Santa fe 07 misfire

Hello. This post will contain bad english.

I have Santa fe 07 with misfire codes on cylinder 2, 4 and random.

I have done compression test and it pass with the specs.

After engine goes to closed loop and after about 1 minute on idle the engine starts giving misfire the codes says cyl 2 and 4 and random. When i listen to the injectors only 4 stops "ticking" when listening on it (This engine will shut of the injector after 46 seconds after failure by the ecu) if i am correct these injectors are ground sided. the rest of the injectors are not being shut of by the ecu. I let my Hyundai garage trubleshoot and they said "The injector looses ground and you need new ECU and that costs 2000$". After i said that the injector is ground sided switch and it will shut of after 46 seconds they said "What the hell are you talking about????". I sent the car to another garage for a smoke leak test they found no leaks (This garage made a mistake to diagnose a bad fuel injector pump on a disel car before after they only installed the belt wrong). They are the only garage near me with smoke machine but i dont have to much trust in them.. i decided to pull of the plenum to do a compression on all cylinders (The previous was only on the 2-4-6). What i found is somewhat strange i think. Oil everywhere and the bolts on the intake manifold Y V6 Engine. where all very loose. In my head this can be the cause of my misfires on idle and i will change all the gaskets. please look at the images and tell me if you think if it was leaking or not. Seems like the oil is caused by that i can blow air trough the PCV valve from both sides (I hope this is that problem). Forgot to take images when i removed the intake Y but both sides looked like the images i attached

Hi torsson,

Yes, you are right. Those lossen intake manifold bolts can cause misfire.

What i can not still explain is the pcm shutting off all injectors.

Can you confirm again?
1. Engine stars
2. Engine jumps to closed loop
3. After 46 seconds, pcm shuts off 4 of the 6 injectors
4. Engine stall

Is it possible that the ECUs strategy is shutting the injectors down to protect the cat from getting unburned fuel and getting damaged?

I’m not familiar with that vehicle however I’ve seen it on other makes. It sounds like that is what is happening here and direction would move away from ECU/injectors and move toward ignition or mechanical misfire.

I would go toward a leak down test.

How is a vacuum gauge reading?? Bouncy? Solid? Also what are trims like? Is this variable valve timing?

Yes you are correct about the ecu does this to save the cat. And becuase it is ground sided injector's of course it will "loose" ground from the ecu. Why the authorized hyundai dealer did not read the repair manual i dont know.

Forgot to meantion in my post of what STFT and LTFT looks like at idle. Almost identical every time i have checked.
Bank 1
ST: 3.1%
LT: 13.8

Bank 2 (The bank with cyl 2 and 4)
ST: -2.3
LT: -14.1

And when i give it some throttle everyting goes to 0.0 on both banks

Cheryl: It was a garage that did the smoke test and only said "No leaks where found".

I will do a leakdown test tomorrow and see what i can find.

i took of the valve covers cause there was some small oil leaks but the differences of the oil on Bank1 and 2 is suspicious in my head.

What did your compression testing show once you got the intake off to test all six cylinders?

i took of the valve covers cause there was some small oil leaks but the differences of the oil on Bank1 and 2 is suspicious in my head.

Are you referring to the difference in darkness between the rear and front bank? That's pretty typical, in my experience. It's down to the arrangement of the PCV system - one valve cover is connected to the fresh air side, the other to vacuum. One side always ends up looking cleaner.

John Curtis: I did a leakdown test today.

Cylinder 1: 45% Air coming out of exaust
Cylinder 2: 15%
Cylinder 3: 15%
Cylinder 4: 15%
Cylinder 5: 45% Air coming out of exaust
Cylinder 6: 15%

The ones with 15% i could not find where it went and they where not EXACLY 15% but somewhere between 12-17%

The spark plugs on 1-3-5 looked red'ish and 2-4-6 looked just normal.

guafa: No sorry for my bad english the ecu ONLY shuts of injector on cylinder 2. But gives me Misfire code on 2, 4 and random. Did a leakdown test with the results in post below

Hi guys, i'm sorry for this huge delay in feedback.

Is there any way we can confirm that pcm is trying to protect the cat?

I mean, 46 seconds could be the time O2 sensor reaches operation temperature and only then jump to closed loop.

I suppose then pcm needs some proccesing time to detect the super rich condition and then shut injectors off.

Can we confirm then by simply observe the loop condition?

To dircard this theory, i would also check O2 sensors activity.

What do you think guys?

Danner has a video on this.


But all the information you’ve posted would be evidence enough for me to sell my time tracking down a other potential causes for the misfire.

You’re idea of using 02 data is a good idea. If you can get the engine up to operating temperature you should be able to shut down the car and wait 5 seconds and turn it on to get the injector firing again it should be richer and should go leaner when the injector stops firing. You could scope injectors too.

Honestly the fact that the injectors are firing once the vehicle is restarted is key here. That is the indicator the ECM is sensing the misfire and shutting down the injector after so many misfire counts.

Another thought is that when running you might see a misfire counter while the injectors are firing but once shut down it may stop.

I think i have found out why Bank 2 is giving me these misfires and low compression. The cam has been having a good meal of metal