Please help me out guys!!!

badstang123 · May 15, 2007

Today I put on some new Bosch 02 sensors. I took it out for a spin after for about 20 mins and the car ran great. Not a huge difference but it seemed to run a little smoother. Then I let it sit for an hour and started driving it again. All of the sudden the car started spudering and losing power. Almost as if I was running out of gas (I have a full tank though). It's the worst when coming off of a stop or something like that. If I'm full throttle the car will run fine or if I have it revved up around 3k or higher and cruise holding it there it seems to do okay. I'm looking at a problem mostly under load. I'm going to go out and poke around right now but any input or help would be appreciated. I also get a popping from the left side like a little backfire or something that sounds likes its in the header or something. idk. thanks.
- Justin

sage2k · May 15, 2007

are your old 02's bad? try putting them back in
it runs fine at WOT because your car stops using the o2's when wot

badstang123 · May 16, 2007

sage2k said:
are your old 02's bad? try putting them back in
it runs fine at WOT because your car stops using the o2's when wot

That's going to be my next step. I'll have to try it tomorrow because it's a little late to be working on the car in the street, since the garage is full. I just don't see how one or both of my brand new O2's could go bad so quickly? It finally threw a check engine light too so I'll have to try and pull codes and see what I find there. Any other ideas would be great too in case the old O2's back in don't fix the problem. Thanks.
- Justin

final5-0 · May 16, 2007

badstang123 said:
That's going to be my next step. I'll have to try it tomorrow because it's a little late to be working on the car in the street, since the garage is full. I just don't see how one or both of my brand new O2's could go bad so quickly? It finally threw a check engine light too so I'll have to try and pull codes and see what I find there. Any other ideas would be great too in case the old O2's back in don't fix the problem. Thanks.
- Justin

Disco the neg batt cable and step on the brakes for about 10 seconds for a pcm reset.

You'll then need to drive it around for a few days for things to settle down.

Grady

BlownFiveLiter · May 16, 2007

You're on the right track. Pull the codes, it may be as simple as the O2 harness not being plugged in completely or something. Did you reset the computer after replacing the O2 sensors, so the adaptave strategy in the computer could relearn all the sensors?

badstang123 · May 16, 2007

I disconnected the battery for about 30 mins when I put the new O2's in. It drove fine for about 20 mins like I said.

Then I went to drive it a second time and it started running real bad after just a few minutes. I filled my tank up because it was a little low, but that made no difference. I got it back home disconnected the battery again pulled the headlight switch and held the brake for ten seconds. After that I inspected all sensor connections under the hood, checked all plug wire connections, cap and rotor, etc. Then I got under the car and checked the O2's to make sure the connections were good and they were in tight. Everything looked good. Then I reconnected the battery took it for a spin and it was almost a little worse. Then right as I was pulling it into the driveway it threw the CEL.

I'm going to switch the O2's out tomorrow and we will see what I find. Bosch 13127 are the right O2 Sensors right? Man...this is frustrating. I hope I didn't fall victim to something else going by coincidence after switching in the new O2's. Good night all.
- Justin

P.S. - I checked fuel pressure on the rail too and it's right at 40 psi

HISSIN50 · May 16, 2007

Good plan swapping back to the old O2's. A parts store dude might have dropped one of your sensors (they dont like impacts) or something like that.

If it was a fox, I'd tell you to disconnect the O2's and run in FMEM. Foxes run great that way but I fear our 94-95's (Grady and the others can give the good info here) run like chit with in FMEM.

One more thought: I always neverseize my O2 threads. Is there a chance that some neverseize got on your sensor elements (if you used the stuff)?

You can also check the O2 switching if you feel up to it (if you have already tapped into the O2 signal wires, this makes it easy. I did that and ran each wire to a SPDT switch so I can read what the puter sees in real time with my DMM). Look for 0.1 to 0.9 Volt amplitude, and a frequency of switching atleast once a second. A bad O2 will often be frozen and this causes some issue (in my experience on the 94).

Good luck Justin.

BlackVert · May 16, 2007

The other thing about O2 sensors is that, since they are designed to measure the difference between the O2 in the exhaust and the O2 in the outside air, they need to let some outside air in. To that end, they are designed to let a little air in through the threads, so if you use some sort of sealant on the threads, they could be not working properly.

Please, someone correct me if I am wrong about this.

badstang123 · May 16, 2007

BlackVert said:
The other thing about O2 sensors is that, since they are designed to measure the difference between the O2 in the exhaust and the O2 in the outside air, they need to let some outside air in. To that end, they are designed to let a little air in through the threads, so if you use some sort of sealant on the threads, they could be not working properly.

Please, someone correct me if I am wrong about this.

