Vacuum Leak
Thread Starter
|
Member
Joined: May 2007
Posts: 18
Likes: 0
Vacuum Leak
I have 1997 F150 / 4.6 l V8 with 156,000 miles. I recently had an issue with the MAF. Finally got it repaired after replacing the MAF and the harness/pigtail for the MAF. Now I am getting a vacuum leak issue. I keep getting the code p1151 which is the HS02 sensor. I also hear a loud sucking sound from under the hood but I can't quite seem to locate it. Per recommendation I took a look at the PCV line and there is no cracks or holes in the pipe so as of now I am clueless. I am just wondering if you guys have any advice before I tear into the vacuum system and inspect every little piece. Thank you.
Senior Member
Joined: Dec 2006
Posts: 43,530
Likes: 817
From: Joplin MO
Have you followed the PCV hose all the way around the back to the rubber elbow under the throttle body?
http://www.obd-codes.com/trouble_codes/ford/p1151.php
That's the front sensor on the driver's side, by the way.
http://www.obd-codes.com/trouble_codes/ford/p1151.php
That's the front sensor on the driver's side, by the way.
Technical Article Contributor
Joined: Oct 2006
Posts: 1,770
Likes: 6
From: Michigan
Well if you recently removed the large air inlet tube to replace the MAF then I would check there first. Especially at the throttle body connection. The clamps may be tight but if the hose is not on the throttlebody all the way it will leak. Check under the throttle body as thats where it's usually not pushed back on all the way. I would suspect it's one of the tubes you just moved around during the MAF replacement.
Technical Article Contributor
Joined: Oct 2005
Posts: 25,641
Likes: 19
From: MI
Right - update both forward O2 sensors as well. 50 series codes are sensor specific.. Same Time.
Also, make sure your PCV valve is a Motorcraft "only" brand. If you can hear the sucking sound or leak under the hood, -you can find it. Just need to try harder I guess, - not sure what else to tell you there lol.
Also, make sure your PCV valve is a Motorcraft "only" brand. If you can hear the sucking sound or leak under the hood, -you can find it. Just need to try harder I guess, - not sure what else to tell you there lol.
Member
Joined: Aug 2010
Posts: 49
Likes: 0
What I do is this, but you need to be careful with your ear.
Cut off about 3 feet of garden hose. Hold one end to your ear, and snoop around with the other end until you find the vacuum leak. This also works for exhaust leaks. But go cautiously. Some of the hissing sounds created can be quite loud.
Cut off about 3 feet of garden hose. Hold one end to your ear, and snoop around with the other end until you find the vacuum leak. This also works for exhaust leaks. But go cautiously. Some of the hissing sounds created can be quite loud.
Member
Joined: Oct 2009
Posts: 69
Likes: 0
From: JACKSON TENNESSEE
x-2 as GLC says theres no way of knowing if your elbow or PCV is bad without following the two lines all the way back to the firewall. its to tight in there to see without pulling the elbow/PCV out. alot of times the pcv valve gets stoped up and gets to hot and melts a hole in the back side of the elbow causeing a vac leak. one thing is for sure if it is the elbow/PCV it will run like chit at low RPM'S.
Last edited by rglass62; Sep 4, 2010 at 02:52 PM.
Technical Article Contributor
Joined: Oct 2005
Posts: 25,641
Likes: 19
From: MI
x-2 as GLC says theres no way of knowing if your elbow or PCP is bad without following the two lines all the way back to the firewall. its to tight in there to see without pulling the elbow/PCP out. alot of times the pcp gets stoped up and gets to hot and melts a hole in the back side of the elbow causeing a vac leak. one thing is for sure if it is the elbow/PCP it will run like **** at low RPM'S.
