[Hovo_K]

2006 SRT8, 120k miles.

Sometimes when I start up my car the RPM's goes up and down from between 650-1000 constantly. It doesn't affect performance and the car drives normally but when the RPM's does surge like that the car will randomly flash the ETC light while driving and simply pulling over and turning it off and on fixes the light issue and sometimes the RPM issue as well. It doesn't seem to have a preference when it will flash the ETC light as it's done it while braking, cruising, and pressing the throttle. It doesn't throw a CEL or any codes. Dealer and Mechanic have no idea.

Im not sure what the problem could be, anyone have any ideas what I can check/replace?

So far iv cleaned my throttle body, recalibrated the throttle body by disconnecting it, and seafoam in the gas. I've ordered a PVC valve and MAP sensor since those are fairly cheap.

 

[magnuman]

2006 SRT8, 120k miles.

Sometimes when I start up my car the RPM's goes up and down from between 650-1000 constantly. It doesn't affect performance and the car drives normally but when the RPM's does surge like that the car will randomly flash the ETC light while driving and simply pulling over and turning it off and on fixes the light issue and sometimes the RPM issue as well. It doesn't seem to have a preference when it will flash the ETC light as it's done it while braking, cruising, and pressing the throttle. It doesn't throw a CEL or any codes. Dealer and Mechanic have no idea.

Im not sure what the problem could be, anyone have any ideas what I can check/replace?

So far iv cleaned my throttle body, recalibrated the throttle body by disconnecting it, and seafoam in the gas. I've ordered a PVC valve and MAP sensor since those are fairly cheap.

How did you clean the throttle body...complete procedure and type of cleaner? You can't "recalibrate the throttle body without a relatively advanced diagnostic scanner that has this recalibration routine. Neither the PCV Valve or the MAP Sensor will likely cause this problem. I recommend you put an advanced scanner on it and see if you can catch some freeze frame or live data so you can see what might be going on. Sounds to me like a throttle body issue or maybe an (Evaporative) Purge System problem. A good scanner can check the components of this system and also do a throttle follower test on the TB.

 

[GordonFreeman]

On my 2005 5.7 I had a weird low RPM/low throttle surge. I replaced the EGR valve and the surging went away.

 

[Hovo_K]

How did you clean the throttle body...complete procedure and type of cleaner? You can't "recalibrate the throttle body without a relatively advanced diagnostic scanner that has this recalibration routine. Neither the PCV Valve or the MAP Sensor will likely cause this problem. I recommend you put an advanced scanner on it and see if you can catch some freeze frame or live data so you can see what might be going on. Sounds to me like a throttle body issue or maybe an (Evaporative) Purge System problem. A good scanner can check the components of this system and also do a throttle follower test on the TB.

I just sprayed some CRC throttle cleaner on one of those blue towels and just scrubbed the inside of the TB and manually pushed the plate in to get inside. l'll see if I get an advanced scanner and see what that shows

 

[magnuman]

On my 2005 5.7 I had a weird low RPM/low throttle surge. I replaced the EGR valve and the surging went away.

This is true, that these are some of the symptoms of a bad (or going bad) EGR Valve but, his is doing this when the engine is cold or warm (EGR is inactive unless stuck when cold),.and also randomly. Because the ETC light is flashing periodically and he's messed with it (even though it was apparently doing it before he did), that's the first place I'd look. If any of that cleaner got into the electronics, it could have done some damage. It certainly would not be the first time this has happened. I think I'd start with an advanced scanner and do the relearn and follower tests first and go from there. With an advanced scanner, you can also check the EGR valve and even functionally check its operation at the various pintle positions.

On yours, you were getting EGR and O2 related DTC's and you were right to change the Valve because you had almost all of the symptoms of a bad valve.. At 205K on the vehicle, if the O2's have never been changed, I'd probably change them, if for no other reason, because of their age and miles. O2 Sensors tend to wear out like spark plugs.....slowly and tend to bias toward the rich side, adversely affecting fuel economy and also become "lazy" and not as responsive to PCM commands as ones that are working properly. A good scanner will also allow you to check the O2 crosscount ranges and fuel trims to see if they are within tolerance..Another clue to their condition would be the kind of fuel economy you're getting. If it's lower than it should be for the type of driving you do, for sure give them a look.