2005 Chevy Tahoe P0300 Misfire Code - no power - stalling - Catalytic Converter
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This is a 2005 Chevy Tahoe with a 5.3 liter that had a misfire, low on power and a horrid exhaust smell. It was so low on power that the vehicle was not drive able. Previously someone attempted to fix this by replacing spark plugs, plug wires and all 8 coil packs. None of which solved anything. The person was told that it had an intake manifold gasket leak that needed to be fixed. I found no intake gasket leak. What I found was a clogged catalytic converter that was causing the lack of power and lack of driveability. The cause of the clogged cat was a bad oxygen sensor that was causing an over rich condition which oddly enough was showing up as a lean code for bank 1. After viewing the data stream is was clear that the bank 1 sensor 1 oxygen sensor was not switching and was stuck lean which caused the computer to dump more fuel in. A check engine light means something is wrong so fix it!!!! If you see a flashing check engine light, it needs to be addressed immediately because it is most likely a misfire type a which was the situation here. If it was fixed immediately it would have just been a $50 oxygen sensor. However, in this case the check engine light was not addressed immediately which cause a more expensive repair. $550 for a y-pipe and catalytic converters, $65 for 8 new spark plugs and the $50 oxygen sensor. That's not including labor charges. All of this could have been prevented if it was addressed when the check engine light first came on.
If you suspect a clogged catalytic converter and you do not have any special diagnostic equipment, there is another way to test. Pull the upstream oxygen sensor (the one between the engine and the catalytic converter). If driveability improves, you have a clogged catalytic converter.
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Ty so much I just bought a 2005 Chevy suburban z71 for $700 it was stalling on drive changed cats n running good again 😎
Similar problem with mine replaced all spark plugs coil packs and injectors, which was all much needed 😅 and has no cats but misfires on mostly 1 and 8 which I can't find out why and it's a random misfire
Where do you recommend getting a good diagnostic from to test where the misfire is?
@4-gear
2 жыл бұрын
You can go to most auto parts stores and have your vehicle scanned to find out if you have a misfire code. Once you identify the misfiring cylinder, you can swap spark plugs, wires and coil with another cylinder to determine the problem. Do it one at a time, swap spark plugs and see if the misfire follows the spark plug to the other cylinder. If it does, then you have a bad spark plug. If the misfire doesn't follow the spark plug to the cylinder you swap it to, then swap the spark plug wire. Repeat the process with the coil if the plug wire and plug do not make a change. When you find the bad part, the misfire will change to the cylinder you swap parts with. I hope that makes sense.
Was it going on engine reduce power
Ik this is two years old so I hope you still respond... Let me ask this.. would a 02 cause a misfire even when you first start..cold... Assuming open loop correct? Slight skip or miss cold and seems to get worse as it warms.. I'm weary I have a cam lobe or two wearing or either a burnt valve. I hear the old sputter coming out the tail pipe but my opinion it's almost a random mis. Nothing extremely consistent. This is the short version
@4-gear
Жыл бұрын
Oxygen sensor will not cause a problem when the engine is cold. Has to be warmed up to be in closed loop. I'd scan it and see what you have for codes. Could be as simple as a spark plug or wire. A clogged converter can cause a random misfire which would be a p0300 code. It's fairly easy to see if the converter is plugged. Remove the upstream oxygen sensor (between the engine and converter) and then go up and down the driveway. If the misfire is gone, you found your problem.
Can you temporary drive the car as you have created the hole with the 02 sensor removal?
@4-gear
3 жыл бұрын
Yes for testing purposes. It will have an exhaust leak but you won't have to drive far to notice the difference if the cat is clogged.
having the same problem. should i just try replacing 02 sensor or what? any info is helpful
@4-gear
Жыл бұрын
I would check to see if the converter is plugged. Also test the oxygen sensor. If the oxygen sensor is bad, replace it.
Having this code and i hear loud noise coming out of my catalytic convertors I believe
what if i have a p0300 code only and the car sounds more like a knocking sound , put new sparkplugs that didnt help.
@4-gear
Жыл бұрын
P0300 is a random misfire. Possibly old plugs and wires so if they are old, I would replace them just as a matter of maintenance. To find the cause, you will have to do some investigating. A good scan tool will help because you can watch real time data streams. There are a number of things that can cause random misfires.
Would that cause reduced engine power? I’ve gotten my throttle body changed 4 times. Could my Catalytic converter be the problem?
@4-gear
Жыл бұрын
Catalytic converter is one possibility but there are many others as well. Hard to diagnose over the internet.
@terrancemcdaniel695
Жыл бұрын
I changed the pigtail to the throttle body and reset codes and reduced engine went away
I had a Malibu bogging like shit thought it was a fuel pump (very common issue) replaced that with a used OEM same shit. Bogging down like shit can't rev over 2500 before it starts to niggardly bog down and almost stall. New injectors spark plugs n all. Absolutely forgot about the cat causing bogging issues too. Since it has a lean code (most likely vacuum) lead me to the fuel pump since I found no vacuum leaks I thought now I know there's a small leak somewhere and that code is unrelated to any of the bogging acceleration issues. Even after working on cars for 10 years I still fucked up my diagnosis procedure you think you're so good you've seen it all and it dicks with you again! 😂😂 I'm checking the car (unplugging the upstream sensor) can't now because it's raining but damn I completely missed this. Did have p0300 though it was caused by p0171. Now I know neither are related. Bad cats happen a lot now all these 2005+ are almost 3 decades old... Cats are crapped out
@alfredough
Жыл бұрын
*2009 Malibu 2.4L
How can I contact you I have a question about mine
so why didn't it throw a P0135 or P0130 for bank 1 sensor 1
@4-gear
2 жыл бұрын
Who knows. I ask that question a lot. DTCs are a guide. Computers are far from perfect. That is why when you get a code you have to test to verify. False codes happen and no codes happen. Example, Ford 6.0 Powerstroke that I recently repaired had a code for cylinder imbalance that was triggered by a bad glow plug but didn't have a glow plug code. 😕 I ohm'd the glow plug and it was an open circuit. It should have thrown a code but didn't.