[Vettezuki]

Who knows how shitty flowing the injectors are . . .

[Shaolin Crane]

New cats definitely take time to burn in.

[Damian]

I wouldn't think it takes too long for a cat to break in. Mine was fine with less than 10 miles on it. Put a high load on it, I'm pretty sure that would do the trick??

[Shaolin Crane]

I've had to drive them as much as a few hundred miles to get them to come in.

[Vettezuki]

Originally Posted by Shaolin Crane

I've had to drive them as much as a few hundred miles to get them to come in.

Thanks for the info. I was definitely wondering if there might be a break-in period. I'm at just over 200 miles, and it's running ok. I am getting the kind of sweeping pattern on the upstream O2 voltage. But the A/F and emissions are swinging rich/lean, high HC/NOX respectively.

[kdracer73]

This car is doing some funky shit ! I have never really had problems with new cats, if the rest of the system is working ok. Most 2007 cars we test are blowing numbers in the 0.02= 0.09 % range...this thing is blowing over 4% co. My Camaro with a cam and no cat probably blows about that.

[Vettezuki]

Decided to change the AF and plugs. The AF was much dirtier than I suspected from a first glance. Couldn't have been helping. The plugs weren't terrible, but a little burnt' worn. Curiously looking down in the cylinders, No. 4 was "wet", with what I don't know, and dirty looking. Drove it around a bit. It drives fine for what it is, more perky definitely. Gave it a couple WOT romps from a stop to see how it would respond and it did fine. Some kind of smell afterward, don't know what it is as I've never smelled that smell before. Maybe some manufacturing remnants from the cat that glot blasted. I don't want to do much like this as if it is consistently running lean under load that's going to thrash the new O2s and Cat.

Checked cylinder 4 after about 40 miles of driving and was much cleaner and dry. So there just might be some cleanliness and function issues that are getting worked out with use.

I'm wondering if the P0037/38 will clear themselves after some number of otherwise faultless driving. The only readiness tests not yet cleared are Catalyst and O2 sensors.

Also noticed the gas cap does not secure, just turns, doesn't seal. Should I care? The evap system readiness passed.

[Vettezuki]

Regarding primary causes for high CO, No. 1 was absolutely true. I don't have any cause for suspecting anything else though.

Below are common faults which are likely to produce high Carbon Monoxides (CO). Carbon Monoxide is a by-product of incomplete combustion. Carbon Monoxide exceeding maximum limits, can be due to a number of emission failures ranging from inadequate air intake to defective engine computer sensors.

1. Dirty Air Filter - The number one overlooked emissions component, yes, "emissions" component is the engine air filter. A dirty air filter will absolutely restrict air flow, thus disturbing the proper 14.7:1 air/fuel ratio required for optimum fuel combustion.

We recommend replacing the air filter at the manufacturer's required intervals; usually every 15,000 miles, or at least before your vehicle's smog check.

2. Faulty Oxygen Sensor (O2 Sensor) The Oxygen Sensor is responsibly for delivering information to the ECU (engine control unit) or ECM (engine control module) relating to the oxygen content in the exhaust stream after it has left the combustion chambers.

The engine control computer will determine how much fuel to inject into the combustion chambers based on this data. The more oxygen in the stream, the more fuel the computer will deliver, and visa-versa. A defective O2 sensor will cause increased carbon monoxide emissions. More about oxygen sensors.

3. Defective Manifold Absolute Pressure (MAP) Sensor - The MAP sensor determines the level of vacuum created during an engine's intake stroke, and sends this information to the ECU. During low vacuum the MAP sensor assumes the engine's throttle is in some degree open, meaning you've stepped on the pedal. It relays this information to the ECU. The ECU, in turn, sends commands to the fuel injectors, or carburetor, to increase fuel delivery.

A defective MAP sensor will not report the correct information to the ECU, thus disturbing air/fuel ratio. Usually when the ECU senses a defective MAP sensor it will learn to ignore its data, and rely on preset values, and other sensors such as the Throttle Position Sensor (TPS), and Engine Coolant Temperature (ECT) Sensor; Fuel delivery will not be as accurate and high CO may result.



4. Defective Throttle Position Sensor (TPS) - Obviously a very important emissions sensor; the TPS relays information regarding the position of the air intake system's throttle plate. The throttle plate, located after the engine air filter and before the intake manifold controls the amount of air entering the combustion chambers. It is usually manipulated by the gas pedal via a cable. On late model vehicles the throttle plate may be controlled electronically. A defective throttle position sensor will confuse the ECU into thinking the vehicle's operator is demanding more or less fuel, when neither is really neccessary. Most often a faulty TPS will cause high CO, as an engine's ECU always prefers to send more fuel rather then less, in an effort to avoid a lean fuel mixture and subsequently higher engine temperatures.

5. Defective Engine Coolant Temperature (ECT) Sensor - Low engine temperature requires more fuel. When the ECU is unable to determine what the engine's accurate temperature is, it will not adjust fuel delivery properly; resulting in high CO. As explained above, the Engine Control Computer prefers to send more fuel rather then less to avoid a lean fuel mixture.

[Damian]

The coolant temp sensor could be your problem. It helps your ECU know if its up to temp and then switches over to closed loop. A lot of cars have 2 different sensors, one for your gauge and one for your ECU. If the one for the ECU is bad, youre stuck in open loop all the time, it just takes forever to get up to temp. On the flip side, Id still think that you would throw a code for it, cant think of it off the top of my head. But I have seen this before on one of my uncle's Saturn. Replaced the ECU coolant sensor and everything ran much better.

[Vettezuki]

Originally Posted by Damian

The coolant temp sensor could be your problem. It helps your ECU know if its up to temp and then switches over to closed loop. A lot of cars have 2 different sensors, one for your gauge and one for your ECU. If the one for the ECU is bad, youre stuck in open loop all the time, it just takes forever to get up to temp. On the flip side, Id still think that you would throw a code for it, cant think of it off the top of my head. But I have seen this before on one of my uncle's Saturn. Replaced the ECU coolant sensor and everything ran much better.

There's only one coolant temp sensor on the Aveo. I have no reason to believe it's not working as I'm reading the temp from ODBII directly, it matches the gauge, coolant flows through the upper rad hose when I'd expect (which is mechanical thermostat AFIK), etc. The MAP sensor is kind of expensive, but the coolant sensor is pretty cheap, so maybe I'll change it just to eliminate it as a parameter.