Looking to purchase a good 02 gas sensor

[buick man]

… anyone one using a particular o2 gas exhaust tuner analyzer for tune ups ? … looking to get one that has the capacity to do carb dual exhaust/bank and fuel injection setups … want something simple, effective and affordable.  I have researched a few possibilities but thought I would post this to see what if any, anyone is using out there and how it's working out for you … don't want to under buy something that is junk and on the other hand too complicated with needless capabilites that I may not ever use either ...

Edited July 2, 2017 by buick man (see edit history)

[Beemon]

I am also very interested in this. I would like to see what the carburetor is doing under all loads to see if a vintage carburetor really is better than a modern tuneable carburetor... (I hope I don't start any fights with this one)

[Aaron65]

https://www.amazon.com/Innovate-Motorsports-MTX-L-Wideband-Ratio/dp/B004MDT8MW

 

This is the one I use.  You can buy an "extension cord" and tailpipe clip to transfer it among vehicles if need be; otherwise, you'll have to have a bung welded into your exhaust system.  I check 40-50 mph cruise, 70 mph cruise, and full throttle AFRs, and it will also verify if that sag or bog you're feeling is lean or rich (and how much).  I do not generally use it to set idle (I use vacuum).

 

One thing I learned is that you should not try to tune for a specific AFR number.  My Mustang gets nervous when it's leaner than stoich and my Firebird runs just fine.  

 

By the way, on these gauges, 14.7 is stoich, no matter what gas you're running.  I called Innovate to check on that.  Therefore, it doesn't matter (according to them) if you are running straight gas, E10, or E85; stoich will show up as 14.7 (because they program that as lambda).  Good luck either way...you can't really tune using plugs for a street car anymore because of the way modern gas burns.  My Firebird's plugs are almost spotlessly clean, and it runs 15.0 on the gauge on the highway with no surging (which is a totally acceptable number).

Edited July 2, 2017 by Aaron65 (see edit history)

[Aaron65]

Here's a picture of my hookup on the Firebird.  Sure, I look like a dork going down the road, but I only need to use the system when I'm tuning something.

[Beemon]

15:1 if I recall was the stoich ratio for ethanol free gas. 14.7 was picked for e10 because it needs to be richer to burn the leaner fuel, and then so on and so forth going down the line. 

 

How do you normally mount your gauge? Under dash? 

[Bloo]

14.7 is for gasoline from the beginning of time. It is by weight, not by volume. Stoichiometric just means an even balance of air to fuel. If you are measuring oxygen, and you are richer than stoichiometric, there wont really be any.

 

I would weld in the bung, up as close to the front as you can reasonably manage.

[60FlatTop]

In 1974 I was figuring out the scoichiometry  of high sulfur coal combustion. For the budding engineer types, the only time we measured anything was to verify we did our job right. Forty-five years years later things get measured to find out what's wrong. There is a difference.

 

I like that dork application, though. My first thought was to push the cruise control button and "verify" that the ratio really does lean out in cruise mode. At higher speeds you can lean the mixture out for better fuel mileage knowing the higher temperatures will be balanced by the high swept volume. Check it and see.

 

That's the kind of nerd stuff discussed over coffee if only two are present, 1:1 nerd talk.

Bernie

[NTX5467]

I concur that stoich is in the range of 14.7-14.8.  That was "it" for real, leaded, normal gasoline in the 1970s and prior.  When E10 came around, the lesser heat content of E10 meant "more fuel" and stoich for E10 is supposed to be 14.2, a little richer than for E0.  I don' recall seeing anything on E85, but I know it has to exist.

 

There are several products to measure O2 levels.  I noticed that in a Holley EFI kit, that they have a special clamp kit so that no welding is needed, just drilling the hole in the exhaust lead pipe, in a particular orientation to decrease the affects of moisture/condensate on the sensor.  

 

On the chassis dynos and such, I believe that "road load cruise" is at 2500rpm.  Although, this might be an arbitrary load factor on the dyno, all things considered.

