Intermittent Computer PCM codes

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Jun 19, 2012 | 12:14 PM

87convpaul

Thread Starter

Intermediate

Joined: May 2002

Posts: 40

Likes: 0

From: Mukilteo WA

Intermittent Computer PCM codes

What causes my 2001 with 55,000 miles to have these codes P0171 & P0174 come and go?

Jun 19, 2012 | 12:25 PM

tblu92

Le Mans Master

Joined: Aug 2005

Posts: 5,375

Likes: 326

From: CA.

St. Jude Donor '13-'14-'15

These are both LEAN codes one left side one right--Typically they are a result from adding mods such as cold air intakes--Also check for vacuum leaks or any intake air tract leak in the air bridge assy.--- If you can get a scanner check to see where your LTFT fuel trims are--To get a lean code usually means the trims are beyond +20 %-
Go to this site to review diagnostics---
http://www.gearchatter.com/viewtopic8886.php

Jun 19, 2012 | 01:04 PM

Bill Curlee

Tech Contributor

Joined: Dec 1999

Posts: 32,910

Likes: 2,402

From: Anthony TX

CI 6,7,8,9,11 Vet

St. Jude Donor '08

What MODs do you have???

Have you checked the PCV elbow for rot/damage that can cause a big vacuum leak?

Ducting between the MAF and the TB for air tight status.

BC

Jun 19, 2012 | 05:01 PM

FKING1

Safety Car

Joined: May 2003

Posts: 3,814

Likes: 105

From: Dearborn Heights Michigan

My highly modified 2000 will throw the P0171 if the motor idles for around 5 min. If I drive off it doesn't. Has been doing this for several years. My mechanic tried to find the prob with no success. No leaks evident.I just reset the code and forget it.

Jun 19, 2012 | 09:59 PM

$$$frumnuttin'

Tech Contributor

Joined: Aug 1999

Posts: 16,376

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From: Should this thoughtful, valuable contribution meet with no acknowledgement or 'thanks' this post----

Quote:

Originally Posted by FKING1

Fred, that is from a cold start, right?

Jun 20, 2012 | 05:02 PM

FKING1

Safety Car

Joined: May 2003

Posts: 3,814

Likes: 105

From: Dearborn Heights Michigan

Quote:

Originally Posted by $$$frumnuttin'

Fred, that is from a cold start, right?

Yes, from a cold start.
I rarely get the code on a hot start.

Jun 22, 2012 | 01:13 AM

87convpaul

Thread Starter

Intermediate

Joined: May 2002

Posts: 40

Likes: 0

From: Mukilteo WA

The only mod is the K & N cold intake & BB exhausts/

Jun 22, 2012 | 01:19 AM

Bill Curlee

Tech Contributor

Joined: Dec 1999

Posts: 32,910

Likes: 2,402

From: Anthony TX

CI 6,7,8,9,11 Vet

St. Jude Donor '08

The ONLY real way to get to the bottom of your issue is to DATA LOG the PCM and see where specific sensor outputs fall.

The major sensors to monitor would be:

LTFTs
O2 Sensor Output Data
WIDE BAND O2 sensor readings

One or more of those values will be WRONG and will be easily seen.

Bill