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02-12-2005, 08:08 PM | #1 |
Scooby Newbie
Member#: 44353
Join Date: Sep 2003
Location: Erie, Pa
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Car is running crappy/bad gas mileage..
I tried searching numerous times..but always came up with what Ive done already..
After starting the car on a cold morning the car will idle rough..and even after the car has been running long enough when I try to accelerate my car just bogs..then when it gets into the upper rpms comes alive. Also, my gas mileage has been poor..roughly 17-19 mpg on the highway..which is sad since my lifted Wrangler with 33s got that. I changed the plugs and wires, fuel filter, and air filter. I even checked the wires again to make sure one wasnt bad. I then ran some potent fuel injector cleaner through it that my work uses, and still nothing has fixed it. My CEL has come on a few times with misfires in 2 and 4. A mechanic at my work called a subaru tech he knew but he didnt know what to tell me. The response was that maybe the timing was off or the fuel injectors were clogged. Ive put up with it this long enough and really want to get this worked out before I start modding it.
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02-13-2005, 10:46 AM | #2 |
Scooby Specialist
Member#: 3198
Join Date: Dec 2000
Location: Portland, OR USA
Vehicle:2005 GT LTD Wagon Garnet Red |
Did this just start happening, out of the blue?
Things I'd try first: Reset the ECU - this is pretty much the first thing I do when having any trouble with engine idle/gas mileage - do a search if you don't know how to do this, lots of threads with instructions. If that doesn't help, I would guess either the electronic choke isn't working correctly, or the MAF is having problems. |
02-13-2005, 04:44 PM | #3 |
Scooby Newbie
Member#: 44353
Join Date: Sep 2003
Location: Erie, Pa
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I reset the ECU a while ago.. and it didnt cure the problem. One thing I forgot to mention was when I first test drove the car in sept. it was really sluggish, like it hadnt been driven hard in its life. Eventually after getting on it enough it seemed to have cleared up. I dont know if that would have affected anything..
I could try reseting the ECU again.. its worth a try |
02-13-2005, 04:52 PM | #4 |
NASIOC Supporter
Member#: 30669
Join Date: Dec 2002
Chapter/Region:
Tri-State
Location: USA, North NJ, 07456
Vehicle:1998 Legacy 2.5GT Silver Sleeper BK, 5MT |
What plugs did you use? Bosch Platinum suck in our cars, use NGK copper (look up a RS for the plug PN).
What wires did you use?, Bosch wires tend to suck in our cars. You have a 97, I assume it is a 2.5L? |
02-13-2005, 05:12 PM | #5 |
Scooby Newbie
Member#: 44353
Join Date: Sep 2003
Location: Erie, Pa
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I think I used autolite platnium plugs and autolite wires.. I found out about using copper plugs after I changed them but thought it wouldnt matter..Yeah its a 2.5
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02-13-2005, 07:20 PM | #6 |
Scooby Specialist
Member#: 3198
Join Date: Dec 2000
Location: Portland, OR USA
Vehicle:2005 GT LTD Wagon Garnet Red |
well, if you've already reset the ECU, I wouldn't do it again.
The cold-weather behaviour sounds like a choke issue, to me, but that wouldn't likely explain the misfire codes. |
02-13-2005, 09:26 PM | #7 |
Scooby Specialist
Member#: 66640
Join Date: Jul 2004
Chapter/Region:
Tri-State
Location: Rochester, NY
Vehicle:1997 Legacy Outback Glacier White |
Maybe your coilpack is going.
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02-14-2005, 01:30 PM | #8 |
Scooby Newbie
Member#: 11330
Join Date: Oct 2001
Location: Gresham, Or.
Vehicle:2003 WRX Silver |
Check your 02 sensor most likley item.
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02-14-2005, 04:19 PM | #9 |
Scooby Newbie
Member#: 44353
Join Date: Sep 2003
Location: Erie, Pa
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wouldnt a bad 02 sensor throw a CEL for that? The only CELs Ive had were for misfires...
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02-19-2005, 05:48 PM | #10 |
Scooby Newbie
Member#: 44353
Join Date: Sep 2003
Location: Erie, Pa
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Also, I occasionally smell fuel when driving around. Nothing is leaking from the tank ..
