Good evening
I have a 99 Ranger 3.0l flex fuel. I was recently driving home and the engine became sluggish. If I buried the accelerator, it would bog out and then eventually accelerate. However, the ride home required high RPMs to keep it tunning. I burned up a 1/4 tank on the way home for a 15 mile trip. Got home. Truck died. I was able to start but it would not idle. Required pressing accelerator peddle about 1/4 to 1/2 way to keep running. Eventually that stopped working. Fuel pressure reads 50PSI on manual gauge. I have replaced coil pack, plugs, wires, fuel filter and TPS. I also have a spare rebuilt PCM. Now when I try to start, it seems like it wants to start, catches a little bit, and then continues to turn over.

I have access to the FORscan OBD for laptop. So I can pull some data. Just not sure which data sets to look at or what other components to look at to narrow it down. Interesting note is the TPS lower voltage values are 1.25. Max 4.69. Also, for the setting of Throttle Position Rate, it constantly fluctuates, even only with the key in the on position.

So my question is:
1. What values/readinga would help to diagnose the problem
2 Why is the Throttle Position Rate constantly fluctuating and is it affecting keeping the vehicle running?

Below is a screenshot of the vehicle with the key on. Initial startup shows the TPS perform self check(not captured). Half way across the graph is trying to start vehicle and pumping the throttle.


Any help would be greatly appreciated.

R/S
Jeremy

 

Key on engine OFF
TPS is a 5volt sensor
It should be just under 1volt with foot off the gas pedal, 20% of 5v is 1volt, so TPS should show 17-19%, just under 1volt
Press gas pedal to the floor, should not see 90-92%, 4.5-4.6volts

Start engine
At idle if TPS is fluctuating a bit then throttle plate is lose, high vacuum is causing it to open and close rapidly, could be broken or weak spring

If its fluctuating a lot then wires are shorted together or TPS has internal short, new or not
TPS has a 5volt wire and a ground wire, then center wire that goes back to the computer, that's the wire you see on the OBD reader


Try this test, Clear Flooded Engine test
All computers have this function to dry out a flooded engine
Key on
Press gas pedal down to the floor and hold it down, TPS at 90% or 4.5v
Try to start engine
It should NOT START, it should not even fire, all the fuel injectors are shut off
0 RPMs + TPS at 90% = shut off fuel injectors, or "Clear Flooded Engine" mode

If engine fires/starts then you have a leaking fuel injector, flooding out the engine

You tested fuel pressure with engine running?
If so leave it hooked up and shut off the key, pressure should hold above 25psi for MONTHS and MONTHS


MAF sensor on OBD reader should be set for grams per second
At idle you should see approximate engine displacement, so 3.0l engine should be 3 grams per second to 3.5gr/sc

After warm up, upstream O2 sensors(sensor 1's) should be rapidly changing from 0.2v to 0.7v, average 0.45v
0.1v is too much oxygen, Lean
0.9v is to little oxygen, Rich

O2s don't work until they are heated above 600degF