Stalling Mystery - Can you help?
Thread Starter
4th Gear
Joined: Jan 2009
Posts: 4
Likes: 0
From: Sugar Land Texas
Stalling Mystery - Can you help?
I've searched and searched but no luck to why this would be occurring. Here's the problem:
My C5 (2001) vette stalls at low speeds, usually while tapping the brakes in a parking lot. It's an automatic.
When it happens:
1. Almost always when it's been sitting in the sun for a little while (>30 mins). Doesn't happen when garaged or in the shade for more than a couple of hours after driving.
2. When the AC is ON. (When the AC is off, the rpms will drop but not enough to cause the engine to die.)
3. At low speed when manuevering in a parking lot -- for example, pull out of the space, put it in drive, get to the exit, tap brakes to check traffic... then STALL.
4. Usually DOES NOT happen after the engine is completely warmed up. After driving a few miles, the issue usually goes away.
Other info:
1. RPM drops below 500, down to 250 or so -- if I'm quick and get on the gas again I can keep it from stalling.
2. Battery volts drop alarmingly - down from 13.8 to 10.5...I don't know what's cause and what's effect -- is the voltage drop causing the rpms to drop or is the rpm drop causing the volt to drop?
What I've looked at:
1. Checked the battery (optima red top) - reads good both while running and off.
2. Had the generator tested at Autozone. They said it seemed fine.
3. Visually inspected the main grounds on the wheel wells (without unbolting it). Seemed clean.
This has been going on for almost 9 months -- in fact it's so predictable I can work around it (and why have haven't taken it to the dealer) but I'd like to get to the bottom of it. Plus spring is coming and it will happen more frequently I'm sure. Anyone have any pointers?
My C5 (2001) vette stalls at low speeds, usually while tapping the brakes in a parking lot. It's an automatic.
When it happens:
1. Almost always when it's been sitting in the sun for a little while (>30 mins). Doesn't happen when garaged or in the shade for more than a couple of hours after driving.
2. When the AC is ON. (When the AC is off, the rpms will drop but not enough to cause the engine to die.)
3. At low speed when manuevering in a parking lot -- for example, pull out of the space, put it in drive, get to the exit, tap brakes to check traffic... then STALL.
4. Usually DOES NOT happen after the engine is completely warmed up. After driving a few miles, the issue usually goes away.
Other info:
1. RPM drops below 500, down to 250 or so -- if I'm quick and get on the gas again I can keep it from stalling.
2. Battery volts drop alarmingly - down from 13.8 to 10.5...I don't know what's cause and what's effect -- is the voltage drop causing the rpms to drop or is the rpm drop causing the volt to drop?
What I've looked at:
1. Checked the battery (optima red top) - reads good both while running and off.
2. Had the generator tested at Autozone. They said it seemed fine.
3. Visually inspected the main grounds on the wheel wells (without unbolting it). Seemed clean.
This has been going on for almost 9 months -- in fact it's so predictable I can work around it (and why have haven't taken it to the dealer) but I'd like to get to the bottom of it. Plus spring is coming and it will happen more frequently I'm sure. Anyone have any pointers?
Advanced
Joined: Feb 2008
Posts: 83
Likes: 0
From: Citrus Hts ca
I've searched and searched but no luck to why this would be occurring. Here's the problem:
My C5 (2001) vette stalls at low speeds, usually while tapping the brakes in a parking lot. It's an automatic.
When it happens:
1. Almost always when it's been sitting in the sun for a little while (>30 mins). Doesn't happen when garaged or in the shade for more than a couple of hours after driving.
2. When the AC is ON. (When the AC is off, the rpms will drop but not enough to cause the engine to die.)
3. At low speed when manuevering in a parking lot -- for example, pull out of the space, put it in drive, get to the exit, tap brakes to check traffic... then STALL.
4. Usually DOES NOT happen after the engine is completely warmed up. After driving a few miles, the issue usually goes away.
Other info:
1. RPM drops below 500, down to 250 or so -- if I'm quick and get on the gas again I can keep it from stalling.
2. Battery volts drop alarmingly - down from 13.8 to 10.5...I don't know what's cause and what's effect -- is the voltage drop causing the rpms to drop or is the rpm drop causing the volt to drop?
What I've looked at:
1. Checked the battery (optima red top) - reads good both while running and off.
2. Had the generator tested at Autozone. They said it seemed fine.
3. Visually inspected the main grounds on the wheel wells (without unbolting it). Seemed clean.
This has been going on for almost 9 months -- in fact it's so predictable I can work around it (and why have haven't taken it to the dealer) but I'd like to get to the bottom of it. Plus spring is coming and it will happen more frequently I'm sure. Anyone have any pointers?
