Help with codes please?

[graham46]

So i'm new to this and its the first time i've tried pullin codes and need some advise.
I got a 92 Ex. Sport 4.0 all stock, for the last week after driving for about 15-20 mins the check engine light comes on. Once i turn the car off and restart it the light if off and will then come back on in 10-15mins. So I believe I should be getting 3 digit codes with my 92 right?
So with KOEO i get: 173 & 179 (in continuous memory)
and with KOER i get: 536 & 538
KOER codes are from not being able to gas and break during test i believe, didnt have anyone to help me, would this stop any other codes from showing up?
KOEO codes are both about heated exhaust gas oxygen: sensor voltage signal indicats rich bank 1 & sensor voltage signot not switching indicates rich during part throttle engine operation.
Any thoughts or ideas on if this is my problem making light come on and fixes or advise on what to do or needs to be done?
Thank You

 

[MrShorty]

The presence of the KOER 536 and 538 shouldn't have prevented any other codes from showing up if faults were detected. If it helps, I usually wait behind the wheel after starting until after engine id is output (watching CEL), then press the brake before stepping out. Then, when the cue for the goose pulse is given, I just goose the throttle by hand from under the hood. It can be done without a helper.

1st thing I would probably check would be fuel pressure. You might need to rig it up so that you can watch fuel pressure while you drive to see if it takes that 10 minutes or so for the fuel pressure to spike.

 

[graham46]

another thing i'm not really sure about but driving around with this going on, will it be doing any serious damage or start to cause other problems?
Also i will look into the fuel pressure to see where thats at.

 

[MrShorty]

If it is indeed running rich as indicated by the O2 sensors, that will eventually plug the cats up. Enough excess fuel will get into the engine oil and dilute the oil which would eventually toast the engine.

From other symptoms (exhaust condition, condition of spark plugs), would you say the engine is indeed running rich as indicated, or is it really running lean?

 

[graham46]

I haven't yet had time to get the equipment needed to check a few things, but. Usually while driving I take it pretty easy and try not to push things too hard with my old explorer, but the last couple days I got up on the gas pedal harder than usual and the light has not come back on yet. Could there have just been some residue or clog of sorts that has been blown out/clean from accelerating harder and reaching higher rpms and the problem worked itself out? Or is this just wishful thinking?
Thanks

 

[MrShorty]

Yes it is possible for the problem to have corrected itself. My own observation is that cars don't usually fix themselves. However, it is difficult to diagnose a fault that isn't there consistently.

I would suggest pursuing checking the fuel pressure and such. If something looks out of the ordinary, then deal with it. If you don't see a fault, then clear CM, and drive it until the problem resurfaces with enough consistency/predictability to allow you to diagnose it.