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Old 05-31-2011, 01:49 PM
06sport88 06sport88 is offline
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Join Date: May 2011
Posts: 2
Default 06 mileage drop after spark plug changes, no codes, no leaks, help???

I have an 06 4.0 sport ranger that has had a drop in gas mileage & power after some tuning up. No codes are thrown.

Tuneup was replacing spark plugs & seafoaming (1/3 in gas, 1/3 in oil, 1/3 in brake booster hose).

MPG calculated every single tank by starting with a 0 mileage trip meter, filling up & diving the trip mileage by gallons of gas. The very next tank after the tuneup resulted in a 3 MPG drop, every tank thereafter continued with the 3 MPG drop.

Diagnostic Info:
- No codes
- Smoke test showed no leaks

Things done to try and fix problem:
- Spark plug changes (tried different motorcraft plugs, then autolite plugs, then just had the dealership do the change)
- Changed oil & filter (a few times)
- Changed fuel filter
- Cleaned MAF
- Cleaned IAC
- Cleaned throttle body
- Cleaned EGR
- Replaced front O2 sensors

I'm running out of ideas. Help?
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  #2  
Old 05-31-2011, 03:01 PM
Badmotorfinger1 Badmotorfinger1 is offline
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Join Date: Jan 2011
Posts: 183
Default Re: 06 mileage drop after spark plug changes, no codes, no leaks, help???

Try disconnecting the battery long enough to reset the ECM (I usually do this overnight) and see if that helps.
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  #3  
Old 05-31-2011, 04:10 PM
06sport88 06sport88 is offline
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Default Re: 06 mileage drop after spark plug changes, no codes, no leaks, help???

Quote:
Originally Posted by Badmotorfinger1 View Post
Try disconnecting the battery long enough to reset the ECM (I usually do this overnight) and see if that helps.
I reset the ECM after making any changes or cleaning any parts.
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