2009 Mitsubishi Galant Carbon Buildup

SUESUE

MEMBER
2009 MITSUBISHI GALANT
6 CYL
2WD
AUTOMATIC
24,750 MILES

I have been told twice now the reason for the bad knocking was carbon buildup, I use high octane only and was told I am buying cheap gas, they said that they had to run a cleaner through to fix the problem. Do you know if this is true, is gas not gas wher evey you get it? I thought any high octane would be fine. Thanks and have a nice day.

Susan

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,709 POSTS

Is it knocking or valve ping when accellerating? Also, review the owner's manual. I don't think a high octane is needed for your car and being as new as it is with only 24K on it, that isn't the problem. If it is valve ping and heard only when accellerating or under a load, it could be a timing issue or a bad knock sensor which is an emission item covered for 5 years 50K @100%.

Let me know about the noise, and I think this should be covered by your warranty.

Joe

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Monday, March 8th, 2010 AT 5:27 PM

SUESUE

MEMBER
2 POSTS

The sound is similar to a spark plug knock sound, also when we bought the car and were using reg. Gas and the car started to mess up, I took it in and was shown a small lable near the gas cap that stated high octane recommanded, at that time they had to replace spark plug and I was told had lots of crud on it. Do I need to worry or go to another service shop to check this out? I wonder if it is because I am a female they think I believe what ever they tell me. Thanks so much for your time and have a great day.
Susan

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Tuesday, March 9th, 2010 AT 6:31 AM

JACOBANDNICKOLAS

MECHANIC
109,709 POSTS

Susan:
I hate shops that take advantage of women. However, they are out there. As far as your problem, they make products to clean the carbon from the engine (inside). If they are correct, that should fix the problem. However, if you still have a valve ping, I would ask that they check the knock sensor. It is a sensor that changes the engine timing to the point right before the valves make noise. That way the engine is running most efficiently. If it is bad, it can cause the problem, and it is an emissions component. Therefore, it is covered for 5 years or 50K with a 0 deductable.

Listen, find a local shop that provides the service I suggested and try it. If that doesn't take care of it, then go back to the dealer and demand they fix the problem under warranty. Make sure to continue using the recommended octane fuel, and let me know if anyone gives you a hard time. I'll be glad to give you advice. Heck, one time I called the dealer for a customer and raised hell. They don't intimidate me and I let them know I understand cars and they can't fool me.

You take care and let me know how things go.

Joe

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Tuesday, March 9th, 2010 AT 9:40 PM