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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.


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 7 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.