OBD I Code Help Please!

[james.oco]

1995 Explorer XLT 95K Miles: For a while now I've had an issue with an intermittent rough idle. Occasionally when I start it up it will idle roughly, though normally it seems as though this happens only when I hold the key and run the starter for just a second too long. And often when I am driving for a while and then come to a stop and idle, a check engine light will come on. It will then go off as soon as I start driving again. After some investigation I cleaned and eventually replaced the Idle Air Control valve. That was not seemingly not the problem. Recently when cold I've had trouble starting the vehicle entirely. It will eventually start though has to crank for about 5 seconds or so. Once the engine warms up I have no problem starting it. I'll also smell gas after a cold startup which makes me think that it's something electrical (wireset, plugs, or ignition coil). Over the past 95K Miles this has consistently been a vehicle that has always started immediately, with very little cranking necessary. I just bought a code reader to see if there were any stored codes, and I did get a few.

KOEO: 327(Memory) - EGR Valve position or Exhaust Pressure Transducer Circuit below minimum voltage

KOER: 167 - Insufficient throttle position change during dynamic response

From what I've read, the 327 points to a bad EGR valve pressure sensor, and the 167 points to either a bad throttle position sensor or a bad coolant temperature sensor. Any suggestions?

 

[dogfriend]

IIRC, the second code may be caused by not performing the KOER test correctly. When you do the test, you are supposed to open the throttle at the correct time (you wait for a signal from the scanner, but its been a long time since I have done it, so I can't remember exactly what the sequence is). If you don't actuate the throttle at the right time, you will get the code. So, you need to make sure you are doing the KOER test correctly.

I would concentrate on the first code. If you have a sticking EGR or a leaking EGR valve, it could lead to a rough idle by leaning out the mixture too much.

 

[blairwag]

Yea, I agree, the 167 code is likely due to you not "snapping" the throttle at the right time. Any time I run the KOER tests, I always run the test multiple times, in case I fail to snap the throttle or turn the wheel appropriately.

But the 327 code might be an issue. First thing I'd do is locate the EGR pressure sensor and reseat the wiring harness connector. Then, clear the code, and see what happens. If the issue persists, and the same code repeats, replace the sensor.