jczz24

I'm back with my 2009 Cobalt SS/TC, 68K miles, GM Performance Stage I PCM flash, Hahn CAI with a K&N, Hahn charge air pipes, Hahn intercooler. I have a BAFX Products Bluetooth Diagnostics OBD II Reader / Scanner and use Torque Pro and Realtime Charts for data logging and code reading.

Over the course of about 6 months or so, I have had multiple random misfires. It started during a heavy rain storm and has progressively gotten worse. At first it was only when it rained. Then it was whenever it was extremely humid, foggy, or raining. After that, it was all of that and when its extremely cold outside. And now, its all the time. At first, I was just getting a random P0301 code, then as it got worse, throw in the random P0302. It would never throw both at the same time though. Soon after, it as a P030(pick a cylinder). And lastly, it's throwing all possible misfire codes, random lean or rich codes, and running like absolute garbage while cruising. Under heavy loads, it runs better, but not great and doesn't built to maximum programmed boost, sometimes misfiring so bad, you damn near kiss the windshield when it does misfire. At idle, it runs like a big block with a huge cam in it, idle fluctuating, cam phase angles at max, spark advanced bouncing between 10 and -5 degrees, and A/F ratio pegged max on the gage. Coasting, it misses, but not too terribly bad. In the past week, I've been able to smell the catalytic convertor, however, there's never been a flashing CEL to indicate that convertor damage is being done. I replaced the plugs and the plug boots tonight with OE style replacements.

The car runs as smooth as ever. However, I noticed after letting it warm up in excess of 160 degrees, I jumped on the interstate at WOT, NLS from 2 to 3, and let out of it at around 4kRPM. About half way through 2nd, I noticed my A/F ratio on the gage was in excess of 18:1 (gage maxes out at 18:1). The A/F gage on the car eventually displayed "No Data Available" I use an app on my phone called Torque to data log. It's a pretty basic app, so I'm sure the data is limited and probably not 100% accurate, however compared to other code readers and OBD scanners, it's been pretty consistent, so I feel like it's pretty reliable. Anyhow, prior to changing the plugs and boots, the A/F gage on the data logger stuck at 29.4:1, and has been ultimately stuck there for a few days. This tells me the car is running extremely lean. When I pulled the plugs, they were carbon fouled and very black. This would make sense if the O2 sensor is bad and giving a false reading. Ironically, after changing the plugs, the A/F gage is reading again. This reading also occurs when coasting, immediately when pushing the clutch in or a short while after lifting off the throttle and decelerating, no throttle and no brake, just coasting. I started rapidly tapping the throttle with the clutch in and the A/F dropped to 12.3ish:1 and then bounced as high as 15.1, fluctuating at idle after that between 13.6 and 15.1:1. Seems to me this is pretty normal for this car, however pegging out the A/F gage on both the display on the A pillar and the data logger is not normal. I'm not driving the car that hard, letting it warm up before jumping on it when I do actually jump on it, and letting warm up to about 100 degrees prior to moving it I'm my driveway and hitting the road.

I'm going to change the O2 sensor in a couple days when I have time. However, I don't think this will fix my problem, and I also don't have time to change it before the weekend.

Any help or suggestions would be appreciated. Should it throw a CEL between now and when I change the O2 sensor, I'll come back and post the DTC here for any help available.

63 Nova SS

iTrader: (3)

I would hope the o2 sensor helps it out. If you have concerns I would not run it hard until you know for sure what that afr is because you could smoke a piston pretty quick if it is running lean under wot.

