O2's like they have gone dead?

[BigM460]

Made a 2nd gear pull on the way home from work and ever since my torque app shows 0 voltage at either O2 and short term fuel trims are running up to 38-39. Barely idles and sounds cammed up?
Any thought what's going on?

[BigM460]

Nobody has any ideas? Is it even possible for both oxygen sensors to go bad after a full throttle blast? Fuel pressure looks fine, but it's running very fat with the O2's flat. Any way to test them? Anything else that might cause this?

Ordered a pair of O2's, but will take a couple days to get.

[fastblackmerc]

Check the connectors and wiring.

[chief455]

Nobody has any ideas? Is it even possible for both oxygen sensors to go bad after a full throttle blast? Fuel pressure looks fine, but it's running very fat with the O2's flat. Any way to test them? Anything else that might cause this?

Ordered a pair of O2's, but will take a couple days to get.
I did not want to comment, as I'm not experienced in these engines or related sensors. It does seem as if both your sensor failed, based on no voltage readings. I'd start there as well.
I believe I found a way to test or temporarily eliminate them by reading google search results - from a truck forum I think. back when I was looking at my sensors last year.
good luck!

[justbob]

I'm thinking your FRPS just took a big fat dump on your sensors and cats or you just sprung one hell of a vacuum leak.


Builder Of Badassery

[chief455]

Nobody has any ideas? Is it even possible for both oxygen sensors to go bad after a full throttle blast? Fuel pressure looks fine, but it's running very fat with the O2's flat. Any way to test them? Anything else that might cause this?

Ordered a pair of O2's, but will take a couple days to get.

https://www.youtube.com/watch?v=QM2jO0_Cah0

[BigM460]

Thanks for the suggestions! I've checked the O2 connectors, is there another plug further up the firewall? Wouldn't the fuel pressure be crazy if the FRPS went bad? Was still showing fuel pressure in the 39psi range.

I've had an issue since installing the headers from time to time after the car wash. Wondering if it's related? Will barely run and skips and sputters until something drys out.

[chief455]

If you have time to kill waiting on the new sensors, I'd try that video heat test on yours. If they prove good, don't need the new ones and need to further diagnose.
If they both fail, pop in the new ones and see if she's cured! Could be related, maybe the sensors were getting wet...
may have nothing to do with them at all = need to test or swap them first, is my thinking.

[fastblackmerc]

Thanks for the suggestions! I've checked the O2 connectors, is there another plug further up the firewall? Wouldn't the fuel pressure be crazy if the FRPS went bad? Was still showing fuel pressure in the 39psi range.

I've had an issue since installing the headers from time to time after the car wash. Wondering if it's related? Will barely run and skips and sputters until something drys out.
That sounds like a connector is getting wet. I'd pull apart all the connectors, clean with electrical contact cleaner and use silicone dielectric grease when reconnecting them.


If you have time to kill waiting on the new sensors, I'd try that video heat test on yours. If they prove good, don't need the new ones and need to further diagnose.
If they both fail, pop in the new ones and see if she's cured! Could be related, maybe the sensors were getting wet...
may have nothing to do with them at all = need to test or swap them first, is my thinking.

How could the sensors get wet when they are inside the exhaust pipes?

[BigM460]

Hope to get home in time to start checking stuff out. Had to catch a ride to work this morning. Running so fat, I'm not willing to chance it.

Pulled and reconnected just about every plug I could get hold of last night with no change. Can't help but think it's o2 related.

[Zack]

Do what Bob said. I have never seen a weatherpack connector leak in my life.

A bad FRPS can do very strange things to the engine

[BigM460]

I'm thinking your FRPS just took a big fat dump on your sensors and cats or you just sprung one hell of a vacuum leak.


Builder Of Badassery

Well............it isn't the frps. Swapped them from my son's Marauder and mine. His car runs perfect, and no changes from mine. Actually smooths up a bit with a self imposed vacuum leak.
Started poring rain before I got a chance to mess with the O2's. Still 0 voltage from either one.

[RacerX]

Does the exhaust smell like unburned fuel?

[BigM460]

Does the exhaust smell like unburned fuel?

