Raw Fuel out Exhaust. Please HELP!!!!

[daveg]

Please someone help….
I own a 94 Explorer 4.0 l with 180,000 on it and have been running into problems with it. Here is some background.

15,000 miles ago this exact same thing happened BUT only in the rain. The truck would run Sooo rich that people wouldn’t travel behind me. It would burn your eyes. Well I replaced the Fuel Regulator but the same thing was occurring. I then changed an 02 on bank 2 and my problem went away…. Wellllll after coming home from Vacation the other day my truck is doing the exact same thing. I decided to replace both 02’s but that did not fix it. (I have not tried resetting my computer yet by disconnecting the battery) At times when I am driving, the truck runs normal for a bit only to act up again. I clean my MAFS and for 2 miles the truck ran great again but then like poo again.
I took some codes from the computer and this is what I have.

177 Heated Exhaust Gas Oxygen sensor voltage signal indicates rich bank 2

181 Heated Exhaust Gas Oxygen sensor voltage signal not switching indicates lean during part throttle engine operation bank 1

186 Injector Pulse Width higher then expected or Mass Air Flow sensor signal voltage is lower then expected.

I know the code 177 to be true because when I removed both 02’s to replace bank 2 (left bank) was black and bank 1 (right ) was whitish.. My gas mileage is about 5 miles to the gallon (no joking)

Does anyone have any Ideas????

Please Help!!!!
-=daveg=-

 

[springtensi0n]

UGH. how's your power? i dont know a whole lot about explorers, let alone 1st gen, but a few years ago in my buick, i had the same problem. apparently one of my coil packs died, so i was only running on 4 cylinders. the power didnt seem like i lost that much, but my gas milage was awful. i also had the same raw fuel smell, probably because 2 of the 4 cylinders were just filling up with gas then sending it out without firing. i hope someone can further elaborate, or correct my post if im wrong =/ good luck

 

[88vert]

Could be a mass air meter problem or maybe a clogged cat

 

[410Fortune]

replacing the 02 sensors without resetiing the computer is counterproductive.

Anytime you change a sensor you need to disconnect the battery.

clean the MAS, IAC, and

then CHECK THE FUEL PRESSURE. You have got a problem if raw fuel is coming out the exhaust, either its running WAY too rich or you are not firing spark in all cylinders....

Raw fuel in the exhaust will kill your 02 sensors faster then anything it will also clog your cat = expensive repairs.....

My $$$ is on the regulator, or possibly no spark in 1 or more cylinders.........

Also you could have a seriously leaky injector, but since you siad you had this problem before and then it went away, I wouldnt think a leaky injector seal would fix itself.........

 

[Glacier991]

If you are THAT rich, forget it being 02 sensor. The ability of the short term fuel trim ( the 02 driven adding or subtracting fuel) is about 10% on rich and 5% on lean... not far enough from the lookup table to create your condition. Your 02 readings are a symptom, not a condition.

Realizing sometimes not everything that SHOULD set a MIL (CEL) will.... I'd expect a misfire sensor if it were a cylinder or 2... a bank ? Maybe not. The fact you have one good bank (or at least not rich) kind of rules out a main airflow problem...otherwise it would be the same for both. ... overall high fuel pressure similarly odd as you'd think it would affect both banks equally.Lack of ignition to one bank is a possible scenario though.

This is one of those tough ones that almost makes you wonder about the PCM itself. I'll be thinking on this one a while....

Happy Exploring

Chris

ps. This is a killer on CATS

 

[Glacier991]

Hmmm... intermittent faults... worse in rain.... I am coming more and more to a connector problem.... What if you disconnect the battery, unplug the PCM... plug the PCM back in, reconnect the battery and see what gives?

This IS a curious one. Especially the wide pulse width vs. adaptive strategy (eg the engine should be narrowing the pulse width as it tries to control the rich mixture, not widening it - although at this level of rich you long ago ran out of adaptive strategy limits (about 30% total between long term and short term fuel trims). PCM is still looming in my mind, but maybe just the connector?

Happy Exploring

Chris

 

[daveg]

Update!!!

Update!!!
OK, I first want to thank the people who replied to the post… Very Intelligent people out there…

Here is what I did. I removed the plugs from the car and noticed cylinders 4 and 5 were black. I replaced the plugs and reset the computer and whata-ya know the truck runs great again. I figured one of 2 things leaky injectors or 2 bad plugs. I decided to put some Chevron Techron in the tank to clean the injectors in case that was the issue.
I am not sure if the problem will come back or not but I have my fingers crossed. If anyone else thinks of anything additional that I could check, I would appreciate it.
I also want to mention that since I cleaned my MAFS, my pinging that has been with the truck for the last 150,000 miles is gone. I even went back to regular fuel !!!!
Thanks again you have all been a BIG help.
-=daveg=-

 

[Alec]

Glad you fixed it.

Even though premium fuel can get rid of pinging, in the longrun it makes problems worse in a motor that's not designed or programmed for it.

 

[410Fortune]

if those two plugs were black and the rest looked normal dont forget to look into your upper and lower intake manifold bolts or gaskets being loose/bad.

This is a real common occurance on the earlier OHV's, they come loose or the gaskets leak like crazy.......

Search for it here........

 

[daveg]

Cool, thanks for the tip. If it was the intake, would the problem disappear for a while then come back?
-=daveg=-

 

[410Fortune]

only as the plugs wear out........it doesnt hurt to check though........