whats up everyone, my 92 vx has an o2 code, and the check engine light comes on after driving for a few minutes. before the CEL comes on i can feel the computer go into lean burn and everything seems fine, then the CEL comes on and it runs alot better, quicker, better throttle response, and smoother accelaration. my question is this; last night all the way from work the light never came on, and the car seemed to buck and miss on acceleration alot, and im wondering why it runs better when the CEL is on. my theory is the bad o2 reading causing the a/f to be wrong, and then going into open loop when the light comes on making it better. just wondering what everyone else thinks.

 

Im thinking you have more codes then just the o2 if your car is bucking. o2 sensor wont cause bucking. Running good or bad.

 

it only bucks when the light isnt on, once the cel light comes on it runs perfect. i have pulled the codes many times and only get the code 48 for the 5wire o2.

 

ttt anybody

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by schardbody &raquo;</TD></TR><TR><TD CLASS="quote">whats up everyone, my 92 vx has an o2 code, and the check engine light comes on after driving for a few minutes. before the CEL comes on i can feel the computer go into lean burn and everything seems fine, then the CEL comes on and it runs alot better, quicker, better throttle response, and smoother accelaration. my question is this; last night all the way from work the light never came on, and the car seemed to buck and miss on acceleration alot, and im wondering why it runs better when the CEL is on. my theory is the bad o2 reading causing the a/f to be wrong, and then going into open loop when the light comes on making it better. just wondering what everyone else thinks.</TD></TR></TABLE>

I had something kind of similar, and I think your theory is right.

I had the same CEL (bad O2 sensor) on my 92 VX that would light as soon as it warmed up. I did not have the experience you describe with bogging or missing, but when I replaced the O2 sensor, the car ran smooth but was down on power, with slower throttle response.

My theory was that when the ECU saw bad O2 sensor it went back into open loop mode, and it made more power since it wasn't leaned out to within an inch of its life (which is the stock VX condition). The rich condition (well, rich for a VX, normal for most engines) would also explain why my mileage was 10-15% lower with the CEL.

So I think you're right, and if you change your O2 sensor, you'll lose the throttle response that you have when the CEL is on. On the other hand, you won't have the stumbling, and you'll get better mileage.

 

yeah, im getting about 36 MPG now and thats 90% highway. also, the stumbling only happens when the CEL light is off, once it comes on it runs great. oh well, i will just wait for my D15b swap in a couple months.

 

you're idea is 100% right. My VX ran really strange when the O2 died.

Prior to the CEL being on it's trying to use the O2 signal and compensate accordingly, which causes it to run like you mentioned.
once the CEL is on it ignores the O2 and runs off the maps directly but -ignition and +fuel.

The same things happen to the rest of the models but it's significantly more with the VX due to it having a wideband.

 

relic you are the man, im still undecided on the D15 swap or new o2 for the VX, my motor only has 100k on it and runs like a champ, but the performance sucks.

 

toss in the O2 and acceleration will be a lot better than it is now.

Honestly I wish I still had my VX some times. Like when I pull up to the pump every 200-225 miles.
I'm thinking of starting searching for a VX for a second car... they are getting really hard to find without a swap.

 

O2's will not cause bucking. I have had 2 different episodes of bucking with simultanious O2 sensor codes. One was the TPS and about 6 months later I had a bad rotor that was rocking on the dist shaft. Both caused the same feeling problem, but the only code that was thrown was O2.

 

amkee, was this experience in a VX??? non-VX owners dont realize the vx feel is alot differant than ANYTHING.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by schardbody &raquo;</TD></TR><TR><TD CLASS="quote">amkee, was this experience in a VX??? non-VX owners dont realize the vx feel is alot differant than ANYTHING.</TD></TR></TABLE>

Have you tried just running with the bad sensor unplugged? The CEL should then be on the whole time and you'll get the richer mix.

 

i dont really know why but last summer we had a really bad storm and my car got a little flooded. i had about 2 inches of water in my car.. after i got all the water out my car was doing the same thing yours was. drive really good when the CEL was on then shitty when it was off. but all i did wat take my ECU out one night and and let it dry everything was fine after that...

 

i thought about unplugging the O2 but it usually goes into open loop pretty quick so its not a big deal. its just like once a month or something that it doesnt come on for a whole trip to or from work. so i guess i need someone to sell me a damn 5wire.