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By Jay at SuperDrift

"Well, there has been many speculations and researches by shops, but we got this "unofficial" explanation straight from the horse's mouth. We can't name who, but he/she worked on the Gen coupe project.

The rev hang (partial opening of the throttle) was put into the throttle body control in order to lessen the blow by gas emission. During the development Hyundai researchers experienced that if a throttle body closes immediately, pressure inside the engine(crankcase) becomes so great, it caused more oil vaporization than usual. This is quite normal for any turbo charged engines, but Hyundai wanted even better emissions and didn't want to deal with the "oil loss" issues. Thus by partially keeping the throttle body open even after gas pedal has been completely released, pressure can escape from engine.

So, here is what we found out. Solution to the rev hang issue will be to fix the throttle body control codes in the ECU, install oil catch can and add oil every month.."



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Well, for all you 2.0T owners, after I replaced the OEM BOV with the HKS SSQV, it eliminated my rev hang completely. That was the very first thing I noticed immediately on the test drive.
 

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This is the second case that I have heard that just putting a better BOV on the car almost completely eliminates the rev hang. I guess if the BOV is more efficient it can effective reduce the pressure faster than the stock one and eliminate the need for the throttle to stay open for so long.
 

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MSUGeoman22: While we will look into it further, in the meantime 4TGEN may be able to give you his feedback on this rev hang. I believe after our reflash, he felt his rev drop faster than before.
 

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Thanks Arvin, I think that it is completely attributable to the throttle mapping and the dual mass flywheel, not the BOV. Not having the throttle closed all the way when the pedal is at 0 throttle between shifts means that no matter what BOV/BPV is installed, the engine will still rev and all of the pressure will be evacuated from the manifold and pipes. Ideally, the throttle should be completely closed which would retain some of the pressure in the manifold and would give quick throttle response time but the factory programming does not allow this to happen. Hanging the throttle open essentially makes the turbo have to start all over again and makes the car feel lumpy and laggy. I can't wait to get some programming to see how this car SHOULD have been from the factory.
 

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There's nothing new or unusual about the throttle not shutting immediately. It's always been that way on most fuel injected cars. The old cable driven throttlebodies usually had a damper installed (called a dashpot) so that the throttle wouldn't shut suddenly. The idle air control valve would also open further (Mitsu stepper type) as rpms increased or increase in duty cycle (Nissan, Mazda, Honda solenoid valve type). This is so extra air enters the engine if you let off the throttle, to keep the car from stalling.
 

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10-FL-006 3/18/2010 GENESIS COUPE(BK) Fuel System 10-FL-006 ECM UPDATE - DTC P0605 OR SLOW RPM DROP WHEN RELEASING THROTTLE
Even though that was released in March of this year it still just references the old update that came out originally. 149 - Logic Improvement, so this is not something new they just updated the procedures to correcting the problem. If you have The latest PA re-flash or the BR Maps loaded on your device then you already have it. I know I got this update several months ago and I verified my ROM ID and it's the same as the new ROM ID that your supposed to have after updating it.
 

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Well, for all you 2.0T owners, after I replaced the OEM BOV with the HKS SSQV, it eliminated my rev hang completely. That was the very first thing I noticed immediately on the test drive.
Did the same mod to mine, got the AGP Kit that doesnt use the blockoff plate but leaves it in the stock location. Still get Rev hang, not as much or as bad but it is still there. Could only be fixed with a reflash. But it doesnt bother me to much anymore.
 

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The latest ECU update fixes the rev hang...was released awhile ago. Well, it does in the 3.8 anyway.
 

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The latest ECU update fixes the rev hang...was released awhile ago. Well, it does in the 3.8 anyway.
Rev hang should only be experienced by the 2.0T crowd, the NA 3.8L shouldn't have this issue at all. No BOV present in NA cars....
 

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I understand that, but there was a rev hang issue with the 3.8 in most of the reviews of it. There was a TSB for it specifically. It's part of the reason the 3.8 A/T did better on the track than the M/T. However, it was ECU related. It sounds like you guys are talking about a mechanical rev hang issue.

I'm coming from a 2.3T car, (Speed 6) and I'm trying to figure out how the BOV/BPV would cause the revs to hang?
 

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I understand that, but there was a rev hang issue with the 3.8 in most of the reviews of it. There was a TSB for it specifically. It's part of the reason the 3.8 A/T did better on the track than the M/T. However, it was ECU related. It sounds like you guys are talking about a mechanical rev hang issue.

I'm coming from a 2.3T car, (Speed 6) and I'm trying to figure out how the BOV/BPV would cause the revs to hang?
From the first post of this thread:

"....
By Jay at SuperDrift

"Well, there has been many speculations and researches by shops, but we got this "unofficial" explanation straight from the horse's mouth. We can't name who, but he/she worked on the Gen coupe project.

The rev hang (partial opening of the throttle) was put into the throttle body control in order to lessen the blow by gas emission. During the development Hyundai researchers experienced that if a throttle body closes immediately, pressure inside the engine(crankcase) becomes so great, it caused more oil vaporization than usual. This is quite normal for any turbo charged engines, but Hyundai wanted even better emissions and didn't want to deal with the "oil loss" issues. Thus by partially keeping the throttle body open even after gas pedal has been completely released, pressure can escape from engine.

So, here is what we found out. Solution to the rev hang issue will be to fix the throttle body control codes in the ECU, install oil catch can and add oil every month.."
Makes a lot of sense, since it can be eliminated using different methods (PA flash, Aftermarket BOV)
 

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Ahhh...I should have read the entire thread. That is an interesting way to keep the pressure down though.

I'll try to pay attention better before posting...my bad.

:)
 
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