now...i spent the money on a new ecu out of a running car becasue he blew his car up running it with no water in it but mine is acting up something else now...any ideas on what to check or something??? please help!!!!
thanks guys

 

[DSM1G90]

You need a MD 128625 ECU for your FWD 5sp Turbo ride .. if you're Federal.

Get the thing wired back up where it was originally supposed to be, get the right ECU and you should be good to go ... Things are so messed up right now with that wrong ECU in there that it's a miracle the thing runs ...

 

[remofzero]

yea the one that came out has md12865 on it, the one i put in is obviously a newer year computer, i cant find a cehap enough one that will work in my car bacuse im so strapped for cash- now im stuck with this computer , my old one and a automatic one- no use of any unless i want issues with all of them! so yea thanks alot man....i just need to know why i have that dying thing going on for that moment .....just dont make sense becasue if im not driving it dont do that!
thanks again

 

[DSM1G90]

True, you oughta see the many different models of ECU's for one particular year and all destined for what model of vehicle they are designed for.

Sad things with computer controlled vehicles now-a-days - all due to fuel efficency, emissions and performance. You throw in the wrong ECU and it takes everything out of the closed loop and puts into an open loop - a loop that prevents the vehicle from running correctly.

Basically, what happens is that you can idle with no problems, but when you add power and put the motor under power conditions, timing and fuel loops, being open as above, get totally messed up and you have serious issues due to the cause of incorrect operations from a wrong ECU.

Good luck in your finds. - DSM

 

[dsm-onster]

I've put a 1991-1994 ecu in my 1990 and there was no issue like this at all. The tach went haywire but the car drove fine. Did you swap pins 6 and 14? If you do this, you still will have a wacky tach. You will have to research this. I can't remember the thread, but you can use a 1990 transistor and hack the harness and get the tach signal inverted to correct this. . .

I've also put an auto ecu in a 5speed and it worked ok. The auto has 390cc injectors, which are slightly smaller than 5speed injectors; but runs those injectors at higher base fuel pressure. As well the auto timing and fuel tables are more aggresive. The TCU controls the transmission. The ecu will not make your car run so bad that you can't boost and drive down the road fine once the fuel trims adjust for the slight difference in fuel flow.

 

[Sarge32]

Keydiver had a small little wire harness to correct the tach issues, when going in a 90. I installed a 92 ecu in my talon as well. Here is a link to what I am talking about.

KEYDIVER Chips -1991+ ECU in a 1990 DSM

 

[remofzero]

so basically what that little "gap" is when the motor feels like its about to die is a loop in my system? it kinda makes sense but not...because the two pins that are supposed to be switched are 6 which is idle position sensor and 14 which is Air flow sensor active filter reset (idle switch) and 6 pin is stock color is green and white and 4 is just green, but on my harness they must of been switched already because 6 pin is green and 14 is green and white already....im just lost on what to try next to get this computer to work right - im not worried about the tach i have ears to listen to my motor i just dont like that little gap thing going on. thanks tho guys!!!!!

 

[Sarge32]

Another thing to note, is to make sure the pins are pushed all the way into the connector. I've seen pins pushed back in the connector making a bad connection or no connection.

 

[BoostedBeaver]

I just put a 91 ECU in my 90 and my wires seem to already be switched two but i switched them anyway and mine works fine. Like mentioned above keydriver has invented this awsome little board with three wires and you just splice into wire 109 and ground it out with the third wire and wa-la your tach issue is fixed for just $30. A new transistor cost 100 by itself and you have to hack your harness so this would be how I would fix that tack. As far as cutting out make sure you have the right ecu then monitor your fuel pressure while driving. Had the same problem ended up being a cloged fuel filter and fuel sock.

 

[dsm-onster]

so basically what that little "gap" is when the motor feels like its about to die is a loop in my system? it kinda makes sense but not...because the two pins that are supposed to be switched are 6 which is idle position sensor and 14 which is Air flow sensor active filter reset (idle switch) and 6 pin is stock color is green and white and 4 is just green, but on my harness they must of been switched already because 6 pin is green and 14 is green and white already....im just lost on what to try next to get this computer to work right - im not worried about the tach i have ears to listen to my motor i just dont like that little gap thing going on. thanks tho guys!!!!!

Try switching the pins anyway. If the problem persists, then I don't think it's a +1991 computer in a 1990 car problem. The swapping of the pins is all that's neccesary for a smooth running motor.

What kind of smoke do you see? White? or dark blue? or black?

 

[remofzero]

well, i got bad news....the ecu that i put in it was deff a 91-94 i think it came out of a 92 or 93 talon tsi- ...so i take it over to the guy who sold it to me - and he plugs it in his obd 1 scanner, well the car was running great - i so did not miss the smoke from the tail pipe ### it ran so rich or the misfire of the cylinders ### it was flooded so bad , it literally ran right =) well he plugs it in his obd 1 computer and revs it up, well on the third revi smelled that smell we all dread and i look at the ecu and theres the smoke barreling out of it- fried. he gave my money back, but now im back to the piece of garbage ecu that has a ton more corrosion on it then that one did and im convinced i need a 90 ecu that works...im not having any luck im thinking of just junking the car and keeping the motor for some odd reason....

