Since I didn't see this anywhere online I thought I would post this.

I have been on a probably futile never ending quest to improve MPG (and oil consumption). But one of the symptoms of a bad purge valve can be bad mpg, or so I read. So since the new mopar part on eBay was 25 bucks or less and the job seemed simple enough I decided to replace mine. Mopar 4891739AA




Instead of mounting this in a normal location like other 5.7 Hemi engines, Chrysler put it way in the back under the cowl near the firewall area next to the brake booster system. NO this is not my nice clean engine bay LOL.


After barely reaching it I simply pulled the top hose off the throttle body. Then removed the unit itself from a small mounting bracket by pulling it forward towards the front of the vehicle. I was able to get the wire harness off with a screw driver moving over the red tab and squeezing it out.

Then worked on the fuel hose quick connect thingie. Not sure what its called. Has a blue plastic tab just visible along the top. Pinched the plastic together and wiggled/pulled the part out (with the plastic tab sill attached to the part to be reused on the new purge valve pump / solenoid).

Hooked up new one in reverse order. Will update if it actually helps anything. But I figured it was worth trying since it's so cheap.

 

Definitely keep us posted. Been thinking about swapping this myself.

 

Forgot to update. I haven't been keeping as close a tabs on my oil consumption as I intended. But I have noticed less of the white stuff in the top of the oil cap and possibly less oil consumption. Really wish I kept track better. Could be anecdotal. Plus the temperatures have increased outside so that would limit moisture at the top of the cap anyway. I also replaced the lost oil I had last time with Marvel Mystery oil it seems to have remained relatively steady since then. Hardly a controlled experiment but thought I would update. No real change in MPG however.

 

Did you change the PCV valve also and running 5-20W oil?

 

Yes new mopar pcv and Mobil 1 5w20

 

Update: No noticeable improvement in MPG with the vapor valve.

Interesting anecdotal evidence tonight of an improvement. I originally bought a new IAC or air charge temperature sensor almost right when I bought it. Then eventually bought a cold air intake. I noticed on the OEM that the sensor I bought from Autozone the basic Duralast line fit loosely in the OEM instake housing. But still stayed in there. So I left it that way. I read online that iac's might not like cold air intakes. So....I swapped the OEM intake manifold box back on there and went back to a fram extra guard air filter. Didn't notice much besides that it was quieter. No big mpg gain.

I ordered an OEM mopar IAC sensor and installed it tonight which fit much more snuggly....it was only one short test. But after resetting the MPG readout I cruised at 74/75. A speed I normally struggled to get 16 only 17 after many many hours straight of driving. On my initial test with the new OEM mopar air charge sensor I was at 18.5 mph at 74/75. Might be a fluke but will be watching to see if it stays that way. I've also been running the 87 octane diablo tune the past 6 months or so (with the 15.5/16 mpg at 74/75mph) So I'm optimistic this combo might be the best bet, back to mostly stock. But we'll see long term. Wondering if I should try the intake again with the mopar sensor.

Later Edit: yeah might have been a fluke getting that 18 at 75. Might be possible but would require a longer run than my test.