[farmerjg]

Do a code clear with your tool. Then scan for codes again without starting it up. What is left then?

Just the permanent codes remain when I do that. The misfires do clear out.

 

[John Clark]

The problem can be with scan tools and these newer vehicles. Generally there are two types of codes. Pending codes are codes that the computer has seen one time but require it to see a second time before turning on the MIL. These codes will show on a scan tool as "pending." Permanent codes are usually what come up when the computer has seen the problem twice and turns on the light. It then sets a "permanent" code. This is called two trip detection. There are also codes that will go straight to permanent without going to pending first. These are continuously monitored systems and codes. If you unplug the temp sensor it will immediately set a permanent code and turn on the MIL. If you have an evap leak it will set a code as pending and wait until it sees the problem again on the next drive cycle before going to permanent and setting a code.

However, on vehicles 2013 (or so) and newer, even if you clear the codes the codes are still stored in a permanent memory and it takes something like 50 or 80 drive cycles without seeing the problem in order to clear even after clearing codes and repairing the problem. These phone based scan tools are good but they have their quirks so trying to figure out what it's telling us. If those codes are in "permanent" status but there's no check engine light then I'd say it's the 2013 or newer issue. If there's still a check engine light on then the permanent codes mean they are active and turning on the MIL and in need of repair.

 

[farmerjg]

Yeah, the check engine light turns on, then flashes, and there is absolutely a misfire. It's not just a code thing, I can feel it and it's down on power.

Every time I turn it off and restart out will run perfectly fine (no code no misfire) for a minute then it sets and misfires.

 

[John Clark]

OK. Let's go with that for now.
While it's running and actively misfiring, unplug the coil packs one by one and see how the engine reacts. If both #2 and #6 are indeed misfiring then unplugging their coils will have no affect on how the engine runs. Unplugging other coils you should hear a noticeable RPM drop. We need to verify which cylinder(s) are misfiring.

 

[farmerjg]

OK. Let's go with that for now.
While it's running and actively misfiring, unplug the coil packs one by one and see how the engine reacts. If both #2 and #6 are indeed misfiring then unplugging their coils will have no affect on how the engine runs. Unplugging other coils you should hear a noticeable RPM drop. We need to verify which cylinder(s) are misfiring.

Unplugging two and six did not change anything. Unplugging the others sent the engine chasing up 1k RPMs and back down

 

[John Clark]

So, definitely #2 and #6 are misfiring. That's good data. Next we need to figure out what's missing. It sounds like it's not the coil, the plug, or the injector since you swapped all those and had no change. Here's the next step I'd try. Unbolt the coil on #6. Start the engine. Slowly lift up on the coil and see if you can hear the coil firing. As you lift it up you should be able to hear it snapping in there as the spark jumps from the coil to the plug. You can also, remove it completely and use an incandescent test light connected to ground and let the spark jump from the coil to the tip of your test light. It won't hurt your test light. We need to know if there is actually spark occuring in those cylinders. Try not to let the coil fire without having a path to ground for the spark. That can damage the coils quickly.

 

[farmerjg]

So, definitely #2 and #6 are misfiring. That's good data. Next we need to figure out what's missing. It sounds like it's not the coil, the plug, or the injector since you swapped all those and had no change. Here's the next step I'd try. Unbolt the coil on #6. Start the engine. Slowly lift up on the coil and see if you can hear the coil firing. As you lift it up you should be able to hear it snapping in there as the spark jumps from the coil to the plug. You can also, remove it completely and use an incandescent test light connected to ground and let the spark jump from the coil to the tip of your test light. It won't hurt your test light. We need to know if there is actually spark occuring in those cylinders. Try not to let the coil fire without having a path to ground for the spark. That can damage the coils quickly.

I only did #6 because of access, but the coil is sparking. I used the rest light method.

 

[John Clark]

Do you get a good strong spark? It should jump out of that coil a good 1/2 inch or so.

Next would be to determine if the injectors are actually being fired. That's a little more difficult. Need some way of getting a test light on the connector. Not sure what you have for tools.

 

[farmerjg]

Yeah, it was good spark. I was certainly a 1/2" away and it was consistent and bright.

That's going to be tough, I have a regular test light. No oscilloscope. I can confirm the injectors had 12V with power on, but obviously that's a big jump to "are they firing?"

What tool would allow you to get under the intake plenum while installed?

 

[farmerjg]

Can I pull the fuel manifold and stick it over a bucket while cranking engine to see if each injector flows?

 

[John Clark]

A T-pin, backprobe, or wire piercing tool are the best things. You need some way to get on the control wire from the PCM to see if the PCM is firing the injector. The PCM will be providing a ground so you'd want a test light connected to battery positive and then probe the control wire with the other end and see if the light blinks.

 

[John Clark]

Can I pull the fuel manifold and stick it over a bucket while cranking engine to see if each injector flows?

That doesn't sound very safe to me. You swapped injectors with no change, correct? So it doesn't seem like an injector flow problem to me. We just need to see if the control signal is making it to the injector from the PCM.

 

[farmerjg]

Noted. Thanks for both comments. Let me see if I can backprobe with the intake installed.

 

[farmerjg]

No way to get to that connector with intake on. I'll need to remove intake, backprobe, then leave it there while intake goes back on.

Just to be clear, which wire is control?

 

[John Clark]

Without looking at a wiring diagram, most of the time, the 12v power wire to each injector will be the same color on all the injectors, or all on one bank. The control wire will be different on each injector. So, whichever wire is not the same color on each injector is the control wire from the PCM.

 

[John Clark]

In many cases, when the PCM sees misfires it will shut down injectors as a strategy to save the catalytic converter. So, it's possible that the injector may fire for a few moments then quit. If you see that, the misfire may be caused by something else and the injector stopping may be normal. If that happens, clear codes, start the vehicle, and try again. See if that's repeatable.

 

[farmerjg]

Injector was firing then turned off when mil came on. I also backprobed cylinder 4 and it stayed illuminated after mil just as a reference point.

Also, this is repeatable.

Intake manifold on and off in under 25 minutes, getting good at this!

 

[John Clark]

And just to confirm, it was misfiring while the injector was still firing, before the computer shut it off?

 

[farmerjg]

And just to confirm, it was misfiring while the injector was still firing, before the computer shut it off?

No. The misfire goes away on its own every time the car turns off. So when you start it it's running fine for about one minute, then it misfires. So the flashing on my test light stops exactly the same time the MIL comes on and it begins to obviously misfire.

Stated another way. I can't actually tell whether fuel off then drives a misfire or if it misfires and then the computer turns off fuel.

 

[John Clark]

So, we know what it's not.
It's not:
Coil
Plug
injector
wiring to coil
wiring to injector


I'd sure like to see that crank sensor on a scope, however, I think it's time to check the timing and/or compression. Something mechanical is up. Something else is puzzling to me and that is you said when you unplugged the good cylinders the RPM actually increased before it decreased. That almost makes me think there is possibly a timing issue.

If you remove the PGM-FI relay I think the engine will crank and not start, right? A quick psuedo compression check can be done by listening to the engine during cranking. Does it sound like all the compression is the same on all the cylinders during cranking, i.e. re-re-re-re-re-re, or does it sound like re-re-reee-re-reee-re-re? Hoping that makes sense.