Interpreting DME Report
04-05-2019, 01:04 PM
#1
Interpreting DME Report
I was looking at a 2012 Cayman BS this week. Nice car and good price.
The DME showed 1000 hours of use, basically no over-revs, but 25,000 'M120_Total number of misfires for all cylinders over the life of the control unit'.
I am fairly knowledgeable about engines, but the misfires has me wondering.... while this is not that many misfires (25 per hour), what causes this many misfires, and how does this compare to other reports.
Your comments are greatly appreciated.
The DME showed 1000 hours of use, basically no over-revs, but 25,000 'M120_Total number of misfires for all cylinders over the life of the control unit'.
I am fairly knowledgeable about engines, but the misfires has me wondering.... while this is not that many misfires (25 per hour), what causes this many misfires, and how does this compare to other reports.
Your comments are greatly appreciated.
04-05-2019, 01:22 PM
#2
Rennlist Member
I was looking at a 2012 Cayman BS this week. Nice car and good price.
The DME showed 1000 hours of use, basically no over-revs, but 25,000 'M120_Total number of misfires for all cylinders over the life of the control unit'.
I am fairly knowledgeable about engines, but the misfires has me wondering.... while this is not that many misfires (25 per hour), what causes this many misfires, and how does this compare to other reports.
Your comments are greatly appreciated.
The DME showed 1000 hours of use, basically no over-revs, but 25,000 'M120_Total number of misfires for all cylinders over the life of the control unit'.
I am fairly knowledgeable about engines, but the misfires has me wondering.... while this is not that many misfires (25 per hour), what causes this many misfires, and how does this compare to other reports.
Your comments are greatly appreciated.
04-05-2019, 08:42 PM
#3
I agree. The coils are a known problem on these cars; fortunately an easy fix. Misfires can occur without triggering an check engine light, although 25,000 seems like a bit much!
04-08-2019, 03:34 PM
#4
Rennlist Member
At 2500 RPM, a single cylinder will fire approximately 416 times per minute. So, driving at that RPM with just one coil misfiring fairly consistently wouldn't take much over an hour of run time to get to 25,000 misfires. That's only 1/10th of 1% of the total hours of use. Misfires are never good, but this doesn't seem to me to be excessive, especially since it's been corrected and has not recurred.