2023 P0300 Code Engine mis-fire thread-2006 H2 6.0L
#13
11-11-2023, 05:57 PM
Cats have nothing to do with a P0300, however you can damage the cats driving with a misfire. Get back to the codes you posted above, eliminate the issue, then decarbonize the intake & valves!
#15
11-11-2023, 07:29 PM
Cats have nothing to do with a P0300, however
you can damage the cats driving with a misfire. Get back to the codes you posted above, eliminate the issue, then decarbonize the intake & valves!
https://youtu.be/O5N_Z1W6mho?si=gwbse1Eyu1E7Yv-r
you can damage the cats driving with a misfire. Get back to the codes you posted above, eliminate the issue, then decarbonize the intake & valves!
https://youtu.be/O5N_Z1W6mho?si=gwbse1Eyu1E7Yv-r
#16
11-11-2023, 08:51 PM
Join Date: Nov 2023
Location: Southern most county in Illinois
Posts: 49
HUMMERZ, great info you shared.
bknap, I won't exactly say rough but it is running not smooth. Monday I'm gonna be back working on it. Got to check out the throttle codes and will likely do a leak down test and need to be checking voltages to coils, injectors, etc.
Thanks again guys.
bknap, I won't exactly say rough but it is running not smooth. Monday I'm gonna be back working on it. Got to check out the throttle codes and will likely do a leak down test and need to be checking voltages to coils, injectors, etc.
Thanks again guys.
#17
11-12-2023, 12:51 AM
I am 99% certain your issue has nothing to do with clogged cats, or anything internal to the engine. You will be doing yourself a disservice if you don't address the smoking gun here FIRST. The last thing you want is to be a couple grand into cat replacement and it doesn't work and you get mad at the truck you used to love and it sits on marketplace at a stupidly low price.
You need to start with the obvious. You have 4 codes here. P0300, P2108, P1516, and U0107.
P2108, P1516, and U0107 are codes regarding the throttle control process. If there is something wrong with this process(ie: the throttle not opening enough or as expected) it WILL without a doubt cause a P0300 misfire code. It would be literally IMPOSSIBLE for these three codes to set as a result of clogged catalytic converters or engine failure.
The first thing that sticks out to me here is the U code. U0107 indicates a loss of communication with the "Throttle Actuator Control Module." Meaning that for a second or two, you're engine computer has no idea what position the throttle is in and cannot control it at all. It cannot talk to this module.
There are 4 reasons a U code would be set
1. The module is faulty
2. The module has lost power
3. The CAN network communication wires are damaged.
4. Something attached to the module has caused it to go down because of an internal short, break, or malfunction.
Let's start with the easiest and cheapest. Power. You should start by checking your grounds as this is a notorious problem with these trucks. Make sure the connections on all the ground lugs are good, the ground strap on the back of the engine is good, and ground to the body is good. There is a guy with a similar issue with his Silverado that has made a decent video showing the major grounds that need attention. I don't agree with the quality of his repair, but it worked.
The next easiest thing is inspecting the harness and connectors. Check every bit of the wire going from the throttle body, across the engine, to the Throttle Actuator Controller located drivers side of the brake master cylinder under the hood stop. Inspect the connectors on the tb and tac as well as all of the wires that come out of it. Its possible that while sitting, a rodent could have gotten into it. Might be worth checking wires under the dash and inspecting the connectors on the gas pedal itself. It's also a good idea to load test your powers and grounds to all the different components. I have also heard about the harness outright failing between the throttle body and controller as well as an ignition switch causing the issue.
If none of these resolve the issue, you could try testing the position sensors and actuator motor in the throttle body, then I would say you should replace your Throttle Actuator Control Module and/or Throttle body.
I'd like to mention your data shows very low idle rpm(568 compared to 650-675 normal) and low MAF reading (1.09 compared to 1.8ish normal). Now this would make sense if you have an awful misfire, BUT your MAP sensor is reading slightly high(more vacuum)12inHg compared to a normal 10-11. Because of this higher vacuum, and low volume of air, its pretty apparent that this engine is starving for air... causing the misfire. And the only reason it would be starving for air like that is if the throttle is not able to open enough for the correct amount of idle air. Now you could also say that maybe the low rpm and MAF reading is from clogged cats because air in must = air out, but if the engine was struggling to get air out, it wouldn't have a disproportionally high MAP reading.
When you do get your vxdiag tool, see if you can communicate with the throttle actuator control module and read codes stored in it specifically.
