So "Freddy" the guy that Auto Zone recommended for some mechanical work plugged in his diagnosis tool into my Subaru computer, a 99 Outback with a 2.2 transplant engine.  It runs like a top but the mpg has been dropping from nearly 400 a tank to around 300.  Misfire codes on cylinder 2,3,4; 1 seems to be OK.  He says it could be wires or coil.  Any thoughts on where to go at this point, since electrical parts are usually not returnable?  Plugs are OK, with no abnormal wear.  

Start with wires. These motors are hard on them. Use NGK or subaru ideally.

 

I have some known good coils if it comes to that, but most likely it's wires.

Tuneup.

 

Wires, plugs, filters, PCV valve then lets see what happens.

Plugs and pcv valve are recent; wires are a couple years old.  I'll check air filter. many oil change places neglect those.  I haven't changed fuel filter in quite a while.  

Was the check engine light on before having it scanned? Has it ever blinked?

This has nothing to do with your misfire codes but, I saw a slight MPG increase of about 2-3 after changing the front and rear diff fluid. I used the Subaru STI diff fluid.

Hey guys, didn't wanna start a whole new thread for a semi-related question.

So everyone says use ONLY NGK Spark plugs. I replaced my plugs about 15K miles ago w/autolite coppers.

Been wondering why I get such crappy mileage and have done ALL the normal tuneup stuff. So i resolved to replace the plugs again w/NGKs.

So tell me if these platinum NGKs are the right ones please. I didn't wanna go with the iridium ones and didn't wanna use the base coppers. So i got these. Will it maybe improve my fuel economy?

By the way I have had no CELs.

If this doesn't then I will do the MSD coil mod.

I've been using the NGK platinum plugs, no problems there.

 

I doubt tranny fluid levels would affect mpg much..

 

Check engine light is on non stop due to map sensor issue.

 

The wires being a cause of misfire rings true but no obvious performance issue there.

 

Fuel injectors a possible issue, not sure what the diagnostic is on those.  

On a 95 just run V-power coppers.

If you want to use platinum, For waste spark systems you need to use NGK Laser double platinum. Single platinum plugs wear too quickly and will cause misfires on one bank.

 

Check engine light is on non stop due to map sensor issue.

Which code?

Edited April 1, 201511 yr by Fairtax4me

I did the MSD coil mod on my 97 OBS. I love it!! I also went with Magnecor wires. Better sound, MPG, and a little smoother acceleration. A couple of weeks ago it started missing and got codes. I thought it was MSD coil so I put the stock one back on. There was a noticeable loss in power. Turned out to be the pigtail, so I put the MSD back on and its all better now. So yea its a great little mod!! Do it!!

My vehicle has too many miles and years to install a high quality set of parts.  I ordered a set of $30 wires that Advance auto will get in today.  Many other parts stores and mechanics are very critical of Auto Zone's Duralast parts, some are better than others.  I'm thinking the dysfunction caliper was clamping up and leading to bad mileage among other things.  Misfire codes are a warning of less than ideal ignition.

Just as a footnote here, but Subarus are very picky about their electronic components, even spark plugs and wires.  Honestly, for the few dollars more vs. the price of a tank of gas and the improved reliability, go for the NGK plugs and wires.  They last longer and give better results. You don't want to "cheap out" here.

 

Emily

The '96 transplanted engine into the '99 Outback requires different spark plug wires than any of the '99 versions.  I'm sure that the Autolite's he had in stock will work just fine and I have no interest in expensive "ideal" wires especially since this may not have needed changing anyway, but was the recommended course of action. So if I had thrown $70 away instead of $37 it would have been doubly stupid.  I will see if this clears up the misfire code.

I just wanted to say I bought a set of subaru wires from the dealership for $31.00 so I am confused on why you would spend $37.00 on a cheap set that is known to have issues with with this engine.

I just wanted to say I bought a set of subaru wires from the dealership for $31.00 so I am confused on why you would spend $37.00 on a cheap set that is known to have issues with with this engine.

