Hey guys,

Im having an issue with my 05 F150 5.4 truck.

Right now I am running a code for P0171.

Truck has been running pretty well lately, then the wife and I were out shopping yesterday and I went to start it and it didn't start as quickly as it normally does.

I turned it over and then as I normally would I quit turning the key, but it didn't start. So I turned it again and it cranked for a few.. Then finally started, but it was running incredibly rough.

No codes at the time. But RPM's wouldn't stay in one place. would jump around.

I sat there for a min but nothing changed so I decided I would try and drive it around the parking lot. I put it in gear and if I would barely touch the gas it would kind of jump/lounge forward. And when I would go to hit the brake I could feel it still trying to go forward.

The RPM's were staying high.

So I tried to just let off the gas and it ended up speeding it self up to 25mph without me hitting the gas. Still running high RPM's.

Ended up driving the truck home (not to far) but I parked it for a while then came back out and started it again and it was then showing the "Emission Control System" light and showing the P0171 code.

I've been reading about the Stuck Injectors on the 05's but wasn't sure this was the same thing.

I have 87k miles on the truck.

I still have a 93 Performance tune on the truck, should I switch it back to stock before taking it to Ford?

What are you guys thoughts?

Thanks

 

With a S/C and all those mods I'd be afraid to take the tune off.

 

So you don't think that I should try and go back to stock?

If I have it taken into dealer, its possibly they will try and reflash it right?

And any guesses what might cause this?

 

You would run an aftermarket supercharged engine on a stock tune? I don't think that would be very wise.

Is your dealer familiar with Roush? If not, I'd find a shop that is.

 

Check the injectors to see if one is leaking. Sounds like it.

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Sorry, I guess I should have made myself more clear.

My stock tune is the stock Roush tune that came with the truck when I bought it.

I am running a 93 perf tune from VMP Tuning.

And my local dealer has done work on the truck before when I had a passenger side manifold go bad. Couple broken studs I think. Been a couple months.

So I guess what I was asking, should I return it back to the stock Roush tune that I have before taking in.

Okay, thanks. Not sure I'll be able to check that myself, but I'll say something to Ford.

 

Yes, put the stock Roush tune back on it, and tell the dealer what it is.

 

Possibly a vacuum leak? Never encountered stuck injectors before, but I have had vacuum leaks before and had some very similar issues. Just my 2 cents...

 

Well, I put it back to the stock Roush tune.. the truck did not like that..

I struggled to drive it the 2-3 miles to the dealer. If I would barely touch the gas it would jump up to 1200-1400 RPMs but then if I didn't hit the gas at a stop sign/light it would drop down to 330-400 RPM's. It actually died once.

I ended up putting it in neutral at stop lights and giving it a little bit of gas so it wouldn't die.

Truck sounded like an old school hotrod with the RPM's jumping around so much.

And once when I was going up a small hill I hit the gas to go, and it went up to 2200-2400 RPM's but doesn't seem like it wasn't go higher than 40mph.


But truck is in the shop now, guess I will find out soon enough. When I switched back to the stock Roush tune, the truck quit trying to lunge forward like it was previously on the other tune. It also cleared the Emission Control Light and the code which I figured would happen when I changed the tune.

 

Well.. Just got back from the dealer. Bill was $72. But I had Ford Owner Advantage cash built up, so that paid for it.

Official cause per the paperwork says..

So pretty happy that was the only issue. Hard to believe that an vacuum leak like that can cause that big of problems.