Idle Issues

[Lawsonmh15]

OK. Well, welcome to the board. Now that's been established, I have a 99 Legacy SUS with an issue that began with the advent of winter. The issue is this. Upon cold start, it idles at about 1200. Put in gear, drops to 800.

NOW. It SHOULD drop to it's normal operating idle (400-450), however, it ONLY drops after I reach normal operating temp AND come to a COMPLETE stop for 4-5 seconds. The problem is that the gas mileage becomes a joke. Not only do I have to warm up before getting on the hwy (a few blocks) but until it does, It just dumps more fuel than can be combusted. Good thing I use semi-syn.

At any rate. Nobody has been able to figure this out yet. Cleaned IACV w/ SeaFoam, replaced all vac hoses...

To my knowledge, there has only been one other person on the USMB board who has either noticed, or had this issue. He's replaced the IACV, Engine Coolant Temp Sensor. I've replaced the MAF. WTF!!!

PLEASE HELP.

[Plays_with_Toys]

Automatic or manual? The thing of it is, when your engine is cold (in winter), it will remain on the rich cycle until it reaches operating temperature, not until you put it in gear. The rich cycle is there to speed up warming the engine. I don't know why the gas mileage would go down, but seeing as how your in centennial, my CO gas mileage has plummeted since the start of winter. A full 10mpg drop.

I think your chasing a ghost and should simply let your car warm up at idle a bit longer. Also, don't accelerate too hard when the engine is in the rich cycle.

[shazapple]

Im assuming youve already reset the computer. Are you sure its not the cold temps and crappy winter gas thats causing your bad milage. What are you getting for milage? Currently I have 23-26mpg which is pretty normal.

[Wiscon_Mark]

that sounds completely normal to me. The engine is supposed to idle higher than normal when its not at operating temp. That's winter for ya ;)

Sha_zapple, you get 23-26? :x

I was ecstatic when I got 25 last week, I average 21.

[Lawsonmh15]

Automatic or manual? The thing of it is, when your engine is cold (in winter), it will remain on the rich cycle until it reaches operating temperature, not until you put it in gear. The rich cycle is there to speed up warming the engine. I don't know why the gas mileage would go down, but seeing as how your in centennial, my CO gas mileage has plummeted since the start of winter. A full 10mpg drop.

I think your chasing a ghost and should simply let your car warm up at idle a bit longer. Also, don't accelerate too hard when the engine is in the rich cycle.

Auto. I understand that it needs to warm up fully prior to dropping, I just don't think you're supposed to HAVE to come to a complete stop for the idle to drop. I also think that a 10mpg drop is far higher than winter gas would, or could, warrant. Granted, we are given ethanol, :roll: but I dump gas in with the current condition and I haven't noticed a 10mpg drop. As far as letting it warm up; I would have to do so for a good 5 mins and HOPE for a red light before getting on to the highway (Which I could hit with a rock).

[Wiscon_Mark]

I dropped from 26-27mpg to 20-22mpg...10% ethanol all times of year (really don't think ethanol hurts fuel economy, its supposed to be more efficient, actually) but anyways...that's not 10mpg...I guess it depends on how hard you drive when you're cold. I take it as easy as possible before the engine warms up. The automatic tranny also takes a bigger hit from the cold because of inefficient shifts and you are stuck in 3rd gear until the car warms up.

[Lawsonmh15]

that sounds completely normal to me. The engine is supposed to idle higher than normal when its not at operating temp. That's winter for ya ;)

Sha_zapple, you get 23-26? :x

I was ecstatic when I got 25 last week, I average 21.

JFC!!! 24mpg is WHY I'm trying to figure out what's going on! I can't believe that type of mileage is reasonable for you. Summer I was getting upwards of 30. I think/know these engines are more efficient than 24mpg. I just need to figure out what the deal is.

I want to know why it is considered normal to have to stop for several seconds for ones' idle to drop in these vehicles. That sounds ridiculous.

[Lawsonmh15]

Im assuming youve already reset the computer. Are you sure its not the cold temps and crappy winter gas thats causing your bad milage. What are you getting for milage? Currently I have 23-26mpg which is pretty normal.

Did you recently buy or sell that car? I think I've seen that exact picture before. I can't remember where, but I'm almost certain, and Yes, I reset the ECU.

[Wiscon_Mark]

you must be doing pure highway miles to be getting upwards of 30mpg.

Also consider this: there are 3 differentials in our cars...3!! That means so many more mechanical parts are cold and much more inefficient.

[Lawsonmh15]

I dropped from 26-27mpg to 20-22mpg...10% ethanol all times of year (really don't think ethanol hurts fuel economy, its supposed to be more efficient, actually) but anyways...that's not 10mpg...I guess it depends on how hard you drive when you're cold. I take it as easy as possible before the engine warms up. The automatic tranny also takes a bigger hit from the cold because of inefficient shifts and you are stuck in 3rd gear until the car warms up.

