Engine misfire at constant speed

[Bobtronique2]

Good afternoon,I experienced some misfires during a constant speed trip today. It is strange, because it never happened before. This occured also two to three days ago. As an example, on a 70 miles long trip, engine did some misfires (3 or 4). It is winter at this time. First experience was at 0 degrees celsius (92% humidity) and today it is -13 degrees celsius (62% humidity). Today I also experienced a high speed idle (around 2200 rpm) for about 10 minutes long period then return to normal.Last summer maintenace done: Serpentine belt change, thermostat replacement, sparkplugs replacement and air filter cleaning (use K&N brandmark).I tought it could be some water in the gas tank..!? So I put gas line antifreeze during last gas fill.Car has 185000 Km. Its a stock Vibe GT 2003.I read some threads already without finding any clues...Any help would be very appreciated! Thanks!

[circuitsmith]

K&N oiled filter? If so the MAF sensor might be dirty.

[Raven]

Did the check engine light come on? If you are ever in the USA, pick up some Techron fuel treatment. It is miracle juice and works wonders at cleaning fuel injectors etc.

[Bobtronique2]

Thank you for replying.Yes, I use K&N oil filter. Never heard about dirty MAF sensor before. I'll have a look on this soon.Is it a normal problem that should occurs often with this type of air filter?

[Bobtronique2]

Thank Raven! I'll see if I can have a hand on this product. By the way, whille trying to find some information about Techron fuel treatment, I remembered that I commonly use regular fuel onmy Vibe GT. I always did that since fuel price rise in 2005. I will make a try before to buy any fuel treatment. If misfiring stop, then I will have my answer. But I doubt this could be the reason. Misfiring never occured before last week...At least if it is a long term degradation of something induced by this habit...

[jkm311]

The long-term effects of buying low-octane fuel for your GT might be the issue.And yes, I have over-oiled my K&N filter that you have. After throwing a code, I cleaned the MAF and problem solved. My write-up of the process: http://forums.genvibe.com/zero...age=1Scroll below my initial post for clarification of where to spray. I had the temperature sensor and the MAF sensor confused. Hope the Techron and/or MAF cleaning help. I would introduce some higher-octane fuel after these procedures. Good luck.

[Bobtronique2]

Thanks Jkm311!I will read the thread immediately...I'll keep you all in touch with any development.Ciao!

[Salsa Guy]

I had a similar problem but it was a bad ignition coil. Then another and another until I replaced the condenser. So far so good no more coil failures over the past 10 months. Knock on wood!