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Old 01-14-2013, 04:33 AM   #1
AT0MlK
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Default Running Crappy

So i have a 1998 Subaru Impreza, and when i first start the car for the day it runs great, i mean PERFECT! Then after about 20 minutes of driving and the car heats up, it starts spuddering, and i lose all engine power and it wants to stall, after i get it into the higher RPMs it runs good, and if i keep a steady RPM it drives good. I have no idea what this could be, im in Japan, and i dont have anything to read codes, any ideas? Also, after awhile the car will run good again for about 5 minutes and start its crap again. Any suggestions would be greatly appriciated, thank you so much. Ive only encountered this problem when the car is warmed up, also today when it did this, i threw it into neutral and pumped the accelerator a few times and a little black smoke came out and it started running good.
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Old 01-14-2013, 06:35 AM   #2
Elbert Bass
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First thought is unplugged or failed ECT (coolant temp sensor). You say you have no way to read codes - then I am to assume you have a lit MIL (check engine light)?
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Old 01-14-2013, 06:52 AM   #3
AT0MlK
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No, no Check Engine Light is on, or comes on.
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Old 01-14-2013, 09:35 AM   #4
pmugabi
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Oxygen sensor is the first culprit that comes to mind. Try running with it unplugged and see if it sovles the problem.

A faulty idle valve will cause a similar problem (but usually when cold and it would be fine when hot). What is your cold idle RPM? When you get it to idle, what RPM does the car idle at when hot?
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Old 01-14-2013, 10:26 AM   #5
toupedave
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Underneath your dashboard there should be a set of green and black male/female plugs. If you plug those in it will put your car in diagnostic mode. Your CEL will flash a set of fast and slow sequences. Here is a link to further help you out on how to do this.

http://www.perth-wrx.com/vb/stock-ec...unit-only.html

If you want further help and in Okinawa, i am in Japan as well. You can PM me for further.
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Old 01-14-2013, 01:35 PM   #6
69subaru360
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I would think bad 02 sensor or bad MAF sensor
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Old 01-14-2013, 03:40 PM   #7
AT0MlK
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Alright, we"ll start from the top... @pmugabi It idles at around 1400-1300 for about 1 minute or so then lowers at a constant 900rpms, doesnt matter, warm or cold.
@toupedave I will try that later today, after work and see what happens, also, im in Okinawa and on Kadena!
@69subaru360 I just ordered a new O2 sensor, hopefully i can solve the problm with that, if not, it looks like im goin for the Coolant Temperature Sensor.... *sigh*
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Old 01-14-2013, 03:42 PM   #8
69subaru360
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Does it have the orange label maf sensor? They go bad all the time with driveability problems and black smoke.
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Old 01-14-2013, 03:55 PM   #9
AT0MlK
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I havent really seen any other black smoke. I personally dont know where the MAF sensor even is. I literally just bought this car last week. Never even saw a Subaru back in the states. I dont know much about these cars.
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Old 01-15-2013, 02:26 AM   #10
AT0MlK
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Used @Toupedave's way of checking for codes and it pulled up 23 - 24 both. Which is the MAF and the Idle Air Control Selenoid.
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Old 01-15-2013, 04:06 PM   #11
Stangy
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clean MAF!
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Old 01-15-2013, 10:18 PM   #12
fxt05
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I've been having the same symptoms. I've changed the fuel filter, plugs, and cleaned maf (mine is a green label). Fuel pressure seems fine and also checked the fpr by unplugging the vacuum line to it. I'll have to swap the o2 sensor and the temp.
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Old 01-18-2013, 11:33 AM   #13
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well I UNPlugged My O2 And Still Having The SamE Problem. OP Keep Us Updated On Your progress.

Edit: I unplugged the o2 this time instead of the temp sensor in the dp. Time to go for a drive and see if that's my problem.

Last edited by fxt05; 01-18-2013 at 06:22 PM.
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Old 01-29-2013, 06:01 AM   #14
AT0MlK
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Well, the car almost took a complete poop on me, i drove it and it was studdering and idleing bad it was terrible, before, i could barely drive it a mile or 2 without it studdering, i decided to completetly unplug the MAF and BOOM, ive drove for over 5 hours STRAIGHT and not a problem yet,,,,, fingers crossed. Its weird too, because ive tried unplugging it before and it wouldnt even run barely, but this time it works just fine. Try that and see if it solves your problem. I also replcaced the fuel filter and put some octane booster inside my tank of 86 octane ( i live on base and thats the highest octane i can get)
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Old 01-29-2013, 10:56 AM   #15
toupedave
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Quote:
Originally Posted by AT0MlK View Post
Well, the car almost took a complete poop on me, i drove it and it was studdering and idleing bad it was terrible, before, i could barely drive it a mile or 2 without it studdering, i decided to completetly unplug the MAF and BOOM, ive drove for over 5 hours STRAIGHT and not a problem yet,,,,, fingers crossed. Its weird too, because ive tried unplugging it before and it wouldnt even run barely, but this time it works just fine. Try that and see if it solves your problem. I also replcaced the fuel filter and put some octane booster inside my tank of 86 octane ( i live on base and thats the highest octane i can get)
Oh good god dont EVER put that octane booster in your car, you can and will fry your rings. If you really want your car to run good get off base gas. Yes i know it is expensive, but your will run smooth as butter, at least with working cars *rolls eyes*. It will also help your hp...
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Old 01-29-2013, 02:24 PM   #16
coupe-a-loop
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All suggestions above sound valid, from a first hand experience though I had a good friend who owned a turbo legacy ej22T and it had this problem for about 3 months before we decided to check for vacuum leaks. We also cleaned the IAC as a precaution but after fixing the one major vacuum leak the problem vanished. If your having unmetered air passing by will make your idle wander and rough, even lead to stalling. So, vacuum leaks, IAC, MAF, 02 sensor. Goodluck.

PS, I think the octane would have to be pretty bad to cause this, in reality you would just get detonation and fry your motor completely. If you are running 86 oct with booster, you should look at getting knock sensor if you don't have one.
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Old 02-20-2013, 12:15 AM   #17
fxt05
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Well, I swapped the o2 sensor and I'm still having problems. I'm going to change the ects next and hope that helps. I noticed I haven't seen my fans turn on in a long time.
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Old 02-22-2013, 06:02 PM   #18
fxt05
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Well, in my case it was the MAF. Replaced that and all seems fine. New MAF's are very expensive but it was worth it now that its all over with. Just wanted to update for people searching for similar issues.
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Old 02-24-2013, 12:07 PM   #19
rob
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Quote:
Originally Posted by fxt05 View Post
Well, in my case it was the MAF. Replaced that and all seems fine. New MAF's are very expensive but it was worth it now that its all over with. Just wanted to update for people searching for similar issues.
If you still have the old one, open it up and check the connections from the pins to the circuit board. People have reported that these sometimes have flaky connections. You could resolder them and keep it as a spare. Glad you got it figured out.

Last edited by rob; 02-25-2013 at 02:03 AM.
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Old 02-24-2013, 12:28 PM   #20
fxt05
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I do Still Have The Old One. I'll Check That Out.
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