Fouled oxegen sensor

General engine tech -- Drag Racing to Circle Track

Moderator: Team

In-Tech
Guru
Guru
Posts: 2021
Joined: Wed Apr 21, 2010 4:35 am

Re: Fouled oxegen sensor

Post by In-Tech » Thu May 04, 2017 10:03 pm

adam728 wrote: I've not tried this method, but will say this: Bosch gives EGT limits of 930°C continuous for both the 4.2 and 4.9 sensors, and 1,030°C "for short time". A healthy propane torch will run around 1800-1900 °C.
So, do we use a TC to find an optimum temp for cleaning and at what part of the flame is that going to happen?

Good topic.

Do we monitor "on/off" times on the sensor while heating with propane or whatever? ie remove fuel source and replace. ie is air good/bad or should we introduce pure oxygen?
Heat is energy, energy is horsepower...but you gotta control the heat.
-Carl

User avatar
MadBill
Guru
Guru
Posts: 14007
Joined: Tue Nov 15, 2005 10:41 am
Location: The Great White North

Re: Fouled oxegen sensor

Post by MadBill » Thu May 04, 2017 10:19 pm

Depending on location within the flame cones, the temperature of a propane torch flame is between ~ 2200 and 3000 ° F. , highest near the end of the inner cone. I expect an O2 sensor would not be happy above say 1500-1600°, so you wouldn't want to cook it for too long...
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

Warp Speed
Guru
Guru
Posts: 2796
Joined: Wed Jun 25, 2008 1:46 pm
Location: NC

Re: Fouled oxegen sensor

Post by Warp Speed » Fri May 05, 2017 5:01 am

In-Tech wrote:
sr4440 wrote:I run up to 10 O2's on my dyno, some are 6 hole some are 12, all are LSU 4.2's

Joe
I will start another post about this. The heater circuit is completely different on the 4.2 and 4.9. I will contact my bosch injector guy in europe and try to get a engineer contact for the o2 so we can get to the bottom of this as far as identifying which is which. From what I have seen, the 4.9 works but not accurately when driven with 4.2 firmware and depending on the circuit will fail the hardware.

Again, I would like to get to the bottom of this. Thank you for your reply.
They both take a different program in the controller.
The sensor themselves differ in both heating circuit and how reference is sensed.
And to the guy that says wide band sensors are junk, about every championship in professional motorsports in the last 20 years has been won tuning with them.........so it appears a narrow band is NOT required! LOL
Can't remember ever seeing a 6 hole 4.2 or 4.9. All of ours have been 12 hole...........?

rfoll
Guru
Guru
Posts: 2334
Joined: Mon Jan 11, 2010 12:44 pm
Location: St. Helens, OR

Re: Fouled oxegen sensor

Post by rfoll » Fri May 05, 2017 8:35 pm

most of the response here talk about carbon fouling. I suggested oven cleaner which will take a years worth of the stuff off the inside of an oven. Is there a reason it won't work,? Has anyone tried it?
So much to do, so little time...

user-23911

Re: Fouled oxegen sensor

Post by user-23911 » Sat May 06, 2017 12:05 am

Carbon is carbon is soot.

Oven deposits aren't carbon, they're hydrocarbon / carbohydrate/ compounds of carbon which turn to soaps when sodium hydroxide is added.

Exhaust deposits are soot if it's running too rich, carbon compounds if it's worn out.

Oven cleaner won't react with soot.

user-23911

Re: Fouled oxegen sensor

Post by user-23911 » Sat May 06, 2017 4:06 am

Lambda sensors / WB / NB o2 sensors have a few things in common with car batteries.
They don't last for ever and they gradually deteriorate with age.
The voltage output depends on the chemistry of what's connected to the electrodes.

But you wouldn't know if you're relying on it and have nothing to compare it with.
That's why you run your NB sensor alongside the WB, the NB is easy to bench test.

If you've got the money, get an exhaust gas analyser too, the numbers are NEVER the same.
Like I said before, they're over rated.
You don't know what you don't know.

It's a bit like the recalibration process (in free air) that needs doing (depending on make and model) when you repower them.

