ok heres the problem

regardless of warm/ not warm, the idle goes from 200-900 in little hops. you can hear the car about to stall and then it will give it more gas. the lights are dimming as well.

current list of mods:
Bruillen full exaust
PRM intake
JUN Flywheel
ACT clutch
2 aftermarket bosch o2 sensors (CE Light is pulling code for one of them)
Denso Iridium spark plugs (recently changed, diddnt solve problem)

I called subaru and they asked about the ce light, i told them and they said it was the 02 sensors, because they are bosch not Subaru.. if i recall correctly the front o2 sensor is 190 bucks =(
the car is also noticibly slower ever since the origional o2 sensors went.
any ideas? should i shell out the dough ? or is it something else?

what year is your car? what octane do you use? bad injector(s)? Try junk yard for the o2 sensors... good luck!

my car is a 99 with 45k miles on it , i mostly use 87 octane, but ive had premium in the car and it runs the same. I think im just running lean or something. Its the loss of power im worried about, i was in my moms 01 legacy gt w/ no mods and it seemed to pull harder from 60 to 80 than my car and hers is an AUTO! lol

I am quite certain it's the O2 sensoirs. Bosch is quality stuff, but either you have the wrong type or they just haven't quite figured yours out yet. Get some OEMs in there and your problem should go away in a few days, provided you get the CEL cleared out.

I'm having the exact same problem. I too have a 99. I too have a CEL, but haven't pulled the code yet. My hunch is that it might be the lightened flywheel. I have an Exedy. I'm wondering if it's maybe too light to keep the engine running? What do you think?

Originally posted by Silverscooby27
I'm having the exact same problem. I too have a 99. I too have a CEL, but haven't pulled the code yet. My hunch is that it might be the lightened flywheel. I have an Exedy. I'm wondering if it's maybe too light to keep the engine running? What do you think?

What other mods do you have? Anything that messes with VE, like intake, headers, exhaust etc. can be a culprit, but I don't see why a flywheel would cause problems. As usual with Subaru I would expect it to be O2 sensor or MAF sensor related.

i agree the flywheel is not causing the problems, but the problem is more pronounced because of it. Ill post more once my 02 sensors get replaced on thursday

Originally posted by booger
i agree the flywheel is not causing the problems, but the problem is more pronounced because of it. Ill post more once my 02 sensors get replaced on thursday

Upon further pondering, I suppose that the increased rates of acceleration/deceleration of combustion could cause strange burns during throttle transition, and might make you spit out some unburnt fuel, which naturally causes O2 CELs.

I was thinking more that the lightened flywheel causes the drivetrain to have too little momentum to keep the engine going like it should. In other words, I think it's simpler than combustion problems, etc. I don't think it's the reason for a CEL though. I've got to pull the codes. Only reason why I mention it is because it is the only thing different with the car since mine started doing it. I'm about 99% sure that my O2 sensors are fine. In answer to your questions about mods, yes, I've got it all and more.

Do you have a PEMS? If so, you might want to retune it, becuase I guess the flywheel can change your VE during throttle transitions. Basically, the crank speed dropping much faster than with the elephantine stock flywheel tossing it around.

Originally posted by booger
my car is a 99 with 45k miles on it , i mostly use 87 octane, but ive had premium in the car and it runs the same. I think im just running lean or something. Its the loss of power im worried about, i was in my moms 01 legacy gt w/ no mods and it seemed to pull harder from 60 to 80 than my car and hers is an AUTO! lol

Well, her car does have the same motor as yours, and 3rd in a 4EAT falls between 3rd and 4th in the 5MT, so 60-80 is one particular range where her car car could feel faster. You'd spank it 50-70 though.

I just paid to have the entire front half of the car re-wired, the ECU replaced and the MAF replaced, so right at the moment, I have no engine management in the car.

Originally posted by Silverscooby27
I just paid to have the entire front half of the car re-wired, the ECU replaced and the MAF replaced, so right at the moment, I have no engine management in the car.

