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Old 12-08-2011, 05:20 PM   #1 (permalink)
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Default Check Engine Light - P0171 & P0174

My car is a 2004 - 6 with the 3.0L V6 and manual transmission. I've owned the car since it had 18 miles on it. It now has about 98.7K mi. I had a problem when I first got the car with the check engine light (<250 miles) but beside that it has run fine. About 3 days ago I got the dreaded CEL. Took it to advanced auto parts and got the P0171 & P0174 both banks too lean.

When I start the car in the morning the car idles high around 1500rmp, usually its around 750-800 rmp... After running it for a while the idle will return to normal. Any idea what may be the problem. I read how to clean to MAF sensor, and may try to do that this weekend. I also notice a burning smell of possibly oil, two days before the check engine light came on, when I went back into the enclosed garage after driving home from work. Noticed this smell again one my way home from home depot after I reversed outta the parking spot, and then about two minutes later the CEL came on... not sure if they are related at all. Have not smelled the bad smell these past two days....I checked the oil level this morning and it seems to be fine.....I had a small oil leak about 3 months ago from a faulty oil plug, so I always park over cardboard in the garage. There are about 5 dime size oil spots on the cardboard from the previous 3 months.


Any suggestions will be greatly appreciated.

Also, I had a tune up about 20-25k miles ago from the stealership about 2 years ago

Last edited by dukerollz555; 12-09-2011 at 09:58 AM.
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Old 12-08-2011, 07:36 PM   #2 (permalink)
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I have the same codes. I also have a rough idle in the AM.

Engine running lean, mechanic and dealership failed to fix it.

apparently I have a exhaust leak. i'm not sure if this is what's causing my codes, but possibly.

i've been doing lots of research, clean your MAF and spray around the vacuum lines with carb cleaner and see if the idle changes are the main suggestions.
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Old 12-09-2011, 01:09 AM   #3 (permalink)
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The codes are indicating lean conditions on both cylinder banks. If cleaning the MAF doesn't help, it may be a vacuum/air leak somewhere inboard of the MAF. Check for split or cracked hoses or loose connections on any hoses leading to/from the intake.

P0171 Fuel trim system (RH) too lean ON 2 Fuel � (See DTC P0171, P0174 [AJ] .)
P0174 Fuel trim system (LH) too lean ON 2 Fuel � (See DTC P0171, P0174 [AJ] .)


All of the CELs are listed on this page for reference.... CEL Codes
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Old 12-09-2011, 08:57 AM   #4 (permalink)
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what 2 wheelin said
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Old 12-09-2011, 09:55 AM   #5 (permalink)
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When I go to clean my MAS, is it okay to spray the wires inside of the "tower". I haven't taken it off yet so I really don't know what is up there. Should I just try to spray the sensors in the tower or just douce everything inside of it including the two wires? Thanks for helping a newbie out.

Edit:

Also, I took a look under the hood last night to see if I could find any leaks, I didn't see nor hear anything while the engine was idleing - this was after I drove home from work though and the car was idling at it's normal 750rpm... Maybe I'll take a listen under a cold start up to see if I hear any sucking or hissing.

Next step though is to try n clean the MAS tomorrow

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Old 12-09-2011, 10:44 AM   #6 (permalink)
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I would also like to note thi issues perhaps to help someone here diagnose my problem....Have been reading the forums this morning and came across this thread:

Fuel Economy???

I've been only getting about 20 mpg recently, driving about 50/50 highway and city. Would this decrease in fuel efficiency be a result of a dirty MAF, or would it be an indication my O2 sensors are bad, and that is producing my too lean codes in both banks.

Thanks!
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Old 12-13-2011, 06:54 AM   #7 (permalink)
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Read my posts. Been through the lean idle.
Engine light on 3 times
Oil light on twice

2004, 3.0 96,000 miles


Flipper and the great NY have really helped me. Thanks a bunch!!!!




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Old 12-13-2011, 03:40 PM   #8 (permalink)
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Just wanted to give everyone an update to my situation. I cleaned the MAS this weekend. It was really dirty and it did clean up nice. Reset the CEL from the disconnected battery, and test drove the car. Car seemed to have a little more giddy up and I thought I fixed the problem. CEL came back on 15 miles later. DAMN.

After I changed the MAF I checked for any leaks, I couldn't find any so I left the hood open and revved it up a little while the window was down. I heard a distinct woosh sound when I pressed on the throttle. It coincided exactly with the increased throttle and lasted only like half a second and would stop once the engine caught up. I have no real mechanical inclination, and thought this did not sound like a air leak because it wasn't constant.

I have a appointment scheduled at the dealer on Thursday, because I think any other repairs are beyond those of my capabilities. I will post what the dealer comes up with.
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Old 12-13-2011, 04:10 PM   #9 (permalink)
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Sounds like the intake boot has a crack in between one of the ribs.
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Old 12-13-2011, 08:30 PM   #10 (permalink)
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Quote:
Originally Posted by flipper66 View Post
Sounds like the intake boot has a crack in between one of the ribs.

What flipper said. We have the same year and miles.
The rubber hose from air box to throttle body. Tuff rubber on the 2004.
THe new one is real plyable

Go to rock auto parts and buy one on line Around 60 bucks Check yours all the way around it, I had a crack in one of the ribs and it was sucking air.

If that is the problem the dealer will charge you 200 - 300 hundred for a 15 minute job.


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