Your well beyond "limp home mode" sounds like you fried the ECM.
Limp-home mode questions
Thread Starter
Race Director
Joined: Jun 2001
Posts: 10,956
Likes: 681
From: Marlboro country MA
Limp-home mode questions
My 92 A4 has just gone into limp-home mode. A whole bevy of signs:
Fans come on as soon as the ignition is switched on
Speedo reads 'zero'
'Service engine soon' light stays on
'Service ASR' stays lit
'Security' light flashes
'SYS' blinks
Digital water temp stays at zero
Digital oil temp stays at zero
Engine cannot run above 3K RPM, runs OK (but rich) below 3K
TC won't lock up
ASR doesn't work
What we were doing just before failure was trying to reprogram the EPROM chip in the ECM. We had swapped it in and out a couple of times, and the laptop connected to the eprom burner crashed. Upon replacing the eprom chip, the car went into limp-home mode. However, when I put back in the original memcal PROM, it stayed in limp-home mode. Although the car is (somewhat) driveable, I need to get this fixed.
My question is: What are the different kinds of signal failure that can cause the ECM to enter this mode? Where should I start looking?
Fans come on as soon as the ignition is switched on
Speedo reads 'zero'
'Service engine soon' light stays on
'Service ASR' stays lit
'Security' light flashes
'SYS' blinks
Digital water temp stays at zero
Digital oil temp stays at zero
Engine cannot run above 3K RPM, runs OK (but rich) below 3K
TC won't lock up
ASR doesn't work
What we were doing just before failure was trying to reprogram the EPROM chip in the ECM. We had swapped it in and out a couple of times, and the laptop connected to the eprom burner crashed. Upon replacing the eprom chip, the car went into limp-home mode. However, when I put back in the original memcal PROM, it stayed in limp-home mode. Although the car is (somewhat) driveable, I need to get this fixed.
My question is: What are the different kinds of signal failure that can cause the ECM to enter this mode? Where should I start looking?
Melting Slicks
Joined: Jun 2004
Posts: 3,032
Likes: 4
That's not necessarily "limp home mode"
My l98 put itself in 'limp home mode' a few times (due to code 43 issues) All that really happened was that it retards the timing to the point you have no power...
I think you are getting "dead ECM mode"
and from the stuff you've done, that supports my guess...
My l98 put itself in 'limp home mode' a few times (due to code 43 issues) All that really happened was that it retards the timing to the point you have no power...
I think you are getting "dead ECM mode"
and from the stuff you've done, that supports my guess...
Race Director
Joined: Oct 2001
Posts: 19,653
Likes: 428
From: Melbourne Florida
Cruise-In IV Veteran
My 93 went into limp home mode...got it back to my garage and it expired...would not start again...turned out to be the ECM...put in a new one and it was good to go....good luck
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Dead ECM basically IS Limp Home Mode! (AFAIK)
Mike, I had something similar happen to myself. I accidently put a chip in backwards in the ZIF socket that I have in my ECM. Fried the ECM the second I started the car! Man what a bitch getting it home! I had no overdrive, it was hard as hell to get it started and running (limp home wasn't designed for this kinda cam,
) and over 3k sucked.
I had to replace the ECM for ~$100 at autozone and then all was fine.
Mike, I had something similar happen to myself. I accidently put a chip in backwards in the ZIF socket that I have in my ECM. Fried the ECM the second I started the car! Man what a bitch getting it home! I had no overdrive, it was hard as hell to get it started and running (limp home wasn't designed for this kinda cam,
) and over 3k sucked.I had to replace the ECM for ~$100 at autozone and then all was fine.
Drifting
Joined: May 1999
Posts: 1,478
Likes: 3
From: Sacramento, CA Money can't buy happiness - but it's more comfortable to cry in a Corvette than a Yugo.
I agree with the rest that you probably fried the ECM. CFI-EFI has a point though, before "assuming" it's bad, you might try disconnecting the battery for a full minute or two to clear any previous codes and learnable settings in the ECM. If that doesn't fix it, you need an ECM.
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Thread Starter
Race Director
Joined: Jun 2001
Posts: 10,956
Likes: 681
From: Marlboro country MA
Good news: ECM is not fried! After reading dozens of posts here on the forum about ECM and CCM codes, I read the CCM codes. The ECM signal was ERR, indicating a faulty communication between teh ECM and the CCM. I carefully replaced the original stock PROM, cleaning the contacts first with aerosol spray cleaner, and NO CODES! Then, just to be sure, I replaced the EPROM we were trying to burn (when the laptop had problems), and MEGA-CODES resulted. I compromised, and put in the Ed Wright Fastchip which I had been using prior to the Hotcam installation. Although this chip is intended for a stock LT1, and the idle is crappy, at partial or full throttle the engine runs smoothly and sets no codes.
Next, I ordered a custom Fastchip for the setup I have, which will arrive tomorrow. Finally, when the EPROM burner is repaired, we'll go back to tweaking the settings on my EPROM. Meanwhile, I have a drivable car again!
Next, I ordered a custom Fastchip for the setup I have, which will arrive tomorrow. Finally, when the EPROM burner is repaired, we'll go back to tweaking the settings on my EPROM. Meanwhile, I have a drivable car again!
