Engine misfire

Tiny
CA7922303
  • MEMBER
  • 2001 HYUNDAI SANTA FE
  • 2.7L
  • V6
  • 2WD
  • AUTOMATIC
  • 310,000 MILES
Have a miss, #4 injector plug pulled, no change, replaced injector, no change. Mass air flow sensor plug pulled, no change. Code reader shows mass air flow sensor at 0 volts, replaced mass air flow sensor, no change. MAF plug shows 12 volts at 1 pin, 0 at other 2 pins. Temperature coolant sensor shows fault code.
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Saturday, November 21st, 2020 AT 11:49 AM

28 Replies

Tiny
ASEMASTER6371
  • EXPERT
Good afternoon,

If you have a misfire on number 4, you need to do some testing.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Check for power to the injector. You should have 12 volts with the key on.

Check the compression as well. Low compression will cause this.

https://www.2carpros.com/articles/how-to-test-engine-compression

Do you have spark at the plug?

https://www.2carpros.com/articles/how-to-test-an-ignition-system

I attached a wiring diagram of the injectors for you as well.

https://www.2carpros.com/articles/how-to-check-wiring

Roy

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Saturday, November 21st, 2020 AT 12:48 PM
Tiny
CA7922303
  • MEMBER
12.2 and 3.8 volts #4 connector, good spark and compression on #4. Any thoughts about the MAF and coolant temperature sensors? Thanks for your help.
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Saturday, November 21st, 2020 AT 3:07 PM
Tiny
ASEMASTER6371
  • EXPERT
You should have battery voltage on one side and 0 on the other with it disconnected.

With the key on and the connector attached, you should have battery voltage on both sides.

No to the other sensors. If they were an issue, it would affect all cylinders.

Roy
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Saturday, November 21st, 2020 AT 3:11 PM
Tiny
CA7922303
  • MEMBER
Any ideas on why I'm getting 12.2 and 3.8 disconnected?
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Saturday, November 21st, 2020 AT 3:31 PM
Tiny
ASEMASTER6371
  • EXPERT
12.2 is good but the 3.8 is not.

What about the other check I suggested?

Roy
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Saturday, November 21st, 2020 AT 3:32 PM
Tiny
CA7922303
  • MEMBER
I'll have to get to it tomorrow. Dark now here. Thanks for your help.
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Saturday, November 21st, 2020 AT 4:13 PM
Tiny
ASEMASTER6371
  • EXPERT
You are welcome.

Keep me updated.

Always glad to help.

Roy
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Saturday, November 21st, 2020 AT 4:25 PM
Tiny
CA7922303
  • MEMBER
#2, #4, #6 injector connectors all read 12.2 and 3.8 with key on?
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Sunday, November 22nd, 2020 AT 7:36 AM
Tiny
ASEMASTER6371
  • EXPERT
Is that disconnected? Or is that with the injector connected?

Roy
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Sunday, November 22nd, 2020 AT 8:08 AM
Tiny
CA7922303
  • MEMBER
That's with all disconnected. I found an ECU fuse on the engine fuse block that was 12V on one leg and 0 on the other. Replaced it and now #4 is firing. Running better, but still not a great idle in drive. Tries to cut off. Could the other trouble codes be at fault? MAF and coolant temperature sensors?
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Sunday, November 22nd, 2020 AT 10:36 AM
Tiny
ASEMASTER6371
  • EXPERT
What other codes? There were no codes listed in your question.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Roy
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Sunday, November 22nd, 2020 AT 10:45 AM
Tiny
CA7922303
  • MEMBER
Mass air flow sensor shows 0 volts on a SnapOn engine analyzer, along with a coolant temperature sensor. I replaced the MAF sensor and still no change in idle with plugged in or unplugged.
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Sunday, November 22nd, 2020 AT 12:32 PM
Tiny
ASEMASTER6371
  • EXPERT
Please tell me the codes.

Did you check the compression and fuel pressure as I suggested?

Roy
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Sunday, November 22nd, 2020 AT 12:42 PM
Tiny
CA7922303
  • MEMBER
I went to a guy I know who has a speed shop to use his scanner, will have to get to a auto parts store to get scanned. Drove vehicle 500 miles last week. #6 cylinder now missing. No effect when I pulled injector wire or spark plug wire. Have spark though. All ECU fuses are 12 v on both legs. Gas mileage is of course way down. Any thoughts appreciated.
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Saturday, November 28th, 2020 AT 8:41 AM
Tiny
ASEMASTER6371
  • EXPERT
As I suggested, check the compression and let me know the results.

https://www.2carpros.com/articles/how-to-test-engine-compression

Roy
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Saturday, November 28th, 2020 AT 10:00 AM
Tiny
CA7922303
  • MEMBER
Compression on 2, 4, and 6 are all around 200.
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Saturday, November 28th, 2020 AT 10:26 AM
Tiny
ASEMASTER6371
  • EXPERT
Okay, put your voltmeter in the connector for the injector. Red lead to the power side of the injector and black to the other terminal. Tell me the volts with the key on.

Roy
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Saturday, November 28th, 2020 AT 10:32 AM
Tiny
CA7922303
  • MEMBER
0 volts at 2, 4, and 6.
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Saturday, November 28th, 2020 AT 6:13 PM
Tiny
CA7922303
  • MEMBER
Any thought about the 0 volts reading? Get 12 on 1 pin 3.8 on the other with ground lead on negative battery, but 0 on both injector pins, also reversed get 0.
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Sunday, November 29th, 2020 AT 9:05 AM
Tiny
ASEMASTER6371
  • EXPERT
Did it read 0.00 or did it read nothing at all?

Roy
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Sunday, November 29th, 2020 AT 12:56 PM

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