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What's your gas mileage?


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Hey everybody! Been awhile since I've been on here as I usually only check when I have an issue :lol:

 

Anyways so my car is running rich, it has for a bit now and I'm very shortly going to buy the msd coil pack upgrade to see if that might help burn some more of this unburned fuel. It might not but for how cheap it is why not try.

 

Now given I do drive the car kind of hard and I know that kills gas mileage so I'm not too worried about what I'm getting but basically if I fill up and before the next fill up I get about 200 miles per tank. Does that seem about right to you guys or should I be looking into what's making it so bad? And if it is so bad where should I start?

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If I am running the AC, I get about 23 mpg combined, without around 26-27 combined. I usually get about 300 miles from Full to 1/8 tank but my gas gauge is wrong because it only takes around 12 gallons to fill it up when the needle is on E.
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An old O2 sensor can let the car run too rich.

 

An exhaust leak upstream of the O2 sensor can let air into the exhaust between exhast pulses. The O2 sensor will see this and tell the computer that the car is super lean put in tons more gas.

 

I'm sure some more ideas will come along.

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Yeah got the whole new exhaust done all professionally with the engine refresh including O2 sensors. My MAF sensor has the pen on it from a junkyard and I have cleaned it with that spray stuff but what are the chances it can still be that?
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It was a legitimate maf cleaner. Cats are brand new, exhaust is leak free. Vacuum lining was recently gone over, O2 sensors replaced. That's why I'm so confused what's wrong cuz I've done almost everything.

 

If it's any help I do lose a bit of power low end, the car seems to hesitate and lurch around a bit with the pedal to the floor at 3k rpm

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Timing belt has jumped. Spark and injector timing out of line. VE off from valve timing.

 

When mine was in this state I could use a 1/4 tank in about 40 minutes. It idled rough, and broke up bad at 3450 rpm. But was fine cruising. If you had less jump than me I bet it wouldn't give any codes at all. (I would get misfire at idle if I let it idle long enough)

 

Pull the accessory belts and timing covers and pull it around to the timing marks. That part is easy. Getting it back in line... Well, I don't consider it hard, but I guess I'm a serious hobbyist now. Beginners may think it difficult or scary. There is certainly lots of info here about changing the timing belt which would all apply to correcting its position.

 

I'd add that when you put the timing covers back on they go a hair past finger tight. They are plastic. You're not holding a bridge up with them. Probably 80% of the ones I see are broken from over torque.

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So being that I only get 180 miles before I fill up, what do you guys think I should look into

 

how many gallons are you getting when you fill up? i get about 330 to 340 a tank, usually get about 14 gallons when i fill up. that is on my ej22 5mt outback, my FWD only wagon with ej22 gets about 27 usually, and my GT sedan ej25 gets roughly 19-25 depending how i drive it. but if driven normally i can get about 350-400 out of a tank, filling up with 15 gallons.

 

as for what to look for, depends on how your car sounds, runs and feels. id probably start at the o2 sensors and the fuel delivery

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The timing was also done multiple times and it's for sure spot on, had to do it multiple times due to a bolt backing out behind the intake cam sprocket so the timing is for sure good

 

I am getting about 13 gallons usually (not sure how large my tank is tbh) but I drive a 2.5 sedan and drive it pretty aggressively. After about a week I total out 180 miles before I'm back close to empty. The car runs and sounds great except for the loss of power in a very small rpm range. It feels like it's over-fueling the hell out of its self pretty much.

 

As for the O2 they are for sure good reading well, and fuel delivery I took the car to a shop and had them run this cleaning thing they promote and it just cleans everything with an acid flush through the car. It ended up working well because the injectors orafaces were extremely clear upon inspection. Is there a chance an injector is leaking?

