Bringing TBI and Multi Port Fuel Injection to a New Level.     EFI Conversions and Tuning! Seattle to Portland! E-mail Tuning Consultant!
Results 1 to 9 of 9

Thread: TPI in limp mode

  1. #1
    Carb and Points!
    Join Date
    Apr 2013
    Posts
    5

    TPI in limp mode

    I finished my auto to T56 swap a few months ago in my 91 Z28 and have yet to wire up the VSS converter. When I started the car the fan came on immediately and the Check Engine light came on. They both run solid from turn of key and stay on. Was told its in limp mode as I couldn't connect the ALDL to pull codes. Was told to change the ECM but no change. Was wondering if the VSS not being connected can cause this? How likely is it that my PROM is bad? Can anyone point me in a direction of how to start?

    thanks
    Kris

  2. #2
    Super Moderator
    Join Date
    Mar 2011
    Location
    Camden, MI
    Age
    28
    Posts
    3,026
    lack of VSS wouldn't do it....

    since you swapped ECMs already, i'd say your PROM(or possibly entire MEMCAL) is probably the issue.
    1995 Chevrolet Monte Carlo LS 3100 + 4T60E


  3. #3
    Carb and Points!
    Join Date
    Apr 2013
    Posts
    5
    Thanks. Now to find a memcal.

  4. #4
    EFI GearHead ! EagleMark's Avatar
    Join Date
    Feb 2011
    Location
    North Idaho
    Age
    57
    Posts
    10,477
    Getting into Limp Home Mode is pretty hard, but it points to chip/memcal as Robert said. I've yet to see a chip or Memcal go bad without human intervention and even then it's hard.

    VSS won't cause it, LHM is total failure backup. So back step what you did? Any pins in harness bad or bent, wiring, short. The Memcal didn't just go bad, something happened and it's probably fixable.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  5. #5
    Carb and Points!
    Join Date
    Apr 2013
    Posts
    5
    Yes I agree. I did do something that was a silly mistake being rushed and very tired. After the trans swap and installing the LT1 starter I somehow managed to hook the wires up wrong and connected the battery. Had zero power in car. Went back and swapped the wiring back to the proper way. Car got power and ran but in limp. I'm assuming that's it as it wasn't in limp prior to the swap. I changed the ECM and used the original Memcal and still in limp. Only other thing I touched was snipping the wires off the auto shifter and set up reverse lights and clutch switch.

  6. #6
    EFI GearHead ! EagleMark's Avatar
    Join Date
    Feb 2011
    Location
    North Idaho
    Age
    57
    Posts
    10,477
    Maybe a fuse or still a wiring issue? Still don't think you hurt a memcal... ECM maybe...

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  7. #7
    Carb and Points!
    Join Date
    Apr 2013
    Posts
    5
    Thanks... I'll start with the fuses. On OBD1 in limp with a solid engine light ... Does that indicate emissions failure? What sensors can trigger limp?

    Kris

  8. #8
    Super Moderator
    Join Date
    Mar 2011
    Location
    Camden, MI
    Age
    28
    Posts
    3,026
    sensor failure won't really trigger LHM.... i can't speak definitely for the TPI code, but i don't think even multiple sensor failure will trigger it.

    in LHM, you'll probably fail emissions test standards 10-fold. it's that bad when you don't have the main processor doing the work.
    1995 Chevrolet Monte Carlo LS 3100 + 4T60E


  9. #9
    Carb and Points! jimmykicker's Avatar
    Join Date
    Mar 2013
    Age
    46
    Posts
    6
    Quote Originally Posted by Z1LE View Post
    Yes I agree. I did do something that was a silly mistake being rushed and very tired. After the trans swap and installing the LT1 starter I somehow managed to hook the wires up wrong and connected the battery. Had zero power in car. Went back and swapped the wiring back to the proper way. Car got power and ran but in limp. I'm assuming that's it as it wasn't in limp prior to the swap. I changed the ECM and used the original Memcal and still in limp. Only other thing I touched was snipping the wires off the auto shifter and set up reverse lights and clutch switch.
    Working on one tired is always a mistake. I stop now when I get tired because I start making dumb mistakes. I cooked my dash wiring in my 84 like that once by connecting a brown wire (taillights, inst cluster) to ground. Brown...not black... That cost me about a week of my time trying to source a wiring harness from a 26 year truck that wasn't in worse shape than mine.

    Also when I did my swap to the TBI? I checked everything but the relay in the harness....guess what? It was full of broken pieces of stuff (I was unaware of it at the time.) Well there is a constant hot in there and wires that lead back to the ECM for fuel pump energizing....sounds bad? Yes. I plugged up the wiring harness to the ECM that was connected to a 20 amp (too high) fuse in an auxilary fuse box....the lights dimmed and it killed my ECM before I could snatch it loose. Made me really mad. I am guessing it grounded out to the negative post on the relay and killed it before the 20 amp blew. Live and learn I guess. Fortunately they are cheap and plentiful....

    Never work tired. You will regret it.
    Last edited by jimmykicker; 04-23-2013 at 01:36 PM.
    1984 x-cab s-10 (4.3 Killer). 3.4L GM crate engine 87 S10 TBI fuel system swap with 4.3 TBI and bored intake, Edelbrock headers. 3.42 locker rear end swap. Flowmaster Exhaust, B&M shift kit, V6 Cavalier e-fan. She runs....good!
    2000 Blazer 4x4 Stock
    2009 Scion Xb...think this thing needs a turbo...hmm
    1982 Suzuki GS750T...Perhaps the most awesome motorcycle ever built?

Similar Threads

  1. '95 LT1 tip-in Stumble in SD mode?
    By sherlock9c1 in forum GM EFI Systems
    Replies: 14
    Last Post: 06-10-2014, 06:54 AM
  2. 7747 highway spark mode.....
    By Fastmax32168 in forum GM EFI Systems
    Replies: 10
    Last Post: 01-20-2013, 02:44 PM
  3. 16147060 transmission "limp mode"
    By Drac0nic in forum GM EFI Systems
    Replies: 14
    Last Post: 09-12-2012, 07:23 PM
  4. Mode 8 Silence
    By RobertISaar in forum TunerPro Tuning Talk
    Replies: 8
    Last Post: 02-22-2012, 02:49 PM
  5. 7747 Highway Mode?
    By EagleMark in forum GM EFI Systems
    Replies: 45
    Last Post: 07-29-2011, 06:13 PM

Bookmarks

Posting Permissions

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