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EricFromCT, Auto Technician
Category: Mazda
Satisfied Customers: 3697
Experience:  20 years dealership experienceASE Certified L1-L2
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I have a 2007 mazda cx7 with cylinder 4 missfiring. I replaced

Customer Question

I have a 2007 mazda cx7 with cylinder 4 missfiring. I replaced all 4 sparkplugs mand all 4 coils and reset the ecu the problem went away for a few days but then came back and now the car is shaking and backfiring with smoke from the exhaust when I accelerate at high speeds and the check engine light came back on saying cylinder 4 missfire again. Any ideas what may be causing this?
JA: Cars do make very odd noises -- They help the mechanics figure out what's wrong. They are terrific with my old Grand Cherokee. Are you hoping to fix this yourself?
Customer: yes if possible
JA: Great! What have you tried so far?
Customer: did you read my first response?
JA: Anything else I can tell the Mazda Mechanic before I connect you two?
Customer: just what I already told you thanks
JA: I'm sending you to a secure page on JustAnswer so you can place the $5 fully refundable deposit now. While you're filling out that form, I'll tell the Mazda Mechanic about your situation and connect you two.
Submitted: 1 year ago.
Category: Mazda
Customer: replied 1 year ago.
My 2007 Mazda CX 7 Turbo has a check engine light stating Cylinerd 4 Missfire, the vehicle shakes and sputters and backfires with smoke coming from the exhaust when accellerating at high speeds. I have replaced the sparkplugs and coilsand reset the check engine light and the problem went away for a few days and then came back so I replaced the spark plugs again and tried rearranging the coils and re setting the check engine light again but it continues to say cylinder 4 missfire no matter what whit the same problems. What could be the problem and what can I do to fix this?Thank you
Expert:  EricFromCT replied 1 year ago.
Hi. At this point it is possible that a fuel injector has a problem, a wiring problem to the cyl 4 coil, or a problem with the engines computer. You can either swap the injector to a different cylinder and see if the misfire changes, or you can use a test light (or a noid light preferably) and check if the coil is being grounded by the ecu when the skip is happening.
Expert:  EricFromCT replied 1 year ago.
Or possibly a wiring problem at the #4 coil connector.
Expert:  EricFromCT replied 1 year ago.
Can you do these checks yourself?
Customer: replied 1 year ago.
Thank you I will check the suggestions you gave me and then fallow up with you shortly after to let you know the outcome.Thank you again for your assistance
Expert:  EricFromCT replied 1 year ago.
You are welcome and please let me know.
Expert:  EricFromCT replied 1 year ago.
Let me know if you have made progress with this and please rate the service provided. Thank You
Expert:  EricFromCT replied 1 year ago.
I see you keep viewing my responses. Do you have more questions for me? Rate my service positively and have a great day. THanks.