Fuel mileage dropped about 20%??
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Cadillac SRX First Generation Forum - 2004 - 2009 Discussion, Fuel mileage dropped about 20%?? in Cadillac SRX Forums; Hi, I'm fairly new to this forum but, I have a couple of questions. I bought a 2006 SRX with ...
  1. #1
    bubba783 is offline Cadillac Owners Member
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    Fuel mileage dropped about 20%??

    Hi, I'm fairly new to this forum but, I have a couple of questions. I bought a 2006 SRX with approx. 40K miles on it about a year ago. I have always checked my mileage at most every tank of gas and noticed this car in my first couple of months owning it got approx 26mpg on the highway. I had a check engine light light up and it was determined that a 'cannister vent solenoid' was the culprit. This was replaced and from then on I noticed that my mileage had fallen to about 21mpg at best. Could replacing this solenoid make this big a change in my mileage?

    2nd question: I've noticed that when I'm driving at speed (above 35-40mph) when I let off the accelerator it feels like I've put the brakes on. The car slows down very fast. Is this also normal? Could the two problems be related? One other thing, I read from other posts that while driving at highway speeds sometimes that a few of you move the gear selector over to manual to keep the trans from shifting down too often via the cruise control. Would this just be 'moving the selector over to the right, or also to the right and UP? Any help from any of he experts would be greatly appreciated.

    Thanks, Bubba

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    carguy2006 is offline Cadillac Owners Member
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    Re: Fuel mileage dropped about 20%??

    HI bubba783, had the same light and it was determined that the 'cannister vent solenoid' was bad. My 08 V6 always gets ~21/22 on the highway, before and after solenoid was replaced. I read that dealers are reprogramming/detuning the SRX during maint repairs to reduce chance of engine/transmission repairs. I never noticed any change in mine following any repair work.

    Re the manual mode on the transmission, move selector to the right and the indicator in the instrument cluster should should show "5" or 5th gear. In this mode you can then move the selector forward or back to up or down shift as needed.

  4. #3
    bubba783 is offline Cadillac Owners Member
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    Re: Fuel mileage dropped about 20%??

    Thanks carguy2006. I didn't think I was that bad at math but, evidently I am... ; ) Maybe we just had a good day when we were'nt driving too fast (maybe 60-65) and had a tailwind. This is my wife's car and she is EXTREMELY satisfied with the car overall except for the mpg, especially in the city. She never keeps track of it, she just fills it up and goes.

    RE the shifter question. So, just moving it to the right will keep the trans from downshifting on 'not so steep' hills most of the time? This is my first Cadillac and my first time with this type of shifter. I've owned performance cars in the past (1995 Impala SS, 1972 Chevelle and currently a 1991 Corvette 6-speed). I just thought this shifter was just for use when I needed to 'feel the power' or for not wanting the car to shift unless I told it to like, rocking it when stuck in snow or mud. Since mine is an'06, when I move the shifter to the right, will I still see the shift position on the instrument cluster? I don't recall seeing the position any other time. Or maybe I'm just not paying attention... Anyway, thanks for the reply. Hope this response wasn't too 'wordy'..

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    PJ1520 is offline Cadillac Owners Connoisseur
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    Re: Fuel mileage dropped about 20%??

    Yes, when the shifter is moved to the right side manual mode position, the gear you are in will appear in the cluster. The transmission will not upshift to a higher gear until adequate speed has been reached, to prevent lugging. In that scenario, the gear you are in will just blink on and off.

    There is also a safety feature that prevents manual downshifts that will over-rev the engine beyond the redline as well.

    On my 07, which has the six speed, in automatic mode the transmission will upshift into 6th at about 45 mph if the car is not under load.

    Which engine do you have? At an uninterrupted 60-65mph on cruise control, over an extended drive (over 50 miles), you should be able to attain the EPA rating of 23 mpg highway. Above that you are lucky!

    PJ

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    Professor Wizard is offline Cadillac Owners Connoisseur
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    Re: Fuel mileage dropped about 20%??

    My V6 gets 15 / 19.

    Before the Timing Chain replacement it got 17 / 23.

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    PJ1520 is offline Cadillac Owners Connoisseur
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    Re: Fuel mileage dropped about 20%??

    PROF.........what do you think caused that decline in fuel mileage? Different or new timing chains can't negatively affect fuel mileage like that, can they? Ouch!!!!!!!

    PJ

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    dkozloski's Avatar
    dkozloski is offline Cadillac Owners 10000+ Posts
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    Re: Fuel mileage dropped about 20%??

    Outside airtemps are one of the larger milage factors. During warmup the fuel mixture is determined by lookup tables rather than closed loop operation using the 02 sensors. The colder it gets the longer this takes. In extreme cold temps(-40F) 10 MPG or worse can be experienced. All the milage gripes occur in the spring and the fall when the weather changes.
    Don't mess with Binky Bear!


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    PJ1520 is offline Cadillac Owners Connoisseur
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    Re: Fuel mileage dropped about 20%??

    Quote Originally Posted by dkozloski View Post
    Outside airtemps are one of the larger milage factors. During warmup the fuel mixture is determined by lookup tables rather than closed loop operation using the 02 sensors. The colder it gets the longer this takes. In extreme cold temps(-40F) 10 MPG or worse can be experienced. All the milage gripes occur in the spring and the fall when the weather changes.
    Yes, but these are highway mileage figures, once the engine has reached operating temperatures. Not short hop, city mileage figures. Warmups and reformulated Winter gasoline with a higher ethanol content might come into play, but not in PROF's case.

    PJ

  10. #9
    08SRX's Avatar
    08SRX is offline Cadillac Owners Enthusiast
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    Re: Fuel mileage dropped about 20%??

    Quote Originally Posted by PJ1520 View Post
    Yes, but these are highway mileage figures, once the engine has reached operating temperatures. Not short hop, city mileage figures. Warmups and reformulated Winter gasoline with a higher ethanol content might come into play, but not in PROF's case.

    PJ
    Good point on the ethanol - this is very common in the Midwest. Ethanol does not have the same energy has gasoline and so you end up using more fuel to travel the same distance. Pumps may typically have as much as 15% ethanol blended in.

  11. #10
    bubba783 is offline Cadillac Owners Member
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    Re: Fuel mileage dropped about 20%??

    pj1520, Thanks for the input. I have the 3.6 V6 in mine. Plenty of power when I need it but, the MPG is a little disappointing. BTW: any thoughts on the 2nd question I had? When I let off of the accelerator it feels like the brakes are being applied. Is this normal? And also, as far a MPG is concerned, would deactivating the 'Stabilatrac" feature produce anymore MPG?

    Thanks again.

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