What are you getting? sounds like the makings of a monster setup.

Not what I'm getting. . .what blew up and just got fixed. DOH!

Another heartbreak story of a turbo kit gone bad. I figure I'll try again in the near future.

Crappy. Was it excessive knock or did the electronics go belly up?

short in a wiring harness, took out the harness, the ECU, the MAF. The engine did have a TON of knock although it went away with the J&S knockguard. Never had the car running right.

i have seen a lot of similar problems, though only on stock cars. legacys, and imprezas alike. the mass air flow is a likely culprit, as well as bad o2 sensors. those go bad quite often. but another problem could be the idle air control valve. its not something i can really explain on here. but any qualified subaru mechanic would know what it is, and how to clean it out. it gets pretty junked up with oil from the pcv system. probably an 1.5-2 hours labor. just a thought.


-PJ

Originally posted by Silverscooby27
short in a wiring harness, took out the harness, the ECU, the MAF. The engine did have a TON of knock although it went away with the J&S knockguard. Never had the car running right.

Getting a full rebuild before too long would be a good idea if you plan on making any more power out of the car. EJ25s are about as knock-resistant as most motors, but it's still going to cause a slow painful death if any of your ring-lands are broken.

Yeah, I'm not sure what I'm going to do yet. I am going to get it running back to normal first.

this may sound stupid but it happened to me so I do know from firsthand experience. My car started doing the same exact thing and everytime I started it it would be harder to start....it turned out to be not having enough water in the battery. So check that first. Everyone on any impreza board is first to jump at the worst case scenario. I blew my map sensor and everyone was like...oh it's a piston...you threw a rod...you blew a head gasket...you need a new engine..blah blah...but CHECK THE BATTERY FIRST....have a good day. ;)

Hehe, that's a good point. We should all remember to do the simple (meaning cheap) fixes first, would save many a headache.

I had the exact same problem before! This happened just two weeks ago, and my car got the CEL. My technician cured the problem easily with just replace new spark plug wires. Everything is fine now, back to normal! Hope this help!

Speaking of, does anybody know if Nology is making wires for the EJ25 yet? If so, anybody using them?

If you have a '99 2.5, get the MAF sensor replaced.

It should be covered since it was recalled late last year.

I used to have the same problem and it 99% went away when they replaced it.

Bleh, I had to reregister and now my post count is soooo low again...

Originally posted by Rez
If you have a '99 2.5, get the MAF sensor replaced.

It should be covered since it was recalled late last year.

I used to have the same problem and it 99% went away when they replaced it.

Bleh, I had to reregister and now my post count is soooo low again...

PM Alex, he will hook you back up.

I was working on this problem tonight on my 99RS also.
I had the MAF replaced on recall this past summer, even though the car ran fine.

The car started hesitating very intermittently first, about 1 time in a half hour at speed on the freeway, then when I stopped, the car wouldn't idle.. It was cold and damp.

Tonight I checked the PCV, vacuum lines, plugs wires etc, all the cheap stuff. tomorrow I will clean the Idle valve.

BTW, my check engine light was not on. It only went on tonight when I forgot to attach the MAF sensor, and now it is still on.

Can anyone teell me how to get the code, or turn off the light?

Thanx

>I called subaru and they asked about the ce light, i told them and they said it was the 02 sensors, because they are bosch not Subaru.. if i recall correctly the front o2 sensor is 190 bucks =(


Hee Hee, the OEM front O2 sensor is made by Bosch. I changed my front sensor not too long ago and it cured a lot of ills. I got an OEM one from Drivewire.com for around 55 USD, have a look here for details on that:

http://www.scoobymods.com/forums/showthread.php?s=&threadid=1039

One quick thing to check is the condition of the wire ends up at the coil pack. They tend to get crapped up I've found. Give them a good cleaning and hit the ends w/ some Dilectric grease too.

Peaty