Ethanol is MUCH less efficient. The best mileages I've registered have been on road-trips to sea-level states. From what I understand, ethanol causes fuel to burn at 80% the efficiency of straight gas.

[Lawsonmh15]

you must be doing pure highway miles to be getting upwards of 30mpg.

Also consider this: there are 3 differentials in our cars...3!! That means so many more mechanical parts are cold and much more inefficient.

You have no idea, 22K since June. Well, I guess now you do. 2 oil changes last August... :shock: I know. My lady's a pilot and she used to NOT get buddy passes. First trip to New Mexico (One WEEK after purchase) to visit her in Farmington while she was in her flight program, I was going through the Cucharas and hit a deer doing 40. That was when I fell in love with the Subie. Crumpled hood, loose headlamp... Dead deer. Pissed at first, then realized that all I would have to pay was about $450 instead of $1500 plus. Since then I've done both o2's, crankshaft pulley, struts, tires, alternator, cleaned IACV, Re-grounded, both batt. cables, battery, Fuel Filter, Vac Hoses, and I'm sure a bunch of other shit I simply can't think of right now.

[shazapple]

Im assuming youve already reset the computer. Are you sure its not the cold temps and crappy winter gas thats causing your bad milage. What are you getting for milage? Currently I have 23-26mpg which is pretty normal.

Did you recently buy or sell that car? I think I've seen that exact picture before. I can't remember where, but I'm almost certain, and Yes, I reset the ECU.

Ive had this car for almost 2 years now, but I have made a few posts about me repainting parts of it.

www.fueleconomy.gov (http://www.fueleconomy.gov) reports the mileage as 21/27 city/highway

Im not sure what vehicle youre comparing the Outback to, but you have to remember its a heavier car than similar year Subarus, and it has larger tires.

I have my tire pressure up to 36/34 front rear because the stock 30/28 is waaaaay to low. Some people inflate it to a few PSI under the tires max.

[Wiscon_Mark]

I have my tire pressure up to 36/34 front rear because the stock 30/28 is waaaaay to low. Some people inflate it to a few PSI under the tires max.

I might want to try this...I usually set it at the factory setting.

[Pwise2326]

Unfortunately as was mentioned before, Subaru's are designed to idle a little higher in colder temps as the warm-up cycle, however, this higher idle process only burns a fraction of a fraction more in gas than normal idle (normal idle for our cars is 650-750, 400 would be dancing too close to stalling). If you can't let your car run through the whole warmup cycle (which takes roughly 5 minutes, with the idle gradually working its way down to normal (750)), its not a big deal at all. Once you start going (at least in a 5MT) the car kicks out of the high idle cycle once the throttle is pushed in - there may be a difference here between manuals and autos, since autos have all the idler pulleys and extra crap that the 5MT's don't need to worry about). If you need to come to a complete stop...gas it to the end of your driveway, and hit the brakes before entering the road. If the setup is different on the autos, then youre going to have to deal with it for the >5minutes it will be running like that.

Nothing you change on your car will keep it from entering that warm up cycle, unless you have a laptop and a standalone ECU system running instead of the stock system.

If gas mileage is really an issue (remember, for most BD/BG/BK models up to mid 99 (with the exception of 2.2's - unless later ones were DOHC), BD/BG/BK's with the EJ25's were rated at 22mpg City, 27/28mpg highway (auto/manual). Getting 26mpg isn't that bad off, and may be an issue from a dirty air filter or spark plugs/wires that might need some replacement - not even this severe. Get a simple tune up, change your oil - sometimes the grade and type of oil (dino or synthetic) can have an effect on your gas mileage...for example, when I got my car I continued using dino oil (non-syn) as the previous owner had and the car ran excellent. I decided to add some Seafoam to clean out the sludge and switch to synthetic....BIG MISTAKE! my seals started leaking and my gas mileage plummeted...it was too slick for an older engine (I have a MY98). I have since been using a Synthetic blend with excellent results, my mileage as improved ( back to normal) and the leaking has slowed a bit. Also, adding things like lucas oil to your pan for the first tank of gas will plummet your mpg's until the lucas breaks in a bit and loosens up. As well, make sure you are using the recommended 5w30 oil grade, or you will have problems in colder temps. 10w30 drops my gas mileage in the winter as well...had to get that cause my supplier didn't have any 5 at the time, but for 10 bucks for the oil and filters, I figured what the hell. I figured wrong -- granted I probably dropped only 2-3 mpg, but then again that can add up.

So, to sum up, a. clean your air filter, b. get an oil change with the proper grade oil and of the synthetic blend or dino persuasion, c. change your spark plugs/wires, d. run some Chevron Techron or other preferred fuel injector cleaner through your lines.

