Mazda CX-9 This larger SUV adds a V6 option, as well as more cargo room, to the CX-7 option.

'11 Misfire Issue- Need Input

  #1  
Old 11-16-2016, 09:16 PM
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Question '11 Misfire Issue- Need Input

Hello Everyone- so my '11 GT with 73k miles just had a strange engine vibration last Saturday in the drive way upon a cold start and when I popped the hood the motor was shaking about an inch front to back with the check engine light(CEL) coming on. Restarted motor and it went away. That night, it returned while driving home with the same CEL coming on again but this time the misfire was obviously bad and felt like stalling was only a matter of time. Changed all 6 plugs the next morning but issue remained upon start up. Took to dealer and their diag showed cylinder #2 injector was at 3 Mils when should be at 11-12 Mils like the rest. Bought a new injector and just replaced on Cylinder #2 tonight but now engine will not stay running and misfire continues?

Question- Does the car need to be reflashed after an injector is replaced so the ECU can update a change or does this not matter? Not sure what else to try at this point unless its the coil for #2, but not sure what else it could be? Anyone run in to this issue before by chance? Dealer only suggests to replace all injectors at once along with all coils but with Cylinder #2 being the only misfire code I didnt see the point in that extra $. Any help or tips are appreciated so thanks in advance!
 
  #2  
Old 11-17-2016, 06:25 AM
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Aftermarket coils are cheap as chips on eBay.

Ignition coil Mazda CX-9 2011 | eBay
 
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Old 11-18-2016, 01:53 PM
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Thanks Grim I may go that route after the diag. scan being done today again shows. I was hoping that the low reading on the injector would be the only culprit but now I wonder if the coil could also have played a part in that cylinder? I'll let the board know when I hear back- thanks for the advice I appreciate it!
 
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Old 11-18-2016, 09:59 PM
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What you can do is swap the injector with another cylinder, scan it & see if the misfire moves cylinder with injector, also swap the coil, then the plug & see if the misfire moves cylinders with the movement of parts.
 
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Old 11-19-2016, 08:57 PM
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Yes Grim great idea- I also thought about that process as well to try to isolate if it was truly am injector issue for the cylinder #2 and swap them out to replicate on another cylinder. From there I was going to purchase a new coil online as you suggested and do the same and sort of run a trial by fire(pardon the pun!) and try to narrow it down. I just had to get the 9 back from the dealer and have them tell me what the codes read since I do not have a scan tool myself unfortunately.

But it turns out none of that was needed at all? I just picked the 9 up this afternoon and all is fine with no codes or rough idle at all- apparently a PVC valve that was not connected all the way-or not at all during my injector swap was identified as the issue of the roughness and throwing all types of lean bank codes and electrical wiring issue codes as well from what the service writer told me as the cause of the problem. I was skeptical at first as I did the injector swap carefully and did not miss any hoses or electrical connectors during the removal and reinstallation of the fuel rail simply because of how catastrophic it can be if I get that wrong for me and my family! Without be not being able to speak with the tech and master tech directly who worked on my car Friday and this morning at first, I felt initially like they took an easy out and blamed the customer who changed his own injector since it would have been the easiest cause of blame. However this dealer is very good and I have nothing but great experiences with their honesty though and my service writer even told me that the techs said it was easy to do because when they themselves move the manifold around it has happened to them as well? I cannot rule myself out though as anything is possible no matter how careful I was being so I really am just happy that the injector I replaced ended up being good and the car accepted it fixing the issue at the end of the day. Plus the dealer took extra time and made sure no other codes came up after the PVC disconnect was identified so I was truly shocked in a good way that they took the time to look it over and did not charge me for another diag. fee. They said after the PVC valve was reconnected it started back up like normal with no misfire codes and no issues at all. Driving it home was completed normal with no shaking or CEL's lighting up so I am happy it is back to normal.

Thanks for your insight it was a helpful plan of attack for what could have been a lengthy trouble shooting project if I had never known about the PVC valve they found for me! I appreciate the help especially being a new member the first time on this forum so thank you again Grim!!
 
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