my 06 3500 dually cummins is idling at close to 0 when in park or drive and while cruising if i let off the accelerator.

it also revs at 3k rpm goin 75-80 mph.

trucks is completely stock except for exhaust and it did the same thing before and after 5" straight exhaust

it is an auto

31" tires

 

Looks to me that you have a tach problem not an RPM problem.

 

That's normal. It's a fuel saving thing. I can actually time the compression strokes with an hour glass on mine. It's about 5 seconds between ignition 'pops' and sounds like a drum being beat really slow when it idles.

Or maybe the tach is broken? Nah.... It idles at zero.

My tach actually has been behaving lately.... I would still like to check it and see how far it is off when it misbehaves. Then again, I guess mine's an auto so I shouldn't need the tach except for performance monitoring.

 

its an 06 thing they seem to go out mine is doing it to. i just drive by ear

 

I just rolled 50k yesterday, but I have no signs of a tach issue. Idles at about 750 or so, and runs 2k at 65 2.3k - 2.5 at 70-75ish

 

give it time mine didnt start it till about 140k

 

mine runs from 0 to below the zero peg, sometimes it stays around 4000 rpm. need to fix it but just have the time.

 

It's a common problem on the '06. I sent mine out last week to a place that repairs them for $179 including shipping prepaid both ways and 2 yr warranty. I'll report how it turns out. Takes 2 weeks. The replacement cluster installed by dealer is around $500. Odometer is in the cluster (not ecm) and new must be set by dealer or it won't work. With the repair option you get the one you sent back so no odometer concerns. I have manual trans and bad tach drives me crazy. Mine was bad at 60,000 miles

 

Hum this is interesting. I have never heard of this being an issue until this thread. Is it a manual or automatic thing?? or both?

 

Mine is an auto, so it's both transmissions. Mine started at about 65,000 miles. Doesn't do it often, but it just seemed awful odd that my truck was idling at 500 rpm's sometimes....

 

It's the tach. Can do a instrument cluster diagnostic test to verify if it's the tach. Hold in the odometer reset button and turn the ignition key to the ON position. This will cause the gauge needles to sweep and step and the warning/indicator lamps to illuminate. If the needle doesn't sweep it's the IC.

BTW, the tach died in my Magnum RT about a month ago. Replacement cluster mailordered is $850!

MikeyB

 

850 bones!!! HOLY SMOKES!

 

Needless to say it's not going to be fixed anytime soon. Most likely I'll ordered a used one off of ebay for less than $100 and cannibalize for parts.

MikeyB

 

No doubt! You may be able to find one at a junk yard, but even junk yards are trying to sell parts for near new oem prices these days.

I found a guy that was parting his truck out to get my fog lights (rock shattered one of mine) OEM was 183 bcusk for one, I got the set for 55 bucks shipped.

 

I've only had my truck a short while but noticed it on the test drive and then it got worse. I searched some threads and there is some write up on it. One person said the solder in the boards was weak and resoldering it fixed it. The cluster is not really made to be taken apart so I figured I would let this mail order guy fix it. At least it will have a 2 yr warranty. I'm anxious to get mine back and try it.