I have a problem with the Ecoboost 2.0 engine. Cylinder 3 misfires shortly after starting. After warming up the engine works well.

The problem has been going on for a long time, I visited several services, no help for now.

What has already been checked/done:
- replaced spark plugs
- swapped ignition coils between cylinders, the misfire is still on the same cylinder
- checked compression of 12 bar on each cylinder
- injectors replaced with new ones

I am sending a graph of parameters from forscan, after starting a cold engine . After a few minutes, the controller counted almost 100 misfires.
Any ideas?

 

Looks like you may have a lean burn, log fuel trims at idle and 3000rpm for ~30 sec on each.

 

Uploading the logs. The same order of charts as before (first chart is short term fuel trim, second chart is the long one.) The engine was not fully warmed up at the time.

~3000rpm



Idle

 

How are you determining it is in #3 cyl?

 

The last 10 driving cycles show an average of 20 misfires. Some of the cycles were on a warm engine. Normally it is around 60-100 misfires on 3rd cylinder when starting from cold

 

Thank you for the info.
I would start with a compression check and see if we have good compression when cold.and warm in that cyl.

One we know all is OK there we can move on to other checks. Can you do this?

 

I did check the compression on cold engine but didn't check when warm. I figured out that the engine wouldn't work well on warm if there was a compression issue

 

Post the number when you have them,

I would also like to know the ECT (Engine Coolant Temp) when cold (is it the same as the IAT, Intake Air Temp) and when misfire starts.