I've been chasing some misfire codes for a few weeks now. My car is a 2010 fusion hybrid with 166k, the codes stored vary between P0301 and P0300. I additionally see P0300,P0301,P0303 as soft codes that clear when the vehicle is shut off. The misfire appears to only happen during idle when the car is already warm. Mostly when I am sitting in the vehicle with the heat going and the car calls for more heat so the ICE kicks in. If i start driving, i can feel the hesitation quickly clear up. I have searched these forums and google for keywords i felt would be relevant but was unable to find anything that matched.
Isoheet added to half tank of fuel and topped up with premium gas from a different popular station
New motorcraft plugs (5000 miles ago)
Measured coil pack resistance all within spec to each other,during trouble shooting i additionally swapped coils 1&2 and 3&4 to see if misfire codes would follow (they did not)
measured injector resistance, cyl 1&2 11.2ohms, cyl 3 14 ohms, cyl 4 9.6 ohms - note all injectors have oily/gas wetness on connector. Harness, and fuel rail connections are all bone dry.
Visually inspected balance of connectors on harness - everything dry and clean.
listened to injector firing (1&3 have a different sound but do fire - see below)
Removed & Cleaned throttle body & wiped out intake of major grime
Flooded intake area with map gas to check for intake/vacuum leaks - no surging or smoothing
head temp sensor visually inspected - clean/dry connector
Today I checked the new plugs and piston tops again to see if there was any visible damage. Cyl 1 had a clean spot on the piston but, 2&3 were normal, i did not check cyl 4. Besides color differences, all pistons were dry. All spark plugs were dry and near identical color/gradient with the exception of cyl 2 which appeared to have a little blow by so i assume that was slightly loose.
I had intended to replace all 4 injectors due to the residues on the connectors and varying ohm readings, but then I noticed today that Cyl 1&3 injectors stop and start firing at the same times (when engine runs rough) which brings up so many questions. When they do fire, they have a slightly deeper click compared to injectors 2 & 4. I tried calling a local dealer and asking if there were any reason injectors 1 & 3 would stop firing or if there were any TSB for ecm/pcm updates etc - they were not very helpful. I will be back probing the injectors tomorrow to see if they are getting power when they stop firing, maybe they are both sticking and its fuel pressure related or something - seems fishy.
Any advice is greatly appreciated.
-Would the atkinson cycle (or any other FFH programming) tell injectors 1 & 3 to stop firing at the same time? It seems odd that the engine would try to run on 2 cylinders, or that both injectors would intermittently work simultaneously.
-I understand this is a coil on plug design and direct injection, but would cyl 1&3 have any other electrical commonality that i can check?
-Does sync reside in the PCM? I have random sync problems (latest version installed) that require a reboot for bluetooth to function properly - electrical problems? related?
-Should I replace all the injectors due to the wet connectors and clean the harness with connector cleaning spray before taking it to a shop?
-Any other advice on things to check before i bring it to a dealer?
Edited by sjgush, 29 December 2017 - 06:16 PM.