ok. i do have a rough idle upon cold start up and very slight on hot start up. every once in a great while she will stumble on light acceleration. wot is perfect. still kicks the 2500HD in the neighberhood around. he is stock right now. i hooked up a vaccumn gauge to it. cold start up reads 14 psi for right around 5 to 7 seconds and then climbs to 21 psi and will hold steady. on hot start up it goes right to 21 psi and stays there. has anyone else hooked up a vaccumn gauge on a cold start up to get a reading?i am teeing into the fuel regulater for the reading.

 

I ran a vacuum gauge for about 8 months on my truck. I hooked it in on the passenger side of the intake. I used a T fitting in the large vacuum line.
My readings were about normal, 20 lbs (I'm at 3000+ feet) steady.
Did you have a specific question?
My truck idles smooth, but with 25-50RPM of waver. Has since new.

Chris

 

what is your reading at idle when you first start her up cold. does she go straight to 20 psi or does she sit at about 14 to 15 psi at first then climb to 20 psi. this is after it has set overnight.

 

I have an Autometer to install in mine (along with Trans Temp), but it's the full-sweep electric one. Haven't installed it yet because I need to find a home for my Edge first...

Keep in mind that vacuum is read in inches/Hg or 20". Pressure is rated in psi or 20#.

 

oh yay i know what the readings are. im chasing down a rough idle on cold start up.

 

When it is cold and the idle is high it is at about 16 lbs for about 15-30 seconds. That is until the throttle plate is closed and the vacuum goes up. That's just the fast idle.
Chris

 

ok cool. then mine is right. thanks. i have had to replace the intake gaskets and was wondering if something was wrong. but since it is a common deal i think i am going to unload the tunes and take to the dealer for a tsb on rough idle and stuttering on take off.