Houston, we've got a problem...

[karaoke_carlos]

Performing a Key On, Engine Off test, I received codes 173 and 176.

According to my code reader reference, that means I have an HEGO sensor fault (rich) and HEGO sensor fault, always lean.

Could someone please shed some light in "plain english" on how to fix this problem?

Thanks a bunch!

C:>

 

[bergz0]

check your oxygen sensors. they might be bad. HEGO(S) stands for Heated Exhaust Gas Oxygen Sensor (HEGOS) 173 code is right or rear and 176 is left or front.
here is a website to help you out, get back to me if this was helpful or not thanks buddy:
http://fordfuelinjection.com/index.php?p=31

 

[karaoke_carlos]

Thanks for the hint. I will go purchase a couple of these tonight... and let's see what they do.

 

[MAKG]

Thanks for the hint. I will go purchase a couple of these tonight... and let's see what they do.

STOP.

No code condemns a sensor. It is a HINT. Any part of the feedback circuit OR A REAL CONDITION could cause that.

It's cheaper to pay a competent technician for diagnosis than to replace two (or four) good oxygen sensors. If you're going to guess, you're not going to fix it.

 

[bergz0]

Makg look at the url i sent him. it tells him why the codes are on and for what 02 sensors

 

[bergz0]

and i can get him a 20 percent discount at my work and ship however many he needs to him for 8 to 10 dollars. that applies to anyone. you guys need something let me no. shipping may change if item is bigger

 

[MAKG]

and i can get him a 20 percent discount at my work and ship however many he needs to him for 8 to 10 dollars. that applies to anyone. you guys need something let me no. shipping may change if item is bigger

Well, that's very nice of you. But the cheapest HEGO sensor for these retails at over $50, so with your discount and shipping, that's a $90 guess. That's more than an hour of diagnosis. Sure, it MIGHT be two simultaneously dead HEGO sensors, but it's not very likely.

 

[bergz0]

how many u talkn bout?

 

[karaoke_carlos]

Changed O2 sensors

Well, I've changed the O2 sensors, and the 171 and 173 codes went away. I proceeded to re-run the cylinder balance test and I still get a 20 (second cylinder problems).

I used a "cheap" Harbor Freight test light to see if I am in fact getting a spark from the Coil Pack, and I am in fact getting a consistent spark. This leads me to believe I either have an injector stuck in the OPEN position, or I have something else wrong in that cylinder.

Any other suggestions/ideas?

Thanks again,

Carlos

P.S. I went ahead and replaced bot O2 sensors, since the truck sat around for a while and it was abused for who knows how long. Right now, I'm just trying to get to the point I have a reliable truck for daily commutes of 1-10 miles. Just so I can work on my other car.

 

[bergz0]

so it worked in a way right?

 

[karaoke_carlos]

We definitely made strides in the right direction. I still can't figure out what's going on with that (*&^(*&%^)( second cylinder. I'm going to leave it alone for a couple of days and get back to it next week, once I've had a chance to research and think more about it.

Thanks for all your help!

Carlos

 

[MAKG]

OBD-I mixture codes are not terribly reliable, and a misfire BY ITSELF can flip a lean code; compensating for that can flip a rich code in the other bank, since no amount of fuel can use up oxygen in a misfiring cylinder. Sound familiar?

You don't really know if you have made any progress at all, and you clearly haven't solved the problem. That's what I meant by a $90 guess. You didn't get anything for that $90.

As for replacing them because they are sitting, WTF? Oxygen sensors aren't milk. They don't go bad from sitting. In fact, they do ABSOLUTELY NOTHING until heated up to over 600 deg F. The eventually get consumed, but not in a sensible vehicle lifetime (my Prizm has almost 300,000 miles on its factory original sensors, and they work fine).

You picked a tough project to learn on. You're clearly jumping to conclusions, and you need a pro's help.

 

[karaoke_carlos]

You're probably right. And I did spend money that I might not have had to spend. However one of the oxygen sensors had a poorly made splice that was no longer connected. I knew I could match up the grey and black wires, but the two white wires were a wild guess. I decided it was easier/better to eliminate THAT part of the issue, and the other was a "while you're in there" type of thing. But yes... it's starting to look like it's probably something internal... and that's going to be the challenge. I didn't really PICK the project, the project picked me! I'm just trying to get past it so I can concentrate on my other project.

 

[MAKG]

If those wires are the heater circuit, it doesn't matter in which order you hook them up. It doesn't even matter all that much if you don't hook them up at all (as long as they don't short to ground). HEGO sensor heaters tend to be VERY weak and kinda pointless compared to a good hot exhaust stream. Try it out with electrical solder if you want -- 600 deg F is enough to melt it.

But yeah, bad splices can be at issue. Seen it done. Cursed the guy who did it. I prefer to splice with solder and heat shrink, but it should never be necessary in this spot.

I think your real issue is cylinder #2. You can inspect the spark plug after running for a short time to see what's going on (is it wet with fuel? carbon fouled? damaged? widened? bridged?). You can also verify the spark plug wire is doing its job with a timing light (on #2 instead of #1) and test the injector for shorts or opens with an ohmmeter (if it's shorted, you'll probably need a PCM as well).

When you ran the cylinder balance test, was #2 completely dead (no response at all) or just weak?

 

[karaoke_carlos]

Thanks for your response. I haven't run the truck long enough yet, to be able to get a reading on Cyl2 spark plug. I did, however, run the compression test, and I confirmed that it is firing, using a spark testing tool (don't know what it is called), so I can see that the spark is in fact being generated.

I don't know if the cylinder is dead, as my code reader only spells out the cylinder that has an issue. The next step, I guess, is checking the injector. I will go ahead and see if I can troubleshoot it with the ohmmeter. not sure what a PCM is.

Thanks again!

P.S. I just remembered... when i took the heads off... that cylinder's spark plug had no electrode whatsoever. That was the cylinder that failed and the head was cracked between #1 and #2 cylinders. I wonder if the issue is related.

I think your real issue is cylinder #2. You can inspect the spark plug after running for a short time to see what's going on (is it wet with fuel? carbon fouled? damaged? widened? bridged?). You can also verify the spark plug wire is doing its job with a timing light (on #2 instead of #1) and test the injector for shorts or opens with an ohmmeter (if it's shorted, you'll probably need a PCM as well).

When you ran the cylinder balance test, was #2 completely dead (no response at all) or just weak?