02 Denali idles rough with a/c on

[mlsins]

My 02 Denali seems to have two problems, both of which only seem to surface when the a/c is running. The most constant problem is that the engine idles rough. Turn of the a/c and it runs as smooth as when it was new. The other is sometimes at acceleration i hear what sounds like something coming apart. It only happens at low speed and again only when the a/c is on. A/c seems to work ok, nice and cold. Anybody got any ideas on either of these problems?

[mickes]

The sound you hear under acceleration probably is detonation (spark knock, pinging). Sounds like someone put a bunch of marbles in your engine. You hear it mostly while accelerating and more so on the hotter days. If you are using 87 octane gas, try some 89 or 92.
I had both the problems you are having with my 2000 at about 35k miles. What I did was install some A/C Delco platinum plugs and a K&N air filter. 40k miles later it still idles like new and no pinging while using 87 gas. As a side effect, I picked up 2 mpg.

[nick0750]

this is a common occurance with this vehicle there is a software update for your vehicle through the dealer.