Hey everyone. Within the past year my vehicle had all new coil packs and spark plugs replaced, as well as new fuel filters and fuel pumps. My car has been running really well since, but just for kicks I decided to do a misfire count on my engine. The results are as follows:

45-minute drive
Cylinder 1: 5 misfires
Cylinder 2: 5
Cylinder 3: 2
Cylinder 4: 0
Cylinder 5: 3
Cylinder 6: 0
Cylinder 7: 1
Cylinder 8: 9
Cylinder 9. 18
Cylinder 10: 15
Cylinder 11: 7
Cylinder 12: 4

These numbers are significantly lower than before replacing components, but I wanted to know if these numbers look normal to a DB9 with fresh coils/plugs and fuel delivery, or if this is indicative of another issue? Seeing the elevated numbers on the bank holding cylinders 7-12 made me wonder. Vehicle is a 2005 DB9 with 7000 miles. Just over 1k miles on the new components.

 

You probably already know this but has the engine management system logged misfire correction?

 

What were the numbers before? Did you use OEM parts also. If your reading any numbers is fine as long as it's not high numbers quickly. Like 50 count in 5 min. If the corrections are learnt, then it will read. No corrections stored you receive 0's or no data displayed.

 

I'm assuming those are misfire counts per cylinder, but you've not mentioned if they are Type A or Type B.

I could play with throttle to hover around 1200rpm and force misfires to occur that are flagged as Type B, heck I could hit a pothole and trigger a Type B from slowing the drivetrain.

The important thing to know is if that's Type A, because that would indicate you have an issue with those values in 45mins..if those are Type B counts, then I'm not concerned..

 

It has been learned. Confirmed with my scanner.

Numbers before the coil/plug/fuel pumps replacement were as follows:

127
124
63
58
35
100
8
7
19
6
6
8

Those original parts were low mileage but high age. 5,000 miles and 15 years, respectively.
Yes per cylinder. Unfortunately I don't know the difference or how to find out between A or B. Can you please share with me how to understand which types mine are?