 

People don't realise that dealerships can be competitive with aftermarket these days, especially with the internet.

The '96 transplanted engine into the '99 Outback requires different spark plug wires than any of the '99 versions.  I'm sure that the Autolite's he had in stock will work just fine and I have no interest in expensive "ideal" wires especially since this may not have needed changing anyway, but was the recommended course of action. So if I had thrown $70 away instead of $37 it would have been doubly stupid.  I will see if this clears up the misfire code.

what nipper said +1.

I live in CT and use subarupartsforyou.com in Milford CT (Perkins dealership)

They happen to be local to me and their prices are very competitive.

Most people get turned off by the high prices of dealerships, especially their labor rates.  Last time I went to one, they did not have the part and couldn't order it on my 99 Outback.  

If you can post here, you can order from a dealership on line. No one ever said have them do the work, just get the proper parts from them.

Being a high mileage engine i would start my diagnostic with a compression test. I've seen more then a few people dump a bunch of money trying to get a slap wore out motor to run. . .

After confirming compression. . .

 

Fix the map issue! That could definitely cause a multi cylinder miss.

 

Also check for,

oil in the plug wells

YES, YES, YES on the correct NGK plug

Wires should have dielectric grease at plug and coil ends

 

Quality fuel, and a regular dose of seafoam goes a long to.

Thanks for the feedback.  Spark plug wires replacement and knock sensor and now the check engine light is finally out for the first time in over a year.

 

Also fixing the brake caliper means that possible drag there is gone.

 

Also with my replacement of the radiator a week and a half ago, by myself at the area Auto Zone lot(!) now I don't have bubbles in the radiator which were probably a result of the cracked radiator which none of the mechanics who looked at it suggested.  I should be getting top mpg now, but I haven't checked the compression, but lots more power now.

Most people get turned off by the high prices of dealerships, especially their labor rates.  Last time I went to one, they did not have the part and couldn't order it on my 99 Outback.  

 

Yeah I got turned off when they wanted something like $30 just for wiper blade refills not long after the Baja was introduced and had to order them so I went to an autopart store replaced the entire arms with Bosch.

 

Last time I went to the dealership was to buy a plastic screw cover for the tailgate trim for my Baja. Just that piece was $9.00 .

 

I need this piece that holds the weatherstripping in place. I haven't been back to the local dealer to see what this is going to cost. Since it's much smaller and in a less conspicous location, I thought I might try an autopaint store to see if there is something close that would fit it.

 

 

My low mpg continues.  I've had this 95 LS for about 1.5 years.  Mileage has also been low the entire time I've had it (about 12-14 mpg with mostly city driving).

Stock EJ22 with this work done in the last six months:

 

PCV valve

NGK copper plugs

NGK wires

Denso front O2 sensor

Fuel filter

Air filter

Timing belt

Clean MAF sensor (also tried swapping in a yard sensor...no change)

Trans flush (last summer)

Front/rear diff fluid (last summer)

 

I've had a P0441 come on a few times.  I have replaced a few pieces of vacuum hose and that seemed to fix it, but now it is back on again.  The mileage has been the same with or without the code.

 

I only have a basic code reader, so I can't get much info from OBDII.  I borrowed a friend's reader that has more functionality to see what I could see but couldn't make out much (limited info through OBDII because it is a 95?).

Looking for suggestions on how to identify and address the mileage issue.  

 

Does anyone know what info I should be able to get from OBDII with the right reader or using a cable/laptop/program?

I don't have the answers to those technical questions, but my mpg is back up to 25 or better.

The most common cause of poor mileage on these cars after worn plugs and bad wires are the engine coolant temperature sensor (the 2 wire one that talks to the ecu) and the knock sensor. The temperature sensor throws no code when it's going south, it simply tells the ecu the engine is cold. When the engine is cold it dumps more fuel to "warm" it up, which never happens so it keeps throwing more fuel than is needed at the motor. The knock sensor cam also fail without a code (they do sometimes throw codes but not always) when it starts to fail the ecu will pull timing and throw in more fuel to combat the knock.