P0300 Mystery
Thread Starter
Senior Member
Joined: 02-13-2006
Posts: 142
From: Detroit, MI
Sorry I didn't post sooner, I ran out of time before work but managed to pop my air box to see what I wrote down. My compression test results were 160, 145, 135, 160. From what i gather that's neither good or too bad.
Yes, correct plugs. Good tip, I'll take a peek at the manifold nuts. I'll look on my other HHR too. Just in case.
New information: making it a bit more complicated. After a cleaned up the fuel injector ports and put new ones in, i cleaned the hell out of the throttle body. It was quite gunked up. I sprayed alot of throttle body cleaner down there to clean it up. When I started it, it ran rough for a little bit and blew some white smoke. It took about 20 minutes for P0300 to return. the other night after deciding to post I cleared the code and drove on an errand to look at live data. The code hasn't returned, but still runs rough in idle. I don't know, I fully expect the code to return.
Maybe the SeaFoam idea might be the way to go. I looked at some videos how to use that stuff. Maybe clean up the oil gunk too like you said. I'm thinking of possibly even pulling that intake position solenoid and cleaning it. Bet it looks nice (<sarcasm, lol)
I only been on short trips to work since i cleared the code. Work is les than 5 miles away. You guys might like my job. I test drive new and prototype vehicles for Ford. Sometimes camouflaged. I'm not supposed to say much more that that, NDA and all, but i certainly don't want a new Ford, lol.
Yes, correct plugs. Good tip, I'll take a peek at the manifold nuts. I'll look on my other HHR too. Just in case.
New information: making it a bit more complicated. After a cleaned up the fuel injector ports and put new ones in, i cleaned the hell out of the throttle body. It was quite gunked up. I sprayed alot of throttle body cleaner down there to clean it up. When I started it, it ran rough for a little bit and blew some white smoke. It took about 20 minutes for P0300 to return. the other night after deciding to post I cleared the code and drove on an errand to look at live data. The code hasn't returned, but still runs rough in idle. I don't know, I fully expect the code to return.
Maybe the SeaFoam idea might be the way to go. I looked at some videos how to use that stuff. Maybe clean up the oil gunk too like you said. I'm thinking of possibly even pulling that intake position solenoid and cleaning it. Bet it looks nice (<sarcasm, lol)
I only been on short trips to work since i cleared the code. Work is les than 5 miles away. You guys might like my job. I test drive new and prototype vehicles for Ford. Sometimes camouflaged. I'm not supposed to say much more that that, NDA and all, but i certainly don't want a new Ford, lol.
Senior Member
Joined: 12-05-2014
Posts: 3,371
From: Northern Ohio
Yeah, the compression test results are not terribly happy. A leak-down test might tell you if it’s valves or pistons or even a leak between 2 & 3. The difference between a valve job and rebuild if probably the difference between keeping it or selling it.
The car may have been driven a lot of short hops, ,so the variation could also mean no leak at all but a bunch of carbon in 1 & 4. Fuel quality went to #377 during the pandemic, for good reasons and it provided an excuse. I would take the car on few long drives at highway speed to try to burn of any carbon. I think there are a few products that supposed to help with that. Road trip!
Meijer sells “Top Tier” fuel cheap.
Did you remove the throttle body to clean it so you could get both sides? Clean the MAF sensor (and make sure you plug it back in.)
The car may have been driven a lot of short hops, ,so the variation could also mean no leak at all but a bunch of carbon in 1 & 4. Fuel quality went to #377 during the pandemic, for good reasons and it provided an excuse. I would take the car on few long drives at highway speed to try to burn of any carbon. I think there are a few products that supposed to help with that. Road trip!
Meijer sells “Top Tier” fuel cheap.
Did you remove the throttle body to clean it so you could get both sides? Clean the MAF sensor (and make sure you plug it back in.)
Administrator
Joined: 10-13-2011
Posts: 40,091
From: Welland,Ont Canada
Those compression numbers aren’t terrible. Seafoam or Marvel Mystery oil , Lucas fuel additives might help clean out the valves and piston rings. Run 2 or 3 tanks of top tier fuel , Shell , BP , Exxon , Wawa for instance.
a valve job isn’t all that hard , you do need a special tool to release the valve keepers , but cross that bridge only if the numbers don’t improve.
a valve job isn’t all that hard , you do need a special tool to release the valve keepers , but cross that bridge only if the numbers don’t improve.
Moderator
Joined: 01-23-2009
Posts: 26,539
From: Fredericksburg,VA
If you really think "TopTier" means anything here is a complete list of brands:
https://toptiergas.com/licensed-brands/
https://toptiergas.com/licensed-brands/
Moderator
Joined: 01-23-2009
Posts: 26,539
From: Fredericksburg,VA
I was very happy when I used SeaFoam for top end cleaning. I had a coked up oil control ring.
Dump a couple oz in each cylinder, let sit overnight, start up and watch all of the white smoke for a few minutes. Oil consumption ended,
I tried the drizzle into the TB thing, wasn't very happy. Maybe cleaned the exhaust valves. I did not test compression.
I did the in the oil thing, seemed OK didn't screw anything up.
The problem with in the gas tank is that only cleans the injectors. If you had a carb it would clean the intake valve, but the problem is usually in the exhaust valve
Dump a couple oz in each cylinder, let sit overnight, start up and watch all of the white smoke for a few minutes. Oil consumption ended,
I tried the drizzle into the TB thing, wasn't very happy. Maybe cleaned the exhaust valves. I did not test compression.
I did the in the oil thing, seemed OK didn't screw anything up.
The problem with in the gas tank is that only cleans the injectors. If you had a carb it would clean the intake valve, but the problem is usually in the exhaust valve
Senior Member
Joined: 03-29-2022
Posts: 1,241
From: Davison MI
I was very happy when I used SeaFoam for top end cleaning. I had a coked up oil control ring.
Dump a couple oz in each cylinder, let sit overnight, start up and watch all of the white smoke for a few minutes. Oil consumption ended,
I tried the drizzle into the TB thing, wasn't very happy. Maybe cleaned the exhaust valves. I did not test compression.
I did the in the oil thing, seemed OK didn't screw anything up.
The problem with in the gas tank is that only cleans the injectors. If you had a carb it would clean the intake valve, but the problem is usually in the exhaust valve
Dump a couple oz in each cylinder, let sit overnight, start up and watch all of the white smoke for a few minutes. Oil consumption ended,
I tried the drizzle into the TB thing, wasn't very happy. Maybe cleaned the exhaust valves. I did not test compression.
I did the in the oil thing, seemed OK didn't screw anything up.
The problem with in the gas tank is that only cleans the injectors. If you had a carb it would clean the intake valve, but the problem is usually in the exhaust valve
Senior Member
Joined: 12-05-2014
Posts: 3,371
From: Northern Ohio
I like Seafoam but after any procedure that might get significant amounts of cleaner product in the oil, I would change the oil very soon if not immediately, because I’ve read some horror stories about engine seal damage.
Even GM changed the instructions for their DI valve cleaning kit to add an oil change after completion.
CRC Intake Valve and Turbo Cleaner instruct to change the oil. IDK about Berryman or STP.
Even GM changed the instructions for their DI valve cleaning kit to add an oil change after completion.
CRC Intake Valve and Turbo Cleaner instruct to change the oil. IDK about Berryman or STP.
