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Discussion Starter #1 (Edited)
(Disclaimer, before the crucifixion squad come along and tells me to use the search function I would like to say, I have, and there has not been a single example similar to mine. The closest thing I found was on a VW forum about the jetta's which didnt help much as I own a sexy Korean beast not a jetta and no one had an answer there either. So spare me your cross and crown of thorns and help me out)

I have a 2010 Genesis Coupe 3.8 Track. I purchased it in April with 109,000 miles after selling my bk1 2.0t. Car ran great but soon after leaving the lot the CEL came on just my luck. Ran the code and it was a P0333, knock sensor bank 2 not responding. I decided to just live with it and just cleared the code every time the CEL came on until I got to fixing it. Since I've had the car I've put around 5k-6k miles on it. Now where my problem started. I was sitting at a red light, once the light turned green I put the clutch in put the car into first gear and started to slowly get on the throttle to get that nice smooth takeoff. My car revved up to 1,300 and the clutch started to grab and I moved forward a foot, all seemed well. Then, it happened. The revs dropped and I lost all throttle response. As I sat nervous and confused in the middle of the intersection, with what seemed like 20 cars behind me wondering why I was stopped, I frantically pushed the clutch in and put it back into gear and....nothing at this point the light was turning yellow I repeated this process two more times until finally I got throttle response back...... for a whole 10 feet then I lost it again. Luckily I was 50 feet away from my house during this occurrence and was able to make it back home. This would not be the first occurrence however. It has been an ongoing problem and has even occurred in 4th 5th and 6th gear rarely.

I have gathered data on the problem
1. It generally only occurs from a COMPLETE stop going into 1st or 2nd but has happened in other gears such as 4th 5th and 6th rarely
2. Instead of completely stopping if I can keep the car rolling enough so that it is not necessary to use the gas (to much) to keep the revs up and to keep the car from stalling the issue will not occur
3. After letting my car sit over night (at least 7 hours and usually in the garage which is generally cooler, I have a theory that heat may have something to do with it but that is unconfirmed) and starting it up and driving to work from my experience the issue will not occur the first 2-3 times after putting it into first and coming to a complete stop.
4. The longer I sit at a stop, the more likely the problem is to occur when I try to move from first.
I'm sure there is more I'm missing but these are the important ones

Things I have ruled or are unlikely to be the cause of the issue (So don't recommend these things unless you have a solid theory to back up your reasoning)
1. Spark Plugs/Coil Packs/Fuel Pump - The car Idles fine, drives fine besides the feeling that the car isn't making full power, there is not bogging or shaking or jumping of the revs.
2. MAF sensor - I mean, it could be this but i tried driving with it unplugged and the issue still occured so maybe it is the issue but I find it unlikely.
3. Any sensors that throw CEL's - Why? you may ask. Because there is no check engine light. Yes thats right zero. You may be thinking "Well you said you cleared the codes every time it came on". This is true, HOWEVER every time the CEL came on I ALWAYS checked to see what the code was and it was ALWAYS a P0333 which I eventually fixed.
4. Throttle Body - This is for the people who actually read everything I've written thus far and not for the people who I know are going to only read the title and immediately go to the comments and say "It's the Electronic TB duh". Why Have I ruled the Electronic TB out? Because as I said previously there is no CEL. The one benefit of having everything electronic is that anytime something goes wrong a CEL will pop up, especially for the throttle body. There are like 20 codes for the throttle body and I'm not getting any of them.
5. Limp mode - To my knowledge limp mode allows the car to keep moving not completely shut off all throttle response. If it were limp mode I'm assuming I'd be able to keep moving just at a very slow pace. In my case I can't move at all.

Moving on to things it could be
1. Throttle Body - Now before any of you comment saying "I thought you just said it wasn't the throttle body" Yea I did, but guess what, sometimes its the things you most least expect it to be. And I mean it seems reasonable, no throttle = bad TB. But as said previously no CEL Which makes it seem unlikely.
2. Vacuum leak - Seems reasonable, but again I'm not getting any codes.
3. Blown fuse?
4. Fried ecu?
5. Brake pedal sensor - The reason for this one is, I used to own a 2.0t and for anyone who has tried brakeboosting in a 2.0t knows, if you press the brake while on the gas the fuel will completely cut off. If you want to brake boost you have to let off the throttle and then push the brake pedal in slightly then push the throttle down again. So I'm not sure if the brake sensor is faulty causing the throttle to shut off, but then why is the issue concentrated to first gear? Just a theory.

