Hi all

About 10 days ago my Mazda 3 (2006, stick shift, ~50K miles) started behaving strangely. Now whenever I shift to a higher gear while accelerating, the RPM jumps up and the car starts shuddering. As I still keep pressing on the gas pedal the car then stabilizes. This happens more when switching from 3rd to 4th and 4th to 5th gears, and is becoming a problem picking up speed like when I'm about to get on an interstate and need to accelerate.

I never had this problem before and could get huge boosts of speed no pressing the gas pedal and now it starts to vibrate.

Can anyone tell me why this could be happening? The only thing I changed in the vehicle was switched fuels (87 to 89 octane) around 2 weeks ago so I don't know if it is bad gasoline ...

Thanks

Floody

 

if it's in gear and the RPM's are rising - sounds like the clutch is slipping.
Or do you mean between gears the engine races? - in which case it could be a sticky accelerator, or the cruise control going whacky.
I guess if there was a lot of moisture or something bad in the gas it could cause issues, though the 87-89 switch shouldn't cause anything on its own.

 

Don't waste your money on 89. The higher octane gas just makes it harder to detonate and is a waste of money and won't fix anything unless your engine is pinging for some really strange reason.

 

89 is only gonna help if you adv your timing, but thats a diff story