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Old 05-25-2013, 08:57 PM   #1
AmericaOverland's Avatar
Join Date: May 2011
Location: On the road in Texas
Posts: 684
That rum-rum noise...

Hey guys,

I had my PCM changed out (covered under federal emissions warranty!) two days ago, and I noticed since then that it has been idling VERY smoothly, whereas before, it would jitter a bit between 550 and 800. Also, when I would be going fast enough for the automatic to shift into the overdrive gear around 45 MPH and drop the RPMs down to about 1500, you would get that beautiful, low "rum-rum" sound. Since the PCM change-out, that rum-rum is gone, and you get a smooth, stable low ruuuuuuum sound that gradually goes away as it gets up in speed. What kind of problem did this indicate? I didn't get all the codes that the PCM was registering, but the ones I could see from the odometer was P0031, 37, 51, and 57, which point specifically to the oxy sensors. I immediately noticed the sound changes, before the tires got changed out today for BFG All-Terrain T/A KO tires.

Edit: black-side out.

2005 Jeep Wrangler Unlimited (LJ), silver w/black top auto 4WD, two-part Jeep Sleeper - Scout Recovery Vehicle

1977 International Harvester Scout II, red w/white top manual 4WD - Jeep Recovery Vehicle
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