jczz24

UPDATE: Driving to work tonight, the car ran great. Drove it more than the 2.4 miles test drive earlier (about 14 miles). It did go lean on the A/F gage on the A-pillar, but only when decelerating approaching a couple stop lights and when I disengaged the cruise control as I hit an off ramp. I never got into it as it' had more power at mild throttle tonight than it has in a very long time and didn' really need to get into it getting on the interstate. I set the cruise around 70 or just shy of it. The A/F gage fluctuated between 14.3 and 15.1:1 on cruise control, and as stated, pegged at 18:1 decelerating (no throttle). As soon as I got back on the throttle, it came back down to normal. I have never noticed this kind of response before when the car ran good, before all the problems started happening, so I really cannot say whether this is normal or not. To the best of my recollection, it would go lean instantaneously and stabilize around 14.7+/- under the previously described conditions. However, during the drive after the plugs were replaced when it went lean at WOT concerns me and makes me believe going lean on decel like it is, is not normal. I did not jump on it on my way to work, so I don' know yet if the lean at WOT was just a response to dirty sensors due to the bad plugs. I did pour a bottle of Techron in 3/8 of a tank of gas thinking there was more in the tank (just filled it up maybe 75-80 miles ago) to clean up some of the crap that has fouled everything, however Techron has always been good to me keeping the guts pretty clean and not causing any issues regardless of how much gas is in the tank. So I don' believe the Techron is causing or even slightly responsible for any of the issues I'm having.

Not sure if this flooding of information is useful or not, but I'm trying to provide as much information as possible to help diagnose the issue. I apologize for not running the data logger on my way to work as I was running a bit late, so I have no information to go off of from that. Hopefully I'm providing enough information to someone with a little more experience than I have with this kind of issue.

cluelessk

All cars go lean during deceleration.

jczz24

Maybe so, but they don't stay lean. As I stated, before, the lean condition before the problems was instantaneous and only last maybe a second. Now it's going lean and staying lean. I get it doing it during fuel cutoff when the clutch isn't pushed and my foot is off the throttle. That takes several seconds to go into fuel cutoff and use to return to a normal A/F ratio once I was stopped or the clutch is pressed and the car was at idle. It does not do that now. It goes lean, like it should when no pedals are pressed and the vehicle is moving, but it stays there after falling to idle and on the clutch. That is not normal. I feather the throttle while on the clutch and the A/F will return to normal. If cruising and I press the clutch, for example when on a down hill descent, instant lean, even with the engine at idle when moving. That is not normal. It does not matter what the vehicle speed is, when the clutch is pressed and the engine is at idle, the car should not be in fuel cutoff, or running leaner than the gage is capable of displaying. The gage pegs at 18.0:1. The data logger, when this happens, maxes out at 29.4:1. I'm going to try to change the parameters in the data logger to get an exact number; not that I feel it matters, numbers like those I'm getting are bad enough, and the car still runs, so it's getting something, just not a proper amount.

ECaulk

iTrader: (6)

Start looking at the connection for the O2 sensor and verify the battery is good.

jczz24

Battery is about 6 months old. This problem started long before I replaced the battery. I'm using an Optima red top now as opposed to a OE replacement. And I checked the O2 connector for the sensor in the manifold when I threw plugs at it. It looked good to me, no signs of corrosion or loose or damaged pins/terminals. I did not check the connector for the downstream O2. I'm fairly confident that is ok though as all my codes before were upstream O2.

Now, with all that I've put out, I drove it to work last night and drove it home this morning. As stated in last night's update, she runs real good, but just has the flaky O2 readings. Seemed better this morning than last night, but it's still there. So, tomorrow, I'm gonna change the O2 sensor for a wide band and see what happens. It may just need driven with good clean components.

As far as fuel delivery at WOT? We'll work that issue later. I'll just do my best to stay out of it for now.

ECaulk

iTrader: (6)

As I know Optima doesn't make a direct fit, check the terminal connections and grounds, if the ground is messed up it will cause some serious issues in readings but the car will keep running.

