fuel economy Fixs

Carbix · Post by **Carbix** » Sun Apr 15, 2007 10:17 pm

around -10psi i get a really fast clicking sound from what sounds like (from the inside of my car) its coming from my glove box to turbo area, any Ideas if this sound could be killing gas?

jefferson · Post by **jefferson** » Tue Apr 17, 2007 2:05 am

Something I would think about changing is the coolant temp sensor. A malfunctioning one can greatly affect the mileage the car gets. If it is telling the computer the coolant is too cool then the mixture is going to be rich and the mileage will reflect it.

Jeff

aspect · Post by **aspect** » Tue Apr 17, 2007 5:14 am

Turn down the boost?

Seriously, if you want gas milage, a 15 year old awd turbo car is probably not the best bet. Worn out engine components, worn transmission components, and rusty/dirty/gummed up drivetrain components all contribute to this problem. Even in neutral, my car is much harder to push than a new impreza just because of resistance in the old bearings and running gear. Any type of piston blowby is 100% wasted combustion...also keep in mind that your old MAF and related components, and the old electrical system that connects them, all contribute to inaccurate tuning especially when they are connected to an ECU that is way out of date in terms of air/fuel control. Bad grounds all through the system either screw up ECU functions or require extra electrical power from the alternator which is converted into direct mechanical resistance.

If you want stock fuel economy, replace your wheel bearings, cv joints, rear differential, transmission bearings, engine bearing, piston rings, valves, all engine sensors, wiring harness, battery, alternator and turbo. As well as cleaning out the intake, intake manifold, removing carbon deposits from the header and uppipe, replace all cats...

My point is that any old car is going to gradually get worse and worse gas milage. Turbo legacies suffer from increased engine wear over time, and use more fuel by design. The AWD system has an awful lot of moving parts that all contribute to total friction load as well.

Imprezive wrote:One word. Coasting. If you have a manual just take it out of gear in spots where there is a slight downhill slope. I coast for about 40% of my morning commute into town hahaha

Actually, in most cars you will use *more* fuel using this technique, as any decently programmed ecu will cut injector duty cycle down to nothing when you are engine braking. It takes more power to idle a motor with the clutch disconnected than it does to keep a motor going that's being forced to spin by the drivetrain.

Carbix · Post by **Carbix** » Tue Apr 17, 2007 7:01 am

that could be the case with costing but im not 100% sure on that. I have a Stand Sunfire 2.2 95... When i cost big hills on the Cock i get like 750km to a tank...sooooo that concept can varie

555BCTurbo · Post by **555BCTurbo** » Tue Apr 17, 2007 7:14 am

aspect wrote:Turn down the boost?

Seriously, if you want gas milage, a 15 year old awd turbo car is probably not the best bet. Worn out engine components, worn transmission components, and rusty/dirty/gummed up drivetrain components all contribute to this problem. Even in neutral, my car is much harder to push than a new impreza just because of resistance in the old bearings and running gear. Any type of piston blowby is 100% wasted combustion...also keep in mind that your old MAF and related components, and the old electrical system that connects them, all contribute to inaccurate tuning especially when they are connected to an ECU that is way out of date in terms of air/fuel control. Bad grounds all through the system either screw up ECU functions or require extra electrical power from the alternator which is converted into direct mechanical resistance.

If you want stock fuel economy, replace your wheel bearings, cv joints, rear differential, transmission bearings, engine bearing, piston rings, valves, all engine sensors, wiring harness, battery, alternator and turbo. As well as cleaning out the intake, intake manifold, removing carbon deposits from the header and uppipe, replace all cats...

My point is that any old car is going to gradually get worse and worse gas milage. Turbo legacies suffer from increased engine wear over time, and use more fuel by design. The AWD system has an awful lot of moving parts that all contribute to total friction load as well.

Imprezive wrote:One word. Coasting. If you have a manual just take it out of gear in spots where there is a slight downhill slope. I coast for about 40% of my morning commute into town hahaha
Actually, in most cars you will use *more* fuel using this technique, as any decently programmed ecu will cut injector duty cycle down to nothing when you are engine braking. It takes more power to idle a motor with the clutch disconnected than it does to keep a motor going that's being forced to spin by the drivetrain.

