Hello forum,

My last post ended with me buying an 04 D with the 4.7L engine...this one starts with a problem.

Twice now I have pulled up to a stop light and the idle rpm's have dropped to around 300 and when I try to take of it feels like I am taking off in 2nd-3rd gear. No power, barely any movement. After revving the engine a bit, it goes back to normal operation with no problems. The last time it happened it did the same as described above followed with a loud knocking noise which didnt sound good.

Any input would be appreciated.

Thanks,

Mark

 

Maybe the throttle position sensor needs replaced,
FF

 

+1 for the TPS. Relatively cheap part to, around $35 or less from O'Reillys or Advance, if memory serves.

Funny note... those TPS units are the same ones they used on older engines in the Dodge Dakotas and Rams since at least 1994, hence why they should be easy to find and pretty inexpensive.

When we bought my wife her Dingo, it had 80k on her, and she had a severe hesitation off the line, rough idle, and delayed acceleration even during normal driving. Replaced the TPS, as I'd read on other forums that they don't last long on the 4.7s, and sure enough, most of the hesitation went away. Finally cured it completely after a CEL code popped up for misfire on cylinder 4. Replaced the coil pack for that cylinder, and now she is rock solid (also did a regular tune-up as well, new plugs and etc.).

 

Thanks for the replies!

Wouldnt the TP sensor cause low/moving idle all of the time? This has only happened a couple of times in the last 8 days. Other than those few times it has ran perfectly with the idle right at 650 rpm's with no fluctuation. One thing I did do was put 89 octane fuel in it with the first fill-up, the manual calls for 87. Would this cause a similar effect? I was thinking of putting 87 octane fuel with a bottle of C-foam and see if it happens again. Is C-foam a good product to run throught the fuel?

Thanks again for your help, i appreciate it.

Mark

 

89 octane shouldn't cause the problems you're discussing. Usually it will not have much difference than regular 87 just a little more expensive. As for Sea-Foam, I like it and its nice to put half the bottle sucked thru a vacuum line going to the intake, and the rest of the bottle in the tank.

Also check the IAC valve. This can cause all sorts of weird idle problems such as low RPM or stalling out.

 

I am somewhat having the same issue. '04 5.7l Hemi 102K. Replaced a coil, cleaned fuel injectors, checked for vaccum leaks, and replaced spark plugs. I was getting several misfire codes previously. Now I have no codes and for the first few days it was working great. Now when I come to a stop the first run of the day, it stalls. Usually I can start it right back up and no stalling the rest of the day. Yesterday it stalled and I had to punp the gas pedal to get it to start. Today, stalled and started right back up. Truck used to idle at 650RPMs and now only idles at around 500. Other times I come to a stop the RPMs will drop to about 300-400 but immediately go back to 500. I'm thinking fuel pump, but I don't know for sure. Any ideas?

 

Before doing anything expensive like the fuel pump, check/replaced the TPS and IAC. Much easier to get to and much less expensive then the fuel pump.

And no, they wouldn't necessarily cause it to happen all the time. They can be temperamental.

 

Change the TPS and IAC. They are next to each other on the throttle body. Easy to change with a #25 torx. Had same idle and hesitation problem with wife's 06 4.7L with 81k miles. Just under 100 bucks and 20minutes, problem solved.

 

Thanks for the input. Once the snow stops I will replace both the tp sensor and the iac valve. Will let you know what happens. Thanks again.

Mark

 

Quick question. When i start it up and the abs, brake, oil temp, etc...lights come on, shouldnt the check engine light come on briefly as well? It does not and i was wondering what that would mean? There is a "chime" about 5 seconds after starting up the vehicle.

Thanks,

Mark