 

[dsm-onster]

Luck has nothing to do with whether or not a 1991+ ecu works in a 1990 car. It's not like some 1991+ computers are built differently or some 1990 harness are built differently. . .

Isn't it possible that some thing in the wiring harness is some how frying the ecu drivers or other circuits?

Other than that, you'll be jsut fine with another 1991-1994 ecu. As long as you swap pin 6 and 14 you will not throw a code. . . It WILL run right if your harness or the ecu is not crap.

But If you are serious abotu scrapping the car, please shoot me a pm. I'll get a flatbed and take that rascally dsm off your hands for a reasonable price.

 

[dented_coffee]

the ecu of a 1990 is totaly different of all of the eclipses all together. fuel pressure is different all arround as well (NA=47-50psi) (M/T TURBO=36-38psi) (A/T TURBO=41-46psi). it could be fuel cut or a fuel related problem as well. seems how its an automatic ecu your probably feeding it to much fuel and its choking out AKA flooding out. fuel cut to where maximum fuel flow is reached and is swiched off for a split second. i have been doing work on the eclipse sence i was 9 and im turning 20 here and i have been dealing with it everyday and thats not an exageration to say that.

 

[steve]

Isn't it possible that some thing in the wiring harness is some how frying the ecu drivers or other circuits?

You already know the answer is yes.

Besides a shorted ISC any of the other solenoids and relays or their harnesses can short and damage the ECU.

 

[dsm-onster]

^^^^I suspected this because I fried one of my eproms (90 eprom at that) several years back from some short in my harness

the ecu of a 1990 is totaly different of all of the eclipses all together. fuel pressure is different all arround as well (NA=47-50psi) (M/T TURBO=36-38psi) (A/T TURBO=41-46psi). it could be fuel cut or a fuel related problem as well. seems how its an automatic ecu your probably feeding it to much fuel and its choking out AKA flooding out. fuel cut to where maximum fuel flow is reached and is swiched off for a split second. i have been doing work on the eclipse sence i was 9 and im turning 20 here and i have been dealing with it everyday and thats not an exageration to say that.

A/T ecu runs 390cc injectors at 43.5 psi. M/T ecu runs 450cc injectors at 37psi. 450s at 37psi only flow 415cc ( 450 X SQRT[ 37 / 43.5 ] ). This means that the stock m/t injectors and stock m/t fpr that in his car are running only 6.4% over what the ecu thinks are there (415/390). This is well within the fuel trim range. His short term (O2) trim will cancel this out fine until the rest of the trims catch up.

 

[remofzero]

thanks to everyone who posted in this thread! all the help has tought me alot, so now that i am going to just sell the car for as much as i can get being i have to much in it but the motor is strong and was the top end was just rebuilt - im going to wait till i return from the service and jsut buy a new platform because i will be back right after winter- so im selling the car now and will have to buy a new one upon my return THANKS GUYS!!!!

 

[deerhunter0881]

make sure it is a dsm when you come back, so you don't have any time too do anything but fix it , good luck come back safe

 

[remofzero]

yea so today my clutch went to the floor- and my motor started to rumble- i was driving so i pulled it back up with my foot and then the car went fine but then it got real bad and when out of gear it was fine till about 3grand rpm and it would rumble- then it wouldnt do anythign but rumble after i put it in gear and started it with the clutch in and now all i get is a starter spin...not fun- im deffinitly going to sell this thing i got a new motor in it with 40k and many many new parts in it as well as some not on it- so i will deff keep on the site and ill be back better then ever when i come home- just got to sell this thing now thanks guys

 

[dsm-onster]

Your firewall side transmission bolt fell out? or never was installed? . . . Ask me how I know

. . .Possibly broke the radiator side engine/tranny ear. Yes you will need a new block or be innovative enough to get the front motormount/rollstop to double as a bellhousing bolton point.

Or you could just have fubared your clutch. . .

 

[awdtalon11]

You Could send your ecu to motoguys.com and they will rebuild it for 200 and if you can send your bad one in and get 100 bucks back i just did it and my ecu is perfect now.

 

[dsm-onster]

^^^Steve and I are saying he'll just fry every ecu he puts in his car.

 

[remofzero]

ive decided to just give up on this car- probably needs a transmission clutch flywheel- the whole nine yard besides a motor and half shafts- im not messing with it i think im just going to sell it- i got to many new parts and cant sell the car for half what i got into it so yea im just goign to get rid of it around town i think-

what would you guys say i could get from it? all the car needs is maybe -well at MOST- a tranny, clutch (everything with it pressure plate throw out ect), ecu and clutch master cylinder- everythign else is new in the car so what could i get ? the motor was just rebuilt so yea....