05 Balt bogging down.No power.

I have an 05 Cobalt with the 2.2 Ecotec. Here is what has been done so far. Had head gasket replaced.Had a wiring problem to fuel pump.Ran a wire from another fuse direct to fuel pump ( Checked the wire from front to back and it is fine ).Put on a new fuel filter.Changed spark plugs. Also filled tank at 3 different stations, 3 different brands, to rule out bad gas. Put in a bottle of Isopropyl dry gas.Here is the problem - When I accelerate the car bogs down.Up a hill I am lucky to go 20 mph. Gas mileage dropped from 31 mpg to 17 mpg. Even up a small hill top speed is about 35 - 40. Here are the codes from the code reader ;PO30 - HO2S BANK 1 SENSOR 1 HEATER CIRCUIT. PO130 - 02 SENSOR CIRCUIT MALFUNCTION (BANK 1 SENSOR 1 ) and last PO101 MAF or VAF A CIRCUIT RANGE / PERFORMANCE. I assume that PO130 is the O2 sensor ( Located on exhaust in front of cat conv.) . Is there a chance that could cause the problem ? I noticed it losing a little power a week ago.Then the wife came home from work 3 days ago and said she had to pull over to let traffic go by because it wouldn't climb hills. I test drove it and found she was actually right. Temp runs normal. It ranges from 189 on open road to 215 in town. I would think if the cat convet. was clogged it should heat up. But is it possible that isn't always the case ? On the level I can get the car slowly up to 65, but if I try to accelerate it quickly it will bog down. By quickly I mean the normal acceleration to go from a stop. I have to baby it to go.Thanks in advance.

Most likely a problem with the MAF (VAF - voulume air flow is the same thing) sensor, given the code and symptoms. O2 sensors will very rarely create drivability problems this bad. The MAF sensor measures the air going into the engine by using 2 or 3 wires and it measures how much current it takes to keep them at a preset temperature. The more air that flows over them, the more current it takes. What usually happens is you get some "fuzz" that makes it through the air filter and it collects on these wires. That increases the surface area, and allows more heat to dissipate from the wires. The PCM then sees more air coming into the engine and it therefore gives more fuel.

Try unplugging the MAF sensor (located somewhere on the air intake tube, after the air filter and before the throttle body). I have yet to see one of these cars, so I can't say for sure where. If it runs good/better with it unplugged, remove it and clean it out with air intake cleaner (not a bad idea to clean it even if it doesn't help). Gently blow it dry and then let it air dry for 5 minutes. If there is still liquid in there and it drips on one of those wires, there's a very good chance it'll crack. Same thing when you spray it out... so let it cool off for a few minutes before you spray into it.

The O2 sensor codes may be a result of it running rich. The heater performance one, if I remember correctly, only means that it takes longer than a preset time for it to start reading in the 14.7:1 range. That, of course, will never happen with it running so rich. The other one I suspect may be a redundant code. Anyway, fix the MAF code first and see if the O2 codes go away.

Most likely a problem with the MAF (VAF - voulume air flow is the same thing) sensor, given the code and symptoms. O2 sensors will very rarely create drivability problems this bad. The MAF sensor measures the air going into the engine by using 2 or 3 wires and it measures how much current it takes to keep them at a preset temperature. The more air that flows over them, the more current it takes. What usually happens is you get some "fuzz" that makes it through the air filter and it collects on these wires. That increases the surface area, and allows more heat to dissipate from the wires. The PCM then sees more air coming into the engine and it therefore gives more fuel.

Try unplugging the MAF sensor (located somewhere on the air intake tube, after the air filter and before the throttle body). I have yet to see one of these cars, so I can't say for sure where. If it runs good/better with it unplugged, remove it and clean it out with air intake cleaner (not a bad idea to clean it even if it doesn't help). Gently blow it dry and then let it air dry for 5 minutes. If there is still liquid in there and it drips on one of those wires, there's a very good chance it'll crack. Same thing when you spray it out... so let it cool off for a few minutes before you spray into it.

