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Code P0171 after replacing spark plugs!

17K views 25 replies 9 participants last post by  speleos 
#1 ·
Check engine light, and service stabilitrak message comes on after I replaced the spark plugs myself. Is it possible that I didn't install the plugs correctly? All cables are plugged in correctly. My RPM seems to fall slightly at idle. Please help. :shrug:
 
#3 ·
Start checking for any sensors you may have unplugged and forgot to plug back in. The one on the air cleaner housing comes to mind. Sparks plug can either be screwed in or not screwed in, so I doubt you installed any wrong unless you put one in and forgot to tighten it. Don't see what year your Acadia is so I don't know if you had to remove the intake manifold to get to the rear plugs (DI engines) or not.
 
#4 ·
ls973800 said:
Start checking for any sensors you may have unplugged and forgot to plug back in. The one on the air cleaner housing comes to mind. Sparks plug can either be screwed in or not screwed in, so I doubt you installed any wrong unless you put one in and forgot to tighten it. Don't see what year your Acadia is so I don't know if you had to remove the intake manifold to get to the rear plugs (DI engines) or not.
:ditto:

Also a good idea to check all the vacuum hoses to see that they're installed properly. Read through this post and see what others have experienced: http://www.acadiaforum.net/index.php?topic=9795.msg156863#msg156863
 
#5 ·
Speleos said:
:ditto:

Also a good idea to check all the vacuum hoses to see that they're installed properly. Read through this post and see what ......

I found this. Looks like there used to be a hose connected there. But I can't seem to find any unplugged hoses. Anyone know what goes there? This actually might be the problem.
 
#6 ·
"I found this. Looks like there used to be a hose connected there. But I can't seem to find any unplugged hoses. Anyone know what goes there? This actually might be the problem."

Sorry, can't see your picture. Attachments don't work on this forum. If you start a gallery on the forum and post the picture there, you can link it into this thread. I don't think you have enough posts to link anything from an off-forum site.

That might be a vacuum fitting for something on another car that uses this engine and just needs to be capped on the Acadia. It could have a cap fit into the top engine cover. Plug it and see how your car runs.
 
#7 ·
Speleos said:
"I found this. Looks like there used to be a hose connected there. But I can't seem to find any unplugged hoses. Anyone know what goes there? This actually might be the problem."

Sorry, can't see your picture. Attachments don't work on this forum. If you start a gallery on the forum and post the picture there, you can link it into this thread. I don't think you have enough posts to link anything from an off-forum site.

That might be a vacuum fitting for something on another car that uses this engine and just needs to be capped on the Acadia. It could have a cap fit into the top engine cover. Plug it and see how your car runs.
I think you are correct. So I plugged in the rubber nipple like plug and the stabilitrak traction message went away. But the check engine light is still on. Does it take a while for the engine light to go away? Also, I switched my plugs for 2 reasons... One because I hit the 100k mark 8000 miles ago, and the other was because my Acadia cranks very slow. I think it's getting worse. Anyways, after the new plugs, it's still sluggin when I crank. My battery reads 14 never below 12. What could it be? Thanks.
 
#8 ·
j2theess said:
I think you are correct. So I plugged in the rubber nipple like plug and the stabilitrak traction message went away. But the check engine light is still on. Does it take a while for the engine light to go away? Also, I switched my plugs for 2 reasons... One because I hit the 100k mark 8000 miles ago, and the other was because my Acadia cranks very slow. I think it's getting worse. Anyways, after the new plugs, it's still sluggin when I crank. My battery reads 14 never below 12. What could it be? Thanks.
The CEL can go out on its own after a few start cycles. You can also clear it by pulling the ECM fuse, wait about 10-15 seconds, and put the fuse back into its slot. With respect to the 'sluggish' start, the battery can have enough voltage but be low on starting (cold crank) amperage. That happens as a battery gets older. Might want to have a load test run on the battery, or just replace it.
 
#9 ·
Speleos said:
"I found this. Looks like there used to be a hose connected there. But I can't seem to find any unplugged hoses. Anyone know what goes there? This actually might be the problem."

Sorry, can't see your picture. Attachments don't work on this forum. If you start a gallery on the forum and post the picture there, you can link it into this thread. I don't think you have enough posts to link anything from an off-forum site.

That might be a vacuum fitting for something on another car that uses this engine and just needs to be capped on the Acadia. It could have a cap fit into the top engine cover. Plug it and see how your car runs.
Bingo! Same thing happened to me when Scott changed my plugs. That vacuum cap got cracked and I got the same messages. He put on a new cap, cleared the check engine code and it was fine. Sounds like the OP's battery is due for replacement.
 
#10 ·
j2theess, you run a risk of losing some computer info and everything going to default settings when you replace the battery - like radio presets, driver-set DIC functions, and 'adaptive' learning of computer controls in the transmission modules - especially if it takes you a while to do the job. You can keep things powered enough to maintain the info by using a power adapter plugged into the cigarette lighter-like accessory socket. Somewhere on the forum someone has discussed where to get this tool and how to use it. One thing nice about changing the battery without that power adapter - all the trouble codes will be cleared.
 
#13 ·
I had the same issues after recently changing my spark plugs on a 2008 Acadia. Was getting engine trouble light with P0171 and P0174 codes. StableTrak alarm and rough idle.

The small rubber vacuum cap above the #2 spark plug got bumped and knocked off. Replace the rubber cap and temporarily pulled the ECM fuses to reset the codes. Problem is gone and engine is idling properly.
 
#14 ·
Same thing happening to me right now.
Do you have a picture of the cap and where I might find this? Do you have a PN for the cap?
 
#18 ·
Found it for you. It's number 9 on the diagram.
9106
 
#19 ·
Really appreciate this speleos. I can totally see how this could happen.
My son has the vehicle at work, so I am going over to look at it this morning. Been trying to track this down for several days now since I was off work.
I found the other thread with the picture too.
 
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#20 ·
My son has the vehicle at work, so I am going over to look at it this morning. Been trying to track this down for several days now since I was off work.
Hope it all works out for you/him. Photo in your link shows how easy it is for someone to fabricate a cap which will work, too.
 
#22 · (Edited by Moderator)
Strange things can happen. Many years ago I changed the plugs on my wife's 1967 Chevy wagon. After the plug change it ran terrible. So, obviously I figure it must be something I did when changing plugs.

Pulled each plug and checked it for gap. All plugs were good with no broken ceramic and gap right on. After much head scratching and looking at everything I could see with a bright flashlight I could find no problem.

Finally took off the distributor cap. Voila!! Problem found. Rotor had broken. Not enough to prevent wagon from running, The contactor had just moved a few degrees. Just enough to let it run, but run rough.

I had not touched the distributor when changing the plugs.

George
 
#23 ·
I should mention the I was getting intermittent codes p0106 p0171 and p0174 as well as the stabilitrak when this was happening.
I would erase them in between trying to diagnose.
Sometimes only p0106 (MAP sensor) would come up, sometimes only p0171 and p0174 (MAF sensor bank 1 and 2 lean) and sometimes all three codes would come up at the same time. I actually bought a new MAP sensor and canceled the order since I didn't need it.
Haven't had any problems since I plugged the vacuum port. Thanks again to speleos and everyone that posted.
 
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#24 ·
Good to know, encadia. Thank you for the follow-up. Happy New Year to you and yours.
 
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