VortechC5

iTrader: (6)

My VMAX has developed a rough idle when it is first started. Sometimes the idle will drop below 500 rpm in park. The idle smooths out after about 15 seconds.

The dealer can reproduce it but can't seem to be able to do anything about it because no codes are set.

Has anyone else had this problem?

GMCtrk

iTrader: (27)

sounds electrical in nature

I had a problem similar on my truck, it would idle/stumble and then smooth out, turns out it was the battery going out. But it was 6 years old. I can't imagine your battery is already shot.

VortechC5

iTrader: (6)

The battery "should" be ok. The truck only has 5k miles on it.

Llaverito

iTrader: (4)

I friend has an 07 ECSB Vmax and it also had rough idle, it would sound like it had a cam, I did some idle tuning and fixed it.

VortechC5

iTrader: (6)

Did that 07 have the problem when warm or just on cold start?

MeanZ71

iTrader: (6)

+1 on the tuning

Allgonoshow

iTrader: (1)

mine does the same thing, will even stall some times
sounds like it has a big cam at idle, especially with the headers and exhaust
i think it's tune related for me

is yours stock tune?

VortechC5

iTrader: (6)

Mine is all stock including the tune.