Note, when it happens in other gears such as 4th 5th and 6th the issue happens while I AM ALREADY IN GEAR. Not when changing gears

I do want to mention that I did have the top half of the engine taken apart to have the timing chain inspected. And I forgot to get a new intake manifold gasket. I didn't know if a leak from that could be the issue, seems unlikely however as I'm not getting a code.

Also, I originally thought it was the P0333 code causing the issue since I just kept clearing the code instead of actually fixing it. So I replaced the knock sensor once the issue started but it didn't help.

Another note, I installed a pair of sequential Spec d tailights the day before the issue started happening. I want to note I originally thought the lights were broken so I unplugged the resistors in the lights.I don't know if doing so could have messed my ecu up. I think its unlikely as the resistors are there so that the led's don't go out.

Also I didn't know if my repeated clearing of the knock sensor code could have messed something up.

I have plugged in my obdII sensor and all the throttle values seemed fine when driving, when the issue happened it would say I wasn't pushing the throttle in as I expected. My mpg estimate was terrible however.

I apologize for the long explanation but I wanted to make sure I included all the details instead of just saying, "I don't have throttle in first gear. help".

Little side note: I'm in college right now and I don't have my car for obvious reasons, so any theories given I won't be able to test until November when I get back for break, but any help is welcome, Thanks.
 

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Discussion Starter #3
You can get a OBDII data monitor and watch your accelerator pedal values and the throttle position sensor values to see if they react as they should.

Limp mode generally limits rpm to 1300.
I watched my throttle position but not my pedal position as well, I assumed that throttle position = pedal position but if not that is something I will definitely keep in mind. And I don't think it is limp mode as to my knowledge limp mode allows you to keep moving but at a slower pace, in my case I cant move at all. In any case thank you very much for the advice.
 

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I wouldn’t rule out the throttle pedal itself either. Not sure if it throws a code or not, but it’s nothing more than a potentiometer, and if it’s beginning to fail, or developing a dead spot, it might behave this way.

A resistance sweep across the pedal travel might reveal it.
 

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Discussion Starter #9
I wouldn’t rule out the throttle pedal itself either. Not sure if it throws a code or not, but it’s nothing more than a potentiometer, and if it’s beginning to fail, or developing a dead spot, it might behave this way.

A resistance sweep across the pedal travel might reveal it.
I have a decent knowledge of cars but I'm unfamiliar with what a resistance sweep across the pedal travel is, would you mind explaining.
 

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I remember this happening to me when my car was maybe 2 months old back in 2010. It happened twice then went away, never to happen again in the last 8 years.

The thing that strikes me is, like you experienced, once the clutch is out, the throttle doesn't respond, but more importantly, the engine idle doesn't even kick in at the right spot - it would stall out if you left the clutch out instead of just coasting around 1000RPM like it does when you ride the idle.

I'm positive the throttle body was being commanded by the ECU to be more closed than it should be and 100% completely ignoring the throttle when the clutch pedal sensor wasn't engaged. It pretty much acts like the car was supposed to be shut off, not running, even though ignition and fuel are still fine.

Since it's never come back, I tend to believe it's an ECU calibration bug. Between Hyundai, SFR and BTR, my ECU has been reflashed a bunch of times, so maybe it's been weeded out. I've had zero pedal/TB sensor issues since, so I can't imagine it's a messed up potentiometer.
 

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I have a decent knowledge of cars but I'm unfamiliar with what a resistance sweep across the pedal travel is, would you mind explaining.
the pedal has 2 potentiometers, one increases in resistance, and the other decreases, when the pedal is pressed.
This way is can more accurately know it's position.