Ok the possibles: -O2 sensor (no codes thrown though) -Coil pack Anything else I should look for? Its getting annoying only getting 230 miles per 13-14 gallons |
02-19-2005, 07:44 PM | #11 |
Scooby Newbie
Member#: 75964
Join Date: Nov 2004
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im with the o2 sensor, maybe the distributor, same thing happpened with a friends car, replaced o2 sensor and distributor and it was fixed
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02-21-2005, 12:27 PM | #12 |
Scooby Newbie
Member#: 44353
Join Date: Sep 2003
Location: Erie, Pa
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Well I picked up a new o2 sensor so Im going to replace that tonight when I install my Borla header..
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02-21-2005, 12:45 PM | #13 |
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Join Date: Nov 2004
Chapter/Region:
NESIC
Location: Boston, MA
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Some easy to check/fix possibilities:
* check grounds (drkwtsn was having similar problems with his car - only intermittently - and turned out to be a bad ground connection). * MAF dirty (if your running a K&N type filter that has oil on it) - can be cleaned GENTLY with brake cleaner then onto the bigger stuff mostly mentioned here already... |
02-21-2005, 01:59 PM | #14 |
Scooby Newbie
Member#: 66222
Join Date: Jul 2004
Chapter/Region:
NESIC
Location: Saratoga Springs, NY
Vehicle:2000 Legacy '68 Spitfire |
Well, I just heard this on Cartalk 20 minutes ago. If your car is also taking longer than normal to heat up, your thermostat might busted. If it's turning the fan on too soon, then the engine isn't getting hot enough, gas not vaporizing correctly / pooling -> bad mileage. I think another sign they had was used oil smelling like gas.
This was an older Explorer they were talking about, but hey, ya never know! |
02-21-2005, 09:50 PM | #15 |
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Join Date: Sep 2003
Location: Erie, Pa
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Well I installed the header and new o2 sensor.. we'll see how the gas mileage goes.. I am going to do the grounding mod next to smooth things out. Also, a mechanic at my work pointed out that an injector may be clogged. Looks like I need to run some more fuel injector cleaner through it.
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02-22-2005, 08:24 AM | #16 |
Scooby Specialist
Member#: 55541
Join Date: Feb 2004
Chapter/Region:
MAIC
Location: BFE, Pennsylvania
Vehicle:05 325ciC 98 Legacy Wagon |
Don't forget, in the North, we get crappy gas in the winter. I went from getting 25-27 mpg, to 20-23. It also makes my cats smell really bad.
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02-22-2005, 09:19 AM | #17 | |
Scooby Specialist
Member#: 41012
Join Date: Aug 2003
Chapter/Region:
E. Canada
Vehicle:1998 Legacy L |
Quote:
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02-22-2005, 12:23 PM | #18 |
Scooby Newbie
Member#: 27677
Join Date: Oct 2002
Chapter/Region:
Tri-State
Location: Philly
Vehicle:2005 STI Crystal Gray |
JeffyP86 I am having the exact same problem as you. I have just replaced my spark plugs and wires, and run some fuel injector cleaner. I only got 204 miles from my last tank of gas. That is horrible, I normally get around 275-295. If you figure out what is causing this problem let me know.
-Jon- |
02-22-2005, 01:09 PM | #19 |
Scooby Newbie
Member#: 44353
Join Date: Sep 2003
Location: Erie, Pa
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I dont think its the gas..since its been doing this since I bought it (mid september 04). I guess we'll find out soon enough.
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02-22-2005, 05:57 PM | #20 |
Scooby Specialist
Member#: 59934
Join Date: Apr 2004
Vehicle:2005 Legacy GT Wagon Atlantic Blue |
Don't know how anything this radical can happen without throwing a CEL. The "obvious" would be O2 sensor. Anyone tried checking the temp sensor that tells the computer that the engine has heated up? Mine failed in the opposite direction - it thought the engine was always hot. I did get a CEL, but a restart always cleared it.
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02-23-2005, 01:36 PM | #21 |
Scooby Specialist
Member#: 32503
Join Date: Feb 2003
Chapter/Region:
TXIC
Location: Johnson City, TX
Vehicle:2011 Tribeca 1995 Legacy Wagon |
If you're running out of things to check and it's been doing it since you bought it, you might want to do a compression test to rule out anything serious internally. Those symptoms (rough idle, opposing cylinder misfires, and bad fuel economy) were all things I experienced when I bent some valves.
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