P0301
09-27-2012, 01:19 PM
#27
Senior Member
Usually, you start small: plug gap, plugs, coil, etc. Most of the time the misfire is ignition-related.
However, you could have a clogged injector. I'm coming from an SRT 4, but some troubleshooting techniques don't really change. Sounds like your plugs were fouled, also. Iridiums are sometimes too cold of a plug for the engine, unless you're making a lot more power (i.e., worthless IMHO). If you're close to stock boost levels, just use the stock plugs. You want the largest gap without blowout (some don't know you make more power this way). I don't even have my Cobalt SS/TC yet (next week--crossing fingers), but I plan to learn as much as possible about this vehicle.
However, you could have a clogged injector. I'm coming from an SRT 4, but some troubleshooting techniques don't really change. Sounds like your plugs were fouled, also. Iridiums are sometimes too cold of a plug for the engine, unless you're making a lot more power (i.e., worthless IMHO). If you're close to stock boost levels, just use the stock plugs. You want the largest gap without blowout (some don't know you make more power this way). I don't even have my Cobalt SS/TC yet (next week--crossing fingers), but I plan to learn as much as possible about this vehicle.
09-27-2012, 03:01 PM
#28
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No I replaced the seals and it still misfired so we hooked it up to the tech2 and watched the injector pulse and under any load it would just drop off it wouldnt spray any fuel
09-27-2012, 06:22 PM
#29
They're telling me that it's cylinder 3 coil now..., it ran rough for them this morning, so they checked it, and said cylinder 3 misfired. They checked the plugs - that one is fouled. They're also telling me they'll replace the plugs for $140... Told them to just save the plugs, I'll install them myself... Save the $100 they're trying to charge me for a 15 minute job. Asked them to keep the ticket open in case P0301 still pops up, but they said they have no recordo of first cylinder problem and all warranty tickets have to be closed by the end of the month, which is tomorrow fit them.
Need to go argue it now.
Need to go argue it now.
09-28-2012, 01:25 AM
#30
So after talking to them for a while, I picked up a car and some OE plugs... We'll see where that takes us. They did the fuel system diagnostics, and everything checks out fine. They want to make sure the plugs somehow aren't it. Plus plug #3 is fouled out. Now that they changed the coil #3, hopefully changing the plugs will fix the issue.
If not, plugs are eliminated as a cause, coils are eliminated, fuel system is eliminated, and next thing is to look deeper into the engine. Hoping all this fixes the issue, but if not, I'll keep you guys posted.
If not, plugs are eliminated as a cause, coils are eliminated, fuel system is eliminated, and next thing is to look deeper into the engine. Hoping all this fixes the issue, but if not, I'll keep you guys posted.
09-28-2012, 07:56 PM
#33
And... They were wrong. Replaced plugs with brand new OEM ones.. Took it for a drive: misfire with flashing CEL, no code. Went straight to dealer... Even though the code didn't pop up, there's a history of 40(!) misfires since last drive cycle. He goes ” that shouldn't happen”... Really?! But now since the coil is new and the plug is new - they have to dig deeper, so they scheduled me for Monday.
And, since it's a repeat problem, I believe there is no deductible on extended warranty this time.
And, since it's a repeat problem, I believe there is no deductible on extended warranty this time.
09-29-2012, 12:16 AM
#35
Either way, hopefully we'll know Monday.
Here's what my plugs looked like after just two weeks in the car:
Here's a comparison of the "old" (two weeks max) plug and the new OE plug that just went in today.... Hopefully they'll fix it so I won't ruin the new plugs... It gets expensive quick to buy new plugs every two weeks.
And that's the comparison to the cleanest one
10-01-2012, 10:00 PM
#36
So the car is in, they've had it since last night... they said they'll need to keep it overnight again... got me into a rental for the night... They've already started opening up the valve cover and were talking about taking off the cylinder head. He's got two technicians working on that.
10-02-2012, 08:38 AM
#38
Senior Member
Did you notice the center electrode has been cut in half/worn compared to the "newer" one?
I'm coming from an SRT 4, but do you think you have leaking plug seals?!
This kind of sums up the condition to me:
"Q: What is a "fouled" spark plug?
A: A spark plug is considered fouled when the insulator nose at the firing tip becomes coated with a foreign substance such as fuel, oil or carbon. This coating makes it easier for the voltage to follow along the insulator nose, leach back down into the metal shell and ground out rather than bridging the gap and firing normally.
Many factors can contribute to spark plug fouling. The air/fuel ratio may be too rich as a result of incorrect carburetor adjustment or a poorly performing fuel injection system. Worn piston rings or valve seals may allow too much oil to leak into the combustion chamber, leading to oil fouling. The ignition system may not be performing properly. Prolonged idling or continuous low-speed driving may keep the spark plug from reaching its optimum operating temperature. Using too cold a spark plug can lead to the same problem. Finally, a dirty air cleaner can create a too-rich condition which can lead to fouling.
Fuel, oil and carbon fouling can all be the result of different causes but, once a spark plug is fouled, it will not provide adequate voltage to the firing tip and that cylinder will not fire properly. In many cases, the spark plug cannot be cleaned sufficiently to restore normal operation. Therefore, it is recommended that a plug be replaced once it is fouled."
I'm coming from an SRT 4, but do you think you have leaking plug seals?!
This kind of sums up the condition to me:
"Q: What is a "fouled" spark plug?
A: A spark plug is considered fouled when the insulator nose at the firing tip becomes coated with a foreign substance such as fuel, oil or carbon. This coating makes it easier for the voltage to follow along the insulator nose, leach back down into the metal shell and ground out rather than bridging the gap and firing normally.
