02 Sensor getting killed in lightning headers
 

so just got my EFI system up a running, using the NGK afx wideband 02 sensor kit for tuning only, megasquirt computer, anyway have killed 2 02 sensors in about 1 hour of run time, seems fine till ran pretty hard then go dead...one was a brand new one and the other was a known good one we pulled off our race car, pulled it out after running..no sign of water..but maybe just hit them on deaccel ?? and then look fine ?? these are 5 wire heated ones and are not cheap...the bung is in about 2" past where tubes go into collector, way forward of the water dump...it is a 500HP with a procharger..assuming it has to be a water issue ? anybody make one that will stand up ?? thanks Rob

Mild Thunders idea!
 

Mine get wet when I`m idling so I wait till I`m running for about 5 minutes or so .. must be dry by then, then I power em up. If you`re way rich that will also kill them fast

which ones are you using ? we may be some rich but not a point where runs bad at all so ??

Wideband sensors do not like heat. They might be too close to the exhaust port. On my car engine I have been using the same AFX sensor for over 5 years with no issues with an a/f in the 10s. It has to be either water or heat killing them.

It is about 2.5" back from where collector starts, so do not think it could be heat...also the last one came off our race car and had been on there for over a year...so still thinking water...bung is in the factory location where lightning installs them...my real question then does somebody make one that water does not kill in mins, I know the ones in std cars live in moisture from the cat convertors...

When you say it kills it do you mean outrageous readings or an error code on the reader? I am getting outrageous reading and believe it must be water so I tonight did a little work on the tailpipes to stop any reversion that will hopefully fix it. It seems like water splash even though I see no signs of that.

works fine for about a hour then reads full rich, you can tell it's not..them in a min goes all lean...then pull sensor out later, looks fine, try to cal and will not..dead...killed 2 in just hours...

I've run into that before on standard Lightning headers. Wasn't even running a big cam, but reversion kept killing sensors.

I have the same problem, I will be watching this thread.

seems somebody would have to make one that would live...

Water will kill them. I have not heard of one that will take it.
When did they go stupid, when you were idling or under power? At idle I would think water, under power I would think heat??
They want them mounted at close to 12 O'clock to let them drain any moisture out of them. I just read in my Innovate info to not run 12v to them in the pipe without the motor running. Condensation could hit the hot sensor and permently damage the sensor. They also warn against heat. Over 900* and you need to install a heat sink or use an extender to move it out of the exhaust stream to run cooler.
Like you say, it seems like water is the issue. If you are getting any reversion that will kill them. Try running the motor with a spark plug in the hole, then remove it, see if any water sprays out, should be dry exhaust. First time I saw reversion was on a test stand, at an idle you could see the water creep back up the ID of the exhaust pipe.
Any chance the headers are leaking? That would add some water to the pipe?? Did you slow down before it died? I ran mine without the mufflers once and idled back to the dock. Sensor was DOA. Mufflers back on and I have little trouble with it. Mine are dry all the way out, no mixing of the air and fluids. But my tails drag in the water at idle and no wake speeds.

Amazon has the sensors at a reasonable price from what they used to cost..
Hope that helps.
Dick

I have the same headers with the factory bung. You have to run the motors for few min to dry the sensor out before turning them on. I also shut it down if i'm going to idle for long

I have CMI's Tube Tops, they put the bung in the bottom of the collector. I had bungs welded into the top of the tails, but I have only killed two sensors in 4yrs. I run them all the time.

I have big tubes and I have innovate wide worked great for a few times out. Then started going full lean when I would nose the boat up getting on plan.But always worked at idle. Then it would come back after alittle bit of wot. Then got real bad, and would not work at just at idle??? So got a new o2 sensor and did free air and took boat out same crap no work. So bought a hole new set up from them, did not want to play there gay warranty crap send in wait two weeks ect ect. So I feel the gauge is bad.... I hope.....will know this weekend. Sucks all this and about 3 hours run time on the hole thing....
Skydog

I've run my Bosch 5 wire O2 on and off for 5yrs. I have a little bit of moisture at and idle and try not to have them in during long idle times.
I would try to use some O2 extenders to try and get it out of the stream of moisture.

http://www.ebay.com/bhp/o2-extender

IMO those extenders won't work. The sensors have to be in the flow of the exhaust or it will not get an accurate reading.

