The dreaded P0171 and P0174 codes on the 2005

fourmustangs

fourmustangs

TJ Enthusiast
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Joined
Apr 10, 2017
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280
Location
Houston, TX, United States
Codes showed up today. Codes had come up previously but I hadnt drove it much, but now time to fix.

New parts done.
Valve cover gasket with new pcv groments.
2 new O2 sensors Sensor 1 Bank 1&2


The motor runs super smooth and quiet. It has a small air whistle sound so not sure if that is normal as its not very loud and does not change tone with pumping the accleration. It does shimmy a little when coming to idle in gear(auto) at say a stop light. I feel it has plenty of power on accleration.
One hose that attaches to the intake from the back groment of valve cover that has a split in the outer rubber(if I pull that up the engine starts to acclerate) I used a zip tie to see if that helps right now.

so other culprits?

Fuel
Vacuum leaks
No MAF correct
Idle air
?

I do have a new OPDU to put in, just haven't done it. I need to check the spark plugs as well.
 
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So since i feel i have a perfect steady idle at 700rpm would it be a vacuum leak?

And since it is in both banks for sensors would it really be exhaust manifold crack?


So maybe just check fuel pressure
 
Disclaimer "I'm definitely not a mechanic, but I play on on the inter-webs some time"

That said maybe vacuum line is leaking, intake gasket maybe? It doesn't sound like the throttle body since the noise doesn't get louder but again I am definitely not a mechanic. I hope it gets sorted out on the cheap side though.
 
My 05 just threw these codes today (P0171 and P0174). Runs smooth, Idles smooth @around 700 rpm, I guess I need to check my fuel pressure, any other things to look out for?
 
0171 and 0174 indicate the engine is running so lean that it can't add enough fuel to compensate. So you could have bad fuel press, clogged fuel filter, have an air leak or the o2 sensors think you do... bad o2 sensors.
 
05Rubicon said:
Fuel pressure was a good steady 60 psi, Replaced MAP sensor, all is right in MY jeep world again! FIXED!!!
Click to expand...
or so I thought, it threw the codes again, and again...went ahead and replaced upstream O2 sensors and fuel pump for good measure, drove another 700 miles and it threw the codes AGAIN! Did a little more digging and found it could possibly be the TPS, found the lock for the TPS connector is missing and the connector was loose (almost disconnected). reseated connector and secured with a tywrap. No more codes for the last 2k miles. Fingers crossed!
 
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Update...Replaced TPS connector and ran with no tywrap and the codes came back, reinstalled tywrap and cleared codes and has been good for over 5K miles with no codes.
 
Would this happen to be the same thing on a 2002 TJ 2.5? I already replaced the fuel pump and ordered the GOOD O2 upstream sensor. I’ll also go through and check the vacuum lines, exhaust manifold, and the things mentioned here on this thread. Curious to see what else might be the issue.
 
05Rubicon said:
Update...Replaced TPS connector and ran with no tywrap and the codes came back, reinstalled tywrap and cleared codes and has been good for over 5K miles with no codes.
Click to expand...

Did this end up being the fix for your p0171 and p0174 lean codes? My plug stays on but the tab has had better days. It’s on my list of connectors to replace so I’ll keep my eyes on this after I do the repair. Thanks!!!
 
05Rubicon said:
It has been over 2 years now and the codes never came back!
Click to expand...

I just got the P0174 code only. What are you referring too as tywrap, did you install it at the TPM end or the sensor? Pictures by any chance? I am going to see if my scanner will read barometric pressure and see what the reading is, that might help confirm if it’s the MAP sensor.
 
Danarch said:
I just got the P0174 code only. What are you referring too as tywrap, did you install it at the TPM end or the sensor? Pictures by any chance? I am going to see if my scanner will read barometric pressure and see what the reading is, that might help confirm if it’s the MAP sensor.
Click to expand...

I put a long thin tywrap around the throttle body and around the TPS connector, and to date the codes have never came back.
 
Talking about these? I’ve called them tie straps. Thanks.

IMG_1056.jpeg
 
05Rubicon said:
That's them! Tywrap = Tystrap = Ziptie all the same
Click to expand...

Sound good. I’ll be doing my investigation. Trying to see if there is a way to test the MAP sensor barometric pressure, not sure if my scanner has that function or not. From what I understand that is a good way to tell if the sensor is bad.
 
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