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Misfire or bad performance

Tiny
JACOBANDNICKOLAS
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Hi,

Okay, this doesn't add up. It indicates a lean condition, but watching the STFT, they appear normal. In a perfect world, you want them at 0%. However, between -10% and +10% is considered normal.

When the scan tool was providing live data, was the engine running rough?

Joe
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Saturday, April 16th, 2022 AT 4:44 PM
Tiny
KAYVA
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Hello Joe,

The engine was not running rough. What if it ranges -17 to 12 a few times when I’m driving the car?

Thank you,
Kayvan
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Saturday, April 16th, 2022 AT 5:14 PM
Tiny
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Hi,

That would be normal under a load. I need the STFT when it is running rough. That will let me know if the cause is related to a fuel ratio issue.

I realize that may not be easy to do. LOL If possible, try to get it and let me know what you find.

Take care,

Joe
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Saturday, April 16th, 2022 AT 6:43 PM
Tiny
KAYVA
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Hello Joe,

I hope all is well. I recently had my check engine light come on, and checked the code it was P0301 Cylinder 1 misfire. As I stated earlier the sparks have been changed recently. I will take it to my mechanic tomorrow or so and have them check the fuel pressure.

Sincerely,
Kayvan T
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Friday, May 13th, 2022 AT 11:05 PM
Tiny
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Hi,

Thank you for the update. I'm sorry to hear you are still dealing with this issue. If you have a chance, let me know what you find out from the shop. I'm interested in knowing.

Take care,

Joe
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Friday, May 13th, 2022 AT 11:11 PM
Tiny
KAYVA
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Hi Joe,

It’s been a long time since our last email, hope everything is fine. I have an update for you, in short, the motor needs to be replaced, it’s wearing out. I inserted a picture of the comments from the mechanic.

Sincerely,
Kayvan T
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Saturday, December 17th, 2022 AT 2:36 PM
Tiny
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Hi,

Thank you for the update. By any chance, did he provide the compression readings? Also, the P0301 is likely because oil got into the spark plug tube. If cylinder 3 compression is low, I would have expected a P0303 as well.

If you do have the compression readings, let me know.

It's nice to hear from you. I hope you have a great Christmas and holiday season.

Take care,

Joe
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Saturday, December 17th, 2022 AT 10:42 PM
Tiny
KAYVA
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Yes, he told me cylinder 3 is 30 % lower, and the others are a bit off as well. And yes, there is oil getting onto the spark plugs. I hope you have a good holiday as well.

Sincerely,
Kayvan Taherpour
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Sunday, December 18th, 2022 AT 12:27 AM
Tiny
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Thanks for the update. I wish you a great holiday and if you have a chance, let me know how things turn out for you.

Take care,

Joe
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Sunday, December 18th, 2022 AT 2:45 PM
Tiny
KAYVA
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You as well, and I also do see a P0421 “Warm Up Catalyst Efficiency Below Threshold Bank1”, and a P300 multiple cylinder misfire. I did have a rough cold start today morning. Again, thank you for the time, and hope you enjoy your holiday and new year.

Sincerely,
Kayvan Taherpour
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Saturday, December 24th, 2022 AT 10:58 AM
Tiny
JACOBANDNICKOLAS
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Hi,

The P0421 shouldn't cause the misfire unless the converter is clogged. However, a failing heated oxygen sensor can set the P0421. The PCM detects that the HO2S output fluctuates from lean to rich in a short amount of time at specified times continuously after recovery from fuel cut control. So, this can be an upstream heated oxygen sensor.

At this point, we need a live data scan tool so we can check the oxygen sensors' voltage readings. Here is a link that explains how to do it.

https://www.2carpros.com/articles/how-to-test-an-oxygen-sensor-02-sensor

The P0300 is not limited to any one cylinder, but instead random cylinders and misfires. Which potentially moves us away from cylinder 3. What was the outside temp this morning when you started the vehicle? Also, is there any way the individual that checked compression can provide the readings?

Considering the symptoms, I suspect (theory) the oxygen sensor may be the cause of all issues. Check it out and let me know what you find.

Take care, Merry Christmas, and I look forward to hearing from you.

Keep Warm. It's -6 here and a ton of wind. UGH!!!

Joe
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Saturday, December 24th, 2022 AT 4:30 PM
Tiny
KAYVA
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It was 7 degrees this morning when I started the car, and the cold start was very bad - the car was shaking and struggling that I felt to turn it off, and few dashboard lights were coming on such as the flashing check-engine light. After half a minute or so I tried it again, and that time it started okay. The dashboard lights were clear. However, a few hours later the check engine light came on prompting me to check with scanner.

I will have them take a look at the oxygen sensor.

-6 degrees is very cold, and with wind.

Thank you for the input, it helps. Merry Christmas.

Sincerely,
Kayvan Taherpour
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Saturday, December 24th, 2022 AT 5:19 PM

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