2014 Honda Accord cylinder 2 misfire

2014 Honda Accord 2.4 liter. Came to us from another shop, customer was driving it, it started running rough, check engine light was flashing so he pulled over and had it towed to another shop. That shop replaced the spark plugs, coils and MAF sensor. Still running the same he decided to have it towed out of there and now it’s at our shop. It has a constant cylinder 2 misfire, keep in mind a tune up with OE parts was done… I just need some direction/ideas as what to check next? I’m trying to think of possible causes for a single cylinder misfire other than plugs and coils? The coils are all firing, I did check them for spark, the injectors are under the manifold on the back of the engine, so back probing them may be impossible, I did take a listen to them and they’re all clicking, I pulled the plugs just to make sure they’re OE and they are, there is no signs of excessive carbon in the cylinders and none of the plugs smelled like fuel, no signs of excess fuel, I know that’s not a great test but it’s all I have without pulling it apart. It does have a high pressure fuel pump on the side of the head, it also makes what sounds like chain slack or even piston slap, when it hits 2000 rpm’s. I’m not sure if I’m describing that properly, I can’t tell if it’s just making that noise because of the miss, or if there is actually an engine mechanical issue. It also stalls after raising the rpm’s to 2k, when I let of the pedal the rpm’s drop and the engine cuts out. The last thing I did since I had the plugs out was a compression test and all cylinders were the same at 180 psi. I should have added this, when you first that the car (cold start) it idles around 2k and seems to run fine, no noise, as the car heats up it stumbles and runs rough and misfires on cylinder 2 stay constant. What next?

How can I delete this or would that be up to an admin to do? The car is fixed, it ended up being a fuel pump. I contacted the shop and had them talk through everything they did and why. Aside from the misfire it also had a low power issue, they said it felt like clogged converters or a mass airflow issue. I hooked up the scanner and went into obd direct, took it for a drive and this time I saw misfires in all cylinders and the check engine light came on during my test drive for a p0087, low fuel rail pressure.. I took a reading of the pressure with a gauge in between the pump in the tank and the high pressure pump. The spec is 57-64 psi and when I started the vehicle my pressure was bouncing all over, 30-80 psi.. I did some research on global obd under parameter descriptions, went to fuel pressure and read a low delivery quantity will give the same symptom as a blocked exhaust or mass air flow sensor related problem. This matched the shops description as well as what I experienced when I drove it. Long story short I did a few more checks (back pressure test) just to be sure inspected the high pressure pump but came up with nothing there.. There is a TSB about the code P0087 saying to go a head and replace it the high pressure pump, but based off the pressure coming from the pump in the tank we let the customer know about the TSB as well as our readings, they authorized the fuel pump and car is being released today, running fine!

We can delete this thread if you want? But you've provided a lot of useful information that others might find beneficial in the future. It's up to you!

No don’t delete it keep it up, because I have an update.. car came back, a day later with the same code and same symptoms. This time I removed the rear seat, went straight to the pump and eliminated the high pressure pump, hooked directly up to the pump with a pressure gauge and got a steady 60psi…. I then went to my original test area which was on the firewall and took another reading of my pump pressure this time I’m T’d in so in tank fuel pump is behind my gauge supplying pressure and high pressure pump is in front of my gauge and my pressures were bouncing again 30-80 psi… This was a tough one for me, the TSB said to just change the high pressure pump, but other literature I read was conflicting in stating that a low delivery to the high pressure pump would cause the symptoms we were having and originally when I tested it where Mitchell told me to test it, my readings were off as far as delivery to the high pressure pump. I didn’t think that the high pressure pump would have any affect on my pressure gauge as the as the high pressure pump was after my gauge this is still confusing to me. I’d really love an explanation on this if anyone can explain it that’d be great. As far as the customer goes, we are a family owned shop, it’s a long time customer and we are making it right with the customer, they’re getting a high pressure pump at cost and waiving the diag fee… I’ll keep ya posted..

Is there any type of fuel pressure regulator between the in tank pump and the high pressure pump?

Did you test the powers and grounds to the in tank pump? Maybe an intermittent issue with either of those circuits?

You might hook up a scope to those circuits while driving and see if you have any drop outs.

There are two regulators. One on the pump in the tank it’s apart of the pump assembly and another on the high pressure pump. The regulator on the high pressure pump is computer controlled, it uses the rail pressure sensor readings to calculate the pressure.