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Code P0171, hesitates and has a rough idle?

Tiny
MAZDA2017
  • MEMBER
  • 2017 MAZDA 3
  • 2.0L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 72,085 MILES
I can feel it shake and vibrate while I drive. I changed spark plugs and MAF did not really help but the code on the OBD changed to suggest p0171 reinstall air duct intake.
Tuesday, August 30th, 2022 AT 9:29 AM

15 Replies

Tiny
KEN L
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Yep, it sounds like you have a cylinder misfire which will cause the P0171 code. Let's remove the spark plugs and do a compression test. Remove all spark plugs and this guide will should you how:

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

Please run down this guide and report back.

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Tuesday, August 30th, 2022 AT 6:10 PM
Tiny
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Thanks, I will try this out.
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Tuesday, August 30th, 2022 AT 6:30 PM
Tiny
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But would a bad coil pack cause the system to run too lean? That is what the check engine code is saying for P0171.
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Tuesday, August 30th, 2022 AT 8:49 PM
Tiny
KEN L
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Yes, it is for a lean system which a cylinder misfire will cause, 14-1 14 parts air to one part fuel, so 14 parts of air enter the system. Lean
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Wednesday, August 31st, 2022 AT 12:06 PM
Tiny
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I changed the coils it definitely drives better, but the check engine came back on after a drive and starting it up for a second time.
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Sunday, September 4th, 2022 AT 10:31 AM
Tiny
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Still saying engine running too lean but drives good. I don't understand why when I fill up the gas tank the range usually says around 500. Now the system running lean the range is around 380.
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Sunday, September 4th, 2022 AT 7:23 PM
Tiny
KEN L
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After the repair did you clear the codes? And with the problem fixed you must drive a few tanks out so the computer can relearn the range estimate.
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Monday, September 5th, 2022 AT 9:51 AM
Tiny
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I took the negative terminal off before changing the coils which would have cleared it. After I drove it and started it, it came back on and alright I guess I will have to wait a few weeks for that though.
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Monday, September 5th, 2022 AT 11:17 AM
Tiny
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Under the hood even if I drive for 10 minutes it gets really hot, the coolant level keeps going to L. I filled it up the other day but back at L, I don't think its leaking.
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Monday, September 5th, 2022 AT 11:26 AM
Tiny
MAZDA2017
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  • 2017 MAZDA 3
  • 2.0L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 72,388 MILES
Check engine code says p0171 and suggests reinstalling air duct. I'm getting poor fuel economy, RPMs are accelerating and decelerating poorly, and on short drives my car seems to get really hot quick. Do you think that could be the coolant sensor with code p0171?
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Tuesday, September 6th, 2022 AT 6:00 PM (Merged)
Tiny
KEN L
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P0171 System Too Lean to the overheating problem will not affect this. Have you tried to replace the thermostat?

Here is a generic guide so you can see what you are in for with instructions for your car in the images below:

https://www.2carpros.com/articles/replace-thermostat

And this can help as well:

https://www.2carpros.com/articles/engine-overheating-or-running-hot

Check out the diagrams (below). Please let us know what happens.
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Tuesday, September 6th, 2022 AT 6:05 PM
Tiny
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I have not changed my thermostat I was stuck between changing the thermostat or coolant sensor. So, do you think the symptoms I am having would be caused more from a faulty thermostat and not a coolant temperature sensor?
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Tuesday, September 6th, 2022 AT 6:12 PM
Tiny
KEN L
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It could be either, which is why I wanted to do the thermostat test to see if it has failed.
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Wednesday, September 7th, 2022 AT 12:27 PM
Tiny
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I did not see what to do with a thermostat test. Do I have to flush out the coolant to replace it or can I just replace it? I know some will shoot out.
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Wednesday, September 7th, 2022 AT 12:47 PM
Tiny
KEN L
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When you remove the thermostat, drop it into a pan of boiling water, it should open quickly. Yes, before you begin drain the coolant out of the system to minimize spillage.
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Thursday, September 8th, 2022 AT 9:32 AM

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