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Dr. Hamman
Dr. Hamman, Automotive Engineer
Category: Car
Satisfied Customers: 6286
Experience:  30 years experience, Repairing, building, & designing, automobiles.
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2007 suzuki sx4: /30,000 miles idles a little..warmed..spark plugs

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My 2007 suzuki sx4 w/30,000 miles idles a little rough when warmed up. Changeg the spark plugs. used double platinum ngk. not any change. maybe a little worse. Also put fuel injector cleaner in before I changed the plugs. Is there anything I can do to solve this problem. Runs great at al speeds.
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Dr. Hamman :

So does it idle poorly, but run good when it is driving.

Customer:

yes, I changed the spark plugs and it did not change. Previously added injector cleaner. Runs great but idles a little bumpy. Sometimes worse than others. Smooth when engines cold.

Dr. Hamman :

I would suspect a vacuum leak. This is a super common problem, and it has the exact symptoms you have. They can be tough to find but I have a trick. Get a can of WD40 and spray it all around the intake manifold, and vacuum lines with the engine idling. If you you hit a vacuum leak with the WD40 the engine will speed up for a second or two. I would also suggest using some good quality fuel system cleaner, dirty injectors can cause a similar problem.

Dr. Hamman and 13 other Car Specialists are ready to help you
You really need to check for vacuum leaks, they are the most common problem causing this type of problem, I would say 9 out of 10 times the problem will be vacuum leaks with your symptoms, thanks for the accept, and the positive feedback.