Ok folks, been driving the dodge for a day or so and fortunately there are no more codes. However, the idle is a bit higher than it should be, high 900s. I’m pretty sure it’s not the iac valve, I already cleaned it and went through the throttle body and idle drama that comes with it. And it’s surging slightly. I can feel it and see the speedometer bouncing. What could cause this? Thanx, Lynn

 

Vacuum leak.

 

I’ve smoke checked and sprayed a bunch of Wd-40 every where. I can’t find one. Any suggestions where to look? What about clogged injectors?

 

Speedometer? Or tach bouncing? Does it bounce only at idle, or while driving as well?

Have you checked your plenum? They are a notorious failure point, and spraying stuff around won't find it. Gotta physically look into the intake manifold, and see what's up. If you see oil pooling in there, it's blown. There is a thread all about the plenum issues stickied at the top of this forum.

 

It’s my speedometer thats bouncing, at idle so far. I’m gonna go out and mess with it here in a minute. I’ll check the plenum as well. Thank you

 

Correction, mr HeyYou, it is the tachometer that’s bouncing and not the speedometer. I bought a new obd2 scanner and it shows 5 o2 sensors for my truck as well. Is there another sensor that could be reading as a o2 sensor? I get readings on it and everything but I have no ideas where or what it could be. Thanx Lynn

 

I was unable to come up with a diagram for your exhaust, so I have no clue where your sensors would be..... How many cats on your truck?

Tach bouncing is likely a misfire. Is the idle unstable?

 

There’s slight engine surge. I have one cat on my truck I suspect there’s supposed to be two though. The exhaust is not stock. I have several diagrams from the service manual. I have a diagram that shows 5 cats but it says heavy duty, no engine size, and as far as I know my truck is a medium duty.

 

 

I am going to guess the 8.0 and 5.9 HD are similar...... On my 98, I think I only have two O2 sensors, both before the cats, that used to be right after the manifolds. (my exhaust isn't stock either) But, mine is federal emissions.....