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Old 05-21-2014, 09:48 PM
Josh8loop Josh8loop is offline
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Join Date: Sep 2011
Location: Port St. Lucie, Florida
Posts: 39
I am having a similar issue. When I first bought the car I was getting 32MPG in town. Over the last year or so the fuel economy has been slipping to the point now where I'm at around 26MPG for the same type driving. No codes in the computer according to ScanGage. Power has always been lower than it should be as indicated by the 9 plus second 0-60 time.

I keep track of the fuel economy on so that helps in comparisons. Air, fuel filters, Glowplugs, thermostat(with temp sensor) have been changed. I cleaned the EGR valve, the MAF sensor, MAP sensor, and dielectrically greased most all electrical connectors under the hood in an attempt to maintain the vehicle and also to regain lost power & fuel economy. I even removed and reseated the fuses in the fuse box to ensure I didn't have any high resistance contacts there.

After reviewing the information online about how this injection control scheme works and the various sensor inputs I am wondering if I have a fuel temp sensor problem or perhaps an O2 sensor issue. Both those inputs help the vehicle decide how much fuel to use by way of adjusting fuel rail pressure and fuel injection duration. I am currently testing my fuel temp sensor which according to CDI literature should be a NTC(negative temp coefficient) type. Not sure what the resistance per temp spec on it is however.

I wonder if the OP has considered checking or replacing the fuel temp sensor or perhaps the O2(Lambda) sensor?

2005 E320 CDI

2002 VW Jetta TDI

Last edited by Josh8loop; 05-21-2014 at 10:10 PM.
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