My C5 (2001) vette stalls at low speeds, usually while tapping the brakes in a parking lot. It's an automatic.
When it happens:
1. Almost always when it's been sitting in the sun for a little while (>30 mins). Doesn't happen when garaged or in the shade for more than a couple of hours after driving.
2. When the AC is ON. (When the AC is off, the rpms will drop but not enough to cause the engine to die.)
3. At low speed when manuevering in a parking lot -- for example, pull out of the space, put it in drive, get to the exit, tap brakes to check traffic... then STALL.
4. Usually DOES NOT happen after the engine is completely warmed up. After driving a few miles, the issue usually goes away.
Other info:
1. RPM drops below 500, down to 250 or so -- if I'm quick and get on the gas again I can keep it from stalling.
2. Battery volts drop alarmingly - down from 13.8 to 10.5...I don't know what's cause and what's effect -- is the voltage drop causing the rpms to drop or is the rpm drop causing the volt to drop?
What I've looked at:
1. Checked the battery (optima red top) - reads good both while running and off.
2. Had the generator tested at Autozone. They said it seemed fine.
3. Visually inspected the main grounds on the wheel wells (without unbolting it). Seemed clean.
This has been going on for almost 9 months -- in fact it's so predictable I can work around it (and why have haven't taken it to the dealer) but I'd like to get to the bottom of it. Plus spring is coming and it will happen more frequently I'm sure. Anyone have any pointers?
Thread Starter
4th Gear
Joined: Jan 2009
Posts: 4
Likes: 0
From: Sugar Land Texas
Do you mean an exhaust issue? Like the cats are plugged up?
I forgot to mention, I also had at 60K miles (now at 70K) the fuel injectors cleaned. I also use Techron periodically because my fuel gauges are sensative to high sulpher gas and it keeps it from reading empty for no reason.
Also I scanned the codes - one historical U1000 but it doesn't seem related.
I forgot to mention, I also had at 60K miles (now at 70K) the fuel injectors cleaned. I also use Techron periodically because my fuel gauges are sensative to high sulpher gas and it keeps it from reading empty for no reason.
Also I scanned the codes - one historical U1000 but it doesn't seem related.
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Look for vacuum leaks and especially the PCV line to the throttle body connection tube. It can develop holes on the bottom side of it, out of sight. Once you are sure you've covered all the obvious things, pulled your codes and so on, do an "Idle Relearn" procedure. Its posted here in the forum by several members.
Advanced
Joined: Aug 2008
Posts: 84
Likes: 5
My car had the vacuum line on the back of the intake left off when it was changed to a BBk intake. It would almost die coming off of the highway going down the offramp to the light. It also idled poorly. My hvac controls wouldn't work either ( they are vacuum controlled).
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Thread Starter
4th Gear
Joined: Jan 2009
Posts: 4
Likes: 0
From: Sugar Land Texas
Thank you, great suggestions. The idle IS a little rough as well. Maybe a slight vac line leak that comes when certain parts expand in the external heat?
I think I'll take off the whole intake and look at everything top to bottom.
I think I'll take off the whole intake and look at everything top to bottom.
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Be prepared for issues trying to reconnect the small black plastic line at the rear of the intake manifold connecting to the MAP sensor. If you extend it just a little, its a lot easier to work with. For just rough ildle by itself and no obvious vacuum leaks, I would be replacing the plug wires and possibly the plugs too depending on their age and condition. Did you pull the codes? BTW, while you are back there, check that the grounds on the rear of the driver's side head are tight. If they come loose, the problems are a lot more serious so I doubt that you have this issue, but since you will be right there, check them.
Thread Starter
4th Gear
Joined: Jan 2009
Posts: 4
Likes: 0
From: Sugar Land Texas
Followup:
The maf and throttle body cleaning did the trick. I took everything off and sprayed it down with cleaner. After a month I'm having no problems and there have been plenty of 80+ days here in Houston. Thanks for all the input.
The idle stayed at 1100 rpms after the procedure but came down to 550 after driving about 15-20 miles. I let it idle in the driveway for about 10 minutes also. Runs silky smooth now.
The maf and throttle body cleaning did the trick. I took everything off and sprayed it down with cleaner. After a month I'm having no problems and there have been plenty of 80+ days here in Houston. Thanks for all the input.
The idle stayed at 1100 rpms after the procedure but came down to 550 after driving about 15-20 miles. I let it idle in the driveway for about 10 minutes also. Runs silky smooth now.
