Po171-Po174
02-10-2016, 08:17 AM
#1
Senior Member
Thread Starter
Po171-Po174
I got these lean codes today and it says PCV I've replaced the elbow last year and I didn't hear hissing when I opened the hood and don't think I felt air around it. ( it was running so I couldn't tell )
02-10-2016, 09:48 AM
#2
Follow the pcv hose to the back of your intake and check the connection for deterioration. Those elbows are usually the problem. If not start with the basic, change air filter, clean MAF sensor.
02-10-2016, 11:35 AM
#4
We have a 2003 5.4L 2v Exped 151K and all the vacuum hoses, not just the elbow in the back, were cracked or in poor condition. The PCV line itself has 3 elbows. One small hose under the air filter tube was broken. Another hose behind the battery was split. The PCV system intake tube elbow on the driver's side valve cover was in poor condition. Also, look for cracks or leaks in the tube between the MAF and the throttle body.
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Fordfan2006 (02-10-2016)
02-10-2016, 02:30 PM
#5
Senior Member
I had the p0174 cleaned MAF and elbow reset it and code came up again. I then replaced the throttle position sensor and reset it. Code never came back. I am not sure if it was was the throttle position sensor or not but code did go away. The sensor cost me 30 bucks.
02-10-2016, 02:38 PM
#6
Senior Member
Those hard to find problems with such DTC's can be a IAT grommet leak or a bad/missing MAF o-ring.
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02-11-2016, 12:13 PM
#8
Senior Member
Sounds like it could be. What are you warm idle rpms in park ? Post the exact number and yea, has to be at operating temp.
If I had to guess at this point, sounds like a PCV leak. Can't be sure. Could be the black or white emissions lines as well. Those can leak over by the batter box and firewall usually.
If I had to guess at this point, sounds like a PCV leak. Can't be sure. Could be the black or white emissions lines as well. Those can leak over by the batter box and firewall usually.
Last edited by Jbrew; 02-11-2016 at 12:15 PM.
02-11-2016, 12:52 PM
#9
Senior Member
Thread Starter
Sounds like it could be. What are you warm idle rpms in park ? Post the exact number and yea, has to be at operating temp. If I had to guess at this point, sounds like a PCV leak. Can't be sure. Could be the black or white emissions lines as well. Those can leak over by the batter box and firewall usually.
02-11-2016, 01:35 PM
#10
Senior Member
Yea, you have to be specific. That can't be right. Not unless something is very dirty, plugged up totally or the factory tune has been modified.
Last edited by Jbrew; 02-11-2016 at 01:39 PM.