If you have codes for the upstream O2 sensor anything odd related to the wideband reading is why. Wideband sensors go bad sometimes it happens. Also visually looking at a connector is not a good way to determine if there are connection issues.

jczz24

UUPDATE: Not sure if it is much of an update as it is the possibility of useful information for someone else to be able to help me. Oh this car is frustrating the hell out of me. I just got back from letting my son drive the car. Upon startup, the A/F gage displayed "No data available" again. I looked t the data logger and the A/F ratio was maxed at 29.4: again, and was for most of the drive. About midway into the drive, the CEL came on for a confirmed fault P2177 (System too lean off idle bank 1) and a pending fault P2097 (Post catalyst fuel trim system too rich bank 1). The car was running like absolute garbage again too. This is the first time I have seen a post cat code. No, it is slightly wet outside, not enough to turn on the wipers, but definitely leaving water spots on the windshield. Reference the original post where all these problems started when the atmosphere was wet. Starting to think I have moisture intrusion into a sensor connector or even the PCM somewhere, or my MAF is failing, even though it's providing responsive readings..

63 Nova SS

iTrader: (3)

If you let out of the gas on deceleration in gear it will cut fuel and will go to something like 29, that's what it does. It shouldn't go there if you are giving it throttle. If you listen close enough you can hear the engine sound change when it does this. It doesn't need much fuel at all just to coast in gear.

cluelessk

It seems like you have other issues. You shouldn't be losing signal for your A/F gauge.

From what I've read in your posts it sounds like you've felt like you tracked down the issue and you might be looking in the wrong direction.

jczz24

BIG NEWS UPDATE: I downloaded a program for my PC that connects through the BAFX OBD II Bluetooth module I already have. The data on the PC seems to be consistent with any other data logger or diagnostic tool I've plugged in to this thing, as well as the gauges and user/driver monitors built into the car. And, this program I can capture freeze frame failure records at the time the CEL comes on. Now, all this said, I'm leaning hard on a short somewhere, I just need to find it. Why? Because the past few days, the weather hasn't been too terribly bad, not enough to make the car run like crap, just slightly temperamental from time to time. Tonight it really sucks, steady rain and snow. The CEL is on, the car is running so bad, the CEL started flashing (I know, cat damage being done when this is happening). So, I pulled the Freeze Frame/Failure Records and here's what I have;

Confirmed Diagnostic Trouble Codes
-P2177: System Too Lean Off Idle Bank 1 (Powertrain, Generic)

Pending Diagnostic Trouble Codes
-P2177: System Too Lean Off Idle Bank 1 (Powertrain, Generic)
-P0303: Cylinder 3 Misfire Detected (Powertrain, Generic)
-P0304: Cylinder 4 Misfire Detected (Powertrain, Generic)
-P0302: Cylinder 2 Misfire Detected (Powertrain, Generic)
-P0300: Random/Multiple Cylinder Misfire Detected (Powertrain, Generic)
-P0301: Cylinder 1 Misfire Detected (Powertrain, Generic)

Permanent Diagnostic Trouble Codes
-none

Freeze Frame #0
-P2177: System Too Lean Off Idle Bank 1 (Powertrain, Generic)
-Fuel system status, Fuel system A: Closed loop (1)
-Fuel system status, Fuel system B: NA
-Calculated engine load: 42.4 %
-Engine Coolant Temperature: 90 °C
-Short Term Fuel Trim - Bank 1: 29.7 %
-Long Term Fuel Trim - Bank 1: -1.6 %
-Intake Manifold Absolute Pressure: 46.0 kPa
-Engine RPM: 787 RPM
-Vehicle Speed Sensor: 0 km/h
-Ignition Timing Advance for #1 Cylinder: -1.5
-Intake Air Temperature: 29 °C
-Air Flow Rate from Mass Flow Sensor: 4.63 g/s
-Absolute Throttle Position: 19.2 %
-Time Since Engine Start: 44 min 50 s
-Fuel Rail Pressure: 2320 kPa
-Commanded Evaporative Purge: 0.0 %
-Fuel Level Input: 92.5 %
-Barometric Pressure: 100 kPa
-Control module voltage: 13.81 V
-Absolute Load Value: 30.2 %
-Fuel/Air Commanded Equivalence Ratio: 1.000
-Relative Throttle Position: 4.7 %
-Ambient Air Temperature: 3 °C
-Absolute Throttle Position B: 19.2 %
-Accelerator Pedal Position D: 21.2 %
-Accelerator Pedal Position E: 21.2 %
-Commanded Throttle Actuator Control: 7.1 %
-Long Term Secondary O2 Sensor Fuel Trim - Bank 1: -0.8 %

