Hello all,
I'm having an issue with my 97 Ranger 3.0 4x2 that I have inherited from my father in law. It starts and idles fine, but has a stutter during moderate to hard acceleration. As long as i dont het into the pedal taking off from a stop, it usually runs smoothly. It did have CEL codes when I got it. I scanned the truck and handled the codes that were stored, which were for a bad o2 sensor upstream bank 1, and fault code on the cam sensor, and an EVAP leak. So far on the truck, I have replaced the bank one upstream o2 sensor. I have also replaced the plugs, wires, coil, and camshaft position sensor on the synchronizer. I have cleaned the MAF sensor. And finally this past weekend, I have also replaced the fuel pump assembly and the filler neck hose. CEL has remained off and not come back on. I have checked vacuum lines numerous times, spraying Carb cleaner around the vacuum fittings and around intake related gaskets and hoses, with no luck. But again, it's hard to tell since it idles smooth. I keep hearing transmission module, and am hoping this is not the case here. Has anyone else had similar dealings with their 3.0's and what was your remedy? It runs good enough to drive, but the skipping and sputtering when I'm in heavier traffic is annoying. Any ideas beyond what I have already done to the truck would be much appreciated.

 

Are the engine grounds -head to firewall- there?

 

I would run some tests on your throttle position sensor (TPS). The computer should use a throttle change (opening) as a que to enrich the fuel mixture for a short period during acceleration, much like an accelerator pump does in a carburator. You can use an ohmmeter to check that the resistance on one pin combination changes gradually as the butterfly opens. Another pin combo (there's a common ground) should not change, it is a constant 5v reference line.

 

From my notes......
Worn TPS: (Throttle Position Sensor) can confuse shifting points resulting in hard shifts.

TPS has 3 wires 5 volt, signal, return and a ground.
0.69v -0.99v = fully closed – 4.5v-4.8v = wide open.
Voltage should change instantly with throttle positions.

Replace with Motorcraft ONLY.

Install as CCW as possible to establish proper “full closed” position.


If you have an OBD2 reader then select TPS to monitor changes.
17% to 19% throttle closed, 5 volt sensor, so 1 volt is 20%, so just under 20% is correct.
% should change instantly when you tap the gas pedal.
Should show 90% at Wide Open, 4.5v is 90% of 5volt.
Also, a shorted TPS can disable fuel injection.