Hello, I am having what seems to be a loss of power which I cannot seem to locate the problem. I will give you as much information as I can. It is a 2000 F-150 4x4 v8 4.6l automatic tranny. I will state the obvious first, please do not ask what codes it is throwing because I have been to aotozone and advanced and I am not throwing any codes and no CEL at all? As for the vehicle I will let you know that the only mod to the system is my cats are gutted, I just recharged the K&N air filter, cleaned the MAF, cleaned the throttle body, replaced the TPS, changed the oil and filter, changed the tranny fluid and filter, checked the 02 sensors to ensure they were connected and working, and still having the problem. It starts and idles fine, but at acceleration it bogs down like Im towing something. Once I get to higher RPMs it is fine. But at times when shifting from gear to gear I will lose power and RPMs seem to drop, then it seems as if it is starving for fuel or air and seems as if it goes into neutral, and eventually catches itself and accelerates again. That led me to replace the TPS. Im now thinking something with the EGR or transmission sensor, but I don't know how a bad transmission sensor would cause the air/fuel symptom it seems to be having. Any help will be greatly appreciated.

 

sounds like you over oiled the air filter and soiled the MAF

 

i agree with tara. just trying clean the maf and possibly put a new filter on. depending on if that is your problem you may have to get maf sensor all together. good luck

 

But wouln't over oiling the filter and fouling the MAF affect all RPM ranges? When I put it in neautral or park I can give it gas and ho;d at 3-4000 RPMS with no hesitation or stumbling. It is at its worst when I go to WOT. I was thinking the filter at first but like I said, I would think that would have an effect throughout the RPM range. It litterally feels like a fuel starvation issue. But I have changed the fuel filter and tested the fuel pump. Only thing I have not done so far is the EGR, which I am going to get to today. But I am not sure if the EGR or relay can have that affect on performance? I believe the EGR and sensor monitors backpressure in the exhaust and manifold, if something within the EGR loop has gone bad can that effect performance and cause low end loss of power, hesitation, stumbling?

 

I had an Explorer that had simular problems and I could not figure it out until I brought it to my mechanic buddy at the ford dealer, after he spent several hours trying to figure it out, it ended up being the motorcraft platnum spark plugs with only 5000 mi on them from Checker Auto! Turns out He says the Motorcraft plugs at checker are not exactly the same spec as the real ones at the dealer! I thought he was feeding me a line of crap but he got me some double platnium plugs at cost and I installed them and it never ran so good!! Amazing the power difference!

Just a thought! you might check it out!

 

Well here is an update and maybe I will get some more feedback. I took it for my inspection today and low and behold I failed the inspection!!! Apparently I dont have any codes because the CEL must be burnt out because apparently I have some stored codes. The codes they gave me were P0156, P1131, P1151. With that I now have another question? Could a bad DPFE sensor be thr ott of y problems such as these codes being thrown and my perfornce issues? Or do you think it is something else...Thanks for the help

 

The P0156 will not affect the way it runs, that's an O2 malfunction on the driver's side rear sensor. All that sensor does is monitor cat efficiency.

The P1131 and P1151 are pointing very strongly to your MAF.

How do you expect to pass an emissions inspection with gutted cats?