I need Help

[niloc1347]

A problem just started with my car about two weeks ago.

I was driving and when my RPMs got upto 2500 the car felt like it was misfiring. Kinda like there was gunk in the fuel lines but it doesn't do it below 2500. Only 2500 and over and the higher the RPMs the worse the problem. When my check engine light came on I went upto the local autozone and had it tested. The tester said low compression in pistons 1 and 3.

I thought maybe the spark plugs were bad so I changed them. I also switched coils 1 & 2 and 3 & 4 to see if the check engine light might show pistons 2 and 4 had low compression. Well the problem conitnued exactly like it had before. Nothing new but this time the check engine light tester said everthing was good even though the check engine light is on. If anyone knows what is going on please help.

[Anub1s]

Um....I'm thinking he told you those cylinders were misfiring, not that they had low compression. If the guy actually told you that the computer was telling him that it had low compression, you need to go back there and punch him out.

Also, if the CEL is on, there's a code there to be read, so the guy was wrong in telling you everything was fine. Reset your ECU, and go drive, if the CEL comes back on report back.

Edit: Also, please report back the actual CEL codes that you get, not the description. Sometimes the discription can be lost in translation, much like I think it is here. I'm guessing the codes were P0301 and P0303.

[niloc1347]

well i don't know about the first time but when i went back i looked at the tool the obd III and it said everything was clear.

i'm not new to the whole greece monkey thing but i am new to working on subaru so please be patient if i ask any dumb questions. i taught myself on a 1980 f100 so all the electronic and computer stuff is new to me.

removing the ground from the battery will reset the check engine light right?

[SD_GR]

i'm not new to the whole greece monkey thing

Off topic but true Greece/monkey story
http://en.wikipedia.org/wiki/Alexand...ece_%28king%29

i taught myself on a 1980 f100 so all the electronic and computer stuff is new to me.

I have a soft spot for old trucks. Welcome again to the forum!

removing the ground from the battery will reset the check engine light right?

Generally yes. To make things more sure and to speed things up, disconnect and press the brake pedal.

However, I am against doing this in your situation. If there was no code now and no code was stored, then resetting won't change anything. OTOH if you do reset then you loose the information that we need to help you. Since you have a CEL, get the code(s).

Whoever reads the code for you will also have an option to reset that sensor that is complaining. Have them do this if possible. That way only that sensor or circuit or algorithm etc. is affected, and the car does not go back to a base state and have to learn maps or timing curves etc.

The early cars were prone to random misfire codes but it's been a long time since then. Had you done anything unusual to the car (washed the engine, cleaned the engine, worked on the engine)?

You're doing all the right things to troubleshoot, swapping positions of ignition parts. As stated if the CEL is on there is a code and there is a problem. See if you can get a good person to help with code reading or see if they rent a code reader.

Are you sure the car has not been modified?

How did the plugs look?

See this link for troubleshooting:
http://www.clubwrx.net/forums/engine...07&postcount=2

[niloc1347]

The whole problem now is that the check engine light is on and i do have a problem driving but the check engine light tester won't give a code. it says there is nothing to check. that's where my main problem is. i can't check to see what's wrong.

the spark plugs didn't have anything excessive on them. before moving the coils around i looked online to see where the piston locations are and what i discovered was the piston numbers go from front to back left to right

firewall
3 4
1 2
front of car

is that right cause that's how i switched them. anyway the point of that is the plugs on above 1 and 3 were gapped almost ten over the maximum they should be. the new one's were already at .27 so i left them alone. i put ngk iridiums in. that's what was already in the car.

the only work on the engine would be the spark plugs and i have had no new problems from that. the only cleaning would be grime off of wires going to the washer fluid and off the battery.

no mods since i've had it. the only mod i believe is the sti hood scoop and the cold air intake. other than that it's all stock. (not that i wanna leave it that way)

[Anub1s]

That gap may definitely have caused the initial proble, but you say you're still experiencing it?

At this point, I'd really say reset the ECU. If the method you're using to pull the code isn't working, or the ECU has no code stored, then I don't see any harm at all in resetting the ECU. If the problem is a lasting one, it will come back, and you can get the code again, if it was an intermittent problem, a fluke if you will, then it won't return, and yay for everyone.

Just as an FYI, that cold air intake may be a root of your problems. What brand is it? I know you're new here, but intakes on Subaru's are extremely finicky. Most of the intakes on the market can NOT be used with a stock car, they have to be tuned for because they throw off what is termed the MAF scaling, or the size of the tube that the MAF is in, or the turbulence of the air running through the MAF sensor. This can cause a lean condition which can cause engine damage, which can rear it's ugly head in the form of misfires.

