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A large group of members has been trying to troubleshoot this issue on my vehicle specific forums including several companies who design tunes along with other products and no one has been able to figure this out. We've got a good number of bright individuals in these forums so I figured I'd give it a shot.
Here are the details:
I have a 2011 Hyundai Genesis Coupe 2.0T although this issue has affected all model years (2010-2012). This car with factory injectors and any brand of aftermarket tunes has no problems. The tricky part is that many of these cars with aftermarket injectors (higher flow) have a hot start problem. I've personally experienced this with two different injector types (Deatschwerks and OEM EVO X) and two different tunes from different vendors. After gathering information from other members, it affects both canned tunes (flashed tunes made for a specific configuration, non user tunable), Haltech ECU replacements (end user tunable) and the CMD (end user tunable). Some members have never experienced this issue although many others have, sometimes with same injectors/tunes.
Here's the problem itself. The car will start without issue when cold. If the car has been fully warmed up (say you drive 30min and then park) attempting to start the car within 10-15min produces a no start. The car cranks but does not start. After the first attempt, if I count to ten, the car will start on the second attempt without issue. This happens far more often with my EVO X injectors than my DW's with the primary difference being that the EVO's have a higher flow rate.
From what I've researched a similar issue happens to EVO owners with aftermarket injectors (another brand altogether) and my co worker pulled aftermarket injectors from his Audi A3 for the same thing.
The Audi is the clue - they (and most likely your Genesis - a very nice little ride, BTW) are suffering heat soak (not the intake kind, though). Two things can (and do) happen: 1) you're getting a tiny "plug" forming @ the injector tip (pintle) or 2) the temps are raising the resistance, causing the injector to "fire" a few milliseconds later than the system "thinks" it is.
Either way, it's not starting (or running well if it does start) until it cools down. Your choice then is to return to the OEM unit or find some way to get cool air to/hot air away from the injectors. One old Audi trick we did was to override the electric fan so it would stay on. Don't know if that's something that can be programmed into an aftermarket ECU nowadays, though. Good luck!
The Audi is the clue - they (and most likely your Genesis - a very nice little ride, BTW) are suffering heat soak (not the intake kind, though). Two things can (and do) happen: 1) you're getting a tiny "plug" forming @ the injector tip (pintle) or 2) the temps are raising the resistance, causing the injector to "fire" a few milliseconds later than the system "thinks" it is.
Either way, it's not starting (or running well if it does start) until it cools down. Your choice then is to return to the OEM unit or find some way to get cool air to/hot air away from the injectors. One old Audi trick we did was to override the electric fan so it would stay on. Don't know if that's something that can be programmed into an aftermarket ECU nowadays, though. Good luck!
agreed, i tend to go with issue number two in this case.
The Audi is the clue - they (and most likely your Genesis - a very nice little ride, BTW) are suffering heat soak (not the intake kind, though). Two things can (and do) happen: 1) you're getting a tiny "plug" forming @ the injector tip (pintle) or 2) the temps are raising the resistance, causing the injector to "fire" a few milliseconds later than the system "thinks" it is.
Either way, it's not starting (or running well if it does start) until it cools down. Your choice then is to return to the OEM unit or find some way to get cool air to/hot air away from the injectors. One old Audi trick we did was to override the electric fan so it would stay on. Don't know if that's something that can be programmed into an aftermarket ECU nowadays, though. Good luck!
We've looked at both options on the forum and they are still under consideration. What would explain the car starting just fine ten seconds after? I can't imagine temperatures dropping by a wide margin unless the injected fuel is cooling the cylinder.
Another thing that we are looking at is that the ECU takes readings from the Engine Coolant Temperature and Intake Air Temperature sensors and adjusts various starting parameters. One member removed his ECT sensor from the block and left it exposed to ambient air which supposedly cured his starting issues. Just another thing to consider.
Last edited by iTsLiKeAnEgG; 08-02-2012 at 10:09 PM..
We've looked at both options on the forum and they are still under consideration. What would explain the car starting just fine ten seconds after? I can't imagine temperatures dropping by a wide margin unless the injected fuel is cooling the cylinder.
Another thing that we are looking at is that the ECU takes readings from the Engine Coolant Temperature and Intake Air Temperature sensors and adjusts various starting parameters. One member removed his ECT sensor from the block and left it exposed to ambient air which supposedly cured his starting issues. Just another thing to consider.
