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Unread 07-10-2012, 03:34 PM   #16
FujativeOCR
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Quote:
Originally Posted by TheSiltSurfer

What grade fuel are you using regular or mid grade? Curious of that would make a difference ? Might land a deal on a compass today unless fiancé wants to $pend on wrangler
87 always as recommended. 89 would be of no benefit in a low compression engine like this. 91/93 even less so.

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Unread 07-10-2012, 03:51 PM   #17
Gramps
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'Low is relative' but agreed on it's a waste of $$ to run higher octane than necessary.

Our compression ratios are 10.5:1.

The GM Ecotec 2.4L I4 VVT Compression Ratio is 8.75:1 because it also has an Eaton M90 Supercharger.

The Lexus Hybrid 2.4L in-line 4 double overhead cam with VVT has a 12.5 :1 compression ratio.
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Unread 07-10-2012, 04:10 PM   #18
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Have you tried running a bottle of Chevron Techron and giving it an Italian tune up? It might help blow off carbon deposits on the internals. Also would a failing O2 sensor cause something like this?
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Unread 07-10-2012, 04:52 PM   #19
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Good call on the 02 sensor. I've yet to have anything new enough, long enough, to have one that went out. When O2 sensors fail, they can't read rich and are slow to respond to changes. This translates into a rich mixture most of the time, which will cause your car to use more gas. Some of the newer computers will notice when an O2 sensor starts to wear out, but most will just keep on adding too much gas. When a car is getting poor mileage, the O2 sensor should be checked.

And yes too on the intake runners being carboned up. It could be. I think it may have to do if this was a gradual or over night change.
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Unread 07-10-2012, 05:42 PM   #20
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Quote:
Originally Posted by Gramps View Post
Good call on the 02 sensor. I've yet to have anything new enough, long enough, to have one that went out. When O2 sensors fail, they can't read rich and are slow to respond to changes. This translates into a rich mixture most of the time, which will cause your car to use more gas. Some of the newer computers will notice when an O2 sensor starts to wear out, but most will just keep on adding too much gas. When a car is getting poor mileage, the O2 sensor should be checked.

And yes too on the intake runners being carboned up. It could be. I think it may have to do if this was a gradual or over night change.
A failing or lazy O2 sensor will trip the MIL if it goes above 1.5 times the allowable emissions.

Just adding a cleaner to the gas tank will only clean the tops of the intake valves,worthless and seafoam is a terrible cleaner.
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Unread 07-10-2012, 09:37 PM   #21
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OE Spec plugs
Always 87 octane
Can't imagine the O2 sensor failing this early but who knows

Haven't had much time to fool with it lately but plan on trying a few things once I get off of work tomorrow and start my vacation days.
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Unread 07-10-2012, 09:38 PM   #22
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Quote:
Originally Posted by tjkj2002 View Post
seafoam is a terrible cleaner.
Not trying to derail my own thread but...how do you figure Seafoam is terrible?
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Unread 07-14-2012, 11:41 AM   #23
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I got 185,000mi on my Compass. It's highway miles. I use synthetic motor oil and currently have Royal Purple sychromax in my transmission. I still to this day get better mileage than the windoe sticker. I seldom ever average less than 30 MPG's somtimes 32 or 33. I usually need to fill up every couple of days. Recently I was on a road trip that was interstate driving. there was alot of construction on speed was limited to 55MPH in alot of places. I had the trip set. I drove 384mi and the tank of gas. I stopped when the low fuel light came on. I filled up and topped off and put 11.6 gal. of gas in it.

384mi. 11.6 gal. gas = 33.10 MPG
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Unread 07-14-2012, 02:17 PM   #24
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Ive never got more than 240 miles on a tank.
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Unread 07-14-2012, 09:22 PM   #25
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Cactus Jack,
Is your Compass 4X4? Mine started getting really terrible milage around 30,000 and has never recovered (80,000 now). Mine is partly due to pair of bad wheel speed sensors & hubs on the rear as well as a bad right rear drive shaft (one hub replaced, saving up for other one & shaft ). It isn't throwing out warning lights like it once did but everytime you make a turn you can feel the entire Jeep balk and shimmy and then correct itself. Sometimes it still wants to drive like I have my foot on the brakes. Just to throw that out there for you. If yours is 2-wheel drive then I simply wore out my fingers typing all this, LOL!!! Hope it helps
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Unread 07-18-2012, 09:04 AM   #26
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2011 Compass 4x4. I have about 33k on it. I have the tires (oem) at 40 psi on the dash pressure indicator. I use synthetic oil. Accelerating from stops I try to never let the tach get above 2000 rpm. I regularly get 30+ on long trips and 23-25 or so around town.
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Unread 07-18-2012, 09:27 AM   #27
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Do you guys have manual or the fancy automatic? I tested the automatic and hated it... didn't feel like it would be safe in NJ where we have no acceleration lanes to speak of, so i stuck with the 5-speed.

I average like 22 according to the on-board computer with a ratio of about 60/40 highway/city, but on the highway it goes up to about 28, which has been consistent since I got it. Also seems much higher on cruise control, if there is actually light enough traffic to use it. Just paid it off at 51k and am planning to keep it and add a used JK to the mix, also a 6-speed.
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Unread 07-18-2012, 10:06 AM   #28
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I have the "fancy" automatic. 16 city w/AC, 17 city normal, 23 highway.
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Unread 07-25-2012, 09:44 AM   #29
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Welp, after a round trip to florida I ended up averaging about 23mpg. All interstate miles and driving moderately fast. Also had a luggage bag on top. I guess I can manage that. I'll be paying it off and trading it for a GC here soon anyway
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