Popping, loss of power, then back to normal

1992 4.0l aw4 obdI np231 178k

Checked for error codes and got

1-2-2-1-5-5

I know the 55 is the end of the sequence and my book doesn't show code 12 if it exists. Code 21, though, is clearly a failing O2 sensor.

Sound reasonable/plausible? Mine hasn't been changed since i've owned it.

Another thing. I accidentally left off the oil cap after adding a bit of oil at the gas station. The stumbling happened before i realized and replaced it. It has not stumbled since. Coincidence? (i'm thinking probably, never heard of the cap causing that issue.

Would a failing o2 sensor cause a funky exhaust smell, by chance? Mine kinda reeks, lol.

http://www.naxja.org/forum/showthread.php?t=1034911&highlight=sensor

This thread may offer some insight. As you can see by my post(#3) O2 replacement fixed my issue too.

Ok cool. I checked out that thread. Sounds like a very good possibility that this is my issue. Especially since its throwing that code, too.

We basically drove over to Chula vista this afternoon, helped load/unload some furniture for a few hours, and then began our drive home. once back in El cajon, about 10-15 miles away it randomly went pop-pop-pop and even at about 1/2 throttle had no power.

It felt like the one time I've run out of gas (jeepster commando, bad fuel gauge).

I let up, and it went away and didn't happen again, even after we stopped for food, and at my wifes school to drop off some furniture.

SO weird. haha.

Thanks for the input, Ronbo.

(BTW, I'm not ruling out a fuel pressure/delivery issue. I'll have to see if I can get my hands on a fuel pressure gauge, before I throw parts at it. I've got a pretty long crank upon start up, too. Maybe thats a different issue)

We'll see how it drives to church tbis a.m. Might be wrenching later, haha.

drove fine, going to and from church, with a bit of popping when we first started out.

Went ahead and got a new bosch O2 sensor and just installed. I figure I have no idea how old the existing one was, so its a good plan any way you slice it.

Do I need to disco the battery for a spell, then reconnect, and go for a drive? (to allow the computer to re-map itself?

or will the new 02 sensor do everything just by being installed?

Oxygen sensor doesn't require a battery disconnect/relearn process.

You said you installed the oxygen sensor but you didn't say if it helped?? Did you install the "pre-cat" sensor? That is the one that is most important to fuel/air mixture. The "post-cat" sensor is basically there just to monitor catalytic converter efficiency.

If it didn't, I would go back and verify fuel pressure with a gauge. Backfiring/popping in the intake can be indicative of a "lean" condition. Proper fuel delivery should be ruled in or out early in the troubleshooting process.

Leaving the oil cap off temporarily should NOT be related to this issue.

Heyh good question. I haven't run the truck long enough to know either way if it has fixed the issue. I hqd enough time to install it, and fire it up momentarily.

By the way. Not sure i have more than one o2 sensor? Its a 1992. Later rigs have two, i think.

I'll probably take everyone on an ice cream run tonight and see how it goes.

truck ran great on the way to work today. only 20 miles, but a good test, none-the-less. I'll have to sniff the exhaust and see if it helped with the sulfer smell.

I still had a long crank this morning, but maybe thats a check valve or battery issue. My battery is pretty old, from the looks of it.

power restored, no popping or losses of power so far, and exhaust smells much cleaner. Still a bit "sulfery" but OMG, its no-where near what it was.

Seems like the rig is much smoother and more powerful @ 55-65 now. Just my seat of the pants assessment.

Oh, and I'm thinking that my long crank is likely a battery getting a bit old. I'll probably swap that out fairly soon. (when I can afford it..haha!)