I don't see a dead spot of exhaust gases collecting in front of the sensor.
I'll buy a set of extenders and do some back to back comparisons.
It has to work better than a dead sensor.
[ATTACH=CONFIG]505626[/ATTACH]

these are heated 02's, so again don't think heat is the issue...mine are @ 12oclock, seemed like we ran around easy just dialing in the tune, no real long runs, for about 1 hour..then made a decent long WOT pass...soon as I backed of and came off plane..went dead...

I'll be watching to see how this turns out - I have Lightnings that I will be running on mine when I get the engine finished. Mine have the divorced collectors with an internal pipe that slides into the main collector of the header to extend it an extra 9 inches or so. Was planning to actually run collectors with silent choice eventually, but I know running O2 sensors with this setup will not work. So I was going to have a bung added to my regular divorced collectors and run those temporarily while I get the tune set up on the motor, then switch to the SC later. I guess I'll have to watch this thread to see if you come to a good solution.

getting $$$$ at $150 per sensor !!! I think I'm close we can tune from here without it..but really wanted to keep it on..can't believe how easily these thing take a crap !!!

Just wanted to add to the thread, for what its worth.

The AFR during the WOT run was between 11-11.5. Rich yes, but not kill the sensor rich...so its not pig rich killing the sensor. We ran this sensor and the first one for a while (the first one longer, probably close to 45 min) before we ran it WOT and it was fine, idling through the no wake, on and off plane several times, etc. Its not until we stand on it and then start to slow down...thats when it starts reading either 9.0 rich or this time it went 15.0 lean and stayed there.

Its also in the same location Lightning installs the bung from the factory, so thats why its frustrating that it doesnt work.

Boat has 4" slash cut tips with no flappers, FWIW.

Guess we'll have to start tuning it via spark plugs like "back in the day" :coolcowboy:

To the guy that did some work to his to keep the reversion water out, what did you do and have you tested it yet?

Thanks
-Allyn....ezstriper's son

Toolate - I have inserts that make my KE headers dry to the ends of the tips. There is a connection at the tailpipe where these inserts meet to seperate the exh gas from the water. I removed the insert last night and put silicone in the seal area to stop any water that may be leaking from the water side to the exhaust side. I haven't tested yet, this weekend I will. My LM2 is going way lean like 45-50:1 so I am thinking its water. I also ordered a new sensor last night from amazon (thanks Mr G) for $47.5 and will be trying that as well.

Gotcha, sounds like you did some pretty involving stuff...I hope it works for you!

I think it's just the header design. I have lightnings on my boat that turn down and it's never killed an 02 sensor, but the standard lightnings seem to not drop very much and collectors are kind of short before water dumps in. Any 02 sensor is going to fail if water gets on it.

Somebody had suggested these extenders a while back. I had bookmarked the page so when I decide to do EFI I can put bungs in my Lightning headers. I'd like to know how you welded the bungs in place.

http://www.innovatemotorsports.com/x...cat=250&page=2

I have this coming too... we will see

http://www.ebay.com/itm/O2-oxygen-se...#ht_2607wt_843

Just pulling the sensor out of the pipe some will not affect the reading at all will it?

TY

I would say yes.

How much, I dont know but they are designed to be stuck into the exhaust path to get a good reading.

If you decide to go that route, use it and tune it. Write down some different RPM's and what the AFR was at each RPM. Then pull the 90 out and stick the 02 right in there and go run it at those RPM's you wrote down and check the difference.

