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Discussion Starter · #1 · (Edited)
Hey ya'll. I need some input on possible solutions to my CEL that keeps coming up. I got ahold of a code scanner and have some info for you to look over.
The code I had was: P0171 too lean bank 1

Here is the scanner data and freeze frame of the car at idle:


Control Module
$07E8 CAN OBDII
Since DTCs Cleared
MIL Status OFF
Misfire Monitor N/A
Fuel System Mon N/A
Comp. Component N/A
Catalyst Mon N/A
Htd Catalyst N/A
Evap System Mon N/A
Sec Air System N/A
A/C Refrig Mon N/A
Oxygen Sens Mon N/A
Oxygen Sens Htr N/A
EGR System N/A
Stored Codes
P0171 System Too Lean Bank 1
Pending Codes
P0171 System Too Lean Bank 1
View Freeze Frame
DTCFRZF P0171
FUELSYS1 CL
FUELSYS2 N/A
LOAD_PCT(%) 24.7
ETC(°F) 153
SHRTFT1(%) 18.8
LONGFT1(%) 29.7
MAP(kPa) 11.2
RPM(/min) 813
VSS(km/h) 0
SPARKADV(°) 11
IAT(°F) 108
MAF(g/s) 0.415
TP(%) 22.4
AIR_STAT OFF
RUNTM(sec) 119
EVAP_PCT(%) 0.0
FLI(%) 54.5
WARM_UPS 1
CLR_DIST(km) 12
EVAP_VP(Pa) 0.265
BARO(kPa) 29.8
CATEMP11(°F)887.00
VPWR(V) 14.359
LOAD_ABS(%) 20.0
EQ_RAT 0.999
TP_R(%) 8.2
AAT(°C) 102
TP_B(%) 22.4
APP_D(%) 19.6
APP_E(%) 9.8
TAC_PCT(%) 12.5

I cleared the CEL and I will do a drive and see if the code comes back.

I view some live data like the SHRTFT% and it was up and down ALOT from 0 to 18% I wish I could show you the graph but the scanner doesn't transfer this info.

So far, I;ve cleaned the MAF twice and cleared the CEL by disconnecting the battery and allowing the ECU to relearn the airflow. The CEL came back after one 20 min dirve. I checked all the clamps for tightness to make sure there wasn't any umetered air entering the mani. none of this has had any lasting effects.

The change to the intake was adding a 45 deg elbow upstream of the MAF to move the filter away from the hood (it was rattling against it). The maf section wasn't moved other than being pushed into the coupler about an inch closer to the TB.

The next thing I'm going to try and do is removing the elbow I added and seeing what happens. I can also video the SHRTFT graph at idle with my camera to show you guys if you need to see it.

Thanks in advance!
 

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What kind of intake is it? I can't remember...

Is the MAF sensor plugged in good and tight? No leaks there?
 

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Discussion Starter · #3 ·
This is a custom intake. The sensor wasn't removed prior to the CEL be thrown. I'm assuming it is the same code that is being recorded now. Since then, I've removed and replace it and made sure it was in tight.
 

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i had this problem and i had to reconnect that little hose going from the intake piping into the engine cuz it came off
 

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The vacuum hose?

Chris, you don't have that do you? Don't you just have a breather on yours?
 

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Discussion Starter · #8 ·
right, no PCV hose going to the intake. Fact, there isn't even a nipple on the intake to connect one! (Took it off, lol).
 

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Are you able to put it back on?

I'd say give it a shot...
 

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Discussion Starter · #10 ·
not really. I had to remove it because there wasn't enough room to have that piece along with all the others. It never had a problem driving all the way to ohio without it so why would it start now? doesn't seem connected to the current issue.
 

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I blame it on your excessive racing...

And your terrible driving skills.

Obvious fix there, replace the driver...

JK :)
 

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I know right....

WE DIDNT START THE FLAME WAR, IT WAS ALWAYS BURNIN SINCE CHRIS BE NOOBIN
 

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Don't think that's the problem.
this happens to my car after a dusty couple of days....

also whenever i worked on the car...if i didnt have my maf in exactly perfect...it would throw that code. and this is with either my winter intake...which u have seen chip and my cai.
 

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this happens to my car after a dusty couple of days....

also whenever i worked on the car...if i didnt have my maf in exactly perfect...it would throw that code. and this is with either my winter intake...which u have seen chip and my cai.
Yeah. I just figured it wasn't a dirty MAF because he's cleaned it and still got the code.

There is a problem with the LNFs throwing codes with aftermarket intakes because the MAF is really touchy about it's placement.

Maybe your MAF isn't in a good position to read the air flow properly, Chris?
 

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Discussion Starter · #16 · (Edited)
hmm. that is possible. with the elbow upstream of the maf, it could be altering the airflow enough to throw the sensor off. I might try different positions for the maf as well to see what happens.

I cleared the DTC like i said earlier and went for a drive. I did street and freeway and the cel didn't come back. I took a recording of all the PIDs to if they reveal anything. Is there a particular one you guys need to see?

Wierd, nighthawk243's post dissappeared...

The answer is yes, I tried disconnecting the battery for a time and draining the system.
 

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I'd make sure if it is a homebrew setup, that the MAF is sitting correctly centered in the tube to make sure it is metering all the air across the hot wire. It could be operating fine, just not seeing everything. Or maybe you did what I did, and pulled a wire out of the MAF connector... Man that was bad, check your wire connections.
 

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Discussion Starter · #18 · (Edited)
Well, the live datastream shows that IAT and MAF readings are functioning properly so it doesn't appear to be a pulled wire. possibly it's intermittent. I know the MAF itself is located in the same position in the tube, no change there. In fact it couldn't be changed if i wanted to. Only thing I can change is the orientation of the sensor on the tube by rotating the MAF tube section in place.

I have a 30 frame live datastream record if anyone wants to see it.
 

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Then try it in a few spots and see what happens. Also my MAF failure was intermittent.
 
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