Author	[Modern View]
James Williams 07-25-2012 11:07:31 170.215.50.10 Report to Moderator	After the first 10 miles while driving I get dentonatin,or valve plng,mostly at high RPM when Im on the throttle,Ive cleaned the PCV valve,checked the MAF.Im to the point of wandering if I have a manifold leak.I checked the codes and they are PO 171 & PO174,need your help,Seemed like it started all at one time,its 175,000 miles on the motor.The truck Idels and runs good jimmy [Reply]   [No Email]
robgIN 07-25-2012 16:53:29 70.224.33.205 Report to Moderator	Re: Ford F150 4.2 in reply to James Williams, 07-25-2012 11:07:31   those codes are for lean bank 1 and 2, so most likely a vacuum leak, pcv hoses and elbows are the most common problems. With that many miles could be upper plenum gaskets getting hard and leaking also. The egr on that engine goes into a port along the center of the intake and it has orifices into each port. Those orifices tend to plug with carbon over time and block the flow of egr causing ping, many times all but one or two port will be completely plugged and all the flow goes to 1 cyl and it feels like a miss. [Reply]  [No Email]
wisbaker 07-25-2012 12:34:38 207.118.151.73 Report to Moderator	Re: Ford F150 4.2 in reply to James Williams, 07-25-2012 11:07:31   Had a similar problem on an 01 F-150 with the 4.6. Problem went away when I changed the fuel injectors, I suspect one was not passing enough fuel and the cylinder would get to lean and she'd knock. For what it's worth Ford couldn't diagnose it and my dealer claimed it's normal and they all do it. Goggle the codes they might tell you something it might have something to do with a temperature sensor so the computer is not setting the right fuel mixture when it's cold. [Reply]  [No Email]