Hey Bob - any chance you know Ford's strategy for lighting up the CEL and how they detect misfires ? Seems like a high threshold for triggering a CEL, a few engine mgmt system I'm familiar with detect misfires by measuring the cps pulses, another detection method was ionization current monitoring which Saab used. Would be nice to know how Ford detects misfires.
Here is a link to Ford's 2019 OBD system description. Misfire determination starts on page 20.
Ford uses the Crank Sensor, and it can pick up cylinder acceleration speed of each cylinder.
the logic used seems pretty complicated seems odd that things like bucking and hesitation doesn't trigger a CEL, have to assume Ford needed to set a fairly high threshold to avoid frequent customer visits to service with a cel. conversely though on high output GDI engines - depending on the cause - doesn't take a whole lot of misfires to potentially inflict some harm to engine.
There are numerous possibilities for this and needs a Live Data Monitor for various PIDs when this is occurring.
But with no check light triggering (On) then the Crank Position Sensor is not seeing the misfire, the misfire monitor is not enabled without inputs from the ECT, CHT and IAT1 & IAT2. So, any of the temp sensors can be reading incorrectly and triggering this.
No code misfires are difficult to T/Shoot and requires you to monitor different sets of PIDs to isolate the issue.
1. EGR Related PIDs - mainly focus on what is the position of the EGR Valve
2. EVAP Related PIDs - mainly position of the EVAP Purge vale
3. MAPT - Pressure & Temp Readings
4. CPS & CPS - Sensor readings are they (In Sync)
5. Fuel Trim Data
6. O2 Sensor Data
Being that the tech picked up misfires on Cyl #4, I suspect one of the following in order of probability.
1. Injector #4 - Failing when hot
2. Vacuum Leak - at Cyl #4 port (Intake) of (Head) - (Expanding when hot)
3. Crank Position Sensor losing Cyl #4 position when it's hot
4. Dirty (Intake Valves) (Inspect with Borescope)
As most of the other systems would not just affect cylinder #4, so I would focus on #4 first and branch out from there.
It may only need a (KAM Reset) or more specifically a (Misfire Neutral Correction - Reset) as the PCM may have locked in - This is normal for #4 cylinder
Relative Compression Test - Will help in pinpointing a compression loss via (Scan Tool) by doing a automated test using starter amperage draw (when cranking) you want your readings to be (O) if not at (0) indicates a possible compression issue in that cylinder and then a true compression test can be performed to help isolate (Valves/Rings) or Gasket Leak
Cylinder Balance Test -Monitors Cyl performance and allows injector (kill individually) and you note the RPM drop for each cylinder. This helps isolate an injector issue as a injector kill that does not affect RPM drop indicates an issue with the injector.
Relative Injector Flow Test - This test is automated, and it disables the spark and automatically cranks the engine using a set pressure on the fuel rail and pulsing the injector for a specified time. It reads the ending fuel rail pressure and notes how long it takes for each injector to dispense the fuel from starting pressure to ending pressure. Should be 140ms +/- 15ms
Ref: Test from my Truck for Fuel Injector Flow Test
There are numerous possibilities for this and needs a Live Data Monitor for various PIDs when this is occurring.
But with no check light triggering (On) then the Crank Position Sensor is not seeing the misfire, the misfire monitor is not enabled without inputs from the ECT, CHT and IAT1 & IAT2. So, any of the temp sensors can be reading incorrectly and triggering this.
No code misfires are difficult to T/Shoot and requires you to monitor different sets of PIDs to isolate the issue.
1. EGR Related PIDs - mainly focus on what is the position of the EGR Valve
2. EVAP Related PIDs - mainly position of the EVAP Purge vale
3. MAPT - Pressure & Temp Readings
4. CPS & CPS - Sensor readings are they (In Sync)
5. Fuel Trim Data
6. O2 Sensor Data
Being that the tech picked up misfires on Cyl #4, I suspect one of the following in order of probability.
1. Injector #4 - Failing when hot
2. Vacuum Leak - at Cyl #4 port (Intake) of (Head) - (Expanding when hot)
3. Crank Position Sensor losing Cyl #4 position when it's hot
4. Dirty (Intake Valves) (Inspect with Borescope)
As most of the other systems would not just affect cylinder #4, so I would focus on #4 first and branch out from there.
It may only need a (KAM Reset) or more specifically a (Misfire Neutral Correction - Reset) as the PCM may have locked in - This is normal for #4 cylinder
Relative Compression Test - Will help in pinpointing a compression loss via (Scan Tool) by doing a automated test using starter amperage draw (when cranking) you want your readings to be (O) if not at (0) indicates a possible compression issue in that cylinder and then a true compression test can be performed to help isolate (Valves/Rings) or Gasket Leak
Cylinder Balance Test -Monitors Cyl performance and allows injector (kill individually) and you note the RPM drop for each cylinder. This helps isolate an injector issue as a injector kill that does not affect RPM drop indicates an issue with the injector.
Relative Injector Flow Test - This test is automated, and it disables the spark and automatically cranks the engine using a set pressure on the fuel rail and pulsing the injector for a specified time. It reads the ending fuel rail pressure and notes how long it takes for each injector to dispense the fuel from starting pressure to ending pressure. Should be 140ms +/- 15ms
Ref: Test from my Truck for Fuel Injector Flow Test
There are two ways to cut warranty costs: 1) make a product that sucks less 2) pretend the problems don't exist. I'd guess ford went #2 on this one.
3/8 fuel line . Perfect . Just crazy I didn’t throw any codes and no cel . Crazy how one wire touching a bolt would cause the symptom to buck . But it does kinda makes sense with he issues I have had
My fan hoe seems to be ok, but I just doused it with protectant for good measure. I check it often.
I’d swap it out before it fails. Better to be proactive considering how many issues this stupid design causes when the hose fails, and how easy and inexpensive the fix is. I used a 90 degree silicone hose from HPS.
