For the past month or so i have gotten a service engine light on. It started when i was driving in a hvy down poor on the way home. Then the next morning it went off after i drove for awhile then came on AGAIN and went off. Final the last time it came on it stayed on. I got it scaned everytime the light came on and it was the same code P0154 (slow response from o2 sensor passanger side)

Now i went to my buddies shop and we cleared out the code and then for around 150 miles the code didnt come on at all. Till i was at a stop light and it started missing really bad then the light came back on.

Its been missing every now and then for the past couple months but only at idle and its normally when the a/c is on. Today it did it pretty bad and that was when the light came on.


1. How can the ac running cause the car to miss more?
2. Could a spark plug loose or a wire loose cause it to miss and then throw a code like that? Everyone at the shop including me have never heard of a slow response o2.
3. Would a 'slow response' o2 cause a car to act like that?? BTW the o2 are about 2 months old.

At 1st i thought burnt wire but i got under the car and where the wire goes into the wire loom it was wedge inbetween the LT1 and the cross member where it goes up to the computer and that wire has been sitting there for 5 months so theres no way its just not burning through it and the wires didnt appear to be melted at all. Can anyone else come up with something??

 

I think you should have a closer look at all the wires. Reset all codes. Then swap the O2's to see if the problem moves to the other side. If it moves, the O2 is bad. If it doesn't, the wiring is more likely the problem. Then replace the plugs and go from there.

Now if you want to read the book I wrote, you can. I'm home sick this morning, obviously suffering from verbal diarreah. That's funny right there, I don't care who you are.

Read only if you are bored or interested.

You have a problem that compounds itself. First of all the "SLOW" problem is a common failure for O2's and I'm surprised your shop has never heard of it. When the PCM sets a 0154, it goes into open loop. If your shop scanned it, I'm also surprised that they didn't see that either. As you should know, when it's in open loop, it runs rich. This can cause fouled plugs which inturn will eventually misfire.

I noticed you have headers in your signature. How long after installing them did the problem occur? There have been many on this sight that have found their O2's quit working soon after the install of the headers. Some have said it was caused by contamination from some sort of residue left in the pipes. I don't know if this is true or not but when I did mine, I ran the engine for a while with the O2's out before installing them. The other cause is air leaks in the exhaust system causing the slow response.

Another common problem with header install is poor routing of both plug wires and O2 wires. Burned wires causing misfires, running rich causing contamination of the O2s and fouling of the plugs.

Yet another problem during header install is needing to extend the O2 wires. Some will simply cut and solder the wires between the O2 and its connector. This too can present problems since the O2's get atmospheric O2 from the wire passages in the rear. Also possibly causing the "slow" response.

You didn't mention removing of the cats or that you had SIM's so I assume you have cats intact. Running rich with those installed will cause their eventual failure and even clogging.

As far as the AC goes, if you're already in open loop due to the O2 failure, when the AC comes on, it only causes an even richer condition (albeit minor) from loading the engine.

One other thing, if you are truly misfiring, you should have gotten a SES for that. Check for the misfire counter and see which cylinder is misfiring. I've seen many later model LT1s that have loose plugs that many times can't be tightened. This is usually accompanied by what some untrained ears call a ticking sound. The seasoned ear hears a shh shh shh sound like air rushing out an opening.

Sorry long

 

Well the new O2's went in after the headers were installed for about 3 months. And they went in whenever i got the computer from madz28.com.

Right its is missfiring ALOT more quick im going to check all the plugs and wires today and check them out to see if they are tight still and everything.

As far as the air sound i did hear something like that the other day. I've only heard it once or twice and it happened every 5-10 secs but i only hear it when the car is off. Its kind of like water heating the headers and sizzling which i thought it might have been from the AC.

And the car has no cats. Would a bad wire or plug cause it to throw the slow response tho?

 

So what about the misfire counts?

Do you have any other codes?

Do you have SIMS?

 

My experience thru 4 weeks with that Oxygen sensor specific code plus random misfire (DTC P0300) was this:
I replace spark plugs and both pre cats oxygen sensors with a pair of brand new ACDelco's.
48 hours after, my car SES light came on with P0154 in first place and P0300. The car stumble, hesitate in closed loop reached 45 minutes after the engine was started. Usually, the closed loop is reached 10 or 12 minutes (or less) after the engine was started. After US$500 investment (fuel injectors, MSD spark plug wires, EGR valve, mechanic fees etc etc etc), I asked another reputable mechanic diagnosis.
The new Oxygen sensor had a wire unwelded!!! covered by a black plastic hose and the source of the misfire was the cylinder number 4 because a loose spark plug.
The wire was welded but the DTC went on. So I had to replaced it too...electronic parts...no warranties....go figure....
So, check the sensor wires and connectors, don't discard a new faulty sensor.
The wisdom is in the simpliest things of life.
I sincerely wish you a good luck
dochidalgo

 

i have no idea bout misfire counts.

No other codes.

The rear o2 were programmed out.

I got under it today and 2 of the passenger side wires are cracked. Do you think that could be the cause. I'm not sure how bad they are but atleast 1 of them looks like it could be down to the wire.

and thanks for the info dochidalgo. I'll check that to.

 

Cracked wires can cause a misfire. Have you had the code(s) pulled since it started the miss to see if it is the same one?

 

The misfire counts can be seen thru Tech 2 scanner...
Cracked wires...sure can give misfire.

How about the fuel injectors?.....vacuum leaks? (MAP readings could rule out this)

Good luck
dochidalgo