Diagnostic information provided by OBD Auto Doctor

Here's what I'm getting out of this; the upstream O2 sensor has a wire that when it gets wet, it's shorting to ground (chassis, engine, somewhere metal on the car), thus making the PCM think the car is running extremely lean. The car is trying to flood the engine with fuel, hence the fouled plugs and all the misfires. It is literally flooding out the engine. Stop me if I'm going in the wrong direction, please. Anyhow, now I need to wait for better weather and find another ride to work until I can peel this thing open and see where the problem really is. I'm really hoping its on the sensor side of a connector and not the vehicle harness side of the connector. Any additional input would be greatly appreciated, to include confirmation that I'm looking in the exact direction I need to be looking. I deploy in a month and need this thing fixed before I go so my wife doesn't make the problems worse than I need them to be.

ECaulk

iTrader: (6)

Have you replaced the upstream o2 sensor yet?

The lean code and misfired point to a bad oxygen sensor. It's a under 100 part and about a 30min job the first time just replace it already.

jczz24

Here's where I am at. Last night, I pulled the air filter and cleaned it. It was nasty to say the least. I also cleaned the MAF sensor since I was on that corner of the car. After reinstalling it and not driving the car til this morning, I expected better than what I got. Fortunately, I ordered an upstream O2 sensor last night. Anyhow, the car stuck lean again this morning when I pushed the clutch to slow down for a stop light. I get the whole fuel cutoff thing, but when it never returns, regardless of engine load and throttle position, I find it hard to believe it's in fuel cutoff. Anyhow, after work tonight, I changed out the O2 sensor. The fuel cutoff is doing exactly what I stated before, where it goes into fuel cutoff during deceleration, and when pushing the clutch and the car returns to idle, the AFR returns to normal. It also isn't going lean under boost. In fact, the AFR gage is fluctuating a lot less than it did before I replaced the sensor. Is the car fixed? I'll let you know in a couple days. I need to put some miles on it before I can definitively say yes. But after test driving it tonight, I figure its gonna give me some more fits before I give up and send it to the dealership.

Now, all this said, I need a short ram intake. Anyone have one used and in good condition. If not, would it be too difficult or not recommended to cut up my CAI and shorten it to a short ram intake, bring the filter element up into the engine compartment as opposed to where it is now behind the right fog light? Its a steel tube. A good welder could seal it up for far less than I would pay for a new short ram intake. I'm decent with fiberglass and can construct a box to go around it to protect it from engine heat, so that isn't a problem. I just don't want to spend $300 on a tube and air filter. Heck, I don't really want to spend half that, I'm pretty cheap, even though this lesson has cost me a bit. But did it really?

The plugs were 3 years old; only had about 16k on them, but they were 3 years old. The boots were the original boots, 9 years old. The air filter hasn't been cleaned in probably about a year. The MAF, never cleaned as long as I have owned the car. And the O2 sensor I just replaced was about 5 years old. So did I really waste money, or did I do maintenance that needed done anyhow?

Moral of this story? I need a short ram intake. I feel like the elements I'm sucking into this engine with the filter as low as it is with the CAI, cannot be good for the engine, especially in Va Beach/Norfolk area.

By the way, it took me longer to get my tools out to change the O2, than it did to actually change the O2 on a hot engine. Surprised the crap out of me. I figured I would run into problems. But the old O2 came out relatively easy.

cluelessk

Short ram is going to cause more problems. Unless you go for well designed one like the K&N you'll get turbulent air hitting the MAF.