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Misfire cyl 1&3, injectors stop firing at same time?

misfire p0300 P0301 P0303 Injector not firing

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2 replies to this topic

#1 OFFLINE   sjgush


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  • Location:CT
  • Current Vehicle:ford fusion hybrid
  • My Hybrid's Year:2010

Posted 29 December 2017 - 06:10 PM

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. 


troubleshooting done:

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.

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  • My Hybrid's Year:2013

Posted 30 December 2017 - 10:02 AM

Just went through that with my 13 hybrid. Cylinders 2,3 and 4 misfiring, all started suddenly.
Mechanic could not figure it out so brought it to Ford since it is still under warranty.
Bad Fuel Injector. Got it replaced and problem is gone.
Unfortunately, that might be your case too.

#3 OFFLINE   sjgush


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  • Location:CT
  • Current Vehicle:ford fusion hybrid
  • My Hybrid's Year:2010

Posted 05 January 2018 - 07:45 PM

i replaced all the injectors today. when tested, the injectors were continuously receiving pulses and randomly not firing. sometimes only cyl 3, other times 1&3.


The car seems to run smoother at idle, and has not thrown any codes yet. i assume it to be fixed, will report back if not.

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