this is odd to me. i get about 15-16 mpg city with my 3.9 v6. not worried about my mileage. but mine adles at 800ish warm and almost 900 cold like yours. i just thought it was right. is it not?

 

From what I understood 650 warm is right. My tach was off by about 150rpms though, according to my dad's timing light. With that in mind, mine was probably idling around 750ish warm, which is still too high.

 

now im worried

 

Worried about what? you get 15 mpg jeez!

 

easiest way to set the IAC counts:

1. Remove the air hat assembly.
2. Start truck and let it warm up to full operating temp. Note the idle speed in RPMs: this is the computer programmed target idle. The PCM will attempt to hold this idle using the IAC motor no matter what you do to the set screw.
3. With engine still running (BE CAREFUL) remove the PCV hose which will create a large vac leak.
4. The IAC will close completely to try to correct the idle surge. Wait about 3 seconds and unplug the IAC. The PCM will no longer be able to resist the set screw adjustments as the IAC is unplugged.
5. Slowly reinstall the PCV hose. If the engine stalls, open the TB blades a little bit via the set screw and restart the truck.
6. Adjust the TB blade set screw closed until the idle is about 125 RPMs under the PCM target idle.
7. Turn off truck and disconnect the negative battery terminal for about 30 seconds to reset the PCM. Plug the IAC back in.
OPTIONAL STEP: if you believe that adjusting the TPS voltage is important, you will need to readjust, as you have moved the set screw and changed the zero throttle voltage. You can read up on tweaking the TPS here:http://bionicdodge.com/Download/Spee...d%20Tricks.pdf

If you change the TPS voltage, reset the PCM. I have noticed a difference, others have noticed no perceivable change. YMMV

8. Restart the truck and let it idle for about 30 seconds. Take it for a test drive to verify everything is working correctly.

A scanner is the best way to verify RPMs and the IAC "counts." You're looking for 40-60 counts optimally.

 

My 318 only gets 10-13 MPG, debating on how hard I'm tromping on the Throttle, which is Depressing because my old truck with the 360 Got any wheres from 13-16 MPG.

 

here's an idea about your 10 mpg or less...take the led out of your foot! i understand you just want to feel the power of the 5.2 magnum (who doesn't?) but you certainly don't need to run it up higher than 3k rpm...unless your racing of course or towing. i can do all my accelerating onto a highway with no more than 2500 rpm and i get 14 to high 14's for mpg with my 5.9 3/4 ton. even towing our 24 ft boat or horse trailer i hardly get it past 3k rpm and it gets mid to high 13 mpg. and yeah if you want to figure out what your getting for mpg's for real, fill it completely up everytime and make sure you reset the trip everytime, then you'll be accurate.

 

It's not that loud. I just went through this last week in fact when testing mine. The only thing that you have to watch out for is a fire when doing this. Just run it in idle mode to test it out quick. Don't run it like that or, with the O2 unplugged dangling while you drive around. You'll know right away just from the idle sound. I sure did and, it was a no brainer that the CAT was spent.

Again, you just can't drive around like that with that port open as it is a fire hazard. If you place a heat shield around that port, then, take it for a ride. Just secure the O2 sensor up on top of the tranny to test it around the block.

 

Waiting on money to replace O2. I have isolated the sucking noise. When I turn off my A/C it magically disappears and runs smoother.

 

Now it seems the A/C only blows in defrost, no matter what position the switch is on. Having the A/C off does clear up the sucking noise. Now I'm beginning to believe there is a vacuum leak.