ok this is the story i just got my 3rd gen 7 back from mazda dealer after they rewire the whole car because some idiot put the wrong size fuse on the socket and pretty much fried the whole electric....now after 3 months on work i finally get the car back, i had gasoline left sitting in my car about 1/3 full for 3 months...
now when i drive it everything fine...when i step slowly on gass to bring my car to 6k or 7k rpm its fine, but when i floor the gas pedal in split second while driving, it always stutter, english is my 2nd language so i might not describe this perfectly, feels like it the car doesn't always push and the muffler feels like shooting brom brom brom brom brom , but this ALWAYS happen when im driving and flooring the gas, when i take my rpm up slowly it doesn't do this, so i did a little test and i park my car in neutral and i floor my gas pedal to 6 or 7 rpm and it was fine no problem. this problem only happen when i'm driving...i assume the car been sitting for 3 months so probably they just need new gas and i just need to drive it and get rid of the bad gasoline? my friend told me it was probably spark plug, i'm not a very much machine head so if anyone have info or suggestion i'd appreciate it much thanks!

 

I would try fresh gas first... Just to rule that out. Also pop some new plugs in while you're at it.

 

Take a good long visual inspection at the engine's electrical connections. Make sure they are plugged in all the way and properly. Also check for any cracked hoses that are easy to see..( MAP sensor hose, some near the UIM) Try trhe new gas as jdhuegel1 said. It could be many things if they were under the UIM replaceing the wiring harness.

 

when i bought my 7, the plugs were fouled out. i had the same problem you are descibing. i would definatly replace the spark plugs.

 

also..be very careful...dont want to be hitting any lean conditions while testing for the problem.

if the plugs and wiring are fine...get some fuel injector cleaner and run it through the system. you could have a sticky or dirty injector as well.

good luck...take your time.


jason

 

so is changing spark plug pretty easy? i remember my friend try to do that but 3rd gen engine is so compact its hard to reach any shop i can take to have my spark plug changed?

 

do not go to a dealer....find a local rotary specialist.

ask in the regional forums which shop is closest to you.

j

 

Fuel filter clogged?
Bad gas or gas+water?

It sounds like gas is not enough in that moment. Your car should be knocking at that time, be careful.

English is my second language too, what is your first?

 

I'd guess, in this order:

• Spark Plugs
• Plug wires
• gas

 

It's actually very simple if you put the car up on ramps and change from underneath. If you want to change the plug wires, then you have to remove the intake elbow, throttle body, and loosen the oil filler neck. A little more work, but still not a complex task. I think there is a how-to on Rob Robenitte's site (sticky at the top of this forum).

 

reset ECU

change Spark Plugs

change gas