Hi fellas I appoligise if this has Ben brought up before. A good friend of mine has a dream job opportunity in FL and is moving ASAP and he has allways wanted me to do a custom true dual exhaust with full length headers and an high air filter/intake. (yes i will be crossing over around the transfer case most likely) My most important question is will the stock ECM handle these mods? And if not what is the best tuneing solution with keeping cost at bay? also if stock ecm is good to go with these mods does the ecm tollerate o2 simulators well or will spark plug nonfoulers do the job ? 2000 F 150 5.4 L THANK YOU ALL !

 

First the ECM will handle the mods no problem.
It has a 25% correction range so the mods won't even approach this limit unless something is done to cause it then it will set a code for the cause as explained below.
Second question is more complex.
Removing OX sensors:
You need to understand the front Ox sensors drive fuel injection correction full time.
If they are missing for any reason two codes can be set.
One for open heater circuits and one for sensor inputs missing.
In the absence of the front sensors the ECM goes to 'fixed' (rich) fuel tables to service the fuel needs and fuel mileage suffers big time, hard cold starting and warm up etc.
For the rear sensors, they monitor the cats for overall health.
If they begin to send a signal in phase with the fronts 'switch to often' then this switch ratio is detected as too high and code 420 could be set along with a code for open heater circuits.
You would be opening a bunch of issues for the owner.
Yes OX sensor 'foolers' can be used but it does not fix the results of using them when the proper fuel control is so greatly affected.
IMHO the payback in performance is not worth the ongoing expense afterwards.
Someone needs to think about this and make a decision.
Of course once he is gone you may never get a Christmas card from him once he sees the effects of the mods on his wallet over time..
Good luck.

 

LOL ! Hello Bluegrass 7 Thank you I do Understand about the O2 sensors very well sir. Thank you for the perfect information about that. I apologizes for not stating the fact I was referring to the downstream after cat 02s. As a matter of fact I will be replacing both upstream bank 1 and bank 2 02 sensors. (Actually after about 65k miles 02 sensors do not read as well as they can. I myself consider them wear items like spark plugs and fuel filters in my practice. as you are 100% correct and would never dream of leaving them out of the system. as the fronts are essential to proper engine computer function. Thank you again
has anyone had any experience with these headers ?

http://www.ebay.com/itm/STAINLESS-STEEL-HEADER-EXHAUST-KIT-99-04-FORD-F-150-HARLEY-DAVIDSON-LIGHTNING-/180890936779?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A2000%7CModel%3AF-150&hash=item2a1df0a5cb&vxp=mtr

 

I failed to address the front sensors if your putting them back at the collectors.
Two things about that.
One the OX sensors are expected to provide their correction signal in a very short time to that bank's cylinders by being close to the cylinder head common exhaust point in their stock locations.
Putting them at two or more times the distance can upset this expected timing event.
Two, the OX sensors will be slower to heat and be more uneven vs engine rpm and load at that distance.
Three if an OX sensor is put into one pipe then only that cylinder is controlling the other 3 on that bank. The PCM does not know the difference. There is no common sensing to all cylinders in that bank.
I am not saying it can't be done but what system design parameter will be affected.
Good luck.

 

Bluegrass 7 You are a smart man my friend thank you again for your great info.