I swear I have a vacuum leak. I was looking around to try and find any hose issues. Didn't see any. Started her up. Rev and it only goes to 4500. I know that it's throwing a P0420. Would that actually cause limp mode?
I think that with no load on the motor/free rev it limits it at 4500rpm, how is it driving, if you get on it will it go over 4500????
Do you have the o2 cheater harnesses on? P0420 is catalytic converter efficiency code, could also be a bad o2 sensor giving the PCM a false reading.
I think I may have it mixed up with my old 05 Hemi, that had a 4500 limiter in park and "N", not sure if Dodge did it with these trucks, but I wouldn't want to free rev it over that anyway......
You definitely need to get o2 sims on the rear o2 sensors, but at least it sounds like your revving "problem" isn't really a problem at all.
Thanks for all the replies everyone. About the o2 problem... I do not have a sct. I need to get one. If I get the sct will I still need the sims?
No but you'll need to have good O2s there, they are just tuned out. Could very well be a front O2 acting up which fuel the engine correctly.