QuestionQUESTION: hi i have a 2005 tiburon with a v6 2.7 my question is when you take off the top part of the manifold do you need to replace a gasket
ANSWER: It's considered proper practice to replace the plenum gasket, but you may be able to reuse it without negative consequences.
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QUESTION: hi have a 2005 tiburon v6 2.7 my question is i have 4 deferent codes in my car they are po171 po171pd and po174 po174pd i would like to know what they mean and how do i fix them thanks
AnswerHi, Kyle. You really only have two trouble codes. The "pd" indicates that the codes are pending; this occurs the first time a self-test causes the code to set. The ones without "pd" occur the second time the self-test fails in a row, and the check engine lamp is turned on at that time.
Your engine control module has stored in it the expected amount of time the fuel injectors must be held open to achieve proper mixture based on coolant temperature, air temperature, throttle position, air flow, and engine load. These codes (P0171 for bank 1/rear bank and P0174 for bank 2/front bank) indicate that the fuel injectors must be held open much longer than expected for the upstream oxygen sensors to report proper fuel mixture.
Unfortunately, I cannot tell you what the specific cause as there are several possibilities. Since your previous question involved the plenum gasket, I'd like to know why you were led to ask that question in the first place (i.e. what were you working on or what problem you had at the time), whether there were any problems reinstalling the plenum, and whether a new gasket was used. We can probably eliminate the oxygen sensors as potential issues, since both would need to have failed in the same manner, and that would be a rather unlikely scenario.
Below is an explanation of the most common issues that cause these trouble codes:
1. Mass air flow sensor reports less air than is entering the engine.
1a. This can occur because air enters the engine without going through the sensor. Potential areas where this can occur are the bellows between the air flow sensor and throttle body, intake manifold gaskets, and vacuum hoses and lines (such as vapor purge, brake booster, and PCV).
1b. This can occur because of an electrical issue (poor ground for instance) with the wiring to the air flow sensor.
1c. This can occur due to a defective air flow sensor.
2. Low fuel pressure. This will cause the injector to be held open longer than normal to deliver the same amount of fuel.
3. Excessive alcohol (ethanol) in fuel. Since alcohol is less dense than gasoline, a greater volume must be delivered to achieve the proper fuel mixture. Hence, the ECM will need to hold the injectors open longer than expected.
Without a scan tool (capable of reading the ECM's data stream), this can be a very hard issue to properly diagnose. The typical method is to monitor fuel trim (the amount of time longer or shorter than the expected amount that the injectors must be held open, expressed as a percentage) while checking. Once can pinch vacuum hoses or block vacuum ports to see if there's a change. A combustible hydrocarbon (such as carburetor cleaner) can be sprayed around the vacuum hoses and intake gasktets to see if there's a change.
In addition, dealers have a special fuel test kit designed, among other things, to enable technicians to determine the amount of alcohol in the fuel. It's designed to take advantage of the property of alcohol that it binds better to water than fuel. A certain amount of fuel from the vehicle and a certain amount of water are added to a graduated test tube which is then shaken. By the change in the level of the line separating the water from the gasoline, we can then determine how much alcohol is in the fuel.
