Help Needed With Persistent P0206 on Coyote

[ArizonaBOSS]

I have been troubleshooting an "injector circuit open" code P0206 (cyl 6) since March this year. I had just let the car sit over the summer since it was too damn hot here to think about it and lots of other stuff going on.

What I have done so far (some have been deemed still useful as many existing parts were factory pieces from mid-2011 production):

Replaced the entire engine harness, all plugs, all injectors, all coils, still have the issue.
Tested resistance of each injector and they are in-spec for LU47s.
Verified signal to injectors and coils from PCM using noid lights.
Sent PCM in for repair (new ones on permanent backorder) and they said it's fine and sent it back.
Continuity tested the wires in the new harness (multimeter resistance test) and all are good, noid lights confirm signal is coming from PCM to pigtails for injector and coil.
Took off the valve cover expecting maybe a dropped valve or broken spring but nothing abnormal, no lifters or clips missing.
All grounds for PCM, engine, harness checked, cleaned, tightened.
I have gone through all of the diagnosis and troubleshooting steps in the Ford service manual for this and still the problem persists.

I'm stumped.
Compression test this weekend.

Anyone have any thoughts or ideas on this one?
I might try to see if I can arrange a PCM swap just for kicks, not sure if I will need to reteach PATS or burn a couple HPTuners credits to load my tune to a new PCM.

 

[mwjscn]

Edit: Nevermind, I missed the note where you said you got all new injectors.
When you move the injector, does the problem code follow it?
I know you said you resistance tested the injector, but did you try removing it and confirming it cycles?
Easy DIY way to try it with a cut off section from your old wiring harness or alligator clips:

Doing some researching online on things that may also set the code that you haven't covered, it seems like the PCM expects a certain voltage spike/response from a injector in operation. The crank trigger wheel and sensor provide the PCM context on when this event is supposed to occur, it seems. Perhaps it may be worth performing a crank relearn procedure? Ford calls it a Misfire Monitor Neutral Profile Correction. Shot in the dark, but free to try if you have an SCT Tuner or Forscan and Ford suggests it be done if you ever unplug the PCM anyways.

 

[Dave_W]

If you reset the code (and from Googling it seems the Keep Alive Memory as well), does it come back just idling in place, or do you need to drive around (road vibration) for it to happen? If it doesn't normally do it idling, try shaking wires and tapping connectors while idling (yeah, you probably already did that).

I'm thinking you might need a more detailed picture of the voltage & resistance at the injector than a noid light or simple resistance check of the coil, to better understand what the PCM is sensing to throw the error. See the sections on system background, power probe, & power probe results (which also shows an oscilloscope) in this video.

Googling the Snap-On scope tool in the above video, I found this pages that might help

Quick Tip: Fuel Injector Voltage and Current Tests

And this page actually spells out what triggers a P020x code

Testing a Fuel Injector | Technical Focus | Snap-on

When the injector is to be switched off the ECM opens the path to ground and current flow ceases. This induces a Back EMF (Electro-Motive Force) into the winding and a voltage of 60 to 80 volts is observed. The engine ECM uses the presence of this voltage to validate the electrical operation of the injector. OBD codes P020x will be stored if there is an anomaly with this induced voltage.

So to see that you need to use an oscilloscope, or at least the power probe, as shown in the first video I linked to. it looks like that fancy Snap-On tool is several thousands of dollars, so I'm guessing your best bet is calling around shops in your area to find one that has it, and let them take a look at your car. I know a lot of us like to do our own work, and take pride in the fact that we have the skills & knowledge to tackle most problems, but sometimes you have to call in the pros.

 

[Dave_W]

Another quick thought - I don't know if a noid light is generating the back-EMF spike like the injector solenoid does. Not sure how many cycles it takes before the PCM sets the code, but extended use of a noid light might actually trigger a P020x code if it's not creating that spike after the PCM opens the circuit (disconnects the ground drain).

 

[ArizonaBOSS]

Guys:

Appreciate the input on both fronts.
I didn't type it above but one of the things I originally did was swap two of the injectors in adjacent cylinders to see if the problem moved, which it did not. I actually had a set of new injectors ready to go from Summit at that time, but returned them unopened after that test.

