P0300 code

[abishoff]

So I started getting a p0300 code and the engine is vibrating violently. Took it to the local shop. They said the compression seems low on cylinders 1,3,5 and those are the ones that are missing. Last week I got a code to replace the 02 sensor. I put in a new Bosch sensor, drove 30-50miles and they the trouble started. Idk where to go from here. Any thoughts?


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[2011SSVHOE]

get a code scanner and see what it says now.

 

[rockola1971]

So I started getting a p0300 code and the engine is vibrating violently. Took it to the local shop. They said the compression seems low on cylinders 1,3,5 and those are the ones that are missing. Last week I got a code to replace the 02 sensor. I put in a new Bosch sensor, drove 30-50miles and they the trouble started. Idk where to go from here. Any thoughts?


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First, dont take your vehicle to that shop again. They are inept and not qualified to work on your vehicle. A compression issue did not just show up over night and cause plaguing misfires on just 1,3,5. Check the easy stuff first. Fuel pressure, is it in spec? Low fuel pressure will not throw a code but the engine symptoms of it will which are related to the fuel pressure being low. Which 02 sensor did you replace and are you sure replaced the correct one that the code identified as being "bad". What was the code set for the 02?

 

[abishoff]

First, dont take your vehicle to that shop again. They are inept and not qualified to work on your vehicle. A compression issue did not just show up over night and cause plaguing misfires on just 1,3,5. Check the easy stuff first. Fuel pressure, is it in spec? Low fuel pressure will not throw a code but the engine symptoms of it will which are related to the fuel pressure being low. Which 02 sensor did you replace and are you sure replaced the correct one that the code identified as being "bad". What was the code set for the 02?

The sensor code I got was p0161 which is the passenger side o2 sensor. I believe I have the right part. I took it to the dealership and they are saying there is no compression on cylinder 2 and I need a motor/rebuild. When the sensor was bad, I took it off to make sure I ordered the right one. The vehicle was driven without the o2 sensor installed. Idk if that could mess up the #2 cylinder compression. And cause a p0300. The dealership also said compression on the #1 cylinder is not ideal. So now I'm more lost. Could I have a stuck valve and no compression because it's stuck open?


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[jaywoo65]

P0161 is the O2 sensor after the cat on the passenger side. Is that the one you changed? That has nothing to do with the rest of your current issues. All that does is check how well the cat is doing.

Personally, I'd take it somewhere else and let them do a compression test. Or get a loaner tool from autozone or somewhere and do it yourself. It's not hard.

If you have the vehicle scanned it should come up with something other than just P0300. Should show the actual cylinder misfires (P0302 if it's really the #2 cylinder).

If it is low compression, I'd pull a valve cover and check for sludge. Take a look at the valve springs. Rotate the motor by hand and see if it's something obvious.

 

[abishoff]

P0161 is the O2 sensor after the cat on the passenger side. Is that the one you changed? That has nothing to do with the rest of your current issues. All that does is check how well the cat is doing.

Personally, I'd take it somewhere else and let them do a compression test. Or get a loaner tool from autozone or somewhere and do it yourself. It's not hard.

If you have the vehicle scanned it should come up with something other than just P0300. Should show the actual cylinder misfires (P0302 if it's really the #2 cylinder).

If it is low compression, I'd pull a valve cover and check for sludge. Take a look at the valve springs. Rotate the motor by hand and see if it's something obvious.

Yes that's the one I changed. I'm not getting the p0302 code. The #2 has zero compression and the #1 has low compression. Both places have said that. I do think it's in the valves because it was an all of the sudden issue. The engine have 220k miles or so. So I'm thinking about a rebuild/ replace option. I wanted to do a blown or boosted stroker motor so I guess it's time to start that project.


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