neo1971

my engine light is on, autoparts store says the code means its running lean could be the o2 sensor. i had those replaced awhile back. after doing some searching its looks like a vacum leak or bad MAF or EGR. can anyone help on this before i start guessing on very expensive sensors?

its a 1998 F150 V6

torkum

Gotta watch them parts store boys, they will sell a 02 at the drop of the hat. The O2 is doing its job by trying to compensate for a problem. The most common cause of this code is a leak at the throttle body. Do a search for more info.

A7X

Unplug your O2 harness' closest to the manifold and check connection, clean em up if any corrosion is visible, Clean your MAF, Those are free ish... Check PCV and elbows/hoses replace if necessary, Change your fuel filter... run a bottle of seafoam or good injector cleaner in your fuel, buy a couple cans of Carb cleaner and spray thoroughly around all intake gaskets, intake hoses while engine is running and listen for hiccups/bogging, racing, replace gaskets if necessary... I think I read somewhere that these isolator bolts for the intake man. in the 6cyl's go bad and create intake leaks... but you'd think that'd be on both banks, so you have to find what would cause just bank 2 to run lean... Fuel rail/clogged or failing injector? bad O2? partial gasket failure? Good luck!! Hope you fix er up at low cost round the Holidays dude...

https://www.f150forum.com/f12/naggin...res-fix-17448/

neo1971

thanks for the advise, i will try this. i do have a dumb question thoughwhats bank 2 mean? should i run a whole can of seafoam through the gas? i have used that before 1\3 in the gas, oil. intake. and do this before or after the fuel filter change?

A7X

bank 1 is usually the side where the cylinder is closer to the radiator... you can tell by lookin at the plugs, you know how the cylinders are offset/staggered from side to side? On my 5.4 bank 2 is the drivers side of the engine, Bank 1 passenger... and I'm not sure, I've never used Seafoam just heard it does a good job, I don't think it'd ruin a new Fuel filter, I'd try the filter first... Basically your engine is recieving unmetered air after the MAF, or slipping past a dirty MAF going unmeasured, or not getting enough fuel, clog or faulty sending/feeding device... or your O2 circuitry is bad or the O2 itself... Hope all this helps, Maybe someone could chime in on the Seafoam and help out??? Idk what the instructions say on the can

Good old Bill

Suggest talking to the back counter or wholesale parts people at the dealerships, they work with the mechanics and the other shops in their area. You will find there are gaskets issues on this engine. Not the gaskets between the manifold and cyl head but the manifold and the intake plenium that the throttle body is bolted too.

On Fords, bank 1 is in your case cyls 1-3 and is the passenger side of the engine. Cyls 4-6 is the drivers side and is bank 2.

About 02 sensors, the sensor is telling you of an engine condition out of parameters and is throwing a code. If the sensor itself is out of spec it will print a code for that. Reread torkum's comment, it says it all. 02 sensors take a hit all to often when actually there are not defective.

My 02 4.2 is constructed with a different plenium and is affected by a TSB for the PO171 & PO174, Do what ever tests that you are capable of in looking for the intake leak that is causing the condition.

After complying with the TSB, I went 18 months with out a code being thrown, then I got a hit, PO174. It was very infrequent, like 2-3 weeks and would show its ugly self again. It eventually got worse, 2 or 3 days, then the cause showed itself completely with the brake booster failing. Special ordered the booster for the V-6 and replaced it. Its been 3 months and no more PO174. Point I'm try to make is, other things can affect an engine and the codes printed by the computor. Keep an open mind and proove or disproove every possibility.

Keep sucking Baby, this IS fun stuff.

arch713

does the 5.4 have the same isolator bolt problem?