I wonder is you could try the following to see what happens: have some refrigerant in a can (freon perhaps?), start the motor, turn it off, rapidly spray the base of the coolant temperature sensor to cool it as fast as possible, and then start the motor once more.
I wonder is you could try the following to see what happens: have some refrigerant in a can (freon perhaps?), start the motor, turn it off, rapidly spray the base of the coolant temperature sensor to cool it as fast as possible, and then start the motor once more.
I should probably add the next twist. If I turn the car off and start again, it starts just fine. This seems to occur several minutes after shutting off. Maybe starting 5 minutes after turning off and ending 30 minutes later. Its a narrow but frustrating window.
I run into this in situations like going to the grocery store to grab breakfast before work or trying to start after filling gas.
In all seriousness tho, I haven't got time to read the other thread, but I wonder if it might be a fuel pressure problem.
You've upgraded the injectors, but have you done anything else to the system? Higher pressure fuel pump?
Perhaps some sort of fuel pressure accumulator to make sure the system stays pressurized after a warm switch off.
Older K-jet Audi models could be a nightmare to hot start if the accumulator failed. I know modern injection is a bit more sophisticated than that, but the principles are the same.
Lets face it, if a car doesn't start, it's either fuel or spark.
Perhaps the injectors just aren't putting enough fuel in when compared to stock.
Can it be remapped to allow different fuellings at startup to experiment ?
We've looked at both options on the forum and they are still under consideration. What would explain the car starting just fine ten seconds after? I can't imagine temperatures dropping by a wide margin unless the injected fuel is cooling the cylinder.
That's exactly what happens.
Quote:
Originally Posted by iTsLiKeAnEgG
Another thing that we are looking at is that the ECU takes readings from the Engine Coolant Temperature and Intake Air Temperature sensors and adjusts various starting parameters. One member removed his ECT sensor from the block and left it exposed to ambient air which supposedly cured his starting issues. Just another thing to consider.
Still sounds like heat soak.
Quote:
Originally Posted by iTsLiKeAnEgG
I should probably add the next twist. If I turn the car off and start again, it starts just fine. This seems to occur several minutes after shutting off. Maybe starting 5 minutes after turning off and ending 30 minutes later. Its a narrow but frustrating window
Bingo. That's as perfect a description as possible. "heat soak" occurs after the engine and it's ancillary cooling systems stop, allowing the high heat from the CC (head/pistons/valves/etc) to radiate outward (remember HS science classes), subjecting other underhood components to some serious temps. OEM designs take this into account, but you're changing some of the parameters w/o adapting all.
That's why our old Audi trick worked - a simple reset of the fan controller caused it to run at shutdown and keep running (btw - heat soak is also why electric fans can come on, seemingly by themselves, some minutes after shutdown) for several minutes.
Ray, that's an excellent idea, but try it w/a can of compressed air (sold to clean PCs & stuff). Run the car, shut down, then (holding the can upside down) "freeze" one component at a time & try to start. That'll isolate the problem nicely, and allow you to design a solution (insulation, moving a component, opening a box, etc.)
How consistent is the behavior? To me it sounds like the result of an interlock. Do you or your fellow owners have the ability to watch live fuel system and ignition data? The fact that there doesn't seem to be an intermediary condition (ie running rough) leads me to believe that the computer is waiting for either a temperature variable to fall below a certain point or for injectors to cool down and have the resistances fall back into tolerance.
How consistent is the behavior? To me it sounds like the result of an interlock. Do you or your fellow owners have the ability to watch live fuel system and ignition data? The fact that there doesn't seem to be an intermediary condition (ie running rough) leads me to believe that the computer is waiting for either a temperature variable to fall below a certain point or for injectors to cool down and have the resistances fall back into tolerance.
The fuel pump primes the rail as soon as the key is switched to acc. You can hear it whirring in the background. We've had members test to see if the relay and pump are getting power under these conditions and it seems to be doing its job under all circumstances. Duration seems to be the same as well. Spark has been tested and is working fine.
In terms of frequency of occurance, when I had my DW 550's (they actually flow close to 680cc as the Genesis uses a higher pressure fuel system) it would happen every once in a while. Still often but not on every restart. With my current EVO X injectors it's happening 100% of the time. The EVO X injectors are rated at a higher flow rate than the DW's at the same fuel pressure. My thinking is that this is happening to both injector type's all the time but the EVO X injectors either have a wider occurance window or the window is offset.
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