Many factors can contribute to spark plug fouling. The air/fuel ratio may be too rich as a result of incorrect carburetor adjustment or a poorly performing fuel injection system. Worn piston rings or valve seals may allow too much oil to leak into the combustion chamber, leading to oil fouling. The ignition system may not be performing properly. Prolonged idling or continuous low-speed driving may keep the spark plug from reaching its optimum operating temperature. Using too cold a spark plug can lead to the same problem. Finally, a dirty air cleaner can create a too-rich condition which can lead to fouling.
Fuel, oil and carbon fouling can all be the result of different causes but, once a spark plug is fouled, it will not provide adequate voltage to the firing tip and that cylinder will not fire properly. In many cases, the spark plug cannot be cleaned sufficiently to restore normal operation. Therefore, it is recommended that a plug be replaced once it is fouled."
Last edited by prevsrt4owner; 10-02-2012 at 08:45 AM.
10-02-2012, 08:47 AM
#39
Senior Member
10-03-2012, 12:58 AM
#40
10-03-2012, 01:49 AM
#41
Yeah that center electrode is broken.
Perhaps the result of preignition / detonation?
So maybe the fuel injector for #3 isn't working correctly?
Fuel Injector seal?
Just throwing that idea out there.
Perhaps the result of preignition / detonation?
So maybe the fuel injector for #3 isn't working correctly?
Fuel Injector seal?
Just throwing that idea out there.
10-04-2012, 12:13 AM
#43
So after testing stuff for three days they still haven't found anything conclusive... Put another 30 something miles on in test drives.... Thinking either random electronic failure or ECU.... Either way, they couldn't duplicate, so I picked it back up.... The misfires haven't happened yet... Will drive it around until it gets worse. It's under warranty anyways for the next couple years.
10-12-2012, 03:27 PM
#44
It misfired again badly under hard acceleration when shifting from 1st to 2nd on the way home, blinked the CEL without storing a code. Next morning, when it seemed to work fine, it gave me a solid CEL. Took it back, this time I have P0300, P0301, P0303, and P0304... So I went from one cylinder misfiring, to two, and now three.. Set an appointment for this morning. Showed up expecting to drop it off. All they did was install a recorder in my car and told me to drive it until it happens again so it records data!? Sometimes it seems they just want me to drive it until something bigger fails.
10-12-2012, 04:21 PM
#46
Well, my cylinder 2 is still good. 
It was closer to full temp... And yes, I know about warming it up... When you leave a construction parking lot that has a few hundred cars, you don't want to sit there for 5 minutes warming it up, 'cause you'll be behind all of them so you just drive...
Then, when I have to enter a flow of traffic, I have to accelerate pretty hard, so sometimes it misfires when the coolant is still 20-30 degrees below the full op temp...
Either way, in the rare case that it does happen, it only blinks the CEL a few times... it's usually on a cold morning after the car has been sitting all night, no over revving, nothing... Just sitting there at idle, and then, BOOM, CEL comes on...
Well, I'll just have to see what the recorder does...
Then, when I have to enter a flow of traffic, I have to accelerate pretty hard, so sometimes it misfires when the coolant is still 20-30 degrees below the full op temp...
Either way, in the rare case that it does happen, it only blinks the CEL a few times... it's usually on a cold morning after the car has been sitting all night, no over revving, nothing... Just sitting there at idle, and then, BOOM, CEL comes on...
Well, I'll just have to see what the recorder does...
04-12-2013, 01:54 AM
#47
before swapping injector do a compression test i have seen the exhaust valves the are burnt and will drop the compression by 20 or more psi in that cylinder and cause issue's... if you drive normal 20 psi low in one cylinder you wont notice it unless you look at a miss fire count on a scanner
^^^You were all right. Finally convinced the dealer.... The story below.
So after random misfires for a few months, all the ignition coils replaced under warranty (number 3, then number 4, then finally 1 and 2 at the same time last Friday), the P0301 came back 10 SECONDS after I got into it, before I even left the dealer parking lot.
So I stormed back in, raised a $#!T storm about throwing parts at the car without fixing the problem, demanded the phone number for the service manager, service director, and GM USA... boy did that do a trick. Dropped it off last Sunday after telling them to keep the ticket open.
First they checked the ignition system and fuel system AGAIN! Nothing wrong with them - imagine that... decided to remove the valve cover, but before they did that, they FINALLY did a pressure leakdown test, they got two leaks: one by the turbo on the engine side, and one in the crank case (bubbling out of the dip stick).
They finally troubleshot that it's a cracked ring (which from your advice I suggested it probably was to begin with!!!!)
Now they got all the parts in except for the ring kit which comes in tomorrow. They should be done either tomorrow or sometime early next week.
The best part about the whole thing (besides getting a partially rebuilt engine for free) is the courtesy loaner 2013 Silverado LT Crew cab with 650 miles on it... practically brand new. I'll keep you guys updated.
04-13-2013, 12:53 AM
#49
It's a small crack that developed over time. Random misfire started happening when I bought it from previous owner. The car stayed completely stock as it was driven by his wife while he was deployed. And parts can wear out on any tune, stock or otherwise.
Anyways, dealer is replacing the pistons and rings... But the ring kit is on back order without an estimated time of arrival. The rest of the parts (pistons and supporting hardware) are already here... So I'm in a courtesy loaner again.
Actually, I asked them to switch it from the Silverado to a 2013 Traverse LT
Anyways, dealer is replacing the pistons and rings... But the ring kit is on back order without an estimated time of arrival. The rest of the parts (pistons and supporting hardware) are already here... So I'm in a courtesy loaner again.
Actually, I asked them to switch it from the Silverado to a 2013 Traverse LT