Question about Hyundai XG300
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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Posted on Jan 02, 2017
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