The O2 sensor codes may be a result of it running rich. The heater performance one, if I remember correctly, only means that it takes longer than a preset time for it to start reading in the 14.7:1 range. That, of course, will never happen with it running so rich. The other one I suspect may be a redundant code. Anyway, fix the MAF code first and see if the O2 codes go away.


Still have the no power problem.Car has 103,000 on it.Here is what has been done so far; At 95,000 the head gasket was replaced and head shaved .015. Took out MAF sensor and cleaned. Bought a new upstream O2 sensor and installed.MAF & O2 Sensor codes left.Continued to get an ENGINE MISFIRE CODE. Replaced coil pak & all the plugs (again). Still coding ENGINE MISFIRE. Also disconnected Catalytic Convertor. Still codes and has no power.Goes up to about 2500 RPM's in park, then dies. At wits end right now !! Thanks.

Loss of power when the fuel demand is high could be due to not enough fuel is getting to the engine.

If the MAF output is low, indicating less air entering the engine than true, then PCM will not deliver as much fuel to the intake ports. The mixture will be lean, you'll get misfires and loss of power. The valves can burn if operated this way for long.

MAF might be shot.

The HO2 heater code is saying that the heater circuit on the O2 sensor is either shorted or open. This can be checked with a DVM.

Usually the PCM will run open loop when the O2 is not working, which is supposed to give decent operation based on data from the other inputs (MAF, MAP, RPM, etc.) and the stored LTFT. I don't know what the PCM does if the LTFT is way off.

Usually cleaning the MAF is enough to restore it's operation, but they are sometimes broken rather than dirty. For more information about the MAF, http://www.autoshop101.com/forms/h34.pdf

Another thing to check is the fuel pressure at RPM. If it drops much, then you either have a clog (i.e. fuel filter or inlet screen), a bad fuel pump, or a bad FP regulator. Keep in mind that fuel pressure is designed to vary with the manifold vacuum pressure (more fuel pressure at WOT, less at idle)

Thanks tomj76. I had changed the fuel pump and the fuel filter. I also bought MAF cleaner and took the MAF sensor out twice and cleaned. The upstream O2 sensor was changed,but not the downstream.I do have the fuel pump hooked up to run all the time when the key is on.The wire to the fuel pump I assume must have a break in it.It had stopped working and there was no juice to the fuel pump. So I connected it to another fuse link.Since I replaced the O2 sensor and replaced the coil pak, I get only a 300 code now ( Random cylinder misfire ). That was why I replaced the coil pak.But it still codes 300. I had also replaced the plugs even though there were only 3,000 miles on the old ones. I was wondering about a carbon buildup, or clogged injector ??? The head was shaved .015 when the head gasket was replaced.

It sounds like the codes you were getting are gone now, after replacing the upstream O2 sensor (which is the one that was giving you the codes), and cleaning the MAF plus replacing the fuel pump.

Now you're only getting a P0300, random misfire code.

Do you still lose power climbing hills?

A random misfire seems like it points to a "global" problem (something, like the MAF, EGR, or MAP, or a vacuum leak that affects all the cylinders equally). If you can read the freeze frame data from the PCM, then you might gain some insight into the problem. Also, if the misfire is frequent enough you can use a vacuum gauge or other diagnostic tools to isolate the cause.

If you don't have the diagnotic tools, I can identify. I spent plenty of $$ on unneccesary parts (and wasted time installing them) before I invested in a few diagnostic tools and shop manuals to help narrow down the troubleshooting process.