I think you are overthinking this...because my 1992 Legacy Turbo, with 206,000 miles and 4.11 gears has shown 26 mpg on the freeway, which is actually higher than the stock rating of 25...

Soul Shinobi · Post by **Soul Shinobi** » Tue Apr 17, 2007 6:29 pm

I agree, my 1992 Legacy L gets exactly what it should and it has 255,980 miles.

But it might depend where you live too, being on the cost with salty sea air could cause premature rust and in places you wouldn't expect! That would cause the drivetrain to be a bit sticky I'd think...

icrman · Post by **icrman** » Wed Apr 18, 2007 2:00 am

Just something to think about. I read a post here about coasting in neutral down a hill. I am not sure about how they do it on these engines, but on some vehicles with Electronic fuel injection they cut off the injectors when coasting. So you would actually save more fuel by coasting in gear with them. Since electronic injectors are controlled by pulses they just don't send a pulse at coast.

Its funny on my wifes 93 Legacy any time it is started it really stinks like over rich. Is that normal with all these?
Maybe subaru is trimmed for too much fuel flow? Not sure what the milage is, but it isn't all that great.

Soul Shinobi · Post by **Soul Shinobi** » Wed Apr 18, 2007 2:17 am

No that's not normal, I don't think. Mine smells like burnt clutch no matter how I drive, but that's just mine. You may have a leak in the fuel system somewhere along the line, or it may just be running too rich (start by checking the the air filter isn't dirty).

Also, there was a recall on first generation legacies because there was a manufacturing defect in some fuel tanks. I just looked it up at:

http://www-odi.nhtsa.dot.gov/cars/probl ... search.cfm

And 1993 model did not have this defect, 9500 Legacies from 1992 did (reported on MAR 30, 1992).

jefferson · Post by **jefferson** » Thu Apr 19, 2007 3:23 am

Change your coolant temp sensor and see what happens.

Jeff

Soul Shinobi · Post by **Soul Shinobi** » Thu Apr 19, 2007 3:47 am

Who? The guy complaining about gas mileage or the guy who's smelling gasoline from the car?

92whitelegacy · Post by **92whitelegacy** » Thu Apr 19, 2007 1:52 pm

Carbix wrote:around -10psi i get a really fast clicking sound from what sounds like (from the inside of my car) its coming from my glove box to turbo area, any Ideas if this sound could be killing gas?

I also get this weird little clicking it goes away once the turbo spools down....any thoughts?

yazmo · Post by **yazmo** » Tue Jul 21, 2009 10:09 pm

i got exactly the same problem with mostly everyone here full tank i make 300 km max

i replace pcv valve, coolant temp, igniter, o2 sensor, will try cleanning or get the jesc maf from someone who sell it right now. try to clean trottle body with sea foam and see what happen.

i got the knock sensor but dint install it yet bcuz look like its a big job to do

yazmo · Post by **yazmo** » Tue Jul 21, 2009 10:09 pm

i got exactly the same problem with mostly everyone here full tank i make 300 km max

i replace pcv valve, coolant temp, igniter, o2 sensor, will try cleanning or get the jesc maf from someone who sell it right now. try to clean trottle body with sea foam and see what happen.

i got the knock sensor but dint install it yet bcuz look like its a big job to do

mexicanzero · Post by **mexicanzero** » Wed Jul 22, 2009 2:36 am

alright so now i am geting about 425-450km to a tank and thats mixed nice driving with aggressive flooring.

on the highway i can get 750ishkm to a tank

but it wasnt always like that, when i got the car it was getting about 300km to a tank. stock.

is your car stock? or what mods does it have?

since then the biggest improvements on fuel economy have been. turbo back exhaust-big difference, freed up intake-small but noticeable difference, o2 sensor-noticeable difference, plugs wires pcv fuel air etc-big difference, MSD coil-HUMONGOUS DIFFERENCE, revtronix chip with td-04 and newer jecs maf-very big difference, cleaned maf and replaced coolant temp sensor-noticeable difference, replaced injectors for revtronix chip(one was plugging up and staying open at times with engine off)-very big difference.

but the bigest difference by far is they way i drive. i once drove for a whole tank of gas never going over 3000rpms and generally staying under 2000rpms and i got 500km to the tank and that was before the msd coil and the chip when i was getting 350-400km regularly. but it was no fun

coasting in gear does cut fuel, the car wheels spinning due to momentum forces the trany to turn which is connected to the engine so it forces the engine to turn over therefore requiring zero effort and so fuel is not needed. some modern cars actually cut fuel 100% depending on the deceleration conditions.

oh and the ticking noise you're hearing on boost is the boost solenoid, i'm pretty sure its normal for it to tick. well mine and alot of other peoples do and they still work perfectly.

so in short, free up the exhaust and intake, boost up the spark power(ground mods can help alot here too) and get a good tune for whatever mods you have, the stock tune sucks.

