I was hoping to get some help before I start replacing parts.
2005 Rumble Bee 4x4 5.7L Hemi. 90,000 miles.
The truck runs extremely well, but the odd time, like every 10 days or so it goes into a rough idle, RPM varies, engine light starts flashing. The next day it will run mint again.
I changed the plugs (the old ones looked great), air filter, the Temp Sensor in the air box, cleaned out the throttle body inside and out. I did this about 10 days ago so I figured whatever it was went away.
Today it acted up today and I checked the codes:
P0300 - Multiple Cylinder Misfire
P0172 - Fuel System Rich
P0132 - O2 Sensor High
I was doing some reading on line and some guys have been having issues with broken valve springs with these symptoms, but I don't think the truck would run perfect most of the time?
Today was also a damp day, truck was started up fine, ran well. After a short drive and a restart that is when it started acting up.
Obviously I was thinking of replacing the O2 sensor but would a bad O2 sensor cause a misfire?
Thanks!
Dave
If it drives the system full lean, Yes, Its basically starving the engine.
A few years back I had a 5.7 Hemi Charger with your exact symptoms. Only faults in it was a misfire code.
After lots of trial and error , cking for fuel pressure drops, possible plug wire shorting , Even ckd compression and it was fine. Same deal, it ran fine sometimes,,sometimes not.
I finally decided to pull the valve covers off for a look see. Found a broken valve spring right bank . Fixed it and never heard from the cars owner again