Ooo! I just remembered....you mentioned you reset your ECU? The beauty about Subbie ECU's is for the first 5-10 minutes of your ECU's reset life, how your drive is how your ECU will set yourself...i.e. it can "learn your driving style". Straight from the factory it is "taught" a standard style designed for the "ideal" of the car -- Legacy's in our model years were meant to be family sedans/wagons, used for soccor moms and commuting, not for spirited driving by any means. If you drove your car hard after you reset the ECU, getting onto the gas and such, your ECU will learn to pump a little more juice into those cylinders to give you a little (and I mean a little) extra pep. This comes at the expense of poor gas mileage for the first thousand miles afterwards until the ECU starts moving closer to balance. If you baby the car and immediately hop onto the highway and sit in traffic, it will learn to be a commuter, conserving fuel and running in a mild and moderate fashion...thus helping gas mileage. So, again to sum up, if you went cruising, this is just what your ECU thought you were trying to teach it, so it's giving you a little more juice to fuel your passion. Try resetting the ECU again and taking the car for a nice sunday drive.

Then again, you need to ultimately remember that our cars were not built to get 30 mpg. IF you did, that was a fluke, and you mustve only driven on the highway going 55mph. If you drive a lot on and off the highway, expect gas mileage to be a happy median between the 22 city and 27 highway rating. So to conclude, getting 26mpg avg for a tank isn't really all that bad.

Hope that helped, especially since a full-time AWD vehicle getting 27mpg on the highway is AMAZING! ...many similar model years from other makes in FWD and RWD can't show those numbers!

[Lawsonmh15]

So, to sum up, a. clean your air filter, b. get an oil change with the proper grade oil and of the synthetic blend or dino persuasion, c. change your spark plugs/wires, d. run some Chevron Techron or other preferred fuel injector cleaner through your lines.

A.) Air Filter is clean. B.) Using Mobil 1 10w30 Semi-Synthetic. C.) Changed plugs and wires... Twice (I guess those would fall into the category of "probably a bunch of other shit I wasn't thinking of"). Once with Bosch Plat + 4 = PO301, 303 so went back to the NGK's. OEM Wires. D.) Ran a can of BG 44k through a half tank, cleaned upper engine with SeaFoam, IACV, and periodically run small amounts of SeaFoam through the fuel system.



Then again, you need to ultimately remember that our cars were not built to get 30 mpg. IF you did, that was a fluke, and you mustve only driven on the highway going 55mph. If you drive a lot on and off the highway, expect gas mileage to be a happy median between the 22 city and 27 highway rating. So to conclude, getting 26mpg avg for a tank isn't really all that bad.

I'm not one for one-upsmanship, but I was averaging 28-30 all summer and the BEST I saw was 34.7. And I am liberal with the pedal. I generally drive around 50 city and 80-90 highway.


Hope that helped, especially since a full-time AWD vehicle getting 27mpg on the highway is AMAZING! ...many similar model years from other makes in FWD and RWD can't show those numbers!

Believe me, I love the Subie gas bill. My previous vehicles were a '77 Scout II, '78 GMC K1500, and 'Protege. None got mileage like this... Except for the '99 R6. LOL. [/quote]

[Lawsonmh15]

[quote="sha_zapple":13xhfsca]I have my tire pressure up to 36/34 front rear because the stock 30/28 is waaaaay to low. Some people inflate it to a few PSI under the tires max.

I might want to try this...I usually set it at the factory setting.[/quote:13xhfsca]

This is only effective if your tires are rated far higher than the Subie Recommendation of 28. My first set of tires (BFG Traction T/A's) had a max of 44psi. 28psi caused a 3 mpg drop. I ran them at 34 cold and had MUCH better results. My new Kumho 795 A/S' max at 35psi. Running them at 28psi is PERFECT. The main objective is to get your tires to contact the ground as FLAT as possible. Too much air and you will see major wear on the middle of your tire. Too little and you will see more wear on the sides.

[Lawsonmh15]

Ive had this car for almost 2 years now, but I have made a few posts about me repainting parts of it.

www.fueleconomy.gov (http://www.fueleconomy.gov) reports the mileage as 21/27 city/highway

Im not sure what vehicle youre comparing the Outback to, but you have to remember its a heavier car than similar year Subarus, and it has larger tires.

I have my tire pressure up to 36/34 front rear because the stock 30/28 is waaaaay to low. Some people inflate it to a few PSI under the tires max.

I swear I've seen that pic B4. Good looking ride. What tires are you on?

[shazapple]

Used RE92's! They suck out loud. I beleive the max pressure on them is 44psi. The extra psi Also helps the handling a bit, as the sidewalls of these tires are floppy. on Track days Ill up ot to 40/38 or so