Code P0171?

Tiny
HSNDSOME
  • MEMBER
  • 2009 KIA RIO
  • 1.4L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 205,000 MILES
There is a long cranking time before starting, code p0171 system too lean bank 1. I checked and found no vacuum leaks. I clean mostly all the sensors and same issue. Any help will be appreciated. Thanks.
Thursday, November 14th, 2024 AT 9:46 AM

13 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,921 POSTS
Hi,

If there are no vacuum leaks, the next thing to check is the fuel pressure. If the pump is weak, it can cause a lean fuel mixture.

Here is a link that explains how in general to check pressure:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

If you look below, I attached the manufactures directions for testing specific to this vehicle. The directions include the pressure specifications.

You will need a fuel pressure gauge. Often times, a parts store will lend one to you if needed.

Let me know if this helps, if you have other questions, and what you find.

Take care,

joe

See pics below.

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Thursday, November 14th, 2024 AT 8:11 PM
Tiny
HSNDSOME
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Thanks will check and keep you posted.
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Friday, November 15th, 2024 AT 12:29 AM
Tiny
HSNDSOME
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Good day, the fuel pressure was low, I replaced the fuel pump and no more P0171 code after driving for a few days now.
One other thing I found since a while back gas consumption is kind of high. I service injectors, new spark plugs, throttle and idle air valve service. And other ideas.
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Monday, November 18th, 2024 AT 4:09 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,921 POSTS
Hi,

There is a chance the excessive fuel usage was caused by the computer trying to compensate for a lean mixture. You may find it increases now that it is running properly.

If it doesn't, make sure the coolant temperature sensor is sending the proper signal to the PCM. If it is off, it can affect the air/fuel mixture. Also, make sure the air filter is clean, and no brakes are dragging.

Let me know how things work out for you or if you have other questions.

Take care,

joe
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Monday, November 18th, 2024 AT 7:12 PM
Tiny
HSNDSOME
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Thanks will keep you updated.
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Tuesday, November 19th, 2024 AT 5:35 PM
Tiny
HSNDSOME
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  • 14 POSTS
Good day, after about a week of driving the car, gas mileage is not too good and still a few cranks before starting. I did a scan and code P0327 is showing. I inspected the wire harness, and it looks good. Could you send me testing procedure for the knock sensor?
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Friday, November 29th, 2024 AT 1:02 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,921 POSTS
Hi,

I attached the directions from my manual below. Note that it really isn't a test procedure of the present sensor. Instead, they indicated that you should replace it with a known good one to check. Ugh! Take a look and let me know your thoughts.

If you have a live data scan tool, you should be able to check the sensor parameters when the engine is at operating temperature.

Are you hearing any valve ping or knocking?

Take care,

Joe

See pic below.
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Friday, November 29th, 2024 AT 6:40 PM
Tiny
HSNDSOME
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  • 14 POSTS
I'm hearing valve pinging, I don't have one to try, so I will replace the sensor, I cleared the code and I drove the car so will check to see if the code comes back. But will this cause long cranking to start an high gas consumption. I got 300 km on a full tank of gas.
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Friday, November 29th, 2024 AT 8:36 PM
Tiny
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Hi,

It could cause all that you mentioned. The sensor is used to fine-tune ignition timing to allow the engine to run more efficiently.

If you have a chance, let me know how things work out for you.

Joe
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Sunday, December 1st, 2024 AT 9:58 PM
Tiny
HSNDSOME
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Good day, I replaced knock sensor, no more codes. Still getting a few cranks before start up. Will monitor an let you know.
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Friday, December 13th, 2024 AT 7:44 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

Thanks for the update. I'm glad you got it taken care of. As far as the delay starts, let me know if it worsens. We could have fuel pressure drop off causing that to happen.

Let me know. If I don't hear back from you, I wish you and your family a Merry Christmas.

Take care,

Joe
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Saturday, December 14th, 2024 AT 9:10 PM
Tiny
HSNDSOME
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Hi, I already replaced the fuel pump, and same issue. Will double check the fuel system and see.
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Tuesday, December 17th, 2024 AT 5:15 PM
Tiny
JACOBANDNICKOLAS
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Hi,

If you have a leaking injector, it will cause pressure to drop off. If you have a chance, let me know what you find.

Joe
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Tuesday, December 17th, 2024 AT 7:01 PM

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