 

To best consider AFR "on the road", you'd also need to consider manifold vacuum levels to best gauge when enrichment starts, whether in EFI or Carb.  I used to pay attention to reading spark plugs, but as most of those cars are not in daily use, the plugs are staying put more.  When I was driving my '77 Camaro, the NGK Iridiums in it looked like the plugs have since I've owned it (from new) . . . generally white insulators.  Same with my '70 Skylark after we got RFG.  As long as they're not chalky white, I consider things "good" (as to heat range, ignition max advance, and mixture).

 

On dual exhaust vehicles, I believe you place the sensor on the exhaust pipe side opposite of the heat riser valve.

 

I usually use the "lean best idle" method of idle mixture adjustment.  It's what was used as "factory" on our '69 Chevy pickup, when new, per the emissions decal.  It's worked on  every other vehicle I've used it on, too.  Takes a little time to do, a little finesse of the speed and mixture, but I have confidence in it . . . meter or not.  I set the idle speed by the "exhaust pulse method, in gear".  That, plus the idle adjustment for "lean best idle", plus (when gasoline was still what it was) the hydrocarbon smell test worked well for me on the cars we own.  The pulse test works best on single exhausts, too.  Absent that, automatic trans engagement and off-idle response.

 

After I did the intake, cam, and carb upgrade on my '77 Camaro, I had trouble getting the idle mixture/speed where I wanted it.  I took it to work one Saturday and hooked it up to our BIG Sunn diagnostic machine.  I discovered that when I headed toward the CO level that was supposed to be best, the hydrocarbons went wild, indicating "lean misfire".  So I got out of that!.  What I did discover that the power valve's first stage opened at 10" Hg.  In gear with the a/c on, it idled at 10.5" Hg.  But that first stage of enrichment was not very much of a change, but I didn't need that at idle, either.  So much for that morning!

 

Gauges and sensors are neat, but giving the vehicle combination what it likes can be more important than trying to "hit numbers".  To me, the numbers can be for diagnostics and a final check to see where things might be.  I used to care about "numbers", but now less than then, although still an interest.

 

NTX5467

[Aaron65]

All this talk about stoich is almost certainly accurate, but I do want to verify that stoich on your O2 guage will be 14.7 no matter what gas you're running...it's lambda, or 1.  They set lambda to read 14.7 on the gauge at the factory, so if you're running E10, your gauge will still read 14.7 at stoich.

 

Like NTX said, however, you'll find that tuning the car to run the best usually works the best, but the gauge is great for telling you how far out of the game you are, and it takes a lot of guesswork out of choosing jets/idle feed restrictor/air bleed sizes.

[RivNut]

Remember your basic weather class in 7th grade?  14.7 is the weight of the air at sea level measured in pounds per square inch.  If you live at higher elevations, that number will be smaller because there is less air between you and the troposphere. It won't get larger unless you're below sea level..

[Bloo]

If what NTX says is true it wont. The stoichiometric point will read 14.7 no matter what. Don't put any faith in air/fuel ratio numbers from anything, especially ones derived from oxygen. The problem NTX pointed out is just the tip of the iceberg for calculating air/fuel ratio this way.

 

Stoichiometric is a useful point to know for tuning. It is also a good place to run your idle and cruise mixtures. The car will run great. The maximum gas mileage point will be leaner. There are downsides to using it though.

 

Maximum power is where the engine pulls the hardest, and the ratio needed varies a little by engine. Use a gauge like this as a relative measurement to show which way your changes went and how much. See if the engine makes more power. The actual number is useless. I cant stress this enough.

 

[Bloo]

7 minutes ago, RivNut said:

Remember your basic weather class in 7th grade?  14.7 is the weight of the air at sea level measured in pounds per square inch.  If you live at higher elevations, that number will be smaller because there is less air between you and the troposphere. It won't get larger unless you're below sea level..

 

Yes

 

It causes confusion though because as far as I know, the fact that it is the same number is only a coincidence. We will wind up talking about both these numbers,14.7 (air pressure at sea level in PSI) and 14.7:1 (stoichiometric air/fuel ratio by weight) in just about any conversation about fuel mixture.

[NTX5467]

Per the Rochester Carburetor book by S-A Designs and the similar Holley Carburetor by HP Books, max power should have an AFR of about 12.2 but real max power happens when the mixture is a little leaner than this.