I just replaced the MAF a few minutes ago. It gets a few more RPM's (3400 ) than before,but still no power. If I can remember all that I did so far - Replaced upstream O2 sensor, MAFR, coil pak, plugs, head gasket ( Head was shaved .015 for warpage ) ,disconnected cat convert, replaced fuel pump ( used with 13,000 miles on it ), had to run a jump wire to another fuse because the line lost power to the pump and put LUCAS cleaner in the fuel. There were no codes today after I cleared them, but CHECK THE GAS CAP light came on. Checked it and then restarted. No check gas cap light, but still no power. On my to do list is check the fuel pump pressure. The car always ran cool ( 185 - 200 ) till the head gasket went. It ran cool after the gasket was replaced and the head shaved. But now it is going up to around 215 - 220. There is not enough power to go over 15 - 20 MPH. I had been think a clogged injector ( Why I bought the LUCAS cleaner ) or a crabon build up.What I do know is when I walk into the parts store a big smile comes on their faces. We have 3 vehicles and all are down for one thing or another. My truck is a 1977 Dodge M880 and it has a bad pitman arm. They don't make a replacement. I have a used one coming from Eastern PA. but won't be here till after Christmas. We have a 95 Chevy full size van that needs a comlete exhaust and tires and the famous Balt. But stuck all of our money into the Balt.Thanks all of you for the help so far.:banghead:

How does it sound when you try to get it to go? Any popping sounds? If so, from exhaust or intake? Does it run rough (misfires)?

How do the spark plugs look? Any that are "super clean"? Wet with oil? Fouled with carbon?

What's the exhaust look like? Is it clean, sooty, blue, or white?

It was running good with no miss. But after I put the MAF sensor in it runs a little rough. It isn't popping or back firing like a bad valve. But the plugs I took out had about 3,000 miles on the and were black carboned.But not to the point of being sooty.They were dirtier than I expected for only 3,000 miles.I haven't yanked the new plugs yet to check them.None of the old ones were wet with oil or gas. The tail pipe has always had black in it. Even when it ran good.In park when I give it gas it will go to a max of 3400 RPM's then bog and go down to a couple of hundred.Then idle back up to around 800 - 900 RPM's.Before I replaced the MAF it would only go a max of 3,000 RPM's. Before the AMF it also idled great.But probably the miss has nothing to do with the MAF. Just happened by chance I guess. I

It seems like there aren't any of the classic signs of valve problems, head gasket problems, or piston ring issues.

The plugs sound like they have a little more carbon than normal, but nothing extreme.

The only code you get is the random misfire.

The PCM will act as a governor if RPMs get too high. However, 3400 rpm isn't very high. I don't believe that engaging the governor triggers any code. Since the governor is part of the PCM, it's a software feature. I don't think there is any way for the governor to malfunction and trigger at lower rpm.

The higher operating temperature is a question worth understanding. Check the coolant level with the engine cold. Check the coolant level in the radiator too. However, remember that the engine temp will often be higher when the car is not moving than it is when it's constantly moving. The high temperature could be a sign that the engine is doing more work (i.e. burning more fuel) than normal. This what to an engine when you climb a long steep hill, the coolant temp will often increase a couple degrees.

Since you replaced the MAF, I'd focus on checking that the fuel pressure is not low. Given that you replaced the fuel pump and filter, it's not likely to be low, but there fuel pressure regulator is still a possiblity.

FYI, another possible cause of power loss at high RPM is lack of timing advance.

I think you have correctly addressed the maf and o2 codes. the no power and bogging symtom sounds like either clogged injectors or restricted exhaust. You ruled out exhaust restriction already. Car with returnless fuel systems (which this is) can clogged the injectors as the final injector in the rail acts like a sewer and collects all the crud that would normally return to the tank in systems that have return lines. I would get a fuel injector balance test done.

Usually the car would show a lean condition when the injectors clog.
Does yours scan tool show fuel trim? If trim numbers are over 10% a lean condition is occuring and the ecm is trying to compensate for it. Accelerate hard and watch the trim numbers. Normally the fuel trim should be within +/- 10%.

GM dealers have the AFIT which is a injector balance tester that would confirm this.

