Results 1 to 11 of 11

Thread: need ecu help

  1. #1
    Join Date
    Aug 2003
    Location
    hawaii
    Posts
    3

    need ecu help

    i think i've got an ecu problem in my 90 sc. does anyone know if i can swap an ecu from a 91 sc (my project car) into the 90? in chilton's it says to check trouble codes, the 90 uses a 2 digit, and 91's use 3 digit. anyone know?

  2. #2
    I dont think the 91 used 3 digit codes.
    What makes you think you have a bad ECU?

  3. #3
    Join Date
    Oct 2002
    Location
    Lincoln, NE
    Posts
    2,062
    My Chilton's says the same, 91 and up had 3 digit codes. I'm not sure if it is accurate though as I have found it to be incorrect on more than 1 occasion. That said, how the EEC "reports" the problem is not related to how it controls the engine electronics. I'm not positive about this, but am willing to bet that you can swap out the EECs without any problems. There were no significant changes between '89 and '91 that would lead me to believe that there would be any problems.

    I'll echo mike though...what makes you think that you have an EEC problem?

  4. #4
    Join Date
    Jun 2003
    Location
    Vancouver, Washington USA
    Posts
    1,740
    Aren't the EEC's EPROM burnt with a specific CALIBRATION for a particular year, engine, and/or car??? I think so. That is why if you call around for a used one, the will ALWAYS ask for the numbers on it.

    What is the car doing?? I almost replaced mine a while back and it was something stupid. Wheeehhh!! Saved lots of $$$$$$$

  5. #5
    Join Date
    Oct 2002
    Location
    Lincoln, NE
    Posts
    2,062
    Yes, EEC are specific to certain years, models etc. But when nothing is changed from year to year, the clalibration should remain the same. It wasn't until '94 when the engine changed enough to warrant a different EEC. Granted, in '92-'93, I think, the sc's did not have an EGR which will also play a part in the EEC programing. I'm not sure what models came or didn't come with the EGR in '91. But if they both had EGR's or the '91 didn't (you can easily delete it) then you're ok. That is the biggest difference that you will find with the EECs...EGR or no EGR. (At least until '94 when the changed some other stuff) I'm pretty sure that most everything else was the same. Not sure what year the MAF changed to a larger size, but I was thinking it was after '91. I think that you'll be ok by changing the EEC from your '91 into your '90.

    *Edit* If I want to delete my EGR, I can either custom burn a chip with a tuner or get an EEC from say a '93 when they didn't have the EGR. So the EEC will work.

  6. #6
    Join Date
    Jan 2003
    Location
    Victorville, CA
    Posts
    1,379

    There were 3 EEC's for '90...

    1 for all 5spd, 1 for AOD with EGR and 1 for AOD w/o EGR.

    Lee

  7. #7
    Join Date
    Aug 2003
    Location
    hawaii
    Posts
    3
    here's my problem. it doesn't happen all the time, but it's been doing it more often lately. i'll be going down the freeway at 60mph, the revs will just go crazy. just constantly up and down, like it's mis-firing. i thought it was the trans, but when i put it in neutral (it's an auto, btw) i can still see the tach jumping up and down. sometimes it only does it for a few seconds, sometimes i have to pull over and turn the car off. when it gets that bad, the car will not start again for a random ammount of time. when it finally does start, the tach no longer works... until i give it some gas... then it jumps back into action. sometimes after all this business, the car will just die out while at a stop light... no rough idle, just dies. i just read some stuff in my chilton's, and it might not be the eec, but the ignition control module? i'm really not sure, and i don't really have the money to take it down to a shop and say, "fix my car please". any help on this would be much appreciated. i've already had one sc in the garage for over a year, i really don't want to have this one in there as well.

  8. #8
    Join Date
    Oct 2002
    Location
    Lincoln, NE
    Posts
    2,062
    When was the last time this car was tuned up? Some common causes of the symptoms you describe are: bad plugs & wires or a bad DIS Control Module. Sometimes a bad cam sensor will cause a rough idle with the tach jumping all over. The hardest of that bunch is the plugs & wires. My personal bet is the DIS Control Module. I've had the exact symptoms you describe and it was the DIS module. I think they are around $100 to $130 depending on where you get it from, and it is a very easy fix. All you need is a 7/32" socket and some heat sink. Make sure that you get a nice even coat of the heat sink on the bottom of the new DIS module you're installing. If the DIS overheats, you will still have similar symptoms again.

  9. #9
    Join Date
    Jan 2003
    Location
    Victorville, CA
    Posts
    1,379

    Do the simple stuff 1st.

    As well as the thermal paste, check/clean the connections and harness between the DIS, Cam sensor and coil pak. Loss of tach signal points in that direction.

    Lee

  10. #10
    Join Date
    Aug 2003
    Location
    hawaii
    Posts
    3
    thanks guys, i'll check on that stuff today. last time it was tuned up... i have no idea. i bought it from a guy who claims he never drove it. he traded his friend a boat for it, thinking he could get more money out of selling the car. it ran perfect for a while, then this problem started popping up. i'm pretty sure it could use new plugs and wires too though.

  11. #11
    Join Date
    Oct 2002
    Location
    Lincoln, NE
    Posts
    2,062
    How many miles does it have on it? If it's over 75,000 then do a tune up before anything else. The stock plugs should be replaced about every 60k and wires at least as often. DIS may be bad, but you won't know until you start with the basics first. The tune up should be the first thing you do. I had to on mine just over a year ago when I got it. I got it for less than they wanted just because it ran like crap. I did a tune up and it ran great (for a while...then I did have to do the DIS). Since then I've replaced almost every sensor on it! At least the hard ones...

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •