Engine Start-Misfire on Cold Weather Start

[Stoofpilot]

I have. 2010 4.6. Car left outside last night. On start this morning the car started on what sounded like only four cylinders. Also produced a foul smell. Shut the car down and restarted it and it started fine but the engine check light is on and remains on even though the engine is at normal temp and running fine.

I think I had read about this same issue a year ago. Any thoughts!

Thanks

 

[Cut-Throat]

I have. 2010 4.6. Car left outside last night. On start this morning the car started on what sounded like only four cylinders. Also produced a foul smell. Shut the car down and restarted it and it started fine but the engine check light is on and remains on even though the engine is at normal temp and running fine.

I think I had read about this same issue a year ago. Any thoughts!

Thanks

I've had something similar happen to me twice. In both instances I started the car in cold weather and drove it out of the garage about 30 feet and shut it off, before the car fully warmed up. The next day I started the car and the car was running very rough with check engine light on. After the car warmed up the C.E.L. remained on. Took it to the dealer and they told me the car had 'logged some misfires' ......Duh...

In both instances, I did not let the car warm up fully in cold weather and this produced the misfires......Did you let the car warm up fully before the misfire event?

 

[Stoofpilot]

No, when it started to misfire, I shut it down the restarted it and let it warm up. No problems on second start. I wonder if it's a throttle body issue. Does anyone know if there are TSBs on this?

 

[Cut-Throat]

No, when it started to misfire, I shut it down the restarted it and let it warm up. No problems on second start. I wonder if it's a throttle body issue. Does anyone know if there are TSBs on this?

What I am asking, is what happened the day before the misfire????

 

[Stoofpilot]

The car sat outside unused for two days. Yesterday, my son in law moved the car in to his driveway. Was on probably 1 minute. Did not get warmed up. Just moved. This morning I started it to go out shopping.

 

[Cut-Throat]

The car sat outside unused for two days. Yesterday, my son in law moved the car in to his driveway. Was on probably 1 minute. Did not get warmed up. Just moved. This morning I started it to go out shopping.

Yes, that is EXACTLY what I am talking about. When the car was moved to the driveway and was only used 1 minute, that is what triggered your misfires this morning.......This is the same thing I experienced.

Don't worry about it, just take the car to the dealer and have them reset the Check Engine Light.....Then when it is cold make sure the car is fully warmed up and don't do the 1 minute thing....

 

[BacktoHyundaibychoice]

Nice job, C-T!
That's exactly the cause, and it was compounded by turning it off at the misfire.
Only thing I'd add is that I THINK you don't need to "fully" warm before shutting off, just get past the fast idle and the next start should be fine.
Happy holidays!

 

[Stoofpilot]

Guys, this is all good yet with 43k car, I should not have any misfires. I never had this problem with my old LS 430 or my SL 500. Is this a ECU issue or a fuel injection issue? Ant thoughts to the cause?

Thanks

 

[Cut-Throat]

Guys, this is all good yet with 43k car, I should not have any misfires. I never had this problem with my old LS 430 or my SL 500. Is this a ECU issue or a fuel injection issue? Ant thoughts to the cause?

Thanks

Well, I pulled both my $43K Genesis and my $55K Lexus GS350 out of the garage to sweep the floor one cold November Morning and the following day the EXACT same Symptoms Happened on Both Cars!

But, my older 1999 Lexus GS300 never had this problem......However I never ever got the Gas Mileage that I got with these newer cars. So, I suspect that there is nothing wrong with the cars, but they expect that when you turn them on, they are going to be warmed up properly.

Being an Engineer myself, I know that every advance in technology carries certain downsides and I think you just ran into a very, very , very small one.

Just warm it up a bit! - No big deal!

 

[Stoofpilot]

Re: Engine Start-Misfire on Cold Weather Start-TSB for This

This afternoon I took my wife's Genesis to my local Hyundai dealer and problem. The light had actually done out today. They were able to still see the codes and found out that there was is a TSB for Cold Start problems.

They did a reflash of the CPU and according to them, I am good to go.

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[Cut-Throat]

Re: Engine Start-Misfire on Cold Weather Start-TSB for This

This afternoon I took my wife's Genesis to my local Hyundai dealer and problem. The light had actually done out today. They were able to still see the codes and found out that there was is a TSB for Cold Start problems.

They did a reflash of the CPU and according to them, I am good to go.

Can you tell us the TSB number, so that others may refer to it when talking to the dealer?

I have been to my dealer twice for this problem and they never told me about a TSB. I would like the TSB number to 'convince' the dealer.

 

[BacktoHyundaibychoice]

Re: Engine Start-Misfire on Cold Weather Start-TSB for This

This afternoon I took my wife's Genesis to my local Hyundai dealer and problem. The light had actually done out today. They were able to still see the codes and found out that there was is a TSB for Cold Start problems.

They did a reflash of the CPU and according to them, I am good to go.

Very interesting. I'll see if I can find it at HMA Service tomorrow.
Though I'd call it a Cold Shutdown problem instead.

 

[Cut-Throat]

Re: Engine Start-Misfire on Cold Weather Start-TSB for This

Very interesting. I'll see if I can find it at HMA Service tomorrow.
Though I'd call it a Cold Shutdown problem instead.

Thank You!

 

[Stoofpilot]

Here is what it says on the service document."connected to GDS and retrieved P0300 and P0303 fault traced to and found ECM needed upgrade per TNN 10-FL-015. Retest ok.

That's all it said. Hope this helps.

 

[BacktoHyundaibychoice]

Re: Engine Start-Misfire on Cold Weather Start-TSB for This

Thank You!

Found it, this was the only description. Not very helpful:

DESCRIPTION:
This bulletin provides information related to the ECM software update of some
2009~2010MY GENESIS SEDAN (BH) 4.6L vehicles which experience a malfunction
indicator lamp illuminated with the ECM (Electronic Control Module) system-related
DTC P0300 or P0456:
• P0300 Random/Multiple Cylinder Misfire Detected
• P0456: Evaporative Emission System-Leak detected (very small leak)
APPLICABLE VEHICLES:
• 2009~2010MY GENESIS SEDAN (BH) 4.6L

The rest is just the "how-to" for the techs.

 

[Cut-Throat]

Re: Engine Start-Misfire on Cold Weather Start-TSB for This

Found it, this was the only description. Not very helpful:

DESCRIPTION:
This bulletin provides information related to the ECM software update of some
2009~2010MY GENESIS SEDAN (BH) 4.6L vehicles which experience a malfunction
indicator lamp illuminated with the ECM (Electronic Control Module) system-related
DTC P0300 or P0456:
• P0300 Random/Multiple Cylinder Misfire Detected
• P0456: Evaporative Emission System-Leak detected (very small leak)
APPLICABLE VEHICLES:
• 2009~2010MY GENESIS SEDAN (BH) 4.6L

The rest is just the "how-to" for the techs.

Thank You ! - No wonder I never heard of this, as I have a 2011 Genesis...I would also believe that this would not fix the short start in cold weather problem.

 

[scottdk]

Thanks I'll have them perform this update (maybe they already did?) at my next oil change in the spring. They might have done this, but I can't remember.

 

[Garyneil]

Wow! I just bought a low mileage 2010 4.6 Tau Genesis sedan. Beautiful car, but I'm having intermittent cylinder misfires on cold starts. Sometimes 2-3 days will go by without incident, and then wham. Latest event; cold start generated misfire, rough idle and check engine light. Drove car to dealer and analysis showed cylinder one misfire. They said they had to keep the car overnight and experience a repeat event before fixing. They switched the spark plug from cylinder one to cylinder two, and vice versa. They switched the plug wire from one to three. Drive car for two days and problem reoccurred in cylinder two. Replaced spark plugs hoping that was the cure. Two days later problem reoccurred with rough start and idle and check engine light flashing. Took to dealer and they said the fault code did not register. Found out the car had the ECM flashed sometime in the past for re-calibration due to a TSB out from manufacturer. Apparently is didn't work! Also found out the computer flash event was what they call a "silent calibration" meaning they don't log it into official records for the car. Someone is hiding something! This is happening to too many people and its not getting fixed!!