Some resources here about P1516. If your grounds are bad, actuator motor is failing, or the internal position sensors, it will set this code. A shorted motor, could also cause a power interruption and a loss of communication(U0107) or even fry the TAC module.
https://www.backyardmechanic.org/cau...-engine-power/
P2108- Also shows the diagram for the throttle body connector and where you would load test.
https://www.justanswer.com/chevy/4v5...16-tofind.html
Overall. If I had to take my best guess on one thing, I would look hard into the wiring and grounds. I don't know where this vehicle has been but I saw you said you had some underside paint/undercoating done indicating there may be some rust or undercoating has caked the grounds. You also said it sits and rodents like cars that sit.
You need to start with the obvious. You have 4 codes here. P0300, P2108, P1516, and U0107.
P2108, P1516, and U0107 are codes regarding the throttle control process. If there is something wrong with this process(ie: the throttle not opening enough or as expected) it WILL without a doubt cause a P0300 misfire code. It would be literally IMPOSSIBLE for these three codes to set as a result of clogged catalytic converters or engine failure.
The first thing that sticks out to me here is the U code. U0107 indicates a loss of communication with the "Throttle Actuator Control Module." Meaning that for a second or two, you're engine computer has no idea what position the throttle is in and cannot control it at all. It cannot talk to this module.
There are 4 reasons a U code would be set
1. The module is faulty
2. The module has lost power
3. The CAN network communication wires are damaged.
4. Something attached to the module has caused it to go down because of an internal short, break, or malfunction.
Let's start with the easiest and cheapest. Power. You should start by checking your grounds as this is a notorious problem with these trucks. Make sure the connections on all the ground lugs are good, the ground strap on the back of the engine is good, and ground to the body is good. There is a guy with a similar issue with his Silverado that has made a decent video showing the major grounds that need attention. I don't agree with the quality of his repair, but it worked.
The next easiest thing is inspecting the harness and connectors. Check every bit of the wire going from the throttle body, across the engine, to the Throttle Actuator Controller located drivers side of the brake master cylinder under the hood stop. Inspect the connectors on the tb and tac as well as all of the wires that come out of it. Its possible that while sitting, a rodent could have gotten into it. Might be worth checking wires under the dash and inspecting the connectors on the gas pedal itself. It's also a good idea to load test your powers and grounds to all the different components. I have also heard about the harness outright failing between the throttle body and controller as well as an ignition switch causing the issue.
If none of these resolve the issue, you could try testing the position sensors and actuator motor in the throttle body, then I would say you should replace your Throttle Actuator Control Module and/or Throttle body.
I'd like to mention your data shows very low idle rpm(568 compared to 650-675 normal) and low MAF reading (1.09 compared to 1.8ish normal). Now this would make sense if you have an awful misfire, BUT your MAP sensor is reading slightly high(more vacuum)12inHg compared to a normal 10-11. Because of this higher vacuum, and low volume of air, its pretty apparent that this engine is starving for air... causing the misfire. And the only reason it would be starving for air like that is if the throttle is not able to open enough for the correct amount of idle air. Now you could also say that maybe the low rpm and MAF reading is from clogged cats because air in must = air out, but if the engine was struggling to get air out, it wouldn't have a disproportionally high MAP reading.
When you do get your vxdiag tool, see if you can communicate with the throttle actuator control module and read codes stored in it specifically.
Some resources here about P1516. If your grounds are bad, actuator motor is failing, or the internal position sensors, it will set this code. A shorted motor, could also cause a power interruption and a loss of communication(U0107) or even fry the TAC module.
https://www.backyardmechanic.org/cau...-engine-power/
P2108- Also shows the diagram for the throttle body connector and where you would load test.
https://www.justanswer.com/chevy/4v5...16-tofind.html
Overall. If I had to take my best guess on one thing, I would look hard into the wiring and grounds. I don't know where this vehicle has been but I saw you said you had some underside paint/undercoating done indicating there may be some rust or undercoating has caked the grounds. You also said it sits and rodents like cars that sit.
Last edited by Gavin Costigan; 11-12-2023 at 01:50 AM.
#18
11-12-2023, 02:44 AM
Hey I also found this awesome video with the same issue on a 2003 h2. His codes are different, but I think that's due to the model year. It turns out that whenever he turned the steering wheel, the power steering lines would move just enough to wiggle the connector in the PCM containing the 4 data lines that go to the TAC. He was having the same misfire issue too. PCM connector will be worth a lookover too.
#19
11-12-2023, 07:39 AM
Join Date: Nov 2023
Location: Southern most county in Illinois
Posts: 49
Thanks for putting this all together Gavin, it is very helpful. All of you have been awesome in the help and knowledge you are sharing. I appreciate it and others will benefit as well. 1 big help and where I lack knowledge is your interpretation of the MAP readings etc. Where can I find the info on what engine readings should be normally for idle and even different RPMs? I hoped to find a spreadsheet or doc showing each variable across top and then the RPMs going down and populated each step/line with the outputs on a healthy 6.0l. Whatever the format I hoped to find something on normal outputs for the different components.
