blazinrebel

I pulled the codes from the truck and they said Banks 1&2 were running too lean. Truck runs fine, no hesitation or anything but at first start up it idles (around 1600 rpms) then settles and bounces from 900 to 1100 rpms. Any ideas on what could be happening.

brokenknee

When is the last time you changed your fuel filter? I recently got that code, changed my fuel filter; all was fine after that.

blazinrebel

i was thinking that after i posted. im gonna try that tomorrow and see what happens. ill let you know if it works out. thanks

b4u2

I have the exact same problem. Let me list everything I have done so far.
Replaced fuel filter, cleaned MAF, Cleaned TB, replaced pcv valve, gasket and hose to back of motor, replaced hose from master cylinder to motor, pulled injectors and cleaned them, checked EGR valve best I could, checked TPS as best I could. None of those fixed my problem. When first starting truck the RPM's jump up to 1600 if the air is on (including defrost) it may jump higher than that. So if you fix yours please let me know what you did, and if I fix mine I will post as well. Also checked fuel pressure.

akc150

They are suppose to idle up on start-up then idle back down once they start warming up takes longer in winter than summer. The computer tells motor, unlike carbs with electric choke where u had to pat gas pedal to idle them down. And if a/c on it idles higher even after it warms up that way ur truck wont die at every stop sign or red light. And on defrost in winter it will idle up higher on start-up and then idle down when it starts warming up because the a/c clutch is engaged even on defrost. This has nothing to do with running lean. I have lean problem also and each time I check codes I get 1 of 3 codes left bank lean, right bank lean, both banks lean, like b4u2 throwed kitchen sink at it & o2 sensors, l made a SWAG and replaced gaskets that holds the tb to 90 and 90 to lower intake (1997 4.6) vacuum leak at one of these. Sticky note on here how I found

bien

I have a similar issue, truck was runng fine then the engine light came on,checked codes and 1,2 are lean. When at a stop the rpm idles fine ~ 900-1000 then drops down to 500 acts like it wants to stall. I Checked vacuum hoses for any leaks. Also recently sounds like I have a small exhaust leak.

england

something u may check is that if your map sensor is working correctly make sure there is no cracks in the rubber air line fittings that will also throw off your oxygen sensors

england

i have a 1999 ford f-150 four door four wheel drive and i noticed that i have a break lite on the drivers rear not working and the turn signal isnt as well just changed combo switch any feed back on the problem im more of an engine drive train not a whole lot on the electrical side just know alittel more than the basics