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There is a chance. I don't think it's common. It's also possible that while they had the injectors out the o-rings got damaged and it's just dumping fuel in. (That would be for side feed injectors which I think is what a 97 2.5 has)

 

Also, do you have an intake mod? If that is done wrong it can allow air to resonate back and forth in the intake plumbing so the MAF reads *a lot* more air than is real, so the computer seriously overfuels. That tends to happen at a very narrow rpm range.

 

How does the inside of your tail pipe look?

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The intake is factory, I had to replace the cold air intake with the factory box setup with the little bowl thingy in the fender when I first got the car, just not a fan of cold air intake with how often I'm offloading

 

The injectors sit kinda like diagonally in, there's ports in the intake manifold that they plug into right where the intake manifold meets the block so I'm not positive what kind those are

 

And the tail pipe is very black and full of soot and unburned fuel

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Side feed injectors poke down into a larger fuel rail and the bottom tips come out the bottom of the fuel rail and go into the intake. Top feed injectors have a smaller fuel rail at the very top of the injectors. Side feeds are almost completely hidden inside the fuel rail casting. They have an upper o-ring that keeps fuel from leaking into the engine bay, and a smaller lower o-ring that keeps fuel from leaking into the intake. The lower is also easier to munge when you're putting the injector back in.

 

I'm relatively sure you have side feed, but I'm more interrested in *my* Subarus than I am in all of them in general, so I don't have it memorized when this or that feature changed.

 

The things that I've personally had cuase serious rich where leaking exhaust right at the head (sounds like a bad valve lifter, tap...tap...tap...), jumped cam timing, and plugged cats caused by one or both of the previous two problems.

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Is the snorkus completely intact? There is hard evidence that deleting anything forward of the connection of the air tube to the air box will cause rich running condition.

 

You need to have the complete airbox (upper and lower portion), snorkus box (in the fender), and the air tube that mounts to the radiator support and goes into the side of the fender.

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Given the engine is sort of mismatched parts with a 98 ej25 but there is only 1 O-ring that we had to replace upon the rebuild so I think it's top feed? I'm not too sure, you can see the injectors pretty clearly tho

 

Anyways I do have the snorkus installed, I know that's one of the pieces I had to replace when I very first bought the car but I have not checked if it's sealed still or not since then, just kind of assumed it would stay together but I suppose it's completely likely it has separated. I shall have to take a look when I get some time

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My car is actually getting about the same fuel mileage as you! I just did headgaskets timing belt etc on a new used engine. Now that I'm driving I get about 200 miles to a full tank. I checked my check engine light today tho and found I had an 02 sensor code. And also found the previous owner actually removed the 02 sensor by the looks of it.
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Yeah O2 seems to be a really big culprit with these but the confusing part is a I just dropped 200 on those bad boys along with a couple hundred on the exhaust system so there's no leaks allowing air in either
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Hmm. They're real O2s, not generics right? I guess we're getting to weird stuff like pulling the connectors leading from O2 to computer one by one and cleaning them out. If you go that route you should probably ohm the run before to see if it has measureable resistance and then cleaning and checking again to see if it's better. It sure sounds like there is a problem, but you've done most of the things to fix it already.
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Yeah the O2 cost me about 200 just to get a hold of both of those puppies. So their the better option that O'Reilly provides.

 

Update though, I was just in the McDonald's drive through and my idle dipped a little low (which it does occasionally but never out of the ecu parameter) but this dropped way too low and the car started to idle very rough and giving it gas while staying stationary just to try and keep it alive was extremely rough and stuttery, hard to explain but it was shaking the car slightly. Almost like a misfire? But then I revved it higher, above 3k (which I'll admit is embarrassing with such loud headers in a drive through) but then after that rev it started idling just find and everything was all good

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It sounds like the O2 sensors for sure. When they start to go bad, you can ignore them for about 6 months and the CEL will come and go, but your gas mileage will get worse and worse until the car runs so lean that it'll stall out at low speeds without load, such as coasting in a drive thru or coming to a stop sign. Luckily they are very easy to replace, just get the specialty socket and a few regular socket extensions and flexible/u-joint extensions
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