Need help

[holliwbase]

I have an 86 Ranger 2.9 that idles great but has problems accelerating. It stumbles. I have consistently gotten KOER codes of 33 and 25 and 77. The 33 code says the test was not initiated and I have tested the EGR valve, the sensor and the solenoid and they're all functioning properly. I thoroughly cleaned the passage on the upper intake as well. So why can't the EEC perform the test? Is the EGR system the cause of the stumbling? The fuel delivery system is new up to the FPR and pressure is within specs. I cleaned the injectors and the fuel rail and used a noid light to verify the electrical. The distributor is new but I had to replace the ICM it came with because it was faulty. Inspected the cap and rotor and used the multimeter to verify the plug wires okay and also replaced the coil. It's timed correctly. Just retested the TPS and the MAP sensor and the ECT sensor was replaced. Cleaned up all the grounds sa well. What should I be looking at now?

 

[RobbieD]

Have you looked at the capacitors inside the EEC itself, for leakage or bursting?

 

[holliwbase]

I did and it was okay. I have a second EEC that has been inspected and have the same issues. I'm also wondering if the knock sensor isn't part of the problem.

 

[holliwbase]

I was thinking about my Ranger not doing the EGR test. I came to conclusion that it was a failure to communicate. I proceeded to check continuity on the line from the computer to the solenoid, no problem there. Checked for voltage to the solenoid and it was good. Hooked up my vacuum gauge to the vacuum line going to EGR valve and the solenoid was sending vacuum to the valve. That leaves the pressure sensor. Checked for continuity on the line going to the computer and it good. Getting 4.9 volts from the computer and now the interesting part. Checked the voltage going back to the computer and with the key on but not starting the engine it was sending back 3.2 volts. I put that part on in early December so it's new. I don't know what the ramifications are of the sensor sending grossly exaggerated pressure readings to the computer. It always seems to run rich so I think that is one result. Would this cause stumbling when accelerating?