ive got a 96 f350 sw with a 351w E40D.ive pulled codes ,one code was 23,tps out of range.i got out the meter and verified referance voltage,i checked voltage at closed throttle i got 1v as i opened the throttle voltage increased smoothly up to 4v at WOT.what else could be setting this code?I was having mileage problems as well and one of the other codes was for os2,which i changed and my mileage went up.
I am still having problems ,at idle and speeds under about 20 mph it runs rough and chugs.it also is sluggish under highway speed and seems to be burning rich three of my plugs had a strong fuel smell as well as a sooty tail pipe and occassional light black smoke I tested the fuel pressure if i remember right it was in the 50 psi range and held pressure @ key off.checked all vacum lines.I sprayed soapy water on all the vacum lines with no rpm change.when i soaped up the throttle body i detected an rpm increase but maybe i got the tps wet.I also checked for leaks around the intake.I removed the spout and timed it to 10BTDC.when i reinstalled the spout timing then increased about 3-5 deg.there are no check lights on, cap ,rotor and wires have been replaced.new egr valve installed,there have been no map codes.this truck has always had excessive fuel consumption.i bought the truck from my wifes employer and they complained about the fuel consumption.where else should i be looking for the cause of the rough running,and fuel consumption?i also checked the sensor on the side of the throttle body{evap sensor ?}

 

Question you have a 96 if I am correct that year OBD II was installed on your truck you will need to pull the DTC Codes for OBD II you will need to connect to the DLC ( data link connector) you will not be able to use the flash mode as with OBD I vehicles all OBD II codes are prefixed with a letter followed by a four digit number and require a scan tool

as for soaping the vacuum lines, brake cleaner works best if the idle raises then you are leaking vacuum. also spray around the intake manifold..There are several things that will affect air fuel mixture... engine temp sensor(ECT), IAC, TPS, O2 sensor, MAF, Ingintion timing and strength of spark, As you stated above the comp ECM aka PCM was advancing 3-5'

 

Conditions sound similar to a failing mass air flow sensor or engine temp sensor. Does the check engine light come on when you put the key in? You need to look at the emissions tag and verify OBDI or OBDII, check for federal or california emmisions too, while your there. If OBDII, was the correct O2 sensor replaced? Or did you do all of them?

 

its a 96 but has obd1,i figure maybe it was a late 95 marketed as a 96 not sure though the title claims to be a 96

 

the check engine light comes on for a few seconds at startup.i replaced the 02 sensor and it plugged into the harness and screwed in like the original.the TPS has been replaced with a new one and according to the readings i got its working proper.I dont know whats causing the TPS code.is it normal for the timing to advance a few deg. when reinstalling the spout? I drove the truck today it started to stumble and smoke black from idle to acceleration,also smoked going up a steep hill. i could be wrong but dosent it have MAP not MASS.another question is the IAC located on the drivers side manifold between the fuel rail and the intake?I kinda feel like ive got an overly rich condition.I am scratching my a** on this one

 

96 is mass air. I am having a similar problem with my 93... also AN F 350 with the 5.8. I changed the motor in it and its doing about the same thing. Basically sluggish when you step on the thottle with a little hesitation until you let up on the gass. Check your plugs and look for some that might have more carbon or wet fuel than others, this would be an indication that an injector might be bad. Check you mass air, bolted to you air box for the correct voltage readings. The IAC and ACT are two things Im working on doing tonight, If I find thats the problem Ill let you know

 

iv never noticed that it had mass.i have the 3 wire vacum box bolted to the evaporator housing and i thought that was the whole system.you say the mass is bolted to the air inlet box?and i think i figured the IAC is bolted to the TB and the ACT is the temp sending unit between the fuel rail and intake on the drivers side manifold,am i correct?well let me know what you find in your situation maybe it will help me

 

for the 96 or late 95 you will have the following only one O2 sensor located at the Tee in the exhaust system before the cat.. MAF sensor located next to the air filter box in line on the intake pipe to throttle body..At the Throttle body you will have your TPS located bottom side and your IAC looking at the engine from the front located right hand side of TB. then you will have the ECT (engine coolant sensor)located near the distrubitor{and it will affect idle and fuel mixture if sending a cold signal even if engine hot}Then you will have the EGR and EGRV and the EVP located on top of the EGR valve and the FPRC {fuel pressure regulator control}and finally if equiped the MAP or BP locate near the blow motor assembly passenger side( you may or may not have the MAP with your MAF Ford keeps stating that if is part of my MAF system but thay have yet to locate it in my engine bay..


that would be all your sensors and their locations aprox and I would verify year because a 96 motor is different from a 95 as for componets used and sensors and vacuum systems are different also verify the OBD system..it is possible that you do have a 95 set up in a 96 model truck as for at the end of November 95 Ford was bringing out the 97 model and discontinuing the 95/96 model body style for the F150 and phasing the body style out for the F250 and the F350

 

ive got the MAP but cannot locate a MAF ive got two rubber tubes leading to the TB from the intake box and thats it no sensors anywhere around it. there is a silver box with a cable going to the TB on the driver fender near the firewall? I pulled codes this morning.KOEO i recieved code 111 then i pulled all the sensor wires one at a time to note engine differances.pulling the map made the engine rpm high.pulling the IAC didnt make any differance nor did purge valve.when i pulled the TPSthe rpm dropped.
then i decided to run a KOERtest and i got all kinds of codes but they may have generated from me pulling the sensor connectors. i got the following codes 41,53,85,36,63 and 24.i cleaned the IAC no notable differance. i am going to try the ECT next.resistance should drop the hotter the sensor gets correct?

 

recheck your fuel pressure, 50 is too high for a v8, they should run in the low 30's.

 

I had this problem when my fuel presuure regulator went bad, bad mileage sluggish low rpms, run great at wide open throttle though! I believe 50 is correct for fuel injected 351, as thats what it was for the lightning. When mine went bad itread 85-90 psi on one tank and didn't work at all when I switched tanks 0 psi. Try that.
Good Luck
Chris

 

Must be something in the air. Seems to be a million of these same threads. Including mine. Check the hesitation thread. Good answers there too.