O2 sensor on 1193 X

[wezsitat]

O2 sensor on 1993 X

I did the search and couldn't find how many O2 sensors I have on my 93.

Symptoms are revving RPMs, stalling and bad fuel mileage. I've changed two O2 sensors with no improvements? But I'm guessing I have 4 O2 sensors...

Any thoughts? I'm going to clean the MAF and IAC tomorrow. If that doesn't work?

Shawn

 

[TheJMan]

The 1993s have only 2 O2 sensors. Some of the newer OBD-II Explorers have 4 O2 sensors. Bad fuel mileage could be the result of a failing fuel pressure regulator. Could be a number of things, but my guess is the FPR.

 

[MrShorty]

"Bad" fuel mileage is kind of relative. Explorers aren't known for "good" gas mileage. Just don't want to be chasing a non-condition.

I would pull codes (with or without the CEL being on) just to see what information the computer has in it. I would also check the fuel pressure. Any sense of where your t-stat is opening? I have seen t-stats that open too soon (engine runs a little cold) cause poor gas mileage. Check tire pressure. And so on.

 

[wezsitat]

1993 X

The fuel mileage has never been good, but I'm down to 10MPH. I pulled the codes and received 137/173.

I put the original MAF back after a proper cleaning (had upgraded to MaxFlow). I also cleaned the IAC and still receive the codes.

137- HEGO (HO2S) sensor fault/always rich
173- HEGO (HO2S) sensor fault/rich

I've already changed plugs, wires and 02 sensors. Is the IAC a reasonable next step? Napa has one for $100.00, which sounds expensive, but I have few options as far as auto parts stores.

 

[wezsitat]

Iac

The guy at Napa tried to sell me an IAC that didn't look exactly like the one on my vehicle. It had a black "plug" on the side that looked like a vacuum line or something like that.
I chose not to purchase the part since it wasn't identical to what I have. I'll try Checker auto today and see what they have. Checker says they have it for $20 less!!

Is the IAC a logical step in diagnosing my problem? Or should I go with the FPR? I didn't want to start plugging $$ into this vehicle, but it's my daily driver...

Thoughts?
Shawn

 

[MrShorty]

IMO, buying parts isn't the next logical step in diagnosing the problem. The next steps I would take:

1) Check vacuum line to FPR (fuel pressure regulator) for gasoline (gasoline = bad FPR). Check fuel pressure.
2) Check wiring between O2 sensors and computer. Those codes could be explained by a short to power in the signal wire. What does the O2 sensor signal wire read?

Is the engine actually running rich like the codes indicate, or is it really running lean?

 

[wezsitat]

Fuel Pressure Regulator

Can you tell me where to find the FPR?

I have checked the vacuum lines and they seem to be ok.


The engine is running rich, or at least it smells like it is. I'll have to read the O2 wire later today or tomorrow.

Shawn

 

[MrShorty]

FPR is at the front end of the fuel rail, kind of underneath the throttle body.