P0300 + P0204 Misfire no spark on passenger side 8-6-4-2

[jared999]

Have a flashing CEL, super rough idle. This happened 6 weeks ago and went away.Stabilitrack and ABS have been on the whole time. I hooked up a Tech2 and it pulled P0300, P0204, P0206, P0208 Injector Control circuit.

I installed new spark plugs and wires and still have the same problem.

Using a spark plug tester, I have NO spark at all on the RH Passenger side 8-6-4-2. That entire side isn't turning on because its cool. Driver side gets hot when after I turn on the ignition. I swapped a good known working ignition coil on cylinder 2 on the 'dead' side and still have no spark.

Any ideas where I should look?

 

[jared999]

The issue is intermittent. This happened 7 weeks ago and went away for a month.

 

[Geotrash]

Have a flashing CEL, super rough idle. I hooked up a Tech2 and it pulled P0300, P0204, P0206, P0208 Injector Control circuit.
I read misfire data and Cyl 4 is having a ton of misfires, with Cyl 2 having some but much less. No misfires on 6 and 8. I don't understand why its throwing codes for all 4 on that side.

When I hook up a second code reader/puller, it shows only Cyl 4 having issues (P0300 + P0204).

I put in new spark plugs + spark plug wires because I don't know if they were ever changed by prior owner. This did not solve the issue.
I tried new coils on cyl 2 and 4. This did not solve the issue.
Installed new ECM. This did not solve the issue.

At this point I am trying to properly diagnose the problem instead of throwing parts at it.

I tested the fuel injectors with a multimeter. I am getting 12.9 on cyl 6, 12.9-13.1 on cyl 4 and 12.9 on cyl 2. I tried reading 4 several more times and normally get 12.9 so perhaps I did not have the leads touching properly. I assume those values are correct? after searching online I cannot find expected values. (2009 5.3L Tahoe LTZ Engine code 0). Can anyone confirm those values or point me where to look?

I am thinking of doing the following:
1. using a noid light to check wiring for the fuel injectors
2. using spark tester to check spark for all plugs. Even though the plugs and wires are new, I figure I should still do this. I bought a lisle inline tester but the damn thing isn't big enough so it looks like I'll need to pick up one that will fit the coil connection on this 'hoe.
3. Removing valve covers to see if #2 and #4 lifters are working properly (If I end up doing that I am making sure I have the correct parts / gaskets available in case need to start replacing stuff). From what I can find, the AFM components tend to fail on these motors. #4 is AFM if what I Found online is correct.

I suppose I'll ask the questions again because they are sort of buried in all that.

Why would I get P codes for the entire passenger side, cylinders 2,4,6,8 when only cyl4 (and to lesser extent, 2) are misfiring?

The pax side cylinders share a common ground at the front of the pax side of that cylinder head, so I suspect an electrical root cause. Remove and clean this ground as a step 1.

What impedance / value should I have for the fuel injectors?
Where can I find a pinout for the fuel injectors > ecm wiring? I am thinking maybe I can check continuity vs. having to buy a noid kit.

Each injector has the same pinouts but different wire colors going into them for obvious reasons. Here is the diagram for injector 2.

Fuel Injector Coil Test

Verify the resistance of each fuel injector:

1. Ignition ON, verify the scan tool ECT temperature is between 10-32°C (50-90°F).

¤

If not within the specified range, measure and record the resistance of each fuel injector with a DMM. Subtract the lowest resistance value from the highest resistance value. The difference between the lowest value and the highest value should be equal to or less than 3 ohm. If the difference is greater than 3 ohm, add all of the fuel injector resistance values to obtain a total resistance value. Divide the total resistance value by the number of injectors to obtain an average resistance value. Subtract the lowest individual fuel injector resistance value from the average resistance value. Subtract the average resistance value from the highest individual injector resistance value. Replace the fuel injector that displays the greatest difference above or below the average.

1. Test for 11-14 ohm between each fuel injector.

¤	If not within the specified range, replace the fuel injector.

1. If all the injectors test OK, refer to the Active Fuel Injector Tester (AFIT) Procedure.

Active Fuel Injector Tester (AFIT) Procedure

Note:

• DO NOT perform this test if the engine coolant temperature (ECT) is above 94°C (201°F). Irregular fuel pressure readings may result due to hot soak fuel boiling.
• Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic.

1. Verify the battery is fully charged and all accessories are OFF.
2. Ignition OFF.
3. Install the CH-47976 . Refer to the AFIT User Guide.
4. Turn ON the AFIT and select the vehicle.
5. Follow the setup screen on the AFIT.
6. Ignition ON, perform the Injector Test. The test should run and pass all injectors.

Is there anything test / low hanging fruit I can do before I start tearing into the engine?
I do have a Tech 2 and there is a lot of data available, but I'm not sure what I'm looking at. Perhaps there is something in there related to fuel rich/lean or fuel injectors that can tell me if 2 and or 4 are bad?

You can swap injectors and/or ignition coils and see if the problem follows.

 

[TollKeeper]

Verify you arent having AFM/DOD issues on Cylinders 4 and 6

 

[j91z28d1]

does sound like the coil ground.

if it's the afm, I believe there's normally a tap/tick when they are stuck?

 

[jared999]

The pax side cylinders share a common ground at the front of the pax side of that cylinder head, so I suspect an electrical root cause. Remove and clean this ground as a step 1.


