Rough Idle & Check Engine Light

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mlbasiliere

Rough Idle & Check Engine Light

Post by mlbasiliere »

Hey Guys-

Just bought my old 93 5s sport sedan back after two years out of the
country (from the person I sold it to). I noticed a bit of rough idle
when I first got in it, but it disappeared within a day, not coming
back during a 500 mile weekend. After a morning of cleaning out the
interior and washing the exterior, I popped down to the shops only to
find that the Check Engine light had come on and the idle was
violently rough- even more so when the headlights were on. once the
revs get up it seems OK.

Any ideas what it could be?

Two notes: I did hose out the engine bay, but just with a normal
household hose, and I noticed a nest just behind the right headlamp
and a bunch of (what appear to be) ABS wires chewed on, but none cut
completely through. Hope this helps.

Thanks in advance!

marc
Z1Auto@aol.com

Rough Idle & Check Engine Light

Post by Z1Auto@aol.com »

Check the ISC motor.....first that it is plugged in, secondly that it works (post here if you need the specs..you'll need a voltmeter and ohm meter)

if you run the self diag test you can at least pull the code type (or just post ehre and we cna help you figure out what code it is).

Adam
Josh Colombo

Rough Idle & Check Engine Light

Post by Josh Colombo »

Go to my site www.surrealmirage.com/subaru notes & tips section, engine related. I tell how to pull the ECU codes & what each the codes are.

That should help you figure out what is the problem.

josh
mlbasiliere

Rough Idle & Check Engine Light

Post by mlbasiliere »

Thanks guys-

I pulled down the ECU codes notes and checked the code using the green
connectors (couldn't find the black), which gave me a 2-2, or knocking
problem. As I cleaned inside the fuel filler door yesterday, I
figured that there might be some water or soap in the fuel... I added
a bottle of DriGas and filled the tank with more premium petrol.
Unfortunately, it's still doin' it (15 miles later). It is very rough
at idle now and under acceleration I don't have nearly the power that
I did three days ago. Also, the CHECK ENGINE light has shut itself
off. Why? I keep going through the engine bay, but still can't find
any loose or cracked vaccum hoses... Could it be a cracked manifold
gasket? I hope not. Any ideas would be appreciated!

mbc
ciper_

Rough Idle & Check Engine Light

Post by ciper_ »

You may have two problems occuring at once.

The knock sensor failing was somewhat common, I wouldn’t doubt that if
you measured it that the knock sensor is open (no resistance). This will
cause the ECU to fully retard the timing at all times.

The rough idle is probably not caused by this. Id look at the spark
plugs and wires first.

--
ÿØÿà
John D

Rough Idle & Check Engine Light

Post by John D »

You know what's weird.... a lot of subaru's seem to have the same type
of trouble. .. Rough idle or serious hesitation. For me I notice severe
hesitation in cold weather or very wet weather. I bet within the next 4
weeks (starts to get a lot colder) that we start to have more people
with this problem. I personally think I might be running to rich... but
I'm not sure...

That's just my observation.
axfinn_20902

Rough Idle & Check Engine Light

Post by axfinn_20902 »

Marc: I agree with cipher. check you plugs and wires. A common
accurence when you wash the engine bay is to get H2O around the spark
plug and that shorts it out. If thats' not it try spraying a little
WD40 or such into the plug boots. Dielectric grease is also a good
thing to use between the plug boot and the plug. Hope this helps
and good luck
Oh don't worry about you knock sensor code. That was triggered by
the misfirering you have.
Josh Colombo

Rough Idle & Check Engine Light

Post by Josh Colombo »

You need to find the black connectors. That is how you check the codes.

Josh
Marc

[Subaru Legacy Club] Re: Rough Idle & Check Engine light

Post by Marc »

Well, I found the idle problem-

When I hosed out the engine bay (oddly enough, to make servicing easier), some water got into and caused the driver's side rear plug to short. I pulled out the lead and let it dry out in the sun- problem sorted. Unfortunately, within a couple of hours, the belt that powers the alternator and power steering failed! Another day under the hood, then.

I'll likely replace the wires and plugs as soon as I can, if only for a tighter seal around the problem plug. Will check the throttle body too, if I can find it (the Haynes manual is shocking). Thanks again-

marc
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