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P0302 Code 2007 Chevy Cobalt 2.2L

Model: 2007 Chevy Cobalt Fault Code: P0302 Posted: 2016-09-09 07:02

Hello I am getting a P0302. I have changed out spark plugs, and also swapped out the coil packs from cylinder 2 and 3. I have run some fuel injector cleaner, and the code went away for a little while. It will shift hard from 1st to 2nd gear sometimes, but I think that is tied with the P0302 code. Not sure if this was a coincidence or not, but the code came up a day after I was changing the transmisison fluid, so I am not sure if I bumped a vacuum line loose, or cause it to crack since it does have 212K miles on it. Below is the readings I am getting from the freeze frames from when the CEL light came on. Any help would be appreciated. Fuel Status = 0 byte Engine Load = 31.765 % Engine Coolant Temperature = 116.6 °F Fuel Trim Bank 1 Short Term = 0 % Fuel Trim Bank 1 Long Term = 4.688 % Intake Manifold Pressure = 5.221 psi Engine RPM = 961.75 rpm Speed (OBD) = 0 mph Timing Advance = 9.5 ° Intake Air Temperature = 78.8 °F Mass Air Flow Rate = 4.86 g/s Throttle Position(Manifold) = 27.451 % Run time since engine start = 56 s Fuel Level (From Engine ECU) = 84.706 % Distance travelled since codes cleared = 1.864 miles Evap System Vapour Pressure = -2 Pa Barometric pressure (from vehicle) = 14.504 psi Catalyst Temperature (Bank 1,Sensor 1) = 908.6 °F Voltage (Control Module) = 14.607 V Engine Load(Absolute) = 23.137 % Commanded Equivalence Ratio(lambda) = 1 Relative Throttle Position = 13.725 % Ambient air temp = 77 °F Absolute Throttle Position B = 27.059 % Accelerator PedalPosition D = 19.608 % Accelerator PedalPosition E = 9.412 %

Related fault codes

P0302

Comments (17)

Anonymous 2016-09-09 10:00

the MAP reading at 5.221 will need to be looked at - seams wrong to me. Need to see how that reports. replacing plugs you did use AC Delco nothing else? Hard shifting will your scanner read ALL codes esp manufacturers specific P0999 and up? Is there a remote starter - or added aftermarket devices?

Anonymous 2016-09-09 10:17

Yeah the pressure did seem low to me. Would that be caused by a vacuum leak. Because there are alot of electrical connector and hoses in the area of the transmission fill opening. I'm not sure about about the esp manufacturers codes since I just have an app on my phone that connects to a Bluetooth obd connector so probably doesn't get into that detail. When I get home tonight I was going to use my neighbors highbend scan tool to get more details. I did forget to meaning that there was a plastic tubing from the evaporator purge valve that goes into the engine. I noticed that there was a small crack as shown in the pictures. I did get the nylon piping at the parts store but I could never get it to work properly I'm guessing because I didnt get the water hot enough to mold it. So I just used a rubber hose temporarily until I can look at it more tonight. The misfire came back almost immediately so I'm not even are the rubber hose was a good idea.

Anonymous 2016-09-09 10:42

try KOEO post MAP sensor and barometric pressure readings - lets try to figure that reading out. the same ?

Anonymous 2016-09-09 10:58

Don't mean sound like an idiot I'm just a amatuer mechanic not nothing alot about the computers. The barometric pressure read 14.5 psi. What else would the map sensor reading be called because I am not seeing that option for live data.

Anonymous 2016-09-09 11:20

I just realized what you meant by koeo that what was throwing me off. But yes the barometric reading and manifold pressure was the same with the engine off. Once I crank it up the manifold pressure drops to 4.8 psi.

Anonymous 2016-09-12 13:06

I did some further testing, and found the issue. I did a compression test and got the following reading Cylinder 1 180PSI Cylinder 2 90PSI Cylinder 3 180PSI Cylinder 4 175PSI. I then put some oil in through the spark plug hole on cylinder 2, and the pressure went up to 180PSI afterwards. SO that tells me I have a worn piston ring or cylinder wall which would explain the low intake manifold pressure. I am just confused now if I have a worn piston ring or cylinder wall why I am not burning oil. I have put in some engine restore hoping this may seal up the piston.