I'm not saying you are wrong. But that is definately counterintuitive to me. I'd like to hear some other opinions on this, because I would have never thought of this myself.

Wouldn't you have an exhaust leak then though?

- Justin

final5-0 · May 16, 2007

badstang123 said:
I'm not saying you are wrong. But that is definately counterintuitive to me. I'd like to hear some other opinions on this, because I would have never thought of this myself.

Wouldn't you have an exhaust leak then though?

- Justin

The O2's have a special coating over the wires.
This insulation actually breathes
That is why you don't wanna cut, splice or probe the O2's harness
You always work with the car's harness
as it is made of normal wire and insulation.

When you are in Closed Loop, the O2's should be active and switching
back and forth rapidly like JT talked about.

Sounds like you have done all the simple stuff
It would seem the cel would give you a code that pertains to the prob
I'd wanna know the code before switching out both O2's

If you have a code for only one side ...........
you can do simple things to let you know the prob

Things like swap the new O2's with each other and see if the prob follows
the suspected bad O2
or
Swap the suspected bad O2 with one of the older original O2's

Use the codes to work smart
as opposed to
Just doing a bunch of random work hoping to stumble upon the prob

Grady

badstang123 · May 16, 2007

The thing that is unfortunate is that I bought a scanner the other day but it didn't work. It's one that a few other people on this site have. When I called the tech line for the company they said it is compatible for our cars except for ones in California. So it looks like I'm pulling them manually. I hate it because it's such a PITA. I'll let you guys know what I find out tonight when I get home from work. Thanks for the input.
- Justin

vp6799 · May 16, 2007

Mine did the same exact thing. After checking everything and wasting time, it ended up being the distributor. The holding bolt loosened itself and allowed the dissy to spin with the rotor's momentum. It retarded the timing and made the car run exactly like your describing.

badstang123 · May 16, 2007

vp6799 said:
Mine did the same exact thing. After checking everything and wasting time, it ended up being the distributor. The holding bolt loosened itself and allowed the dissy to spin with the rotor's momentum. It retarded the timing and made the car run exactly like your describing.

That is one thing I overlooked. I doubt it's loose but it's definitely a good thing to check. Thanks for the advice.
- Justin

HISSIN50 · May 16, 2007

And for ease of removal, I do like to use a tiny bit of neverseize on the O2 threads (being careful to not contaminate the element).

badstang123 · May 16, 2007

Okay guys here's the scoop. I needed the thing running right so I didn't even bother to pull codes yet. I went straight to the O2's. Since I got a little backfiring from the right side near the header between when it was studdering and I was trying to hit full throttle I kind of though maybe it was the passenger O2 only that was bad. I replaced the passenger side O2 first. The car ran a little better but still missed etc. Then I put the other old O2 into the driver side. After both were out it runs fine again.

Now where do I go from here. Could one O2 going out make both go out? I did have to drive it for 10 miles or so with it missing, studdering, etc. I mean parts are being made cheaper and cheaper these days, so it wouldn't surprise me if one went bad the first day. But two? I'm just really wondering why this happened. I got the Bosch ones because in the other thread they said they were the ones that didn't go bad And I really hope Napa doesn't give me any crap when I go to return them. Just tell me what you guys think. Thanks.
- Justin

P.S. - I'll post codes later when I get around to it. Pulling manually sucks.

badstang123 · May 17, 2007

I called Bosch this morning and the rep there lead me in a direction I hadn't really though of. His feeling was that I have a different problem and the previous old O2's just weren't sensing things being off as much as they really were. Basically saying that their rate of voltage change was probably a lot slower and closer to .5 v than the .1-.9 that the new ones would be. I hadn't thought of this before but I guess it is possible since I was getting a codes with the old O2's in. What do you guys think? This seems more reasonable considering the fact that I really doubt both new O2's were bad out of the box. Any input would be appreciated.
- Justin

final5-0 · May 17, 2007

Run the codes and get back with us in the morning

Sounds kinda Dr Like ... Don't it

Grady

badstang123 · May 21, 2007

Okay. I swapped the new O2's back in and went back to the stock mass air sensor instead of the Granatelli I have that's calibrated for the 19lb injectors and cold air. The car seems to run well. I'm just hoping it stays that way. I'm going to pull codes tomorrow and see if I come up with anything even though it is running well.

I have one other question. Do the O2's affect WOT driving at all? I've always been conservative with my timing because I seem to get pinging issues now matter what sensors I clean or replace or what gas I run. Now that I have the new O2's in, however, the car just kinda feels like it wants some more timing at WOT. I don't think they do, but the car feels a little different with the new O2's in so I was curious. Thanks.
- Justin

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