Rough @ Idle, Cylinder 1 misfire, Timing belt? Valve? Piston... - Subaru Forester Owners Forum
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post #1 of 6 (permalink) Old 01-21-2009, 06:27 PM Thread Starter
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Rough @ Idle, Cylinder 1 misfire, Timing belt? Valve? Piston...

A few weeks ago I got this problem all of a sudden, the car is rough at idle and the muffler shakes and smokes ...CEL reads cylinder 1 misfire...did a tune up a couple of times (new spark plugs and wires) but the problem still there...a friend suggested the coil pack...another suggested a vacuum leak...another suggested valve adjustment...SUBARU dealer suggested a timing belt that need to be adjusted... What do guys think?
I'' greatly appreciated
99 Forester, 94K

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post #2 of 6 (permalink) Old 01-22-2009, 07:43 AM
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Did you use OEM ignition wires?

Do you have oil in your spark plug well on cylinder 1?

You can check the resistance of the coil pack with a multimeter, but I don't think that's your problem because, if it were, you would also be getting a code for cylinder #2 as well (wasted spark system).

Try detaching and reattaching the connector to the coil a few times to clean off the terminals.

If you have a bad oil leak on the front of your engine, it's possible that your timing belt jumped a tooth. The replacement interval is 105K miles/10 years. A bad tensioner or pulley could also cause t-belt failure, but at 94K miles, I'm not so sure. You could pop off the cover, rotate the crankshaft, and check the condition of the belt.

Valve clearance check/adjustment are specified at the same interval, though I did mine at 135K miles. Get a Felpro valve cover gasket kit while you're at it. It includes everything, but you'll want to order for MY 2000 if you have the Phase II 2.5 SOHC. They list MY 1999 as DOHC. I ordered mine from

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post #3 of 6 (permalink) Old 01-22-2009, 11:28 AM
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Hi, Not trying to be a smart a$$ or anything but, Wouldn't a skipped timing belt also affect the other cylinder on that side? With new wires and plugs, I would be leaning toward the coil pack, injector, or vaccum leak. Valve adjustment out enough to cause a bad enough misfire would be really kinda noisy I would think. I don't think they would tighten? I have always found, that valves will loosen, and need to be adjusted tighter. I would do a compression check on that cylinder, well all of them, and compare. If that cylinder is low, then I would leak down test that cylinder and see where the air is leaking from. If you hear it coming from the oil pan/dipstick tube. Something mechanical is wrong with that cylinder piston/piston ring wise. If you hear air in the intake or exhaust then a valve adjustment may take care of it. If the valves are ok, adjustment wise, then I would say the valves are not closing for some reason, broken spring, cracked valve ect. If both cylinders on that side are low, then inspect the timing belt before any of the other after compression test. This should be enough to keep you busy for awhile. LOL. If it doesn't miss under load and only at idle, it is highly unlikely it is any of the above and then I would start with a good, and I mean good injector cleaning/top engine cleaning. This will remove any carbon deposits that could be causing your headache. Dave
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post #4 of 6 (permalink) Old 01-22-2009, 04:41 PM
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Check spark to the #1 w/ a timing light. Timing light should flash if there's a spark across plug. No spark equals miss, bad plug (not likely) or bad wire.

It could also be a leaking head gasket on #1. Water leaking into cylinder willl cause a miss. Any evidence of engine gases leaking back into coolant?

good luck

See you down the ROW!
1999 Subaru Forester
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post #5 of 6 (permalink) Old 01-22-2009, 05:20 PM Thread Starter
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Greatly appreciated
The compression test stated that cylinder 1 is not getting enough...when making a turn, I can hear some noise that sounds like a liquid moving from one side of the car to another...My liquids are all full...I don;t know if this is related to the misfire and rough idle...I'll play with the coil connections and I'll try a valve adjustment and see if that will do it...
your thoughts!!! keep'em coming.
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post #6 of 6 (permalink) Old 04-28-2010, 09:38 AM
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Mine is idleing below 1000 and it konked out the other day..I've searched a little but can't find an answer whether there is a hex or regular screw to adjust the idle a little bit higher...?? Anyone? I'll do some more searching or email peaty but it's a 97 impreza..I checked Nabisco or whatever already and couldn't find it yet..Just throwing this out there..Thanks guys and gals~

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