[SD_GR]

Although I'd expect a PO171 or similar for a leaning issue, having read your post I agree that installing the correct intake and then resetting the ECU would be worth trying.

[niloc1347]

i've had the car for a year now and this problem just started. i know it can happen but i haven't had any problems with the cold air intake. i'm not sure of the brand i bought it from a guy who worked for a subaru dealership and he had it put on.

[Anub1s]

i've had the car for a year now and this problem just started. i know it can happen but i haven't had any problems with the cold air intake. i'm not sure of the brand i bought it from a guy who worked for a subaru dealership and he had it put on.

Even so, the problems with a CAI are not always immediate. They cause damage more over time more than immediate until something just gives. Also, just because a guy works at a Subaru dealership, doesn't mean he's trustworthy with modifications or with your car at all. There are some good tech's out there, don't get me wrong, we have a couple on this site, but being a tech doesn't make them knowledgable.

I recommend putting the stock intake box on, just to rule it out, because it takes all of 10 minutes to do, and resetting the ECU.

[niloc1347]

oh i know trust me that's why i'm here instead of at a mechanics shop. had my fair share of getting screwed with a smile from "mechanics". just want you to know everything that's going on. i don't wanna leave anything out. i'm here to learn as much as fix my car.

i don't have the stock intake unfortunately. do you know how i can check to see if i have a bad one?

hey another question. what does pressing the break in do to reset the ECU?

[Anub1s]

oh i know trust me that's why i'm here instead of at a mechanics shop. had my fair share of getting screwed with a smile from "mechanics". just want you to know everything that's going on. i don't wanna leave anything out. i'm here to learn as much as fix my car.

i don't have the stock intake unfortunately. do you know how i can check to see if i have a bad one?

hey another question. what does pressing the break in do to reset the ECU?

It's always good to learn how to fix your own vehicle, good on you man.

If you can tell us the brand of it (look on the side, top, bottom of it) we can probably tell you if it's okay or not. If there's no brand, I'm going to say it's a bad one regardless.

When you take the negative cable off it removes power to the vehicle but there are still capacitors inside of the ECU and other places that hold a charge for a while, holding down the brake pedal helps to discharge this.

[niloc1347]

okay i'll check the intake. i wanna stay with cold air any recomendations if i don't have a good one?

how long should i hold it for? i imagine just a couple of seconds.

[Anub1s]

okay i'll check the intake. i wanna stay with cold air any recomendations if i don't have a good one?

how long should i hold it for? i imagine just a couple of seconds.

About 10 seconds or so should do it, but I'd leave the negative cable off for about a minute or so total, just to be sure.

To be honest with you, you're not going to see any real gains out of an intake that's not tuned for. Sure there's some, but nothing noticeable. The only real thing that intake is doing for you is giving you the sound of the turbo and some of the blow off noise. But it's up to you. AEM is a trusted brand if you get the 65mm CAI, which is the same sizing as the stock MAF housing. K&N, SPT, and Cobb are also known brands of intakes that work.

[niloc1347]

okay so next question and i hope you're not getting to annoyed i'm just really curious. is there any mod i would do that would make the cold air intake more beneficial? like upgraded turbo or exhaust. like i said old cars and trucks i can do but the new tuners are all new to me.

[Anub1s]

okay so next question and i hope you're not getting to annoyed i'm just really curious. is there any mod i would do that would make the cold air intake more beneficial? like upgraded turbo or exhaust. like i said old cars and trucks i can do but the new tuners are all new to me.

Not annoyed at all dude, I'm sitting here at work babysitting some work being done thousands of miles away, you're giving me something to do lol.

The good and bad thing about Subaru's and turbocharged cars in general, is that you have to tune your car to get anything out of the mods you put on it. When you start throwing parts at it, like, say, a cold air intake and a turbo back exhaust, you need to tune the car to 1) be able to compensate for fuel and timing for the increase of air entering and exiting the engine, and 2) to actually get the power these modifications make available to you.

Air, timing, fueling. These are the three facets of power making. They have a relationship with one another that is rather touchy. When you increase one, you have to increase or in the case of timing, sometimes decrease the others. There's a lot to tuning that I just don't have the drive or time to type up, so that's the jist of it.

So using this, you can see that if you add a new turbo, or injectors, or free up the flow of the exhaust, you MUST tell the computer how to compensate for it, or how to take advantage of it. There are so many different variables it borders the absurd, but the main thing to remember, is if you want to avoid engine damage, and get the most of your money in parts, you need a tune.

Your next step, in my opinion, is to add a turbo back exhaust and get a form of engine management, custom tune through a shop is preferable, but if you fit the requirements of the manufacturers map notes, you could use the Cobb AccessPort, or the open source method.