Warp Speed
Guru
Guru
Posts: 2796
Joined: Wed Jun 25, 2008 1:46 pm
Location: NC

Re: Fouled oxegen sensor

Post by Warp Speed » Sat May 06, 2017 5:54 am

Results don't lie.............just saying! :wink:

rfoll
Guru
Guru
Posts: 2334
Joined: Mon Jan 11, 2010 12:44 pm
Location: St. Helens, OR

Re: Fouled oxegen sensor

Post by rfoll » Sat May 06, 2017 10:08 am

I have a narrow band, (Edelbrock), and it was a waste of money. The wideband I have may not be up to the task of tuning high end race motors on a dyno, but as a comparator I have found it to be extremely valuable. When gas was up to $4/gal. I was able to tune the QJ on my 79 Impala to produce over 18 mpg. A 2 mpg improvement is worth a chunk of money when gas is $3 or $4 per gallon.
So much to do, so little time...

rfoll
Guru
Guru
Posts: 2334
Joined: Mon Jan 11, 2010 12:44 pm
Location: St. Helens, OR

Re: Fouled oxegen sensor

Post by rfoll » Wed Dec 12, 2018 8:27 pm

Well, I cooked another one. I have been tying to get a carb tuned up for another car, using the Impala's system to adjust the apt in the Quadrajet. I hit it right on the money last night, and all was well this AM, but after the first start and drive and being fine, and drive the second start and drive showed the same problem as the previous failure. One of the things I noticed was the length of the sensor bung is long enough to pull most of the sensor well out of the collector. The sensor was covered with soot. I am beginning to wonder if the sensor needs to have nor exposure to the flow of the exhaust. In all likelihood one of the overly rich carbs I tried played apart in the sensors demise.
So much to do, so little time...

User avatar
MadBill
Guru
Guru
Posts: 14007
Joined: Tue Nov 15, 2005 10:41 am
Location: The Great White North

Re: Fouled oxegen sensor

Post by MadBill » Thu Dec 13, 2018 12:11 am

The interweb is rife with "how to clean an O2 sensor" links. Not endorsing, just saying...
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

adam728
Member
Member
Posts: 116
Joined: Fri Dec 06, 2013 12:53 pm
Location: Michigan

Re: Fouled oxegen sensor

Post by adam728 » Thu Dec 13, 2018 5:38 am

From Innovate

http://blog.innovatemotorsports.com/imp ... o2-sensor/
Getting the Maximum Life Out of your O2 Sensor

Naturally, O2 sensors are designed to live in an environment full of exhaust fumes. The most common ingredients of tailpipe emissions include nitrogen, carbon dioxide, and water vapor with a hint of carbon monoxide and nitrogen oxides mixed in. In contrast, when anything other than exhaust gas enters the exhaust system, it can dramatically reduce an O2 sensor’s lifespan.

The most common culprits—in descending order of importance—include overly rich air/fuel mixtures, improper sensor placement, leaded fuel, oil consumption, coolant, high-zinc race motor oil, and elevated EGTs.
Innovate recommends a 1" bung, which puts just the tip of the sensor in the exhaust stream. Bosch recommends about a 1/2" bung, which puts more of the sensor into the stream.

More than likely extended time running very rich is what's killing them.

rfoll
Guru
Guru
Posts: 2334
Joined: Mon Jan 11, 2010 12:44 pm
Location: St. Helens, OR

Re: Fouled oxegen sensor

Post by rfoll » Thu Dec 13, 2018 9:33 am

The stock carb tuning is about 16:1, it never gets richer than 14. The first one died as a result of a loss of electrical power. I suspect the second one got too much of a carb that ran in the 13 range and would not adjust any leaner. Combined with the short distances driven and cold climate it is likely it sent it on the path to destruction before I got the carb off. When I took the rich carb off, all was well for a week or so, until it wasn't. The bung is the 1" long spare from my Innovate kit. Most of the online stuff suggests soaking them in gasoline. I have access to non alcohol gas here, and I wonder if it would work any better,
So much to do, so little time...

rfoll
Guru
Guru
Posts: 2334
Joined: Mon Jan 11, 2010 12:44 pm
Location: St. Helens, OR

Re: Fouled oxegen sensor

Post by rfoll » Sun Feb 10, 2019 7:47 pm

With 2 dead sensors to play with, I tried 2 different methods of revival. The quick and dirty suggested by a st member was to heat it with a propane torch. It didn't work. The second method from YouTube was to soak it in gasoline. With a dead sensor filling the hole in the collector, I let the most recently fouled sensor soak for a couple of weeks and it came back to life.
So much to do, so little time...

Post Reply