Anonymous 2016-09-12 13:23

lets slow down on the ring/wall repair... There is a possibility that #2 is overfueling causing cylinder wall wash down and low compression.. think POSITIVE ! Not a good thing to leave unattended BUT you are on this code quickly... there are some esy checks (Easier than a rebuild) >> how did #2 plug look- wet dry cleaner than others? Is #2 firing? >> We can do a fuel pressure test then leaving KOEO observe pressure drop ie dropped Xpsi in 5minutes.... >>Smell the eng oil for fuel it ends up there... >> if it is burinig oil the FT's o2 sensors would display that likely show..RICH I suspect the scanner is showing the actual PSI as opposed to inHg confusing a old timer -me

Anonymous 2016-09-12 14:16

I wasn't going to be doing any Ring or Wall repair it honestly isn't worth it:) I looked @ cylinder 2 plug, and it looked the same as the other 3 plugs. I haven't done a pressure test on the fuel line yet. The way I did the compression test was running the engine that was cold for about 10 minutes, and then I pulled the fuel pump fuse, and it died on it's own from lack of fuel. I then removed all the coil packs and spark plug from each cylinder. Then that is how I got the pressure readings I got. Which cylinder 2 showed low compression at 90PSI. I then dropped a little bit of oil in cylinder two and ran the compression test again and the pressure shot up to what it should be. If the cylinder is washed down from overfueling what is the likely cause of the overfuel for just one cylinder a defective or leaky fuel inejctor? What would be your suggestion swap out a fuel injector in cylinder 2 with another cylinder?

Anonymous 2016-09-12 14:46

swap or do the leak down I suggeated

Anonymous 2016-09-12 14:50

Alright I will give that a shot. Weird thing was I put in some engine Restore in on Saturday and now the CEL is intermittent. So there was definitely compression loss, I just need to find the root cause of the compression loss.

Anonymous 2016-09-16 06:33

Ok I did a fuel pressure test, and it showed 48 PSI, and I didn't see it drop much in 5 minutes. So the pressure is good. Is there any other tests I could run on the fuel injector to see if it is leaking or malfunctioning. I do know there is compression loss, just seeing if there is a root cause to the compression loss like wall washing like you said.

Anonymous 2016-09-16 07:23

ok the pressure is holding....good - you did leave KOEO? the pressure seams LOW ... bad - suggest you look up pump specs - I have no time right now.

Anonymous 2016-09-16 07:28

The pressure is good. I check the specs on it. And also one thing I did notice looking at the log of misfires, and I noticed it seemed to misfire alot when the fuel trim was rich. So what I almost wondering is if the resistance of the injector is causing a rich mixture at times. If that is the case the damage has already been done with the cylinder wall/piston rings.

Anonymous 2016-09-16 10:37

your question about injectors led to this TSB #08-06-04-001A... ECT between 50–90°F, the resistance of each fuel injector should be 11–14 ohms. FYI fuel pressure appears LOW (50–60 psi) spec... what did you find before we get a second reference? GTG

Anonymous 2016-09-16 11:09

Sorry if I sound like a moron, because I don't know the acronyms. But if ECT stands for Engine Coolant temperature then that would be my issue tested the fuel pressure after I just turned the car off from driving home. So that could throw the pressure off. As for the Injectors I will give it a shot and test the resistance when I get home and it cools a little while.

Anonymous 2016-09-16 12:02

I would be looking at that compression loss - ideally we would use a leak down tester, compressed air is feed into cylinder - then check for where it is escaping - either the intake manifold, exhaust manifold or crankcase - I am a optimist and never commit to major damage (piston rings) without eliminating all possibilities.

Anonymous 2016-09-19 07:39

I have the same car with you, and have the same issue. My compression reading are 150/90/150/150. CEL on/off every few days. When I speed up after a long stop (1-3 minutes), I can feel somebody push me. If the car or weather is hot, I can feel more often. I changed spark plugs, but still the same. Garage took the compression reading in cold car period, and said piston/engine issue, big money.