Each injector has the same pinouts but different wire colors going into them for obvious reasons. Here is the diagram for injector 2.


You can swap injectors and/or ignition coils and see if the problem follows.

Thank you very much for taking the time to write everything. I appreciate it.

For pinouts, sorry, I meant on the ECM plug side. My thought was to check continuity going all the way to the ECM.

For example, what this guy does starting at 3:40

I updated my OP - Using a spark tester, I have no spark at all on the passenger side 8-6-4-2. Plus, there is no heat coming from that half of the motor. The driver side side heats up/fires up as expected. Spark tests good on 1-3-5-7.

You mentioned pax - is that passenger side? I'll check that ground near cylinder 4

 

[jared999]

Update:

still misfiring. Going to hook up the tech 2 to see if its still the entire passenger side.

 

[Geotrash]

Thank you very much for taking the time to write everything. I appreciate it.

For pinouts, sorry, I meant on the ECM plug side. My thought was to check continuity going all the way to the ECM.

Happy to help. Here are the diagrams for a 2012 Yukon XL Denali because that's all I have access to, but hopefully substantially the same.

I updated my OP - Using a spark tester, I have no spark at all on the passenger side 8-6-4-2. Plus, there is no heat coming from that half of the motor. The driver side side heats up/fires up as expected. Spark tests good on 1-3-5-7.

In my opinion, you have a problem with either the ground or the power supply wire to the passenger side bank of ignition coils. We see this from time to time and it's almost always a poor ground as previously stated, a short in the wiring harness serving that bank's ignition coils (look for chafing of the loom), or a loose/corroded pin in the connector for that bank of coils.

You mentioned pax - is that passenger side? I'll check that ground near cylinder 4

Yes, passenger side.

 

[Geotrash]

I still plan on cleaning up that coil ground on the front passenger side. I think I'm going to get it to local shop to see if they can figure out these intermittent misfires.

Hundred bucks says you clean up that ground and you won't need to take it into a shop.

 

[Foggy]

Whenever you get it all fixed, you'll have to clear out ALL the codes...
The stabiltrack, etc codes come on when there are hard misfires.. this is normal
So make sure you get all the codes cleared so you are not chasing ghosts that don't
really exist

 

[Geotrash]

Whenever you get it all fixed, you'll have to clear out ALL the codes...
The stabiltrack, etc codes come on when there are hard misfires.. this is normal
So make sure you get all the codes cleared so you are not chasing ghosts that don't
really exist

100%. I forgot to mention that. Thank you, @Foggy

 

[jared999]

Hundred bucks says you clean up that ground and you won't need to take it into a shop.

Is this the ground you are referring to?

 

[jared999]

Whenever you get it all fixed, you'll have to clear out ALL the codes...
The stabiltrack, etc codes come on when there are hard misfires.. this is normal
So make sure you get all the codes cleared so you are not chasing ghosts that don't
really exist

Thanks I will be happy to do that when its fixed

 

[Foggy]

I'm pretty sure there is a ground on the drivers side at the rear of the cylinder head too..
Check it as well. I've also heard of the injector and coil (left and right) harnesses going
bad internally... And there is a replacement that gm makes

 

[Geotrash]

Is this the ground you are referring to?

View attachment 404950

Yes, that’s the one! And as Foggy says there’s one at the back as well, but the front one is the one that suffers from corrosion the most due to exposure to the elements coming through the grille.

 

[jared999]

Yes, that’s the one! And as Foggy says there’s one at the back as well, but the front one is the one that suffers from corrosion the most due to exposure to the elements coming through the grille.

OK Thanks. I'm going to get my wirebrush and clean it off very well and then inspect the back one too.

 

[jared999]

In my opinion, you have a problem with either the ground or the power supply wire to the passenger side bank of ignition coils. We see this from time to time and it's almost always a poor ground as previously stated, a short in the wiring harness serving that bank's ignition coils (look for chafing of the loom), or a loose/corroded pin in the connector for that bank of coils.


Yes, passenger side.

The ground connections looked OK. I still took them off and wire brushed them thoroughly which didn't solve the problem. I tested at the ground bolt, I'm getting 12-12.3v at both. I assume if that is the case, that means the ground wiring going to those points is OK.

If I can find one connector for that whole bank (which would then branch off to 4 coil connectors) I will test that connector. Otherwise I will test at one of the connectors (there are two) at the ECM. I will slowly go down the check list (you mentioned 4 areas to look).

 

[j91z28d1]

incase I missed it, what year is it?

and what are you trying to do again? power at the coil plugs? I believe they have keyed 12v and the ecm fires the coils with a switched ground. if you have power and want to check at the ecm pin to coil pack pin for continuity, I can probably pull up the pin out for your truck?


edit. I forget these arw 4 wire coils.. so there's keyed 12v and neg. then one wire that connects to all 4 to the ecm, and one to the ecm to fire it.

 

[j91z28d1]

 

[Fless]

incase I missed it, what year is it?

and what are you trying to do again? power at the coil plugs? I believe they have keyed 12v and the ecm fires the coils with a switched ground. if you have power and want to check at the ecm pin to coil pack pin for continuity, I can probably pull up the pin out for your truck?


edit. I forget these arw 4 wire coils.. so there's keyed 12v and neg. then one wire that connects to all 4 to the ecm, and one to the ecm to fire it.

In the signature...