Question about Hyundai XG300

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My car has been acting up for a few months now and i bought a new fuel filter and got an oil change but the problem only got worse. at first it only seemed like the car didnt want to shift gears but after it a while it grew worse. now it doesnt want to get over 5 mph without losing power and the rps are all messed up.when i push on the gas pedal it doesnt want to accerlerate. sometimes it does get up to speed but it takes it time to actually want to get past 10 mph. i drove the car to kentucky from texas how its been acting and then it wouldnt pass 60 mph without losing power and dropping down to about 45 mph. auto zone sed it could be the air filter or maybe the fuel line is clogged but another auto zone said it was the fuel filter going bad so thats why i put a new one on. but it didnt help the problem at all. so now we think it could be the fuel injector.

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Hard to say.

You say the "rps are all messed up", but did you mean the RPM?
If so, then you could mean that the automatic transmission is not shifting right, and you should check the ATF for level, color, and smell.

But is could also be you mean the engine is not reaching enough RPM because it lacks power. If it has a new fuel filter, then that is not it.
In general, the first thing to do is check all the fluids, like engine oil, coolant, etc.
But assuming they are ok, the next would be to decide if it was a single cylinder (like plug, wire, valve, injector, etc), or something effecting the whole engine (like fuel pump, O2 sensor, PVC foam on the air mass sensor, etc.).

Since you don't say it idles badly or runs rough, I will assume it is systemic to the whole engine.
The first thing to do is check fuel pressure, with a gauge borrowed from a place like Autozone.
(If the engine is not running rough, it can't be an injector because that would only effect one cylinder.)
Don't know what the pressure for your car should be, but I would guess between 40 and 60 psi. You will have to look it up.
If it is low, then it is either the purge valve causing excess vacuum in the tank, or a bad pump (which is usually in or near the tank).

Tell me more so that I can be more specific.

Posted on Jul 28, 2010


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