A few months later now I decided to put all new injectors in (I should have stuck with the data in the first place and not spent the money) and that didn't change anything either.

I did clear the codes using HPTuners and even reflashed the PCM, but the issues persist. The car is definitely missing as I can feel it and hear it in the exhaust pulses. At this point, after watching the diagnosis video posted above (very interesting, actually--helped me confirm I'm not insane), I need to get into the car and do the compression test on each cylinder. I'm guessing at this point it's some sort of issue there.

I did already borescope that cylinder and the top of piston and cylinder walls look good/normal. No scoring on the bore or chipped/burned piston etc. Might be something wrong with the heads as I did have some work done on those prior to putting this version of the engine together. Maybe a seal or seat let go in that hole (speculation). Or maybe the rings gave up in that hole? TBD

 

[mwjscn]

Is P0206 the only code you have? Do you also have P0306?
My understanding is that Ford sets the Misfire code when it notices an imbalance in the Power Balance Table (IDS can measure what each cylinder is contributing based on acceleration of the crank trigger wheel for each combustion event). But to have only P0206 makes it sound electrical in nature, which is where the confusion comes in on how nothing you did changed the outcome.

 

[ArizonaBOSS]

Is P0206 the only code you have? Do you also have P0306?
My understanding is that Ford sets the Misfire code when it notices an imbalance in the Power Balance Table (IDS can measure what each cylinder is contributing based on acceleration of the crank trigger wheel for each combustion event). But to have only P0206 makes it sound electrical in nature, which is where the confusion comes in on how nothing you did changed the outcome.

Both 0206 and 0306. Also triggers the "misfire detected first 1000 revs at startup" code, can't remember OTOH which number that is. But it's doing what you noted above by noticing the imbalance in power.

 

[ArizonaBOSS]

Fired the car up this morning to get it warmed up for compression testing and it's running like a fn top, no misfire detected, felt, or audible, no codes (injector circuit open, misfire, misfire first 1000 revs, etc.)...did MMNPL through HP Tuners while the car was hot.

Going to complete the compression test now to get more data.

 

[Dave_W]

Fingers crossed.

 

[ArizonaBOSS]

Just kidding on compression testing. Not a single one of the adapters I have will engage the threads on any of the plug holes.

Ordered a specialty one from MMR...more waiting. Get to re-install the plugs etc. and warm the car up again once that arrives.

 

[S550AZ]

If you do not find an issue with your compression, Not sure if you already have but check your O2 sensors. I was getting a missfire that looked like an injector and ended up being my O2 sensors with an incorrect voltage signal. We changed them out and runs perfect now.

 

[ArizonaBOSS]

MMR cancelled my order, not sure how I am going to get something that's actually going to thread into the head at this point. Weeeeee

 

[mwjscn]

From what I can find, NGK seems to specify the spark plugs being M14x1.25 thread if you can find a matching adaptor.

 

[67GTA]

MMR cancelled my order, not sure how I am going to get something that's actually going to thread into the head at this point. Weeeeee

This looks very similar

https://www.napaonline.com/en/p/BK_7000112

 

[EF1]

This looks very similar

https://www.napaonline.com/en/p/BK_7000112

For some reason I am thinking coyote spark plugs are 16 x 1.5mm. I know they are an odd size.

 

[ArizonaBOSS]

You guys are right on the M14 thread size. I actually have two adapters in that size, but something about the coyote head makes the threads on the adapters that I have in-house too short to engage the threads in the head. I figured the MMR one *had* to be long enough to work considering their vast experience with the Coyote. I'll keep looking

Got this one on the way now, looks promising: https://www.kprecisionllc.com/store...ion/leak_tester_adapter_M14x1.25_thread_.html

The FRTD one probably is also "guaranteed" to work, but out of stock. https://www.freedomracing.com/14mm-long-reach-compression-test-adapter-am-136.html

 

[Seabas]

I know this is an older threat but was the outcome ?
I blew a coil on cylinder 5 fixed it including PCM and now have the same two failure codes out of no where… curious what the issue was after went basically through all potential issues.