Engine shut off while approaching stoplight
Team Owner
Joined: May 2001
Posts: 87,294
Likes: 1,579
From: Western NY
.....It mainly acts up when I start to come to a stoplight, when I come to a complete stop the rpms want to drop a touch to low, then it recovers. Sits right around 500-600rpms, but the needle will bounce around, will not be smooth like before. Right now that's the only thing different I have done to the Vette in the short span was clean and oil the filter.
Mine has done that every once in a while since it was new. It never stalls, but just 'stumbles' for a second or two, then recovers and smooths out....
Melting Slicks
Joined: Jun 2010
Posts: 2,809
Likes: 3
From: Yorktown Virginia
This is the one I used which I believe was posted by Bill Curlee
AUTOMATIC TRANS:
ign. off
remove pcm batt fuse
wait 5 min
replace pcm batt fuse
a/c off
park brake and block drive wheels(do not use brake)
start vehicle
allow coolant to reach over 176F
shift into drive
wait 5 mins
turn on a/c
wait 5 mins
shift to park
wait 5 mins
turn off a/c
wait 5 mins
turn off engine. off
Team Owner
Joined: May 2001
Posts: 87,294
Likes: 1,579
From: Western NY
After I fixed my vacuum leak mine would stumble and actually stall until I did an idle relearn procedure.
This is the one I used which I believe was posted by Bill Curlee
AUTOMATIC TRANS:
ign. off
remove pcm batt fuse
wait 5 min
replace pcm batt fuse
a/c off
park brake and block drive wheels(do not use brake)
start vehicle
allow coolant to reach over 176F
shift into drive
wait 5 mins
turn on a/c
wait 5 mins
shift to park
wait 5 mins
turn off a/c
wait 5 mins
turn off engine. off
This is the one I used which I believe was posted by Bill Curlee
AUTOMATIC TRANS:
ign. off
remove pcm batt fuse
wait 5 min
replace pcm batt fuse
a/c off
park brake and block drive wheels(do not use brake)
start vehicle
allow coolant to reach over 176F
shift into drive
wait 5 mins
turn on a/c
wait 5 mins
shift to park
wait 5 mins
turn off a/c
wait 5 mins
turn off engine. off
That's good info, although I have a 6 speed car. I'll have to dig out my shop manual and give it a try....
Melting Slicks
Joined: Jun 2010
Posts: 2,809
Likes: 3
From: Yorktown Virginia
Thread Starter
Instructor
Joined: Apr 2010
Posts: 171
Likes: 0
From: Saginaw Michigan
I cleaned the MAF sensor and the throttle body, then did an idle relearn. Took it out for a drive, about 45 minutes, it ran good. I tried everything to get it to stumble, but it didn't.....keeping fingers crossed! Did some hard accelerating, then hit the brakes to get the rpm's to come down fast like they did when it would stall. It went just under 500rpm's and came back up, never felt like it was going to stall or even stumble for that matter.
So far I haven't even felt the surging that used to be present while cruising at a set speed, it all felt pretty smooth!
Now I need to investigate the battery volts on the DIC. They started out at 14.1V....after the relearn it was sitting around 13.6v. During the drive, it didnt like going under load when I was playing with it to see what it would do. I turned the a/c on, headlights, radio etc....it dropped to 11.9V - 12.5v. After I shut all that off it recovered to 13.4 - 13.6v. I'm gonna check out the connections at the starter later today.
So far I haven't even felt the surging that used to be present while cruising at a set speed, it all felt pretty smooth!
Now I need to investigate the battery volts on the DIC. They started out at 14.1V....after the relearn it was sitting around 13.6v. During the drive, it didnt like going under load when I was playing with it to see what it would do. I turned the a/c on, headlights, radio etc....it dropped to 11.9V - 12.5v. After I shut all that off it recovered to 13.4 - 13.6v. I'm gonna check out the connections at the starter later today.
Thread Starter
Instructor
Joined: Apr 2010
Posts: 171
Likes: 0
From: Saginaw Michigan
I checked out the starter connections, everything was tight and clean, no corrosion whatsoever. The ground that is above the starter was good as well. This Vette hasn't seen rain so everything looked really good corrosion wise. It is mainly a Weekend driver and whenever I have a chance to get in it during the week. 2004 A4 Convertible with just under 20,000 miles.
Volts across battery terminals before start were 12.8....after start 14.1. Let it run for awhile, put a load on it...a/c with fans kicking into high speed dropped the DIC to 12.5 with 13.0 at the battery....always .5 volt difference between the DIC and at the battery, when toggling between load and no load. It hasn't stalled/shut off on me since I did the cleaning posted above, but I don't trust what's going on with the charging system right now. Only code I'm getting is the HVAC 0367H. I reset it and that one is always there.
Volts across battery terminals before start were 12.8....after start 14.1. Let it run for awhile, put a load on it...a/c with fans kicking into high speed dropped the DIC to 12.5 with 13.0 at the battery....always .5 volt difference between the DIC and at the battery, when toggling between load and no load. It hasn't stalled/shut off on me since I did the cleaning posted above, but I don't trust what's going on with the charging system right now. Only code I'm getting is the HVAC 0367H. I reset it and that one is always there.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
I checked out the starter connections, everything was tight and clean, no corrosion whatsoever. The ground that is above the starter was good as well. This Vette hasn't seen rain so everything looked really good corrosion wise. It is mainly a Weekend driver and whenever I have a chance to get in it during the week. 2004 A4 Convertible with just under 20,000 miles.
Volts across battery terminals before start were 12.8....after start 14.1. Let it run for awhile, put a load on it...a/c with fans kicking into high speed dropped the DIC to 12.5 with 13.0 at the battery....always .5 volt difference between the DIC and at the battery, when toggling between load and no load. It hasn't stalled/shut off on me since I did the cleaning posted above, but I don't trust what's going on with the charging system right now. Only code I'm getting is the HVAC 0367H. I reset it and that one is always there.
Volts across battery terminals before start were 12.8....after start 14.1. Let it run for awhile, put a load on it...a/c with fans kicking into high speed dropped the DIC to 12.5 with 13.0 at the battery....always .5 volt difference between the DIC and at the battery, when toggling between load and no load. It hasn't stalled/shut off on me since I did the cleaning posted above, but I don't trust what's going on with the charging system right now. Only code I'm getting is the HVAC 0367H. I reset it and that one is always there.
That .5 VDC difference is caused by your ignition switch contacts being dirty or burnt!You can easily fix it:
- C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html
You could have more severly burnt contacts in the switch that causes stuff like your fuel pump to shut off or slow down.
Bill
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Instructor
Joined: Jul 2010
Posts: 192
Likes: 6
I did it a few weekends ago and I would guess that if you jump right into the removal of the switch it might take you 2-4 hours. I took more because I wanted to make sure my problem wasn't related a relay, starter solenoid or ground problem. One of the frustrating tasks for me was wrestling with the removal and reinstallation of the center console.