RPM's drop.
 

My engine is not running smooth lately.
I can feel vibrations throughout the cab although rpm's are steady at 600.
Sometimes it runs smooth,then it is really bad vibrating.

And also,I can hear the airco come on, it is making noise when it does and it stays there until it has turned off.
When this happens,(airco turning on) the number of revolutions drops 50-100 rpm's.
I have never noticed this before.

Is this normal or is it related to the engine not running right.

I don't think this is the rough idle where all you guys are talking about.RPM is steady at 600.
But it is very annoying.

Took of the batterycable with the lights on to reset and used a full tank with injection cleaner in it.

Problem is still there, maybe even a little bit worse.:mad:

What is your opinion on this ?

Just a shot in the dark. It could be a defective IAC. If it is, and the problem gets worse, you'll see the SES light come on real soon.

IAC ?
 

Thanks Dennis,

What is that exactly,IAC.

Ignition Coil ?

#4 had been replaced in April this year.

IAC= Idle Air Control