Anybody have any inside knowledge how the pro engine builders are doing it? I can't imagine they are replacing O2 sensors on a regular basis?

What is Mercury racing doing?

What about Teague or Eddie from young performance?


I am thinking seriously about converting my NA 502's to the Holley system this winter but don't like all this trouble with O2 sensors. As much as carb tuning is a PITA and not my strong suit it might be better than dealing with stuff like this!

There has got to be a fix for this!

I was wondering the same thing...I'm thinking they may dyno a engine, get it dialed in, then just burn the program for that run of engines...and not use the 02 on the engines when in use, but love to know for sure...

X100 guys

who ???

I thought that too but that seems a bit short sighted. Atmospheric conditions are always changing so if you have a system that is constantly learning then this is a must. I am pretty sure the auto manufacturers don't run O2 sensors all the time just for emissions but instead to fine tune engine configuration on the fly?

Seems like we would want to do the same in our boats?

Maybe one of those guys will stumble upon this thread?

Thats one reason the merc EFI is always rich...just making them safe as they can for somebody that would run WOT for 30 mins...

wonder if they do one for use with headers and a std 02 bung ?

Not sure could call them

I think this may be the ticket for us using these headers.

Im thinking about taking that anti fouler and JB welding for steel wool inside (so it wont get blown/sucked out) and then putting the O2 on top of that. That way the water should not be able to wash back up and through the steel wool.

Thoughts/suggestions/criticism is welcome

Ok, checked into Merc H/P engines...they are tuned on a dyno, without water, then ECM's burned so they do not use 02's on the production engines...

I'd run the exhaust completely dry. And I don't mean dry to the tailpipe end and mix water in. I mean pull the water out of the tails right before or right after the transom, and dump it away from the tail pipe via a hose/fitting/bung welded in.

Too loud you say? You can install some mufflers. Drill a small hole in the very end of the jacketed tailpipes right before the muffler. You just want a pisser of water to keep the mufflers from turning blue. The other 95% of the water will be dumping elsewhere via the bung/dump setup.

The problem with the 02's getting wet is a lot of times at idle speeds. You have some reversion going on, and full water mixing in, even far away from the sensor, can be enough to kill it. The 02's can handle a little bit of moisture, but they cant be getting sopping wet. Even cars get a little condensation in the pipes at times.

Something like this. See the water exit bungs?

That is how mine are setup now. There is a 1/4" hole about an 3" from the end of the pipe on the top side of the inner tube. In the video that is where the water coming out of the pipes is coming from but the majority is coming out the dumps. As you can see the 1/4" holes let quite a bit if water into the pixies, I wonder if reversion would still be a problem with the O2 sensor? I have never had a reversion problem but these things do sound sensitive. For me I would probably end up making an adaptor plate that goes between the manifold and the riser to install the sensor into!

http://m.youtube.com/watch?v=Xy-7UolI1No

Goog to know but I am surprised that they "set it and forget it"

I would think you want a setup that is always making small tweaks?? Opinions?

I thought you might fine this interesting. Aqua Power Ltd tested their mufflers on a boat that has reversion problems a couple of weeks ago. Open exhaust clearly had reversion at idle but when the mufflers were used there was no sign of it, the pipes were completely dry. One test doesn't prove that they always stop reversion but they did work on that engine.

Ezstriper, from your pics, it appears that you are running silent choice type exhaust. If so, then the water is entering the exhaust right at the end of the collector. That can't be more than 2-3" behind your sensor. If that's the case, you will never get a sensor to live. I have looked high and low for a sensor that can handle water and there is no such animal. They are all highly allergic to water.

It was asked previously what we do. We tune them on the dyno with O2's. We then tune them in the boat with O2's. Even if we have 2 engines that are completely identical, they will have slightly different cals. We almost never build the same engine twice since we are a custom builder and everyone wants what they want and everyone has different needs and budgets. Even if we did build the same engine again, I would never just put a cal in it and send it out the door. You might be able to get away with that on a 400-500 hp engine, but I wouldn't attempt it on something in the 1000 hp range. When tuning them in the boats, we do go through quite a few sensors unfortunately. I would say that I buy 15-20 per year. For a while, I had O'Reilly's swapping them out, since they have a 1 year warranty. They did it for a while but eventually they caught on that we aren't using them what they were intended for. We use Bosch sensors that are about $60 each.
Eddie

Eddie, excellent detailed answer - thanks from all of us who might benefit from your expertise. How long do the sensors typically last before they expire? I was thinking about installing a bung in one of my divorced collectors for my Lightning headers (they have an internal tube that slips into the collector to extend the dry run of exhaust). That would put the sensor about 4 inches from where the water is introduced. Is that far enough away if I don't use a muffler with it? I figured after the tune I could swap my set of silent choice collectors much like EZ has on his setup.

