2017 Honda Accord 2.4L P0303

Hello, I have a 2017 Accord (180,000 miles) in the shop with a cyl 3 misfire under heavy engine load. It sets P0303 then disables the injector until the next key cycle. I did a quick swap of the coils and plugs with no change. I attached the scope captures which were taken under the misfire conditions. I have attached the leads to all coils feed, cyl 3 battery voltage, and cyl 3 trigger from ECM. I don't like how the battery voltage occasionally spikes or drops out and it seems to happen randomly for multiple coils. No parts have been replaced. Any input is appreciated. Edit: I should add, the downstream lambda goes lean when the fault occurs. 

Thank you for adding the captures.   I agree, there's some spikes and noise going on in the voltage trace, but I don't think I'd sweat it too much. The spikes are always occurring at a coil firing event, which suggests that the spikes are actually just noise picked up by your test leads. Since this was during the misfire, I'm assuming you were using super-long leads (or daisy chaining leads together), which makes picking up noise almost inevitable.

Since the downstream goes lean during the fault, that'd suggest a fuel injector issue. Does your scan tool have the Cylinder A/F Test available? Run it a couple times and see if the #3 injector gets flagged as lean.

Do you have a means of watching secondary ignition?

I do not have a good way of watching secondary ignition on a test drive which is the only time the fault occurs but I agree it is lack of fuel and plan to scope the injector amp draw to see if the pintle hump goes missing.

brianmstoltzfus wrote:

I do not have a good way of watching secondary ignition on a test drive which is the only time the fault occurs but I agree it is lack of fuel and plan to scope the injector amp draw to see if the pintle hump goes missing.
 

Would you mind sharing your captures with us, if you do end up getting injector current waveforms?

FWIW, I don't know that a sticking pintle will show up in a GDI injector current waveform. Not in the same way as port fuel injectors. My experience has been that when these injectors fail, it has less to do with a mechanical problem and more to do with a poor spray pattern/atomization.

This is good to know! I'll definitely share when I get back to this car!