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Old 02-12-2005, 08:08 PM   #1
JeffyP86
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Default 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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Old 02-13-2005, 10:46 AM   #2
gavin
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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.
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Old 02-13-2005, 04:44 PM   #3
JeffyP86
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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
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Old 02-13-2005, 04:52 PM   #4
Charlie-III
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1998 Legacy 2.5GT
Silver Sleeper BK, 5MT

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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?
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Old 02-13-2005, 05:12 PM   #5
JeffyP86
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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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Old 02-13-2005, 07:20 PM   #6
gavin
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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.
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Old 02-13-2005, 09:26 PM   #7
Al_Smokemcrack
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Maybe your coilpack is going.
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Old 02-14-2005, 01:30 PM   #8
Kent
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Check your 02 sensor most likley item.
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Old 02-14-2005, 04:19 PM   #9
JeffyP86
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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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Old 02-19-2005, 05:48 PM   #10
JeffyP86
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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
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Old 02-19-2005, 07:44 PM   #11
Legacy2
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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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Old 02-21-2005, 12:27 PM   #12
JeffyP86
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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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Old 02-21-2005, 12:45 PM   #13
Leadfoot77
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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...
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Old 02-21-2005, 01:59 PM   #14
TRH_legacy2k
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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!
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Old 02-21-2005, 09:50 PM   #15
JeffyP86
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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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Old 02-22-2005, 08:24 AM   #16
styng88
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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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Old 02-22-2005, 09:19 AM   #17
sha_zapple
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Quote:
Originally Posted by styng88
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.
Im getting the same thing. I figured my cat was just going bad, but I guess its just a cold winter type thing.
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Old 02-22-2005, 12:23 PM   #18
crazex
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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-
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Old 02-22-2005, 01:09 PM   #19
JeffyP86
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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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Old 02-22-2005, 05:57 PM   #20
rogerd
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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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Old 02-23-2005, 01:36 PM   #21
jey
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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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