Tech / General Engine Is your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!

91 Camaro being haunted by ECM?

Thread Tools
 
Search this Thread
 
Old 09-08-2024, 12:27 PM
  #1  
Junior Member
Thread Starter
 
CallMeAhab's Avatar
 
Join Date: Sep 2023
Location: Pennsylvania
Posts: 7
Received 0 Likes on 0 Posts
Car: 1991 Camaro RS
91 Camaro being haunted by ECM?

Hey everyone, over the past year or so my 91 V6 has had an on/off again issue where it seems the ECM doesn't know what to do after the battery is disconnected. I have tried to drive it for an entire hour after reconnecting the battery so it can relearn everything, but to no avail. Upon ignition the RPM's will jump up to 15,000 and then slowly come back down to normal idle but will feel quite rough, this is a random occurrence, sometimes it happens and sometimes it will start normally. It feels almost fine while driving, maybe a tad slower than usual, but coming to a stop it will plummet the RPMs almost stalling it. It also doesn't accelerate or shift smoothly when leaving a stop. So far I have replaced: spark plugs, spark plug wires, distributor cap and rotor, air filter, fuel filter, IAC, and the ECM itself. When I got the ECM replacement, it ran better than it ever did. Until i disconnected the battery to install new speakers a week ago, and everything went back to square one. I'd love to hear anyone's input on this issue that has been haunting my Camaro for a while now, thanks in advance.
Old 09-08-2024, 01:38 PM
  #2  
Sponsor

iTrader: (92)
 
Tuned Performance's Avatar
 
Join Date: Dec 2004
Location: Mile High Country !!!
Posts: 15,626
Received 706 Likes on 625 Posts
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: 91 Camaro being haunted by ECM?

Originally Posted by CallMeAhab
Hey everyone, over the past year or so my 91 V6 has had an on/off again issue where it seems the ECM doesn't know what to do after the battery is disconnected. I have tried to drive it for an entire hour after reconnecting the battery so it can relearn everything, but to no avail. Upon ignition the RPM's will jump up to 15,000 and then slowly come back down to normal idle but will feel quite rough, this is a random occurrence, sometimes it happens and sometimes it will start normally. It feels almost fine while driving, maybe a tad slower than usual, but coming to a stop it will plummet the RPMs almost stalling it. It also doesn't accelerate or shift smoothly when leaving a stop. So far I have replaced: spark plugs, spark plug wires, distributor cap and rotor, air filter, fuel filter, IAC, and the ECM itself. When I got the ECM replacement, it ran better than it ever did. Until i disconnected the battery to install new speakers a week ago, and everything went back to square one. I'd love to hear anyone's input on this issue that has been haunting my Camaro for a while now, thanks in advance.
it races to 15k rpm ?
Old 09-08-2024, 02:54 PM
  #3  
Junior Member
Thread Starter
 
CallMeAhab's Avatar
 
Join Date: Sep 2023
Location: Pennsylvania
Posts: 7
Received 0 Likes on 0 Posts
Car: 1991 Camaro RS
Re: 91 Camaro being haunted by ECM?

On a cold start it will jump up to 15k, then slowly drop down to 10k where the cold idle is, until it warms up and slowly comes down to around 5k. On warm starts it will jump right up to 15k, then come down to 5k. Sometimes this happens, sometimes it does not; it seems like the car runs better when it doesn't happen.
Old 09-08-2024, 04:52 PM
  #4  
Sponsor

iTrader: (92)
 
Tuned Performance's Avatar
 
Join Date: Dec 2004
Location: Mile High Country !!!
Posts: 15,626
Received 706 Likes on 625 Posts
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: 91 Camaro being haunted by ECM?

Originally Posted by CallMeAhab
On a cold start it will jump up to 15k, then slowly drop down to 10k where the cold idle is, until it warms up and slowly comes down to around 5k. On warm starts it will jump right up to 15k, then come down to 5k. Sometimes this happens, sometimes it does not; it seems like the car runs better when it doesn't happen.
your tachometer is way off or your about to throw rods. I don’t see that your engine can rev that high.
Old 09-08-2024, 06:38 PM
  #5  
Junior Member
Thread Starter
 
CallMeAhab's Avatar
 
Join Date: Sep 2023
Location: Pennsylvania
Posts: 7
Received 0 Likes on 0 Posts
Car: 1991 Camaro RS
Re: 91 Camaro being haunted by ECM?

Originally Posted by Tuned Performance
your tachometer is way off or your about to throw rods. I don’t see that your engine can rev that high.
Hah! Pardon the brain fog, I have a high fever right now. I meant 1,500 not 15,000. As the 91 RS tach states 5, 10, 15
Old 09-08-2024, 06:41 PM
  #6  
Sponsor

iTrader: (92)
 
Tuned Performance's Avatar
 
Join Date: Dec 2004
Location: Mile High Country !!!
Posts: 15,626
Received 706 Likes on 625 Posts
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: 91 Camaro being haunted by ECM?

https://www.thirdgen.org/forums/v6/1...procedure.html
Old 09-08-2024, 08:50 PM
  #7  
Junior Member
Thread Starter
 
CallMeAhab's Avatar
 
Join Date: Sep 2023
Location: Pennsylvania
Posts: 7
Received 0 Likes on 0 Posts
Car: 1991 Camaro RS
Re: 91 Camaro being haunted by ECM?

Originally Posted by Tuned Performance
I'll try this in the next day or two, thanks! Do you know if this is something that has to be done every time the battery is disconnected? I'm wondering what might be causing it if not.
Old 09-08-2024, 08:58 PM
  #8  
Sponsor

iTrader: (92)
 
Tuned Performance's Avatar
 
Join Date: Dec 2004
Location: Mile High Country !!!
Posts: 15,626
Received 706 Likes on 625 Posts
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: 91 Camaro being haunted by ECM?

Probably if S.A.M is lost
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
IrocZ Chick
Cooling
6
09-24-2023 04:32 PM
ttruelove
Tech / General Engine
9
05-09-2018 10:13 AM
Firebird_Sadie
DFI and ECM
2
09-27-2009 12:22 PM
trueburton
DFI and ECM
1
06-17-2005 07:35 PM
Craig Moates
DIY PROM
34
12-08-2004 04:34 PM



Quick Reply: 91 Camaro being haunted by ECM?



All times are GMT -5. The time now is 08:49 PM.