Of course you would want to do this AFTER you have it tuned where you want so if it does kill the sensor, you'll be ok.

ThisIsLivin - Basically, our welding guy cut out a 2"x2" square where we wanted the sensor, drilled a hole for the bung, tig welded the bung in place, then with the square he cut out drilled a whole the size of the bung so it would slide back over, and tig welded that back on. We can get you a pic if you want, its a pretty slick idea, IMO.

Ok, this is what we have....the silent choice is probably part of the issue...

http://i227.photobucket.com/albums/d...pse6b4071c.jpg

You may be correct that the SC could cause enough back pressure to get the sensors wet. I am also confronting the same issue if I want to run wideband O2 on my boat. My plan was to just use the O2 to get dialed in, and then put a plug in the bungs and run it without the O2. With the supercharger I can see why you would want to run it full time. Was there any concern about getting a true reading with the sensor so close to where the four primaries feed into the collector? I would think that ideally you would want the bung further downstream from there, but I can see that you don't have many options with the silent choice.

What cam overlap and duration are you running? Just curious.

Mmmmmm yea going to pull my mufflers off. See if it helps that will be my step one. I am thinking back I think my problems started right after adding mufflers...

had no choice, checked with lightning and thats the exact location they install at time of build...I cannot believe that there is not a 02 that would not live getting wet at times...when we pulled it out after getting back looked fine...thing that maybe the water cracked the porcelain that we cannot see...

as others have said, this is a common problem. I have a holley computer and use their sensors since they come with the correct connector to plug into the computer harness. after running in the driveway with a lot of water going through, I usually notice the O2 getting rich even though I have not change the tune. I have CMI sport tubes with the factory welded O2 bung on the odd side. supercharger is the new 4.5 whipple. about 1080 hp. I have 2 sensors, one is a spare. each time one goes rich, I either change to the other or dry it and buff off any carbon. I also leave the sensor in while running the boat much of time because the holley continues to tune in closed loop. in each case, over 2 years, the sensors have recovered when dried and cleaned. I doubt that the holley O2 sensor is unique or that they even manufacture it.

are you certain that they are really dead or just wet?

Let me see if the set at the shop has modifications. There have been a couple sets through the shop and all have had some sort of reversion. Large cams and small cams. JimV has welded the tips up and then added water dumps out the back/side of the boat. This is more for water intrusion into the engine then saving O2 sensors so watch for that.

I've burned up two now. First one was completely my fault as the tail pipes I have had the bung at 7 o'clock - condensation killed it. Moved it to about 10 o'clock and worked great for about 5 hours and then shortly after I launched one time it started reading full lean - swallowed a wave up the tail-pipe. Both times, when I blew out the O2, water came out the small holes. Since then, I close the mufflers (switchable) when launching, backing, and coming off plane. Since doing this, 20 hours trouble free. BTW, I too am running the Holley system. Holley uses a Bosch LSU4 O2. Since Holley's version is not readily available at local auto parts store, I have bought the Bosch 17014 (available at most any auto parts store cheap - $46) and just splice the Holley plug from the bad O2 sensor except I keep the cal resistor from the new O2. The sensor is not identical, but it has worked fine for me. Since then I have ordered a new Holley version and just keep the 17014 as a spare.

yes, ours are dead...will show either totally rich or totally lean, and shows need calibrate, which they will not do....

Yea my sensors are bad I did the brake clean in a rag test. They are junk, so new sensor and pull mufflers off and head to water.......
Skydog.

I have recommended this part before and in fact use it. I highly recommend it. I did a direct A / B comparison with the same tune both with and without this heat sink / extender and it had no affect on the AFR. It has a pitot tube like inlet which needs to be directed into the exhaust stream and prevents and reverted water from coming in contact with the sensor.

With the OP using silent choice I highly suspect he is having a reversion issue.

I used that extender and water still got in it

or you can go to your local NAPA store and use the spark plug anti Fowler kit