OK. My computer ( PC ) crashed and just got it back and the Cobalt has sat most all Winter. Other than starting it up and driving a 1/2 mile every couple of weeks, to keep it loosened up, it sat covered in good ol PA snow.Here is all that I have done, new MAF , O2 sensors.New coil pack, disconnected catalytic converter, changed plugs, head gasket, put in Lucas Injector Cleaner.I was told by a GM tech that the only thing left,and probably what the ultimate problem is, that the computer itself is bad.Does that sound reasonable ? Where is the computer located at ? That is about the only thing that hasn't been changed.The car can't get out of it's own way. No power. In neutral I can rev it to between 3,000 and 3400 RPMS, then it bogs. Under power it can barely move.

I don't know the exact location of your computer, but it's been behind the glove box on the cars that I've had.

If you can check the fuel pressure while driving, or get your hands on a OBDII scanner that can read active data, you can check to be sure that you're not losing fuel pressure while running.

A fuel pressure gauge taped in the right position so you can read it while driving (with the hood down and secure) should let you see if the pressure is maintained under load. A scan tool will show high fuel trim if the pressure drops.

If you can check the fuel pressure while driving, or get your hands on a OBDII scanner that can read active data, you can check to be sure that you're not losing fuel pressure while running.

A fuel pressure gauge taped in the right position so you can read it while driving (with the hood down and secure) should let you see if the pressure is maintained under load. A scan tool will show high fuel trim if the pressure drops.

Thanks tomj76 I have to check the fuel pressure. I have an OBDII scanner,one of thsoe cheap $49.00 units. Every time I check the FAULT CODES, I get a different code(s). But almost every time I get RANDOM ENGINE MISFIRE.It also had about an emissions leak (large) which I assume is because I have the catalytic converter disconnected. Last time it said to CHECK GAS CAP.So I went and took it off and re-tightened it.I cleared the gas cap message and it was OK all the while it ran. But went out the other day and started it and the gas cap warning came on again.I do have the fuel pump hooked up direct.When I changed fuel pumps I found that the pump wasn't getting any power.So I ran a wire back and spliced it in. It ran fine for about 4,000 miles after the head gasket/fuel pump replacement.

>I have an OBDII scanner,one of thsoe cheap $49.00 units.

That will read your codes, but to get dynamic data you need one of the more expensive ones. A fuel pressure gauge will give a direct reading so you'll know if there is a fuel issue, or if you should look elsewhere for the problem.

>It also had about an emissions leak (large) which I assume is because I have the catalytic converter disconnected.
If you run without a cat, you'll get codes. The computer can tell the difference. Did you remove it because it failed, or for some other reason?

>Last time it said to CHECK GAS CAP
That's a EVAP system error. The vehicle has a fairly sophisticated system to make sure that gasoline vapor aren't escaping for the fuel supply.

I sounds like you're running a fairly heavliy modified setup there.

wondering if this all started after the fuel pump wiring repair? The system is design to run at constant pressure with the regulator located in the fuel pump module but is ecm controlled through the fuel pump relay. Not completly sure if it would matter or not but wonder if the wiring repair took the ecm out of fuel control?

Fuel pressure test, as per other postings, is needed. spec is 50-60 psi running and shouldn't drop more than 5psi in 1 minute when turned off

The ecm, if your still looking, is located near the left side of the rad.

wondering if this all started after the fuel pump wiring repair? The system is design to run at constant pressure with the regulator located in the fuel pump module but is ecm controlled through the fuel pump relay. Not completly sure if it would matter or not but wonder if the wiring repair took the ecm out of fuel control?

Fuel pressure test, as per other postings, is needed. spec is 50-60 psi running and shouldn't drop more than 5psi in 1 minute when turned off

The ecm, if your still looking, is located near the left side of the rad.

The problem started about 4,000 miles after the fuel pump.I guess the wiring repair could have done that.That gives me another thing to look at.Thanks.