It's the same way the TPS in EFI cars work
It's the same in DBW throttlebodies. It's just that it has a motor driving the butterfly plate, instead of a throttle cable.
 

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I have a decent knowledge of cars but I'm unfamiliar with what a resistance sweep across the pedal travel is, would you mind explaining.

When you depress the pedal, the signal being sent to the ECU is going to have rising values based on how far the pedal is depressed. That’s the only way ECU can “see” where the pedal is and match the throttle body position accordingly. If a dead spot has developed, or is developing, somewhere within the travel of the pedal, the only way to see it is to trace the values that the ECU sees. Probably not the most likely scenario, but still possible.
 

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Discussion Starter #13
I remember this happening to me when my car was maybe 2 months old back in 2010. It happened twice then went away, never to happen again in the last 8 years.

The thing that strikes me is, like you experienced, once the clutch is out, the throttle doesn't respond, but more importantly, the engine idle doesn't even kick in at the right spot - it would stall out if you left the clutch out instead of just coasting around 1000RPM like it does when you ride the idle.

I'm positive the throttle body was being commanded by the ECU to be more closed than it should be and 100% completely ignoring the throttle when the clutch pedal sensor wasn't engaged. It pretty much acts like the car was supposed to be shut off, not running, even though ignition and fuel are still fine.

Since it's never come back, I tend to believe it's an ECU calibration bug. Between Hyundai, SFR and BTR, my ECU has been reflashed a bunch of times, so maybe it's been weeded out. I've had zero pedal/TB sensor issues since, so I can't imagine it's a messed up potentiometer.
Finally someone else who has had the same experience as myself. I just wish my issue would go away like yours did. I was also thinking its ecu related as if it was throttle body related it would throw a code. I happen to live in West Chester pa so when I go back I'll talk to jay and see if he is able to reflash my ecu on the stock data. Thanks for the input
 

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Discussion Starter #14
the pedal has 2 potentiometers, one increases in resistance, and the other decreases, when the pedal is pressed.
This way is can more accurately know it's position.

It's the same way the TPS in EFI cars work
It's the same in DBW throttlebodies. It's just that it has a motor driving the butterfly plate, instead of a throttle cable.
When you depress the pedal, the signal being sent to the ECU is going to have rising values based on how far the pedal is depressed. That’s the only way ECU can “see” where the pedal is and match the throttle body position accordingly. If a dead spot has developed, or is developing, somewhere within the travel of the pedal, the only way to see it is to trace the values that the ECU sees. Probably not the most likely scenario, but still possible.
Much appreciated
 

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Solid positive steps

Ok,

Im' going to zero in on what I've read,..and appropriate things you should DO, which are advantageous for the car even if they dont fix your issue.

You said 109 K,..wow. NA Genesis 3.8 means filthy valves. Lower overall whp, and yes can result in very poor low rpm performance.

With this in mind, pull your IM and,....get an new set of gaskets,..oem. Once again, possible compromised vacuum leaks always result in poor low rpm performance. Take a good look at your valves. I bet they are horrible. It takes a kinetic scrub/blast to correctly address this.

I'm not going to lecture you on the TB,...but being a MAF I would suggest you heavy clean that out as well. But be careful with the cleaners and the sensor.

Do the above
 

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Discussion Starter #19
Ok,

Im' going to zero in on what I've read,..and appropriate things you should DO, which are advantageous for the car even if they dont fix your issue.

You said 109 K,..wow. NA Genesis 3.8 means filthy valves. Lower overall whp, and yes can result in very poor low rpm performance.

With this in mind, pull your IM and,....get an new set of gaskets,..oem. Once again, possible compromised vacuum leaks always result in poor low rpm performance. Take a good look at your valves. I bet they are horrible. It takes a kinetic scrub/blast to correctly address this.

I'm not going to lecture you on the TB,...but being a MAF I would suggest you heavy clean that out as well. But be careful with the cleaners and the sensor.

Do the above
Thanks for the advice, yea the guy who had the car before me did not maintain it well. I know the 3.8's have heavy carbon build up especially the bk2 3.8's being that they are direct injected. A valve cleaning and new gaskets are definitely something I will do once I get back.
 
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