I'm new here so hi to all, I have a 03 D With a 4.7 in it, 42,000 miles. truck runs great, after it warm ups and I'm stopped at a light with my foot on the brake, the truck idles down to 500, 550 or so, it does a very slight miss, if the idle is up around 600 or 700 it doesn't do it, just when it drops to the 500 range, rpm's don't change but you can feel it if sitting in the truck , and you can hear it coming out the exhaust pipe, I cleaned the TB, and the IAC, both looked good before I took it apart, also installed new plugs, would a TPS cause a idle issue, thanks

 

Did you replace the wires when you replaced the plugs?

Can you define the miss a little more, because it might be normal as to how these motors "chug".

 

4.7s do not have plug wires, they are coil on plug ignition, 500-550 is a normal closed loop (warme ngine) idle speed.

a couple thins are did you check the gap on the new plugs as you put them in? yes im aware they are s upposed to come 'pre gapped' but sometimes **** happens and the gaps get messed up,

also did you reset the computer when you cleaned the sensors ect?

 

Gap is good I did check them before installing, no I did not reset puter, I will do that in morning , thanks

 

Hard to define its like a slight vibration you fill when the idle is around 550, periodically happens not all the time, doesn't do it when the ac is on????? Runs normal any other time, just does it after truck warms up.

 

OK, when I this thing burps or misses, I do notice the dash lights dim ever so slightly, hmmm, never stalls or throws a code......

 

It won't do it when the a/c is on since the RPMs increase while it's on. Clean your battery connections and see how that works.

SJ02

 

I will try it but terminals and battery look new, I have plenty of volts...

 

Typical of our 4.7's. I discovered this years ago the first time I shut off the A/c and the idle dropped to 500. It feels like the engine is missing, and after searching everywhere for an answer as to what could be done to increase the idle, I came up empty.

In the winter I unplug the compressor pigtail and turn on the A/C switch and it increases the RPM's and the idle is smooth. If anyone else has an answer to raising the base idle, I'd sure like to know it.

 

I'm thinking it something I ned to live with , truck runs strong, except for that little shutter or waht ever you want to call it.