Gas grade effect on idle?

[Nova2009Mazda5]

Hello, I'm a proud new Mazda 5 GT owner. Only on the second tank of gas. I have noticed a somewhat rough idle at stoplights at various times. Not horribly rough, mind you, but enough to make the sun visor vibrate slightly when it is down.

Has anyone experimented with different grades of gas for their 5 and noticed any difference in engine performance? Dealer told me the 5 runs fine on regular 87 octane fuel, which is what I have been using.

Are there any other known factors/issues that could affect the idle?

 

[BlackCherry06]

The grade of gas won't affect this, but the quality (cleanliness) will over time. What you're experiencing is dirty fuel injectors and / or intake tract. Try running some Chevron Techron fuel injector cleaner through it. Use it at the highest concentration noted on the bottle. My SportTrac has a large tank, so I add two bottles and fill it all the way up. This is the best stuff I've used to date...I've improved performance on several older vehicles with it.

 

[Nova2009Mazda5]

Hmm. I'd be surprised if fuel injectors were dirty/clogged when the car only has only 400 miles on the odometer, although I suppose anything is possible.

I see in other threads that most Mazdas are tuned for 87 octane gas, and that higher grades can actually decrease performance. So maybe my intermittent idle issue has something to do with the engine's computer or some other factor.

 

[62Lincoln]

This engine seems to be slightly rough at idle, especially when running the a/c. I think the roughness is somewhat accentuated by how smooth the engine is once underway.

 

[Nova2009Mazda5]

Thanks 62 ... as a new car owner, I may be hyper-sensitive to anything that seems slightly off.

 

[coolmazda5]

I always go for 87 (there is no need for better gas in this engine), the 'roughness' in idle was due to filling up @ a gas station I never used before (along with poorer MPG). As soon as I went back to my regular station, no issues anymore.