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2003 DeVille DTS
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228 Posts
Discussion Starter · #1 ·
I'm getting about 21-22mpg hwy.
I've seen some chatter about the plenum, could someone sum it up for me?
What/where is it? How to tell if it's failed/failing? How hard to replace? How likely it's causing low mpg? what else to look for, re: mpg?

Thanks
KD in NH, (w/ newly arrived 03 DTS)
 

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13,969 Posts
edit: the illustrations in this post are for 2000+ NorthStar engines (see post#3 for pre-2000 illustration)



#525

often cracks along the bottom side (as seen in this picture below)

 

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HOWEVER

I just noticed that you have a pre-2000 engine listed in your profile (which doesn't have a plenum)

the illustration above is for a 2000+ engine

here's the similar illustration for pre-2000 so you can see the difference



so if you're talking about your new '03 reference my first post, if you're talking about your '98 reference this illustration
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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73,464 Posts
Double post.......................
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Not sure which car he's talking about - the 1998 or the newly arrived 2003. Two very, very different engines, as Rippy has posted.

OP, You need to pull your Diagnostic Trouble Codes from the car's (either one) built in code scanner/reader. it's all done with either the HVAC controls or the dash DIC control buttons.

The DTS should get about 24.5 long haul highway. 21,22,23 long term average in a suburban/highway environment.
 

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2003 DeVille DTS
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228 Posts
Discussion Starter · #8 ·
Thanks, I updated my profile to the '03 DTS.
The longest haul measured so far is 2 day's commuting, ~ 240 miles highway, 72mph, 21.5mpg, anything else has been mixed driving.
Not much of a long haul, but I have no cross-country trips scheduled....

Thanks again; that link is great too.
 

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2010 DTS
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88,155 Posts
Have you checked for a leaky FPR? That said, your mileage doesn't sound to far out of line for a DTS.
 
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