won't hold rpm, at low end

[akrockhound]

I have a new Duramax with 800 miles on it.
If I am slowly driving around (like in parking lot) holding say 900 rpm, the rpm will suddenly drop to idle. If I push a bit harder on the gas it will come up, sometimes drop again before surging back. Basically it drops to idle. It's not wandering.

Above say 1000 rpm it is smooth and steady.

It's an Allison auto transmission.

Just doens't like to hold rpm between idle and ~1000rpm.

It's pretty subtle but this isn't my first diesel and I think its abnormal.

Should I be concerned? Actually I am concerned just wondering if it's too early to bring to shop or if I should watch it for a while see if it gets worse or not.

[SoMnDMAX]

Welcome to the world of drive by wire throttle. Most likely there isn't anything wrong. It'll take a bit to get used to the way the electronic throttle works.

Drive the truck for a while, and see if it improves. I'd be willing to bet it will.

[a64pilot]

Don't sound normal to me, sounds like it may be losing the throttle position signal. If it is the same as my 95 6.5 was there was actually three voltages two going one way and one going the other. IIRC if you lost one of the voltages it would continue to operate but light some trouble light on the dash. I know you are not talking about a 6.5, but it is the only one I know for sure how it works, and I'll bet the Dmax is similar. I think it unlikely you would loose all three.
Others have reported a lack of power in the 03's due to a faulty TPS, I'd have the dealer check it out especially if you can duplicate it for him

[roegs]

Mine does the same thing...kinda feels like a flat spot at lower RPM's. I'm also wondering if its just a characteristic of the electronic throttle system. I've checked all 3 of the throttle voltages with a scan tool, and they appear to be normal. I have around 1200 miles on mine.

[akrockhound]

I asked the dealer service dept and they said "bring it in". They say there's a computer "flash" for the low idle.

I'll let you know if it fixes it later this week.

I notice it pretty much goes away when the truck is all warmed up.

Why Chevy doesn't make sure that their new cars are current with latest flashes before they let new buyers drive them away is a mystery to me!!!

[akrockhound]

THE FIX!!!!!!!!

After reading the Duramax supplement I decided to change my oil filter....This immediately fixed this problem.

Must have been something foreign in the original fuel or just some "matter" in the fuel system from the factory.

I am glad that the Duramx fuel filters are so easy to change (but they aren't cheap!)

[akrockhound]

Sorry in last post I meant I changed the fuel filter, not the oil filter