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Check engine light and codes P0400 and P0171

Tiny
ASEMASTER6371
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The pressure is good.

What is the long term trim at idle?

Roy
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Wednesday, February 12th, 2020 AT 3:46 PM
Tiny
RICHARD HOLLOWAY
  • MEMBER
  • 26 POSTS
Lngtrmft 9.6
Maf g/s 2.85 - 3.15
Idle bouncing between 790-830 rpm
71 degrees F
74 percent humidity
Elevation 840ft
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Wednesday, February 12th, 2020 AT 4:14 PM
Tiny
JOETECHPRO
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Hey RICHARD HOLLOWAY,

It sounds like you may have fixed the vacuum leak and need to reset the long term fuel trim and drive the vehicle.

Please try this and then let us know what you have for the long term fuel trim at idle and 2,000 rpm's if the code reappears.

Regards, Joe
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Thursday, February 13th, 2020 AT 8:40 AM
Tiny
RICHARD HOLLOWAY
  • MEMBER
  • 26 POSTS
10-4 I just reset the long term trim. I'll check the codes again after work tomorrow. The car actually ran smoother with the MAF sensor unplugged during the reset process. I'm still thinking it's a faulty MAF sensor but we shall see. I really appreciate all the help with this issue.
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Thursday, February 13th, 2020 AT 4:02 PM
Tiny
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Get back to us with the result.

Roy
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Thursday, February 13th, 2020 AT 6:37 PM
Tiny
RICHARD HOLLOWAY
  • MEMBER
  • 26 POSTS
P0170 came back long term trim at idle still reading 0.0 at 2,000 rpm's. It's reading 9.4 Freeze frame shows it happened at idle fuel system OL-Fault, 797 rpm, long term trim 0 short term trim 25.
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Friday, February 14th, 2020 AT 2:50 PM
Tiny
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It is running to lean now.

Roy
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Friday, February 14th, 2020 AT 2:58 PM
Tiny
RICHARD HOLLOWAY
  • MEMBER
  • 26 POSTS
Okay, injectors are good. I checked those when I replaced the seals. I know there isn't a vacuum leak anymore. We know the fuel pressure is good. So that leaves exhaust gas leak, front 02 sensor, or MAF sensor.
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Friday, February 14th, 2020 AT 3:03 PM
Tiny
JOETECHPRO
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Hey RICHARD HOLLOWAY,

If unplugging the MAF causes the engine to run better it is highly likely you have a faulty MAF.

You have ruled out an air leak.

As a precaution I would first replace the PCV valve.
Also check the condition of the PCV hose.
If it is cracked or collapsing replace the hose.

I have attached the photo showing the location in the picture below.

I failed PCV valve can cause MAF sensor reading issues and it is a cheaper replacement part before replacing the MAF. I would replace the PCV valve and retest and then I think your next step would be to replace the MAF.

Regards, Joe
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Friday, February 14th, 2020 AT 3:36 PM
Tiny
RICHARD HOLLOWAY
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Sounds like a plan. I will update with results.
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Friday, February 14th, 2020 AT 3:57 PM
Tiny
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Do not be so sure about the injectors.

When was the last time they were cleaned?

Roy
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Friday, February 14th, 2020 AT 4:02 PM
Tiny
RICHARD HOLLOWAY
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  • 26 POSTS
It wasn't with a several hundred dollar special machine, but I cleaned them while I had them out with injector cleaner a long piece of fuel line compressed air and short quick battery pulses.
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Friday, February 14th, 2020 AT 5:28 PM
Tiny
JOETECHPRO
  • MECHANIC
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Hey RICHARD HOLLOWAY,

The injectors could still be a potential but it would be more likely for you to be getting an individual cylinder misfire.

If you have a scan tool with a cylinder power balance test you could run that and see if you have even contribution across all cylinders.

Let us know how you go with the PCV check.

Regards, Joe
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Friday, February 14th, 2020 AT 5:46 PM
Tiny
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When you did that procedure, what kind of pattern did you see when you made them work? You should have seen a conical pattern of fuel flow.

Roy
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Saturday, February 15th, 2020 AT 4:59 AM
Tiny
RICHARD HOLLOWAY
  • MEMBER
  • 26 POSTS
Two of them had the wider conical pattern to begin with so I just did a quick couple of pulses with those. The other two were more stream like to begin with but after about 10 or 15 pulses they opened up and got the same pattern as the the first two. They were essentially spraying like new injectors when I reinstalled them.
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Saturday, February 15th, 2020 AT 9:15 AM
Tiny
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After reinstalling, does the issue still exist?

Roy
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Saturday, February 15th, 2020 AT 9:21 AM
Tiny
RICHARD HOLLOWAY
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Yes that was done when I had the injectors out to fix one of the vacuum leaks.
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Saturday, February 15th, 2020 AT 6:00 PM
Tiny
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Take the oil fill cap off while the engine is running.

See if there is any vacuum at that fill point. Put your hand over the fill and see if there is any vacuum.

Roy
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Saturday, February 15th, 2020 AT 6:33 PM

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