[GMCnet] How do you know if an 02 Sensor is overheating
Neil Martin
In the recent muffler placement thread there was a comment that
"My O2 sensor is just after the header.
it's too hot there, keeps over heating, so I'll have to move it back a ways."
What are the symptoms of sensor overheating? Mine sometimes seems erratic after running a while and I wonder if that might be the cause
Thanks
--
Neil
76 Eleganza
Los Angeles
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Keith V
Neil wrote on Wed, 08 February 2012 12:52
> In the recent muffler placement thread there was a comment that
>
> "My O2 sensor is just after the header.
> it's too hot there, keeps over heating, so I'll have to move it back a ways."
>
> What are the symptoms of sensor overheating? Mine sometimes seems erratic after running a while and I wonder if that might be the cause
>
> Thanks
I have a LC1 Wide band O2 sensor.
It has an LED on it that tells you various things like, it's warming up, all ok and somethings amiss. The something amiss is a blink code that tells you what is going on
Mine says that it's probably too hot...
--
Keith
69 Vette
29 Dodge
75 Royale GMC
Bruce Hislop
Wide Band O2 sensors need to be placed further away to stay cooler.
Mine is a TT-1 from Dynamic EFI (the EBL guy) and is just after the Y where BobR recommends it's installation.
--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
Hubler 1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
John Heslinga
While some of the other responses indicate that wide band sensors may cause problems when hot. My experience with production sensors and production FI would indicate to look at the following first.
While things are clear to be heat related I suspect that there are some other issues at play here. O2 sensors are made to be HOT. in fact we want them to heat up as soon as possible.
The perfect spot is at the end of the header (closer to the combustion source if possible but with headers that's best). If O2 sensors are further away we even heat them electrically. ( they cool too much during idle and low
Speeds. Headers are worse because they lose some of the heat out the metal piping before the sensor.)
A couple of possible problems:
Mostly electrical
Ground
- If you have a ceramic coated header the may not be providing a proper ground for the sensor. The coating at the bung may be interfering with the sensor when things get hot and expand.
- The headers not properly grounding at the heads for the same reason and non conducting gaskets.
- The tail pipes may be grounding properly then move as they heat. ( the pipes are Mounted in rubber but sometimes touch ground)
- Some sensors use a ground wire and that may be poorly bonded to the chassis
- If You do not have a grounding sensor
You may need a grounded sensor to solve these problem
Connectors
-Poorly contacting connectors
-the O2 sensor itself is defective
Sensors come in 1, 2, 3, and 4 wires. You may need to upgrade to the one that works for you
1 wire grounds through the housing and exhaust
2 wire grounds through the grounding wire
3 wire grounds through a common wire to the O2 sensor heater.
4 wire which has separate grounds for sensor and heater
I would think that over heating and moving the O2 sensor is a highly unlikely solution especially if you have headers
Best Regards
John
--
John and Cathie Heslinga
1974 Canyonlands 260
TC4W "Too Cool For Words"
Retirement Projects Galore
Edmonton, Alberta
Neil Martin
Thanks. I do have headers. I'll work on your points this weekend and report in a couple of weeks when we have the next desert trip.
--
Neil
76 Eleganza
Los Angeles
Randy Van Winkle
Neil wrote on Wed, 08 February 2012 12:52
> In the recent muffler placement thread there was a comment that
>
> "My O2 sensor is just after the header.
> it's too hot there, keeps over heating, so I'll have to move it back a ways."
>
> What are the symptoms of sensor overheating? Mine sometimes seems erratic after running a while and I wonder if that might be the cause
>
> Thanks
I didn't see this thread and posted on the muffler placement thread. This is what I posted there and sorry for the double posting:
If you are talking about your narrow band O2 sensor, you do not want to move it back any further. If you have it just after the header that is about where it should be. With headers, normally you needed a heated O2 sensor in order to keep it hot enough because headers generally allows more heat to be given off. At idle, the O2 can get too cold and stop working until the engine is at higher RPMs. Also, you don't want to move the O2 too far down the stream because the delay in sensing mixture and resultant correction can cause some problems with fueling. Generally, the ECM is "timed" based on the O2 sensor being 7 - 12 inches from the exhaust ports. I believe you might have a different problem than your O2 getting too hot. Narrow Band O2 sensors do go bad so that is a possibility - sometimes getting what I call "lazy". A lazy O2 sensor does not switch between rich and lean very quickly and can cause longer periods of the mixture being either too rich or too lean. If you do not
have a heated sensor then it is possible you need a heated sensor because of the headers. Grounds can be a problem with the sensor so that is also a possibility.
If you are talking about a WB O2 (not used to give feedback to the ECM) then that sensor should be placed further down the line because excessive heat can shorten the life of the sensor. The Narrow band and WB sensors work differently from each other.
--
Randy & Margie
'77 Eleganza II '403'
Battlefield, MO
Neil Martin
This is the kind of gauge I have
http://www.egauges.com/vdo_mult3.asp?Type=ATM_Air_Fuel_Wide&Series=ES
or
--
Neil
76 Eleganza
Los Angeles
Jim Kanomata
If the sensor is on the collector section, that is the correct area.
