karuul

Hey everyone,
I have a 04 super crew Lariat 4x4 with the 3 valve 5.4L and auto trans.
The issue I have is a lack of power. 330hp should be able to spin the tires at least a bit in my opinion. First thin I noticed was my TPS is reading no more than 75.6%. I have replaced my TPS and have full travel at the pedal. I don't know if this is related but my fuel system appears to stay in closed loop (CL) even from start up. As well, I can't get my engine to heat up past 86F at least that is what the scanner shows.
I know there is a wealth of knowledge here, and was hoping someone out there might be able to help me out.

MGD

Hi & Welcome!

First - you have 300HP @ the crank on paper. However, the factory PCM calibration forces shifts far too early to ever realize that power. Only aftermarket ( custom tuning) will allow you to see the extra gains.

Second - spinning tires is the worst gauge of output. Too many factors in play - torque management, state of tune, tire mass/compound, available traction/road surface, ambient conditions, weight in bed, gearing, truck model (KR Screw heavier than XL RCSB) etc, etc.

Third - how old are yer front O2's? They may need changing. Here's why: http://vmptuning.com/forum/showthread.php?t=825. After the O2's heat up and light off, they should casue the PCM to drop into CL quickly. OL only occurs at high loads and large throttle openings.

Fourth - with no load ( e.g truck @ idle) the Ford ETC system will limit throttle travel to about where you see it. I see the same. You can certainly try the ETC recal procedure, but YMMV. Remember - it's a torque-on-demand system. The PCM will open the throttle not in direct response to yer foot, but when it's good and ready to after checking a myriad other conditions.

==> http://www.underhoodservice.com/Arti...e_control.aspx


Lastly - not going into OL may be the result of a prexisting fault (pending codes, no CEL). Need to pull those, if any.

best of luck

karuul

So here is an update.
Took a closer look at my O2 sensors with my scan tool.
Results at idle

O2S B1 S1(v) .065-.720
STFT B1 S1(%) -1.6-3.1
O2S B1 S2(v) .795-.815
STFT B1 S2(%) 99.2
O2S B2 S1(v) .065-.710
STFT B2 S1(%) -1.6-2.3
O2S B2 S2(v) .780-.810
STFT B2 S2(%) 99.2

Changed my two rear o2 sensors and no change
Anyone know what the %s are about and why they remain so high?

jamie930

well the rear O2 have nothing to do with fuel management. The rear O2 are only used to compare to the fronts to see if the cats are working

For the scanner showing 86F. Where does your temp gauge read at? It should be right in the center if not you will need to change your tstat. This would also keeps you in the closed loop because the engine temp is cold. So it will burn a little rich to try to heat the engine up

karuul

Any idea what the %s are?

RLXXI

Here's a link that will provide you with all the knowledge you seek. https://www.motorcraftservice.com/vd...tsid=trng_main scroll down and click on gasoline engine performance.

Includes Theory, Operation and the relationships between the systems and system types. Includes use and interpretation of the Diagnostic Test equipment for Fuel/Air, Ignition, Emission Systems and their components.

Same training Ford tech's use.

.

karuul

Thank you so very much!