low idle/stall at stops

[Rylandnc]

Hello all.

 

Iv'e got a 2001 GMC sierra 2500 with the 6.0 (48,000 miles) and it tends to experience momentary low/rough idle or even stall when i come to a stop. Also the volt meter drops way off. I can't tell which happens first. It does this on short distance trips and will even do it on long distance trips is if stop for fuel etc.

 

This condition is worse when backing up. Will also do it if sitting still, put it in gear and back to neutral.

 

When the A/Cis on, it seems to shut off which i am assuming is due to the low voltage disengaging the clutch.

 

The dealer says it is throttle body carbon build-up, but didn't make much difference after they cleaned it.

 

Any ideas out there?

 

Thanks,

Ryland

[100R1]

Hello all.

 

Iv'e got a 2001 GMC sierra 2500 with the 6.0 (48,000 miles) and it tends to experience momentary low/rough idle or even stall when i come to a stop.  Also the volt meter drops way off.  I can't tell which happens first.  It does this on short distance trips and will even do it on long distance trips is if stop for fuel etc.

 

This condition is worse when backing up.  Will also do it if sitting still, put it in gear and back to neutral.

 

When the A/Cis on, it seems to shut off which i am assuming is due to the low voltage disengaging the clutch.

 

The dealer says it is throttle body carbon build-up, but didn't make much difference after they cleaned it.

 

Any ideas out there?

 

Thanks,

Ryland

 

<{POST_SNAPBACK}>

 

 

 

 

I would try to get a local auto parts store to hook up a "free" OBDII scan to see if you have any stored codes. Advanced auto and some Pep Boys near me will do it for free. NAPA even rents them out .

 

If all is good there I would forget the dealer cleaning your Throttle body and D.I.Y., Take your time and let it really soak in.

[silverado3500]

I would also suggest checking for any vacuum leaks, and perhaps the pcv valve.

[Rylandnc]

I would also suggest checking for any vacuum leaks, and perhaps the pcv valve.

 

<{POST_SNAPBACK}>

 

 

 

Thanks....I noticed today that there is a a slight high-pitched squeal when sitting still and in gear (drive). It goes away when in neutral. I'll chek it out.

[mmmikkke]

Sounds like the dealer ignored your low voltage symptom. Your battery--all by itself without the alternator--should have plenty of power to keep your a/c clutch engaged.

 

How far down do your volts drop? 11? 10? 8?

 

If it's 8 or less, there's some load on your electrical system.

 

Next time you drive it try to establish that the lock up torque converter is operating normally.