Thanks again!

The amount of time really depends, but it's not long. I would say that we get, on average, about 5 hours of runtime out of a sensor. I have 4 of the dual sensor FAST units and at least 12 sensors. It's hard to tell which ones I'm using since I just grab a sensor out of the box. Since I work on triple engine boats as well, I keep all 4 of the widebands and the sensors in one large waterproof case. It seems that everytime I tune a boat a have at least one sensor go out. Sometimes, 2 or 3 take a dump.

The distance they need to be in front of the water varies with engines. The larger the cam, the farther away the water needs to be. 4" isn't very much. If it is any sort of an aggressive cam then the sensor will probably get wet at idle. It should be fine while running though.
Eddie

Eddie - thanks for chiming in and I am a little glad that you deal with the same issues as some of these oter guys! If I convert to EFI my O2 sensors will be about 38" from where the water dumps in. I would assume I will be okay!

You should be just fine with them that far.
Eddie

Eddie, thanks for your input..matter of fact was going to call you on this...just had not gotten around to it yet...I agree with all you said..figured the silent choice was adding to the issue..was on the boat when I got it...hoping to get it tuned and remove the sensor...mine seems to get killed after a WOT pass and when you shut it down kills it then...idling has been no issue..best we can tell...we are just getting into the EFI deal and my son(in this thread as well) is doing the tuning..we have a drag radial car we race(he drives/tunes) and have gotten a handle on that for the most part and figured time to put our own EFI setup together...getting closer !!

Wonder what kind of setup Merc has on there new line of catalyst motors. They have o2's in the manifolds in the pictures.

you can bet they have it setup with no water until after the cats...

Update for me, no mufflers on the o2 been great. My mufflers where forcing/spraying water back up header hitting sensor.
Ty Skydog

cool...we opened the drain valve under the headers to bleed off some water, and ran with a angled extender, was careful not to chop the throttle after a hard run..but did not kill #3 !!!! still trying to get the tune dialed in...found throttle body was to small...

Any way to tell if the extension on the o2 messed with the reading of the sensor?

seemed slower to read..hard to tell if changed reading for sure....

ok, just installed valves on the water logs, now can bleed off water and I drilled and tapped the Y-pipe to dump the water in, will run with one open, 1 closed and take temp reading one side to the other with a IR gun...see how much this helps...talked to Bob @ marine kinectics and was all in favor of restricting the water...just no idea how much we can get away with...

I bought that 90* adapter/extension and JB welded a piece of brillow pad inside to help keep the water from getting pushed up to the sensor yet it didnt seem to hurt the air flow by just blowing through with my mouth.
So between that and opening up the water drain on the headers, the sensor lived.

The readings seems to react slower than when it was just stuck in the header, but ran into some other issues so I couldnt tell if it read any leaner b/c of the adapter or not.

Any update on the 90 extender changing o2 readings other than slower

did not help...killed #3 the design of the headers is a killer...

Did it change the readings any

I've used the Innovate 90 degree heat shield for the wideband and it did not change the readings. I was worried it would but it did not.

Hmmm, I guess my plan on putting O2 bungs in the divorced collectors of my Lightnings might not be such a great idea. :(

I would not waste the $$ at this point if they are the silent choice ones...

EZ, I have both. They came with the divorced collectors that attach with the short 6 inch diameter hose. They have an internal pipe that extends the point of water entry about 8 inches. I was thinking about using these to get my readings and dial in my tune, and then switch to the silent choice ones later without the wideband O2. I was planning to just use the wideband to dial in my setup initially. After that it should be pretty static. Not planning on any changes after that, and even if I did, I would just switch collectors again while I do the tune. Think this would work?

if you can get the water to dump about 12" from the 02 you might have a chance from what I've been told, in our deal we could get it to live at slow speeds, cruising, etc, but when did a WOT test and backed down(not quick either) thats when killed it..I would do the 90 extension like we tried for extra insurance...

EZ, have you always run yours with switchable diverters in the collectors, or were you running it with the divorced collectors as I described? Were you running any type of muffled tip? I would think that would also be a factor in back-pressure contaminating the sensor.

we only ran the silent choice deal..all we have, and always in the open position, no mufflers, issue is the water is only a couple inches back from 02 and not much we can do about it...even called lightning and asked...