Question about Chevrolet Blazer
Service engine light is on. Code reads, PO172Bank1 system too rich, I have changed the follow and the service engine light is still on. EGR valve, o2 sensor pre cat, plugs & wires, Rotor &Cap, both nock sensors, any suggestions, Please help
If it's like my FORD, control alt delete and keep driving. If your vehicle is running fine with the light, your maybe able to drive the car until a car mechanic can diagnose your problem. Sometimes the fuel burn-off lines at the throttle body can have extra carbon buildup. I have used CRC Emissions fuel system cleaner through the car with success. BG 44K works wonders as well. I shut the vehicle off while in Park. Then, I disconnect the battery cables safely for 5 minutes. Reconnect battery wires. Start up the vehicle. The light maybe gone now. Service engine lights are manufacture money grabbers. Always have a professional check your vehicle.
Posted on Nov 17, 2013
Injector, map sensor, fuel pressure regulator?
Posted on Nov 17, 2013
Po172 refers to an oxygen sensor. But after you service the part you need to clear the code with an OBD II scanner. You can get a reliable inexpensive one at Harbor Freight. After you clear the code then you to start the car and drive it to see if the code comes back on. Also if you have a vacuum leak this can cause the system to run either rich or lean depending on circumstances.
Posted on Nov 17, 2013
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Posted on Jan 02, 2017
The Exhaust Gas Recirculation (EGR) valve is an important part of the exhaust circulation system of a vehicle. EGR valves have been in use in the United States since the 1960s, when car companies were seeking ways to increase the efficiency of vehicles while also decreasing pollution. When the EGR valve is clogged or malfunctioning, it can cause irregularities in engine performance such as rough idling or valve knock, indicating that the EGR valve should be inspected.
The EGR valve works by routing a small amount of exhaust back into the combustion chamber, where it can be reused. This is done for a number of reasons. The primary reason is that a certain temperature is required in the combustion chamber, and exhaust is much warmer than air taken in from the outside. As a result, the engine need not work as hard to heat the combustion chamber to optimal temperature. The second reason is that the use of an EGR valve helps to reduce nitrogen oxides, which will combine with elements in the atmosphere to form smog.
Many EGR valves are mechanical, and simply have a small valve which opens to allow exhaust into the combustion chamber and closes when it is not necessary, and to keep the air mixture optimal for combustion. Some mechanical versions will not open until there is sufficient back pressure, ensuring that the valve will not be open when the engine is idle or warming up and needs a higher concentration of oxygen for combustion. Electronic EGR valves are also available, and use electronics to regulate the valve.
If the EGR valve is stuck open, it will essentially cause a vacuum leak, leading to inefficient combustion, rough idling, hesitation, and sometimes stalling in extreme cases. This is because the car cannot combust on carbon dioxide from the tailpipe alone-it needs atmospheric oxygen as well. If the combustion chamber is flooded with exhaust from an open EGR valve, it will not function properly. To check and see if the EGR valve is stuck open, have someone idle a parked vehicle with the brake on while you examine the plunger shaft to see if it is stuck open.
If the EGR valve is stuck closed, emissions of nitrogen oxides will rise, and the car may start to knock. Spark knock happens when the fuel mixture in the combustion chamber ignites before it has been reached by the explosion in the cylinder, resulting in a disruption of the engine timing. In this instance, the engine should be warmed up and revved to see if the EGR valve will move.
In both cases, simple repairs are possible. The EGR valve can be clogged, and a simple cleaning of a mechanical EGR valve may solve the problem. In the case of an electrically controlled EGR valve or a more complex mechanical problem, replacement of the valve may be needed. The EGR valve is an expensive motor vehicle component, and care should be taken to ensure that it needs to be replaced rather than repaired. A reputable mechanic should advise you appropriately.
Failure to repair or replace the EGR valve will not lead to a life threatening condition, although it will reduce the life of your car and increase the potential emissions. Especially in areas which require smog testing, an automobile with a malfunctioning EGR valve may not pass.
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Posted on Mar 26, 2009
There may be problem with the mass air flow sensor (very common with Volvo). This causes the fuel system to malfunction.
You may have noticed increased fuel consumption, loss of power and general 'lazyness'.
Better to take it to authorized Volvo service for a checkup/fix.
Posted on Jan 16, 2010
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