We were hired by Pertronix and under the direction of Joe Mondello, we
had to advise the idel location for them to install the bung on their
Headers.Once that was done, they varified that location a Dyno test
and paid us.
The Thorley wnatd me to show them were to put the bung also.
--
Jim Kanomata
Applied/GMC, Fremont,CA
ji...@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
Chuck Garton
Chuck Garton
1977 Kingsley 455
Randy Van Winkle
Neil wrote on Thu, 09 February 2012 17:23
> This is the kind of gauge I have
>
> http://www.egauges.com/vdo_mult3.asp?Type=ATM_Air_Fuel_Wide&Series=ES
>
> or
>
> http://tinyurl.com/7pt6x8y
Looks like you are installing a WB-O2 sensor. I didn't see any installation instructions for this sensor. Many WB-O2 systems use a Bosch sensor. Generally, the specs say the WB sensor should not be put where temps will exceed 900 degrees F. For a Narrow Band, the best place is in the collector area as JimK says. However, I have EGT sensors in this location and they show temps run between 10000 to 12500 degrees F. Because of this, I mounted my WB sensor much further down to allow more cooling of the exhaust gas. Many have installed their WB sensors after the convergence of the y-pipe which gives a true overall view of AFR.
I trust you are not using this sensor to feed info to an ECM? I usually recommend using a narrow band for input to the ECM and the WB for help with understand AFR during WOT or lean cruise. Some modern day systems utilize WB sensors for controlling fuel exclusively but those ECMs are designed to operate that way.
--
Randy & Margie
'77 Eleganza II '403'
Battlefield, MO
Bob Drewes
rvanwin wrote on Fri, 10 February 2012 01:42
> Neil wrote on Thu, 09 February 2012 17:23
> > This is the kind of gauge I have
> >
> > http://www.egauges.com/vdo_mult3.asp?Type=ATM_Air_Fuel_Wide&Series=ES
> >
> > or
> >
> > http://tinyurl.com/7pt6x8y
>
> Looks like you are installing a WB-O2 sensor. I didn't see any installation instructions for this sensor. Many WB-O2 systems use a Bosch sensor. Generally, the specs say the WB sensor should not be put where temps will exceed 900 degrees F. For a Narrow Band, the best place is in the collector area as JimK says. However, I have EGT sensors in this location and they show temps run between 10000 to 12500 degrees F. Because of this, I mounted my WB sensor much further down to allow more cooling of the exhaust gas. Many have installed their WB sensors after the convergence of the y-pipe which gives a true overall view of AFR.
>
> I trust you are not using this sensor to feed info to an ECM? I usually recommend using a narrow band for input to the ECM and the WB for help with understand AFR during WOT or lean cruise. Some modern day systems utilize WB sensors for controlling fuel exclusively but those ECMs are designed to operate that way.
Randy wrote;
{ However, I have EGT sensors in this location and they show temps run between 10000 to 12500 degrees F. }
Wow...that should light up the afterburners !!!
Bob Drewes in SESD (where it is -2* and could use some of that heat)
Randy Van Winkle
Surbo wrote on Fri, 10 February 2012 08:49
> Randy wrote;
>
> { However, I have EGT sensors in this location and they show temps run between 10000 to 12500 degrees F. }
>
> Wow...that should light up the afterburners !!!
>
> Bob Drewes in SESD (where it is -2* and could use some of that heat)
Oops! How did that extra zero get there - never happens with my pension checks. Should have been 1000 - 1250 which is still hotter that the 900 degrees F that most WB sensor specs call for.
--
Randy & Margie
'77 Eleganza II '403'
Battlefield, MO
Matt Colie
Neil wrote on Wed, 08 February 2012 13:52
> In the recent muffler placement thread there was a comment that
>
> "My O2 sensor is just after the header.
> it's too hot there, keeps over heating, so I'll have to move it back a ways."
>
> What are the symptoms of sensor overheating? Mine sometimes seems erratic after running a while and I wonder if that might be the cause
>
> Thanks
I have been wondering about this.
The O2 sensors used for control are often screwed into the manifold. Running temperatures of 900°F are not at all uncommon. It takes about 450F just to get them to start switching right. Hence the HEGO (Heated .... ) That is all I would ever use if I were building another computer controlled engine.
Now, if you are talking about the confirmation (after Cat) sensor, these are often what we are calling wide band, they are somewhat temperature sensitive (iirc) but they are also very easily damaged or contaminated. When this happens, the output voltage seems to get unstable. We would run samples of the final exhaust for O2 against the sensor output and when the sensor came off curve, so note and change at the next service.
Unfortunately, my memory for the subject has played out about there.
Matt
--
Matt & Mary Colie
'73 Glacier 23 Chaumière (say show-me-air) Just about as stock as you will find
SE Michigan - Twixt A2 and Detroit