2500hd Idle Rpm

rrbigdan1 · October 14, 2008

Just bought a (2003 Silverado 2500HD 4x4, 6.0L) with 40K miles for $12K...I could not pass on this deal. However, I've come across a problem with the idle speed.

When the truck is idling the RPM's are about 300-450. My other trucks idle at about 700 RPM and since this truck has electronic throttle I have no clue how to change it...

CAN ANYONE HELP ME? How do I increase my idle RPM’s?

THANKS,

bd

masterp2 · October 14, 2008

are you sure the gauge isn't malfunctioning? I would be surprised if it was that low.

rrbigdan1 · October 15, 2008

Yes, the engine studers too...no OBD codes, no weard noise, no smoke, just the low RMP's.

bd

are you sure the gauge isn't malfunctioning? I would be surprised if it was that low.

Billdog350 · October 16, 2008

Yes, the engine studers too...no OBD codes, no weard noise, no smoke, just the low RMP's.

bd

are you sure the gauge isn't malfunctioning? I would be surprised if it was that low.

I'd recommend cleaning your MAF and changing plugs and wires before digging any deeper. If you've done all of those things, then you can use something like EFI Live or HP Tuners to alter your idle. Most software or tuners will charge >$300 for this so don't expect it to be cheap.

Keep in mind that there is an "idle learn" period after the battery has been reset. If the prior owner/dealer either had to jump start it, replace the battery, or purposely unhooked the battery to clear the codes it will need several ignition cycles to learn the new idle. I noticed that every time I flashed my 6.0l with EFI Live, it would take at least 50 mi and 5 or more ignition cycles to learn the new idle...until then it would be REAL low (300-400rpm) and occasionally stall when coming to a quick stop or turning the wheel at low speeds. Once I noticed what caused it, I was much less concerned.

svensk · October 18, 2008

Just bought a (2003 Silverado 2500HD 4x4, 6.0L) with 40K miles for $12K...I could not pass on this deal. However, I've come across a problem with the idle speed.

When the truck is idling the RPM's are about 300-450. My other trucks idle at about 700 RPM and since this truck has electronic throttle I have no clue how to change it...

CAN ANYONE HELP ME? How do I increase my idle RPM’s?

THANKS,

bd

Something's wrong with it.

anealysr · October 19, 2008

I agree with BillDog mine idles around 500 or so all the time. When I do a hard reset by unhooking the battery it won't idle for about 10 minutes or so. Then all is fine after I drive it a while. But the first thing I would look at is air flow.

chipjumper · November 23, 2008

I bought a '03 2500hd with the 6.0 had similar issues. Unfortunately, I had to drive it all the way from Burlington, VT to Michigan with it barely idling (was fun at the toll stops), and with the engine shutting down to "REDUCED ENGINE POWER" every 75 miles or so. The latter was temporarily fixed by resetting the trouble code. I bought the truck from a used car lot for a very good price so I couldn't refuse.

The idling problem was instantly fixed by cleaning the throttle body. It is well known that these throttle body's need to be cleaned frequently (15k or so?). Mine was completely nasty. It idled like a champ after that.

The Reduced Engine Power trouble was when the PCM would not allow the throttle to go above idle. Note that the 2003's and above have electric throttle control - no throttle cable. Apparently the TPS was getting bad info from the stepper motor that moves the butterfly and therefore going to a safe mode - "Reduced Engine Power". This was the easiest fix of all -- replacing the throttle body at a cost of only $140. Took about 15 minutes to change.

ZARMANALI · December 4, 2008

I bought a '03 2500hd with the 6.0 had similar issues. Unfortunately, I had to drive it all the way from Burlington, VT to Michigan with it barely idling (was fun at the toll stops), and with the engine shutting down to "REDUCED ENGINE POWER" every 75 miles or so. The latter was temporarily fixed by resetting the trouble code. I bought the truck from a used car lot for a very good price so I couldn't refuse.

The idling problem was instantly fixed by cleaning the throttle body. It is well known that these throttle body's need to be cleaned frequently (15k or so?). Mine was completely nasty. It idled like a champ after that.

The Reduced Engine Power trouble was when the PCM would not allow the throttle to go above idle. Note that the 2003's and above have electric throttle control - no throttle cable. Apparently the TPS was getting bad info from the stepper motor that moves the butterfly and therefore going to a safe mode - "Reduced Engine Power". This was the easiest fix of all -- replacing the throttle body at a cost of only $140. Took about 15 minutes to change.

Thank you for this fix. I had this problem for 2 years. I never bothered with it because i thought it would be expensive through the dealer. I pulled the throttle body off and cleaned it. Put it back and wow, what a difference. I was even looking for another truck. Make sure you put the intake hose on tight, because it will lose power. Snug it tight and your good to go.

chipjumper · December 5, 2008

No problem, just remember to use actual "Throttle Body Cleaner" and not "Carburator Cleaner" as the latter will allegedly strip the Teflon coating on the throttle body. I haven't done a chemical analysis to see if this is true but that is what I have read. Maybe we can look at the MSDS info and see if they are exactly the same