Little Help... please? P1404?

[nimrodtoo]

Hi all! Newbie to this site lookin for a little help...

 

I've got a 99 Sierra Classic Z71 w/5.7L with about 107K miles. Love my truck... very happy with it.

The last month or so I've been getting an intermittent P1404 code with a description like "...auxilliary emissions...". The first time it happened was on a highway after hitting a little stop and go. The SES was hard on and I even stopped and turned the truck off for a couple minutes to try and clear it. Stayed on through the 200mi ride but was clear the next morning.

It's come on a few times since then, and I've noticed the idle has been a little "bumpy" and lower than normal during and around the times the SES is on.

 

Anyone have any ideas what I might be looking for? The truck runs fine the rest of the time and the idle is the only thing I noticed that was out of the norm when the light is on.

Little help.... please?

Nim

[dougmac]

P1404 - EGR valve pintle position.

 

You probably don’t have the equipment to examine the EGR performance. Sticking EGR valves are a common problem on GM vehicles.

 

You have a couple of choices:

1) Take it somewhere and have it properly diagnosed and repaired.

2) Throw an EGR valve at it and see if it fixes the problem.

 

Based on this being a fairly common problem, I would be inclined to take a chance and just put a new EGR valve on.

 

You may want to try cleaning it first. I have tried this but have not had good luck….. but you never know, it might save you some bucks.

 

Doug

[nimrodtoo]

P1404 - EGR valve pintle position.

 

You probably don’t have the equipment to examine the EGR performance. Sticking EGR valves are a common problem on GM vehicles.

 

You have a couple of choices:

1) Take it somewhere and have it properly diagnosed and repaired.

2) Throw an EGR valve at it and see if it fixes the problem.

 

Based on this being a fairly common problem, I would be inclined to take a chance and just put a new EGR valve on.

 

You may want to try cleaning it first. I have tried this but have not had good luck….. but you never know, it might save you some bucks.

 

Doug

 

<{POST_SNAPBACK}>

 

 

I didn't think the EGR would effect idle... at least not to a noticable degree. The scanner does not say anything about EGR... more along the lines of "Manufacturer auxilliary emissions... " . Thoughts?

Nim

[Mr. Smith]

P1404 - EGR valve pintle position.

 

You probably don’t have the equipment to examine the EGR performance. Sticking EGR valves are a common problem on GM vehicles.

 

You have a couple of choices:

1) Take it somewhere and have it properly diagnosed and repaired.

2) Throw an EGR valve at it and see if it fixes the problem.

 

Based on this being a fairly common problem, I would be inclined to take a chance and just put a new EGR valve on.

 

You may want to try cleaning it first. I have tried this but have not had good luck….. but you never know, it might save you some bucks.

 

Doug

 

<{POST_SNAPBACK}>

 

 

I didn't think the EGR would effect idle... at least not to a noticable degree. The scanner does not say anything about EGR... more along the lines of "Manufacturer auxilliary emissions... " . Thoughts?

Nim

 

<{POST_SNAPBACK}>

 

 

 

 

 

Yes it would if it is stuck open enough.

[dougmac]

I didn't think the EGR would effect idle... at least not to a noticable degree. The scanner does not say anything about EGR... more along the lines of "Manufacturer auxilliary emissions... " . Thoughts?

Nim

 

<{POST_SNAPBACK}>

 

 

 

The scan tool is giving you a very generic description of the code that is not all that useful for diagnosing the problem. I took the code you provided and looked it up to get a more detailed description. That is where the EGR information came from.

 

The condition for setting the code is an open EGR when it its commanded closed. This means that you are introducing un-metered exhaust gas into the intake manifold. It’s likely that the un-metered exhaust gas flowing into the intake manifold is causing the unstable idle.

 

There is always the possibility that another problem is causing the unstable idle, but this is certainly where I would start. If you had a $3000.00 scan tool that was capable of bi-directional testing, you could easily determine how the EGR is affecting the idle. To be honest, I don’t think it makes sense even attempt to repair the idle problem until the EGR issues are resolved.

 

Doug

[Rammer]

I kept getting the EGR pintle position fault on my Grand Prix. It would clear itself and reapeer a few months later. I finally replaced it, while I was repairing other troble codes. I believe the trucks use the same valve as the 3.8 in my GP, which was $144 for an AC Delco.

An EGR valve usually doesn't open to over 2000 RPM and if stuck open, your idle will suffer. Remove the valve and clean it out with gumout and check passages for carbon build up.