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Discussion Starter #1
well, i've had my baby for less than a month now and have a cel problem. graciously enough it came on about 3-5 days after i bought the car (used) and has juz over 60k on it. i called my dealer and they told me to reset the ecu and do the gas tank trick; if that didn't work then to bring it in and they would fix it.
monday night i took it in and got shafted. they fed me some crap about it not being in the agreement when i bought the car. i can't get them to scan it for free to at least find out what's wrong and im too broke to pay for it (cuz they already took all my f***in money). so my question is if anyone within 50 miles of portland has a scanner that could help me out in exchange for a six-pack and a pizza. my gratitude will also be more than plentiful :D
thanx for any help
 

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General pain in the ass
98 Superu Impreza 2.5 rs...
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3,936 Posts
EEEEE ZZZZZZZ

go to emission testing station, and tell them you want your engine code pulled to fix the CEL. It'll cost you 20$ or free if youre nice
 

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Discussion Starter #3
i know what im doing tommorrow. thanx for the help! you have no idea how much this means to me right now :D i'll tell u though, $53 bucks and whatever the cost of the part is. but the peace of mind will be worth more than the money.
 

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Silver '99 Impreza 2.5 RS
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I have a scanner, but it's a SCSI flatbed scanner, so I don't think that's what you're looking for... ;)

Seriously, if you're looking to get an OBDII code pulled, stop by your local "AutoZone" -- they'll pull it for free.

I just had mine done a little bit ago -- bad knock sensor. Still haven't got a sensor, but at least I know what the light is now!

Sean
www.subrew.com
 

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Premium Member
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If it just came on its probably still running pretty good, but its most likely ur air flow sensor, its a recalled part. Take it to a dealer to check.
 

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Discussion Starter #6
i found a place to get it checked. just need the time to go.
thanx for the help though. i'll mention it when i go but i think i've got a MAS on a MY00.
 

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General pain in the ass
98 Superu Impreza 2.5 rs...
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O2 was recalled, 2000 are MAP based.

correct me if i am wrong but:
mas is when there is a sensor on the intake monitoring ammount of air going in, and map is when cpu is pre programed with ammount of fuel to dump at a given rpm at a given throttle. that's why some times your car will be faster if you dont step on the gas all the way, cause at WOT you by pass cpu.

I heard if you go turbo it's beneficial to downgrade to mas.:eek:
 

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General pain in the ass
98 Superu Impreza 2.5 rs...
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former iclub, i remember people in the aftermarket turbo talking about it, they said something along the lines of better performace with maf on turbo cars.... i dont recall too much cause i was not planing on turbo a stock 2.5... i cant be happy with 6 psi
 

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Silver '99 Impreza 2.5 RS
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The confusion occurs because the two abbreviations (MAP and MAF) are nearly identical, but the "MA" part in each mean entirely different things.

MAF = "Mass Air Flow"
MAP = "Manifold Absolute Pressure"

Both measure different things.

MAF actually measures the mass of air as it passes through the sensor. Most use a wire (or other medium), heated with electricity. As the air passes by the wire, it cools it, and the sensor changes the amount of electricity needed to heat it -- in this way you can tell how much air is going by.

A MAP sensor actually measures pressure in the manifold (vacuum or boost) against a reference pressure (that's where the "absolute" part comes from) and determines the engine's fuel requirements based on this value (and other things like throttle position, air temperature, etc.).

The end result for either system is an engine that runs. The MAP sensors are usually more durable, and aren't generally affected by reversion or other disturbances in the air stream, which can be a problem with MAF units -- especially in turbo application.

MAP-based systems can have issues too, but it's generally only an issue on non-OEM aftermarket EFI systems. People are known to have trouble tuning for a decent idle in some systems (depending on the parameters/inputs available). Also, as people have noted with the Subaru NA cars with MAP sensors, the ECU doesn't know how to deal with positive manifold pressure (like adding a turbo), so extra stuff is needed when adding a turbo, because the ECU can't deal otherwise.

Hopefully that explains it a little bit.

Can you tell I've been researching a standalone EFI ECU for my car? ;) The one I've got uses a MAP sensor, FWIW.

Sean
www.subrew.com
 

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General pain in the ass
98 Superu Impreza 2.5 rs...
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:yikes: ....i love you man but why would some one with map go to maf?
 

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Silver '99 Impreza 2.5 RS
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They probably both have situations where one may be better than the other, but when setup properly, the end result will be quite similar.

For example, my '99 MAF can deal with minor changes to the system (intake/exhaust mods) fairly well, while the stock 2000+ ECU/MAP doesn't seem to deal as well. (at least from what I've read -- I've never personally dealt with a 2000+ car). That's probably not so much of an issue with the sensor itself, as it is with the ECU's handling of the signal, i.e. it's more of an implementation issue when going beyond stock than a problem with the MAP sensor itself.

On the other hand, I've never done more than remove the silencer and add an Amsoil filter to my intake, because I don't trust my '99's MAF sensor (even after I got a new one via recall).

My standalone EFI controller uses a new, separate MAP sensor, so I'll be able to be rid of the flaky MAF and get my intake manifold all fabbed up the way I want.

I don't know if that did more than add more text to an already long and off-topic post, but WTF. ;)

Sean
www.subrew.com
 

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I have an 02' Impreza 2.5RS and that rediculous CEL comes on and off all the time. I haven't done hardly a thing to the car before it came on though. I have an intake and a slap on muffler and it is absolutely obnoxious. I took it to my subaur dealership and they wanted me to leave the car with them for a whole day to figure out what was the problem. I left it with them for half a day and the only answer they could give me was that it was due to engine modifications. If you live around a Knechs auto supply take your car in there and they have a little hand held tool that will turn your CEL off for you and give you an idea of what is wrong on their digital readout. Good luck and does anyone know of a cure for the CEL other than ripping it out completely?:confused:
 

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Scoobymods Guy
2010 Legacy 3.6R Limited
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If your CEL is due to the Cat inneffiancy code you can put a fix on that will fool the second O2 sensor to not come on. That code only tells you that the cat is not working to spec but does not effect the ECU in any way, it just puts the light on is all


http://www.ilpperformance.com/celfix.html

They have a wire in one for 20 bucks

Random tec gave me this info on the subject:

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The alleged problem with low converter efficiency that triggers a Check Engine light isn't real. The OBD II system uses exhaust gas oxygen content to gauge converter efficiency. That's like using fuel pressure to monitor fuel flow. The assumption is that a given pressure in a line of a given diameter will flow a specific volume. However, if there's a restriction in the line, volume will be severely limited, in spite of system pressure.
With the OBD II system, the assumption is that oxygen content behind the converter will be substantially more consistent than content in front of the converter. And that's true when you have a restrictive converter that causes exhaust gases to back up in front of it. But when you increase flow capacity, the residual oxygen content behind the converter is not as consistent, so the PCM erroneously thinks converter efficiency has deteriorated. In spite of the fact that the system "thinks" converter efficiency is below the acceptable threshold, the converter is doing its job and the vehicle will pass an emissions test.
 
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