Hi Folks,
I got a 91 xlt with a check engine light that keeps coming on,
the codes I get tell me its the EGR circuit yet I can't seem to find a EGR valve
32 also got code 42 EGO, already changed the O2 sensor still runs the same
Bad idle stalls as if vacuum leak (can't find a leak new hoses) or flooding out.
Rich exhaust.

Any advice for the Explorer impaired?

Thanks

1) Verify your interpretation of the codes. A '91 shouldn't have an EGR system, so it shouldn't throw any EGR codes.

2) CM 42 is an O2 sensor code that is thrown when the O2 sensor stays above 0.45 V indicating rich. You've replaced the O2 sensor, so we'll assume the O2 sensor is good. You also indicate that the exhaust suggests the engine is running rich as indicated by the sensor. This suggests that the O2 sensor is likely functioning correctly and you need to search for the cause of the engine running rich. Check fuel pressure and check for gas in vacuum line to fuel pressure regulator (FPR).

3) For more detailed diagnosis, does the code 42 also show up in the KOER test? Can I assume that it passed (11) the KOEO test?

Mr Shorty,
Thanks for the reply,
I guess I got ahead of myself, Should read the paper work alittle more carefully, no it did not pass KOEO, I got 84 (EGR-V) & 41(EGO) I hope I'm doing this right!

41 can't be a KOEO code, it would have to be a CM (continuous memory code). KOEO codes are the first set output during the KOEO test, then a separator pulse (code 10 on some code readers/scanners), then the CM codes are output.
Unless you have a rare EGR equipped '91, you shouldn't be getting any kind of EGR codes. If you determine that you do have an EGR system, a KOEO 84 would indicate a fault in the EVR solenoid -- either full open in the circuit or short to ground. Should be pretty easy to find, if you find the EGR system.

Shorty,
Got hold of a reader with a led read out, read everything re-ran the test this time it pass the KOEO also test timing seems tobe workimg fine and now the code 41 is all I got after the KOER test HO2S sensor low voltage / sensor lean.
So what to do rith the info? Who in sending the bad info? How do I make it right?

1st: help me understand what just happened. You re ran the test, and this time it passed the KOEO test, but you got a KOER 41. Did you get any CM codes (2nd part of KOEO codes)? Did you warm up the engine before performing the KOER test? A false KOER 41 will be set if you don't preheat the O2 sensor.

Yes the car was warm before I started and as for the CM codes, I belive they were lost after the shop got the codes for me before I got hold of a reader. Also I tested the O2 sensor for ohms (about 6) and voltage (between 0.01-1.1). The MAP tested good also pins A-B (14 volts) pins C-D (0.3-1.9) at idle. Found a bad Canister Purge Valve solenoid replaced it (no change poor Idle). The Check Engine came on after about 15-20 mins of driving I will run another code test in the AM to see if any different codes come up.

Sounds like you are on the right path, let us know what the new codes are...
91's are known for leaking at the intakes :)

Well here we go the code now is 41 in both KOEO and KOER also she seems to smooth out when I DC a vacuume line at the manifold now i will drive and see what it does. I'm totally confused but not willing to give up.

I'm going to assume it passed the KOEO test.
" she seems to smooth out when I DC a vacuume line at the manifold" -- Any vacuum line or a specific vacuum line?
At the start, you said the exhaust suggested it was running rich. Is this still true? Do the spark plugs give any indication of lean/rich running?
Have you checked fuel pressure?
Are the wires between the O2 sensor and the computer intact?