I not ignoring the codes or other issues and realize the throttle codes are electrical and no connection to cats but they only appeared last week and it hasn't been driven since I got them. So what all of sudden caused them to glitch- wouldn't think ground just went bad sitting there. But **** breaks down just sitting all the time, so I'll be using your material along with others to help troubleshoot them. Always tell wife that anything manmade is subject to failure at anytime. The mis-fire has been there for years off and on as it has mostly sat, only driven 10 minutes at a time, with once a year or so it might go a 30 mile round trip. When I started this process a couple months ago to get it running proper and cleaned up the 1st thing I did was check grounds as I cleaned the frame and underside prior to iron phosphate conversion coating and painting. One that looks good but I haven't removed and cleaned is the ground on firewall so it is on the list as well as revisit the others. Hell I might add a couple as I have the lugs and welding lead wire. I hope to have some answers in these codes before going for cat tests. The PCM connections will be rechecked as well. It was all cleaned externally but not unplugged when cleaning frame. I have the inner fender liners off again for better access and am leaving off till I get it running right so if I need to do a leak down test, plugs again, etc I will have that easier access.
I would of argued for a long time that the cats where fine and had no bearing on the original mis-fire code, but with the downturn in performance and crazy O2 / Fuel trims numbers, along with sound output at tailpipe, I have begun to question them. So muffler shop is 15 mins and he will do a back pressure test and I'll be standing there so we can make a decision. I'm certainly not replacing unless they are plugged/ not working. If they are replaced I would like to think that 15 mins back home they will be fine from damage and I will continue the process.
So, again thanks and I will update as it progresses on what I find.
I not ignoring the codes or other issues and realize the throttle codes are electrical and no connection to cats but they only appeared last week and it hasn't been driven since I got them. So what all of sudden caused them to glitch- wouldn't think ground just went bad sitting there. But **** breaks down just sitting all the time, so I'll be using your material along with others to help troubleshoot them. Always tell wife that anything manmade is subject to failure at anytime. The mis-fire has been there for years off and on as it has mostly sat, only driven 10 minutes at a time, with once a year or so it might go a 30 mile round trip. When I started this process a couple months ago to get it running proper and cleaned up the 1st thing I did was check grounds as I cleaned the frame and underside prior to iron phosphate conversion coating and painting. One that looks good but I haven't removed and cleaned is the ground on firewall so it is on the list as well as revisit the others. Hell I might add a couple as I have the lugs and welding lead wire. I hope to have some answers in these codes before going for cat tests. The PCM connections will be rechecked as well. It was all cleaned externally but not unplugged when cleaning frame. I have the inner fender liners off again for better access and am leaving off till I get it running right so if I need to do a leak down test, plugs again, etc I will have that easier access.
I would of argued for a long time that the cats where fine and had no bearing on the original mis-fire code, but with the downturn in performance and crazy O2 / Fuel trims numbers, along with sound output at tailpipe, I have begun to question them. So muffler shop is 15 mins and he will do a back pressure test and I'll be standing there so we can make a decision. I'm certainly not replacing unless they are plugged/ not working. If they are replaced I would like to think that 15 mins back home they will be fine from damage and I will continue the process.
So, again thanks and I will update as it progresses on what I find.
#20
11-12-2023, 08:49 AM
First lets understand what the ECM uses to detect misfires,
With the the use of 24x and higher crank reluctor wheels and faster computing power the ECM can monitor when each cylinder fires causing the crank to accelerate and decelerate along with knowing where TDC is and when it ignites the fuel/air mixture. The ECM is calibrated during manufacturing (Crank Learn Procedure) to know where TDC is and the acceleration and deceleration rates of the current rotating mass. Knowing all of this information it can detect when a change happens in this process and at what point in the cycle it has taken place. When the ECM detects multiple random anomaly's in the cycle it displays the P0300.
Not only misfires can cause the P0300, a change in rotational mass/balance can also cause this.
Neal
With the the use of 24x and higher crank reluctor wheels and faster computing power the ECM can monitor when each cylinder fires causing the crank to accelerate and decelerate along with knowing where TDC is and when it ignites the fuel/air mixture. The ECM is calibrated during manufacturing (Crank Learn Procedure) to know where TDC is and the acceleration and deceleration rates of the current rotating mass. Knowing all of this information it can detect when a change happens in this process and at what point in the cycle it has taken place. When the ECM detects multiple random anomaly's in the cycle it displays the P0300.
Not only misfires can cause the P0300, a change in rotational mass/balance can also cause this.
Neal