Mazda CX-7, rough idle, misfire etc...Please help

Hi my name is Jennifer, I don't know a whole lot about Mazda or cars in general but I love my Mazda.

So my CX7 is idling really bad at stop lights and such, it comes and goes but for the most part it's there! It seems to be getting worse, it's almost like a puttering sound. I noticed that when this happens my RPMs fluctuate, but when I take off it's fine I can also feel it now when I come to a slow stop. Has anyone else experienced this? I did have a test thing done on it and there is a misfire cylinder 4 engine block also if I am sitting in a line too long in drive with foot on the brake I get a real loud like metal sound from the bottom of the car but if I put it in park it goes away...Any clues?
 
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2003 protege 5
What year is it? Is it turbocharged? Has it had regular maintenance? Mileage?
1st off would be to replace the sparkplugs. If that doesnt fix it then also replace #4 coil on plug. That should clear the misfire code. Then check the air intake tube for cracks and vaccuum lines too. Those are usually the most obvious culprits for rough idle. There are videos on youtube showing the sparkplug replacement if you need visual assistance. The cx7 has basically the same engine as the mazda3 if that expands the video choices.
 

rsvinylgraphics

2008.5 MGM MS3
Contributor
:
2008.5 MS3
You really shouldn't drive the vehicle with a misfire as it can ruin your catalytic converter and they are costly to replace.

Is the metal sound you are hearing like a rattling sound? if so it could just be a loose heat shield on the catalytic converter, most people just remove the heat shield when that happens.
 
What year is it? Is it turbocharged? Has it had regular maintenance? Mileage?
1st off would be to replace the sparkplugs. If that doesnt fix it then also replace #4 coil on plug. That should clear the misfire code. Then check the air intake tube for cracks and vaccuum lines too. Those are usually the most obvious culprits for rough idle. There are videos on youtube showing the sparkplug replacement if you need visual assistance. The cx7 has basically the same engine as the mazda3 if that expands the video choices.
It is a 2007 and yes there is a turbo in it. I only got it a few months ago like in January...I have kept matnince on it but not sure of previous owners.
 
You really shouldn't drive the vehicle with a misfire as it can ruin your catalytic converter and they are costly to replace.

Is the metal sound you are hearing like a rattling sound? if so it could just be a loose heat shield on the catalytic converter, most people just remove the heat shield when that happens.
Kinda of rattling sound my dad did say something about heat shield but hasn't looked at it.
 
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2003 protege 5
The heat shield can rattle and can be remedied by either bending it away or removing it. But the rough idle is another issue. Start with a plug change. That will also let you know if the engine burns oil as the cylinder specific plugs will be oily. If you still get the misfire code replace the coil on plug for that cylinder. If after doing that it is still idling rough but no misfire codes try looking for cracked or broken vaccuum lines and at the air intake tube. The first thing to address should be the misfire as stated it can ruin the catalytic converter. Let us know how that goes and we can advise more from there
 

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