Just smells real rich. It's wanting to idle with a serge, like a big roots blower. Brap..brap..brap..brap.. :eek:

[RacerX]

Did you reset the PCM by pulling a cable off one of the battery terminals?You may even want to reflash the PCM. Reseat all your harness connectors including MAF, IAC, TPS, etc. Pull each individual fuel injector harness offline one at a time and see if there is one that doesn't change the situation (stuck injector?). Check the easy stuff first... Are you able to datalog?

[BigM460]

Did you reset the PCM by pulling a cable off one of the battery terminals?You may even want to reflash the PCM. Reseat all your harness connectors including MAF, IAC, TPS, etc. Pull each individual fuel injector harness offline one at a time and see if there is one that doesn't change the situation (stuck injector?). Check the easy stuff first... Are you able to datalog?

Haven't tried a reset, or a reflash. Stuck injector? Interesting thought. Will mess with it tomorrow after work. Too much rain tonight, and supose to be the same tomorrow. :(

[chief455]

Haven't tried a reset, or a reflash.
I would try this myself, and since both O2's started reading zero volts - it's like they both went bad, or have no input, at the same time. Act of god, but could happen. Free to reflash your tune, free to test the sensors, more info to be gained.

[justbob]

You didn't mention wetness being a factor here. I myself can no longer wash my engine for the same exact reasons. After I yanked my harness, dissected, re taped it, and checked every possible thing, I gave up..


Builder Of Badassery

[lifespeed]

Both O2 sensors failing at the same time is pretty unlikely. Not that it is a bad thing to replace 10 year old O2s, but it is not likely to be the cause of your problem. 0 volts is probably a symptom of the problem causing the rich mixture. They would have to fail the other direction (lean, higher voltage) to cause the PCM to add fuel.

[BigM460]

She's fixed!!!!!!!!!:coolman:

After reflashing the tune, it idled down to a crazy 4-500rpm idle and I could hear a vacuum leak. If it hadn't done that I'd have never heard it over the supercharger noise and it sucking air. On the back, under side of the throttle body. Big leak! Blew that hose off. Couldn't see it until I took off the cover over the throttle cable.

Thanks guys for all the input!

[chief455]

I'm thinking your FRPS just took a big fat dump on your sensors and cats or you just sprung one hell of a vacuum leak.


Builder Of Badassery
+1 for BOB!:beer:

[lifespeed]

She's fixed!!!!!!!!!:coolman:

After reflashing the tune, it idled down to a crazy 4-500rpm idle and I could hear a vacuum leak. If it hadn't done that I'd have never heard it over the supercharger noise and it sucking air. On the back, under side of the throttle body. Big leak! Blew that hose off. Couldn't see it until I took off the cover over the throttle cable.

Thanks guys for all the input!

Aren't there hoses connected to the manifold (that previously only saw vacuum) requiring more-secure attachment once they are under pressure?

[BigM460]

Aren't there hoses connected to the manifold (that previously only saw vacuum) requiring more-secure attachment once they are under pressure?

Just pressed on and it looks a little haggard. Zip tied it until I get something to replace it.

[BigM460]

+1 for BOB!:beer:

Very true!

[lifespeed]

+1 for BOB!:beer:
Agreed, maybe he has seen this symptom before. ;)

[martyo]

+1 for BOB!:beer:

Bob's a hacker.

But I like him any way! :D

[RF Overlord]

Bob's a hacker. Maybe, but he hacks together some of the nicest stuff on this site... :burn:

[justbob]

Bob's a hacker.



But I like him any way! :D

Don't hold back!! :D


Maybe, but he hacks together some of the nicest stuff on this site... :burn:

Thanks Bob. When this is all over can I like get a hug or sumptin? [emoji27]



Builder Of Badassery

[RacerX]

What, no +1 for me since I told you to reflash? ;)
Nice easy fix! I used to have a hose blow off problem on the blower under high boost until I used hose clamps on them. :beer:

[BigM460]

What, no +1 for me since I told you to reflash? ;)
Nice easy fix! I used to have a hose blow off problem on the blower under high boost until I used hose clamps on them. :beer:

+1 for Bill also for suggesting a reflash!:D :bows:
Idle wouldn't have changed momentarily otherwise to hear the trouble.:coolman: