2008 hyundai santa fe P0301 p0305 p0420

Hello guys . Im working on a 2008 hyundai santa fe v6. And i got p0301 p0305. P0420
Start fine but after 42 seconds. The ecm shut off the injector 1 and 5.
If i turn the suv off. And then start again runs fine for 42 seconds and then misfires again and the check engine light star flashing.
Can the catalyst Make the cylinder 1 and 5. Misfire. ? If yes why not the cylinder 3 ? Can 2 ignition coils be bad at the same time? Where to start. ? Thank you guys

Protective shutdown of the injectors on misfiring cylinder to save the catalyst. Yes two two coils can fail at the same time. The common factor is wear/errosion of the spark plug gap pushing the spark plug voltage up eventually the secondary voltage gets insultion breaks down and the spark finds an easier path to the engine ground. As with all transverse V6 engine the rear bank spark plugs and coils get neglected. To test you could swap coils plugs around but personally I would expect to change all plugs and coils for 1, 3 ,& 5

Now i got p0303. Too
Now . P0301. P0303. P0305. P0420
But only start. Misfiring after 42 seconds
May be the cat is clogged because p0420
And back pressure. To all 3 cylinders ?

gerber wrote: May be the cat is clogged because p0420
And back pressure. To all 3 cylinders ?

P0420 is associated with low Catalyst efficiency. (i.e. its ability to store oxygen.) It is not, generally, associated with air flow restriction.

I would ignore the P0420, for now. The 42 seconds is what I would concentrate on. Is it exactly 42 seconds, every time? Does this co-inside with going into closed loop? How do your upstream O2 sensors and Fuel trims respond before, and after, the 42 second point.

As Andy.Macfadyen stated, the pcm will shut down injectors on cylinders with ignition faults, to prevent un-burnt fuel from entering, and damaging, the CAT. If you don't have a scope, inspecting spark plugs and swapping coils from bank to bank might be a good next step.

Well swap all 3 coils. And spar plugs from 2-4-6. To 1-3-5. And still the same. But now come back. Only p0301 and p0303.

P0305 come back too.. 1 thing that I noticed is if I reset thecodes and start the car. And keep the gas pedal at 2000 rpms. The ecm dont shutt the injectors off ..i can keep the gas pedal just above 700 rpms. And no misfire . That make me to think the throttle body Or maf sensor

Check this pictures no misfires.

At this point, I would be grabbing the labscope, as well as monitoring data pids with the scanner, in graph mode, paying close attention to the 42 second time frame. Hoping to see something that would give me a clue. Maybe, even revisit the restricted exhaust possibility. An engine vacuum and/or exhaust back pressure test, maybe.

Hopefully, some others will chime in with some other suggestions.

Well i check the cat. But the p0420 is because the cat. Is straight. It’s empty inside. Someone. Remove the inside part.
So no back pressure from that side. On bank 1
Where i get confused is if i keep the idle at 800rpms. Or up. Wont misfire
Or if i turn the a/c on. Wont misfire

The crank shaft position sensor is a Variable Reluctance Sensor. It produces an AC voltage. The faster the crankshaft spins, the higher the amplitude/voltage output.

Do you have a DVOM?

Thank you for responding. And yes I got the scope

If the crack sensor is not working right should can affect only 2 cylinders?

I, normally, wouldn't think so, but..... . If you have a scope, looking at the cam/crank, certainly couldn't hurt.

I would, also, look at voltage and current waveforms of, both, injectors and coils. I don't know what I'm looking for :huh: ....I'm just looking. Maybe, I'll see it.

Well guys. Im still dealing with this suv
This is some of the pictures that i got
They probably not the best ones. I just star using scope. So give me advice and ideas Thank you
The picturesis bank 2 and the video is bank 1 im still confused with the video and picture Im going to try again. And upload more pictures

This is when is misfiring
It shut off for 1 second. Why?

Is this Primary Coil Control voltage?



Do you have an Amp Clamp?

I just got new pucture. And looks good to me but im new with the scope
So i will need help