Hesitation problems

[explorer98]

I got my engine swap done in my 98 explorer from a 4.0 to a 5.0. It starts right up and idols fine but when you give it any throttle it loads up as if the timing is off. Tried driving it around the block and it had no power at all wouldn't go over 15mph with it floored. Any thoughts of what I could do or try but be helpful.

 

[RonD]

Is it blowing black smoke out the exhaust, like it is flooding out?

Is the MAF sensor from a 5.0l and is it hooked up?

What year is the 5.0l and its computer?

Did the Cam position sensor plugs match?

Make sure the TPS(throttle position sensor) is hooked up and working, it tells the computer you want to go(pushed gas pedal down) and then go faster(pushed it down more).
TPS gets 5volts from computer and sends back 1 volt if foot is off the gas pedal and then up to 4.8volts if foot is to the floor, so the higher the voltage the faster you go.

What is the fuel pressure like, have you tested the pressure at the rail?
Should be approx. 65psi for '98

 

[explorer98]

Its not blowing out any smoke. The 5.0 is a 97 and the computer and wiring harness is out of a 99 along with the cam sensor.

 

[RonD]

Fuel pressure "should" be OK, '97 injectors were for 65psi, '99 computer, and '98 fuel pump as well, assuming its all working

Just looked up Cam sensor for 5.0l
'97-'98 were the same but '99 and up show a different part number, so your cam sensor is from a '99 but put in the '97 engine, which would be correct for the computer I would think.

No smoke means more likely lean mix is the issue.
Opening the throttle doesn't make engine get more gas like on a carb engine, it gets more air so idle will go up, like with a vacuum(air) leak.
So as throttle opens fuel flow in not increasing.

The crank shaft sensor(CKP) gives the computer the base spark timing and injector timing, the cam position sensor takes over spark advance and sequential fuel injection.
If cam sensor is unhooked engine will still run but would be sluggish, not like you describe though, computer would switch to Batch fire for the injector(fires 4 injectors at the same time) and the spark advance would be a guesstimate from CKP signal, so it would still be drivable.
So even if cam sensor was 180deg out it would still run better than you describe, but never tested that.

MAF sensor tells the computer how much air is coming into the intake and at what temperature, this sets the gross fuel/air mix the computer uses for the injectors.
MAF not working right will cause bucking and stumbling as computer tries to follow incorrect data from MAF
O2 sensors are just for fine tuning, MAF is the big gun in the fuel/air side, so O2s couldn't cause your issue.

ETC sensor tells computer engine temp, this will set high idle and rich mix cold, normal idle and mix when warm.

EGR vacuum system if hooked up wrong could foul the fuel/air mix, would think it would stall out through, so not drive at all.

The TPS is the only sensor available to the computer that has driver input, it tells the computer to make engine turn faster, what you want to do not what is being done now.


MAF, O2, CKP, Cam sensor are all just "reporting" sensors, along with ECT, EGR and EVAP.
TPS is changed by the driver