My normally smooth-as-silk 2006 Forester Auto N/A with 115,000 miles on the clock has started intermittently misfiring. It will sometimes run on the highway for 30 minutes without a noticable miss. Sometimes it will misfire four or five times while I wait for a stoplight in neutral. The misfires tend to be more frequent on acceleration. I would almost say bad gas, but Seafoam and dry gas have not helped. The spark plugs were changed at 100,000 miles, nothing else has been replaced. No CEL. Any suggestions would be very welcome. Will I get a scan code if the CEL hasn't lit?

 

One other thing. I replaced the timing belt at 105,000 miles. I also replaced the water pump, all the idlers, and the tensioner. It was very tight, and a struggle to get the new T-belt on. When I removed the pin from the new tensioner I did not see any immediate movement. I figured with all new components there was no slack to take up. Is this normal? Thanks.

Edited February 27, 201214 yr by The Dude

It sounds like spark plug wires to me. I say that because my friend's outback had the same exacty symptoms your describing and with the about same age. I would try OEM Wires. Even if it doesn't solve it, six years is good life out of wires (especially on Subaru, which are sensitive).

just to give you some confidence, i vote wires as well... same issues on our outback.

Cars havent really changed since they dropped coal dust ignition. They still need tuneups to run properly.

 

You need to start with a tune up including the PCV valve. Use the basic plugs sooby recomends and OE wires, anything else can be anything.

I know I'm not helping any, but your original thread title had me picturing a "Hmmm, I KNOW there was an engine here yesterday..." situation.

I know I'm not helping any, but your original thread title had me picturing a "Hmmm, I KNOW there was an engine here yesterday..." situation.

 

 

hehehe thats the first thing I thought too

You are due for a front 02 sensor if it has not been replaced yet.

Does the misfire/hesitation only occur when car is warm? If so, replace that front 02.

You can also test your ignition coil with a multimeter. I don't have the specs near me right now.

You can't touch the collective experience of the posters on this board. I got excellent advise. A new set of spark plug wires instantly cured my "missing" problems. Thanks to everyone who posted a suggestion!!

 

Note: Since NGK spark plugs play well with Subaru engines, I decided to try a set of NGK Premium (Blue) Spark Plug Wires. They were relatively inexpensive and easy to get off Amazon. Physically, they are identical to the Subaru factory wires. So far, they seem to be working great. How will they hold up? Only time will tell.

When I saw the title of this thread my mind immediately pictured someone getting out of work and pop their hood when the car didn't start, only to realize someone had stolen their engine...

were the plugs you put in bosch platinums? they are horrible.

^ I put those in my car once. They're junk. It started running like crap.. Pulled them out to see three looked like this.

 

Plug wires mya look ok (and these may befine). What happens is they have less silicon or inferior silicon to what Subaru specifies from it's suppliers and they break down quicker.

the center electrode will receed into the insulator within just a few thousand miles and cause misfires also. Ive bought cars super cheap because of these plugs and misfires. Same story, I just changed the plugs this year and changed the wires last week when it started missing. almost always some jerk at the chain auto stores recommending them to some diy guy.

Plug wires mya look ok (and these may befine). What happens is they have less silicon or inferior silicon to what Subaru specifies from it's suppliers and they break down quicker.

 

I found that definitely to be the case; once I purchased top of the line NAPA wires. Although the car ran fine, in under two years the boots fell apart in my hand.

When I saw the title of this thread my mind immediately pictured someone getting out of work and pop their hood when the car didn't start, only to realize someone had stolen their engine...

 

Ditto