Poor Acceleration When Warm/Hot

[mdbjohnson]

I have a 2000 Expedition, 5.4, AWD, 145,000 miles, K&N Filter, original owner, very well maintained. Also use 100% gasoline 95% of time. Starts fine when cold and in cool weather but in hot weather, after it has warmed up and in particular in traffic it is very sluggish. It accelerates slow, like it was pulling a trailer. No misfire. When I press the accelerator it starts moving and then the power seems to leave. This week I have replaced alternator, fuel filter, PVC valve and hose to back of engine, cleaned mas air flow sensor, installed 8 new motorcraft plugs, 8 new coil packs, and cleaned IAC control. Still sluggish. No codes have ever shown up when this happens. Does anyone have any ideas?

 

[toms89]

If you had a sct programmer or possible some of the others you could datalog while this occurs and the programmer would be able to read all the sensors and parameters as it occurred and give you an answer.

Short of that my first guess would be the IAT readings are high and its pulling timing. Is your K&N well isolated from the engine heat? Another possibility I can think of is it is detonating and again pulling timing via the knock sensor readings. You did not mention your coolant temps so I assume its in the normal range.

The hotter and more humid it is the less power the engine will actually make. Cool dryer air equals more dense air or basically more oxygen per cubic volume the motor ingest. But your description makes it sound like its losing more than the norm.

Drag racers love cool dry air for power.

 

[mdbjohnson]

K&N is well insulated from heat and has been in vehicle for past 1250,000 miles. Engine is not running hotter than normal. Since new it has never had an over heating problem, even last year when the therm-coupler (fan clutch) went bad it still did not heat up. Tulsa is very hot averaging 103 currently and very dry, humidity around 25%. The vehicle is loosing substantially more power than it should based in temp and humidity. I do have a scanner that reads as vehicle is driven however, not sure what I would be looking for.

Thanks for your thoughts.

 

[toms89]

I assume you are running the a/c which just adds more heat to the motor. My guess would be the Intake air temp readings are almost off the charts and its pulling a ton of timing out of the motor. You loose progressively more power as it pulls timing and this is quite noticable. This compounded with bad air and.....

If I was datalogging I would look at the IAT readings and timing.

It feels like a suana here in Baltimore today with 100 deg temps and 20% humidity. My 2005 5.4 work van was way down on power today with the a/c running and the heat. It has symptoms similar to what your describing. Feels like it has 50% of the power if that pulling away from a traffic light.

 

[cbiii]

Im having a similar problem, only it will actually stutter and chug. If I push the pedal down slightly, it may even stumble and lose speed/power.

 

[jcarter4311]

Sluggish problem while taking off

Hi all,
I have the same problem. Taking off after the vehicle is all warmed up, acts like it's in 2nd gear but I know it's not. I am assuming it must have something to do with electronics, but, electronics are better these days, right?!?!?

I definatley notice it when I have the air on, but when I turn it off, it helps, but still sluggish. I do notice it when I tow as well. I have a 4500 lb travel trailer, seems fine, well as good as it can be, when cold, but later after it's warm, yah, really sluggish.

anyone have any solutions to this?

 

[cbiii]

It seems that expeditions just have a CF of problems and no real solutions.

 

[FloorIt]

I've been having the same problems and found some information on another site that seems to answer all the questions and problems.

http://www.f150online.com/forums/v8-engines/8475-poor-performance-now-its-hot.html

There's two TSB numbers associated with this problem (15431 and 15630).

15431 - LACK OF POWER IN HIGH AMBIENT TEMPERATURES
Some 1999-2002 Expedition and F-150 vehicles equipped with 5.4L 2V engine may exhibit a lack of power condition when the vehicle is operated in ambient temperatures above 100 degrees F, particularly during stop-and-go driving. By design, the PCM calibration retards the ignition timing to prevent detonation when the inlet air temperature (IAT) reaches temperatures above 140 degrees F. If the lack of power condition occurs only when the IAT is above 140 degrees F, do not replace parts in an attempt to service. Engineering has developed a new calibration which will be available early in the first quarter of 2002. If the condition exists in other temperature ranges, proceed with normal diagnostics.

15630 - LACKS POWER IN HIGH TEMPERATURES - REPROGRAM PCM
Some 2000-2002 Expeditions equipped with a 5.4L 2V engine may exhibit a lack of power condition when operated in ambient temperatures above 100 degrees F, particularly during stop-and-go driving. This may be due to PCM calibration, which retards the ignition timing to prevent detonation when the inlet air temperature (IAT) reaches above 140 degrees F. A new calibration is available to service this condition. If the condition occurs only when the IAT is above 140 degrees F, reprogram the PCM to the latest level via the just-in-time process if your WDS communicates w/Fordstar. Also obtain calibrations on the Ford Professional Technician Society (PTS) website - select 'WDS' then 'PCM reprogramming' and click 'Instructions' for downloading. Calibrations are scheduled to be included in WDS release B17.10.

I will be talking to my Ford service department in two weeks to see if I can my PCM reprogramed based on the information above.

 

[mdbjohnson]

Well I replaced a number of parts including the main vacuum hose off the base of the throttle body and a bad Idle Air Solenoid and EGR valve and control module. These did help. Power is still down some. Will take to ford and ask for new PCM programing next.

 

[34Ford]

So I seem to have this same problem. Plenty of power when cold, then gets up to temp is like the guy above said it like Im starting out in a high gear.

I am here in NC and it is no where close to 100 degrees, especially now.

Can these tsb's still be useful here at these low temps?