-Alex

yazmo · Post by **yazmo** » Wed Jul 22, 2009 11:10 am

i am stock but planning to get something like you.

when you mean free up exhaust and intake what do you mean remove the cat and going bigger? what about intake

also was planning on getting diamond coil
what is msd coil! have to go work so maybe you gonna read this before i come back so i wont have to do much research about it.

also i want to get magancor wire, jesc maf

RJ93SS · Post by **RJ93SS** » Wed Jul 22, 2009 5:26 pm

yazmo, the knock sensor is simple, and it can have a huge effect on mileage

yazmo · Post by **yazmo** » Wed Jul 22, 2009 9:20 pm

dont you have to remove the manifold?

kimokalihi · Post by **kimokalihi** » Wed Jul 22, 2009 9:51 pm

icrman wrote:Just something to think about. I read a post here about coasting in neutral down a hill. I am not sure about how they do it on these engines, but on some vehicles with Electronic fuel injection they cut off the injectors when coasting. So you would actually save more fuel by coasting in gear with them. Since electronic injectors are controlled by pulses they just don't send a pulse at coast.

Its funny on my wifes 93 Legacy any time it is started it really stinks like over rich. Is that normal with all these?
Maybe subaru is trimmed for too much fuel flow? Not sure what the milage is, but it isn't all that great.

If they cut the injectors off...how will the engine continue to run?

RJ93SS · Post by **RJ93SS** » Wed Jul 22, 2009 10:01 pm

yazmo wrote:dont you have to remove the manifold?

no, thats bullshit. just a 3/8 drive extension

tturnpaw · Post by **tturnpaw** » Thu Jul 23, 2009 7:15 am

I was getting around 22-24 mixed city and highway. Replaced that POS bypass valve with an upgraded unit and bypassed the boost solenoid to a controller and picked up about 3-4 mpgs. I will stand by my decision to change the stock bypass valve to the blow off valve-recirc because any stock bypass valve that i have worked with has always leaked back in front of the turbo and as a result, ran pig rich.

yazmo · Post by **yazmo** » Thu Jul 23, 2009 11:16 am

RJ93SS wrote:
yazmo wrote:dont you have to remove the manifold?
no, thats bullshit. just a 3/8 drive extension

really i will check that thx

ericem · Post by **ericem** » Thu Jul 23, 2009 2:53 pm

yazmo wrote:
RJ93SS wrote:
yazmo wrote:dont you have to remove the manifold?
no, thats bullshit. just a 3/8 drive extension
really i will check that thx

As long as you dont have big hands its easy. Guys is it possible to damage the knock sensor by over torqueing it. I went past snug and there was a crack noise yet didnt really notice any cracks. I am starting to think i should replace it.

RJ93SS · Post by **RJ93SS** » Thu Jul 23, 2009 5:26 pm

ericem wrote:
yazmo wrote:
RJ93SS wrote: no, thats bullshit. just a 3/8 drive extension
really i will check that thx
As long as you dont have big hands its easy. Guys is it possible to damage the knock sensor by over torqueing it. I went past snug and there was a crack noise yet didnt really notice any cracks. I am starting to think i should replace it.

it only needs 14 lbs, take it off and check for cracks, all it takes is a hairline fracture

ericem · Post by **ericem** » Thu Jul 23, 2009 6:11 pm

whats inside the sensor ? I might just get a new one for curiousity reasons. With the original knock sensor it gave a cel sometimes but i think it got better fuel economy. Well see !

Post by **Legacy777** » Thu Jul 23, 2009 7:17 pm

The sensor is a piezoelectric sensor that creates a small voltage when it detects vibration.

Cutaway of the sensor
http://main.experiencetherave.com/subar ... utaway.jpg

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fuel economy Fixs