lean codes 171 174 upper intake manifold fix

[mandospd]

http://www.explorerforum.com/forums//showthread.php?t=171819&referrerid=30515

This was very helpful to me, particularly in deciding if I could tackle this myself...It was a piece of cake..I have been getting the lean codes and have been looking for vacuum leaks with no success and doing quite a bit of research, I feel that most people that post and swear up and down that it is the MAF or oxygen sensors or fuel pressure are in most cases on the wrong track, if your truck runs good and starts easily, yet, you get these codes particularly in cold weather, you should suspect the upper intake manifold to fuel rail gaskets. Also, I went to a Napa parts store, if you buy the Felpro MS 90733 it contains six gaskets, you will have three extra, it's about three fifty. this set is for 96-97 rangers, if your upper intake manifold is black and plastic go for it it...it will work.

 

[mandospd]

And while you're at the parts store buy an E-7 socket to re-torque the intake manifold studs... they will be loose...it cost me $9.31 to do this repair for that kind of money it is worth doing as preventive maintenance if nothing else

 

[mandospd]

http://www.rangerpowersports.com/forum/showthread.php?t=170324&highlight=fuel+rail+gasket If you feel you want or need to do the fuel rail to lower intake manifold here is another good link.....not all 4.0 litres have this gasket some are a thick hard gasket...personally I would do the fuel rail to upper plenum and see if it improves before pulling the fuel rail from the lower intake maniford as it takes a great deal of finesse as you have now added fuel injectors and delicate o-rings to the mix

 

[RyanD2]

Just did my gaskets last weekend, everything seemed fine, when I started it back up. Went 3 days then the CEL came back on. Always with the same issue P1151 fuel air metering (before and after fix). Now i'm stumped as this is what the shop told me needed to be fixed. Oh well... i'll just keep lookin.

 

[mandospd]

I was never happy with the way my truck idled when coming to a stop, it always seemed a little too high or too slow to come down to normal, when I bought the truck it had the thermo stuck open...I would guess for quite some time...I replaced the thermo and it started idling better because it was finally warming up to operating range but the idle still seemed high..usually indicative of a vacuum leak...when I couldn't find an obvious one I started suspecting the intake manifold and replaced the upper plenum o-ring gaskets, now it idles perfectly, so I know that it was worth doing.

 

[9's]

I was never happy with the way my truck idled when coming to a stop, it always seemed a little too high or too slow to come down to normal, when I bought the truck it had the thermo stuck open...I would guess for quite some time...I replaced the thermo and it started idling better because it was finally warming up to operating range but the idle still seemed high..usually indicative of a vacuum leak...when I couldn't find an obvious one I started suspecting the intake manifold and replaced the upper plenum o-ring gaskets, now it idles perfectly, so I know that it was worth doing.

Did your truck idle high when rolling to a stop?...then kick down once you were completely stopped?

auto or man?