97 ranger 4.0L V6 running lean

[SteadyMobbin13]

so I've been thinking of putting an adjustable fuel pressure regulator to fix this "too lean" issue and for performance. I took a code scanner and came up with P0171/P0174 which means too lean. I've done cold air intake, throttle body, plus4 spark plugs. what I've read and learned is that I would need to install a air/fuel guage to monitor the it till I reach the correct air/fuel ratio, after that it not needed. Also I LOVE MY 4.0L V6!!! till I can 5.0 swap so. It makes good torque and its done me well, i use it for commuting and for the twistys. I know i will need a chip or reprogram it eventually but thats after I get headers and cam. So... will this help me in both ways and what else can i do to sqeeze some ponys out of this?

 

[TrexMex]

so I've been thinking of putting an adjustable fuel pressure regulator to fix this "too lean" issue and for performance. I took a code scanner and came up with P0171/P0174 which means too lean. I've done cold air intake, throttle body, plus4 spark plugs. what I've read and learned is that I would need to install a air/fuel guage to monitor the it till I reach the correct air/fuel ratio, after that it not needed. Also I LOVE MY 4.0L V6!!! till I can 5.0 swap so. It makes good torque and its done me well, i use it for commuting and for the twistys. I know i will need a chip or reprogram it eventually but thats after I get headers and cam. So... will this help me in both ways and what else can i do to sqeeze some ponys out of this?

Do you actually have something happening with the engine? lean condition usually means rough/high idle... P0171/P0174 could be O2 sensors as well IIRC...

why don't you try disconnecting your current FPR first? that should give you an extra 5psi in the fuel rail... dunno that would help, though, as there's so much flow rate you can get from stock injectors...

 

[Ford Doctor]

Installing an adjustable FPR is just putting a band-aid on the problem and not getting to the root cause, which is likely intake gasket leaks, failed pcv valve or vacuum hoses.

 

[bmerr98]

Bad egr valve can throw a lean code too. Can you get it smoke tested to check for leaks?

 

[bigmark303]

I get the same codes on a cold start in 30 degree or lower temps. If the engine is not running rough or losing power then its just a vacuum leak. The lower to upper intake gasket is a common hot spot to throw both those codes with little sign of an issue. Next is just check all your vacuum lines and clean the MAF sensor.

Is the truck running rough or just idling a bit high on startup and not affecting drivability at all?

 

[SteadyMobbin13]

Its been like this over a year now, never had an issue except for the check engine light. The other day I randomly crusied at 100mph for almost a mile and then after that it started sounding like my carrier baering went out. Almost like the drive shaft was hitting something till I realized it was miss firing under load. I'm thinking that could be caused by my fuel pump, the computer did say something about it when i last got the codes checked. I totally forgot about a smoke test tho, will have to do that first. I also picked up a code scanner yesterday finally, so that should me greatly

 

[Dune Runner]

This is what happened to me. I had the same issues. Truck ran fine but CEL wouldn't go out. Had lean codes. I searched forever trying to find a vacuum leak or whatever was causing it. It ended up being the vent line on the top of the fuel tank. It would allow fresh air to be sucked into the line when the charcoal cannister would go into purge mode. That happens almost every drive cycle. It would cause a lean code every time. The line on my tank had just come loose. I snapped it back on and the problem was solved.

 

[SteadyMobbin13]

i found the issue that i should have started with....broken spark plug in cylinder #3 lol wow. in turn the fuel pump was going out and the fuel filter needed to be changed so all in all i didn't waste any money. the other cause for the fuel was the preasure regulator. the lean code is still because of the intake leak but im getting close to the 5.0 swap sooo **** IT!!

 

[cp2295]

Have you replaced the intake manifold gaskets or done the o2 sensors? And just in case your truck ticks replace the rocker arms and pushrods! My truck sounded like vw bug or something.

 

[SteadyMobbin13]

well i broke down and did it. i got an oem gasket kit $240.00 for the ranger. in the prosses i painted the valve covers and exhuast manifolds, BUT i found that i have a crack between a intake and exhaust valve, F-me. i just ordered new set of heads from Heads Only in texas $390.00 with shipping for 2 complete heads. i will post pics just was on a time crunch but now its the waiting game