WB O2 sensors heating up

[ablackFormula]

I didn't get any replies to my last post about hooking up the FAST and the car not running, and I got past that problem (ended up being screwy IAC values.) My WBO2 sensor keeps reading 15.9 as the actual ratio and the number does not change... how long does it take for the O2 sensor to heat up and start changing values, or am I likely to have already melted a wire to it? Also, how do you know when the system is in closed loop?

TIA,
Rob

 

[ablackFormula]

One more question, would somebody with a relatively stock LT1 engine be willing to send me their FAST calibration? I'd love just to see what differences are in mine vs yours, and maybe it'll help me tune mine better. Email it to tomnjery@Optonline.net

Thanks

 

[bobc455]

The WB will start to indicate values that are pretty close before the engine reaches temp. Most people have their closed-loop activate somewhere between 120 and 140 degrees, because by then the O2 is pretty accurate and the warm-up enrichment has dwindled.

I don't know what errors would be generated if there is a bad wire, but I suspect you wouldn't see the little O2 sensor in the corner of C-com.

-Bob Cunningham

 

[norbs]

The heater in the wb o2 takes about 4 amps and its normal to get hot. If you actually pull the sensor out it will be red hot inside. THis is normal, and i have left the key on many times, with no damage to the sensor, just kills the car battery in time. With the car not running it will read 15.9, as the sensor is reading nothing , because the car is not running. The warmup time is a few seconds, but the closed loop delay is 10 seconds to prevent it going to closed loop earlier. The only way see if its in closed loop is to actually see some o2 correction change from 0. If the o2 correction is always at zero its in open loop!. Remmber if you want to run closed loop you must set your limits to the rpm you want the closed loop to work in. Set you closed loop high and low rpm. I will explain this further.


Example

high rpm 1200 rpm
low rpm 900 rpm.



The engine will not go into closed loop until 1200 rpm is exceeded. after 1200 rpm is exceeded the engine is in closed loop until the enginre drops to 900 rpm. If the engine is reved up again to 1199 rpm its still in open loop, at 1200 it will switch over to closed loop again until the rpm drops to 899 rpm then be in open loop again.




Very confusing isn't it. Also you can have warm up enriichment still factored in and have closed loop working, but if theres any afterstrart enrichment you wont' have closed loop until that decays out, ususally 20-30 secs after starting.

 

[bruce]

Originally posted by norbs
The heater in the wb o2 takes about 4 amps

Are you sure about that?.
4 amps?.

 

[ablackFormula]

After having the car run for 5 mins, the actual a/f reading on the dashboard will still read 15.9. I just spoke to Tony at FAST's tech line and he told me its likely to be a fault in the harness, but he couldn't tell me whether I'm looking for a short or a ground or w/e. But I'm about to go jack the car up now and see what I can find, hopefully I'll get lucky. Is it normal to not have the computer in closed loop at idle though? Because now I have the problem of the O2 sensor not reading properly, and I'm about to go see if fixing the timing table helps with the watery eyes problem. Thanks for the replies and keep em coming if ya can!

 

[norbs]

with the key on and the o2 connected i am getting 4 amps battery draw. I forgot the idiot lights on the dash and the coil pack and module, but i can't see that taking much power when not running or firing the ignition. SO it might be slighty less than 4 amps

 

[ijames]

The module could be sitting there putting full current through one coil. I didn't use to think so, but a mechanic friend told me that he's burned up a couple of modules working on different cars for a few hours each with the key on engine not running, while they were digging through some wiring issues.

 

[ablackFormula]

I jacked the car up and checked out the o2 sensor harness, all looks good, no visible wire meltage/cutting. I did not perform a continuity test or check the wires inside the car for visible cuts, but I was mostly worried about melted wires from the headers.

The o2 sensor has been installed in the car for a while, because I originally had the FAST unit hooked up with inputs only, so that when I went to the dyno, I got some hp/tq #'s of the original PCM's control, but was also able to datalog the engine's a/f output with the WB. The O2 sensor worked during that, and was installed that way for 500 miles at the most.

Once I finished installing the rest of the FAST unit (it's outputs,) the O2 is locked at 15.9 as I said before. Do any of your O2 sensors lock themselves at 15.9 until they are fully warmed up? I'm thinking I have three posibilites to my problem: a, is a bad wire which just wasnt visible, which can be replaced. b, I'm just not waiting long enough for the o2 sensor to warm up, or the dreaded c, the O2 sensor is shot for some reason (which I'm hopefully doubting.) Please give me some ideas/insight as it's driving me crazy, and I need the O2 sensors to do any sort of tuning the get the engine to run right!

 

[bruce]

Originally posted by norbs
with the key on and the o2 connected i am getting 4 amps battery draw. I forgot the idiot lights on the dash and the coil pack and module, but i can't see that taking much power when not running or firing the ignition. SO it might be slighty less than 4 amps

Dat's a bit better.
4A is alot just for the WB.

 

[bruce]

Originally posted by ijames
The module could be sitting there putting full current through one coil. I didn't use to think so, but a mechanic friend told me that he's burned up a couple of modules working on different cars for a few hours each with the key on engine not running, while they were digging through some wiring issues.

I would figure the dwell calc., would shut em off if no DRP.
Maybe, the modules had issues?.

 

[bruce]

Originally posted by ablackFormula

The o2 sensor has been installed in the car for a while, because I originally had the FAST unit hooked up with inputs only, so that when I went to the dyno, I got some hp/tq #'s of the original PCM's control, but was also able to datalog the engine's a/f output with the WB. The O2 sensor worked during that, and was installed that way for 500 miles at the most.

Once I finished installing the rest of the FAST unit (it's outputs,) the O2 is locked at 15.9 as I said before. Do any of your O2 sensors lock themselves at 15.9 until they are fully warmed up? I'm thinking I have three posibilites to my problem: a, is a bad wire which just wasnt visible, which can be replaced. b, I'm just not waiting long enough for the o2 sensor to warm up, or the dreaded c, the O2 sensor is shot for some reason (which I'm hopefully doubting.) Please give me some ideas/insight as it's driving me crazy, and I need the O2 sensors to do any sort of tuning the get the engine to run right!

Is it mounted correctly?.
Was this dyno session with a fresh engine?, any RTVs used?.
Always possible for a bad wire.
Unless they have a really poor heater design, it shouldn't take over a min to warm up. Disclaimer, I'm just comparing warm-up times for other WBs using the NTK sensor.
Yes, when they die, the output can just *lock*.

 

[ablackFormula]

The sensor is mounted in the stock location in the header. I've had the stock one mounted there for a year since I put the headers in, and have no problems w/ that. It's the original engine, 120k miles on it, and no rtv was used on the sensor or on that side of the exhaust.

It seems to be that there is indeed a problem, not what I was hoping for of it just not being enough time to heat up. I guess I'll be out there w/ my continuity meter in the morning in hopes of finding a broken wire (beats buying a new sensor!)