 

In the later 1960s, the local Chrysler dealer had a small Sunn air/fuel ratio meter.  They used this to verify how a tune-up came out.  They used it for the final carb adjustment and to see that the power valve was closed at no-load higher rpms.  When the rpms got past 2500 or so, the meter always swumg to the 14.7 mark on the gauge.  It was also possible to set idle mixtures to 14.2, if desired, on those earlier 1960s carburetors, but it usually ended up in the middle 13 range, as I recall.  Everything worked well and we knew things were as they should be.

 

In the case of the Chrysler Lean Burn system, the carb was calibrated for an 18.0 AFR at cruise.  At that AFR, emissions dropped in HC and CO, as NOx increased slightly.  To support that, ignition advance was also increased from normal levels.  A leaner mixture is harder to fire off, time-wise, so additional "lead time" was needed to make it happen.

 

When I discovered the NGK V-Power spark plug, first as an OEM plug for Toyotas, the parts counter hand-out noted that getting more of the flame kernel exposed to the mixture allowed leaner mixtures to be reliably fired by this spark plug gap design.  MORE things to consider!  Spark Plug gap design!!  Later came the .040 "fine wire" electrodes in Iridium!

 

Enjoy!

NTX5467

[buick man]

… Aaron I asked since on another site Innovative use to have a user's site and had phone response but apparently am told that is history … the  unit I am thinking about would have to have the capacity to accommodate an additional pickup for dual exhausts as I am told most only have the one … can yours do duals at the same time or do you need to do each bank separately and with that said, what are the limitations of this gauge your using ?

 

I am looking at this one  http://www.innovatemotorsports.com/xcart/product.php?productid=16355&cat=0&page=1

Edited July 3, 2017 by buick man (see edit history)

[Aaron65]

Mine only does one bank at a time, so you'd have to check and record them separately.  I believe the LM-2 that you linked above will have more features than mine, but mine does have the capability of data logging on a laptop, although I haven't used it.

[buick man]

I thank you for your contribution and input, however just curious … the Amazon link provided shows a product with almost seemingly repetitive thumbs down from the folks who bought this gauge … or should I say the bong sensor that comes with it and at the least apparently Innovative is non responsive to their concerns which reflects some feedback I have gotten from other sites as well,  so … what do you think is going on here ?

[Aaron65]

I'm not sure...I bought mine three or four years ago, and I only use it when I make a carburetor change.  A lot of people like the AEM units, so maybe one of them is worth a try.

[NTX5467]

When we still had some amount of lead in the fuel, it was pretty easy to see if the fuel mixer was pretty much optimized.  The tail pipe's interior surface would usually be "white" from lead deposits and efficient combustion.  When lead was finally deleted, a fluffy black replaced the prior color, although everything was good..

 

I mentioned exhaust output "smell" as this was one of my tuning "tools".  First, I'd set the idle speed "in gear" (parking brake firmly set), a/c operating, etc. to just where the exhaust pulses became one smooooth flow.  This ensured smooooothness.  Then I'd make sure the mixture was optimized.  As the emissions decal on the '69 Chevy pickup noted, adjust each mixture screw for highest rpm, then lean the mixture to get a 20rpm idle speed drop, then return the screw to its prior position.  Seems like these adjustmens were in 1/4 turn increments?  Back and forth between them with minor tweaks to the speed screw, as necessary to maintain the desired idle speed.

 

For the final check, in gear and such, I'd go to the back of the exhaust pipe and put the palm of my hand in the gas flow.  Then I'd smell it after a few seconds there.  If things were "right" (to me), a minimum smell of hydrocarbons would result.  Minimum hydrocarbon output = best.

 

On that particular vehicle, I ended up with a "N" idle speed of 780rpm, which seems too high (then and now).  Dad didn't like the way it went into gear, but that model year of Chevy pickup had higher line pressure in the THM400 than similar cars did.  BUT, he could sit in the field talking to friends/workers all day long without any overheating or similar, just a smooooth idle and cold a/c (with the driver's window down).

 

I also discovered that when I tried to slow it down, it would idle rougher in gear.  Plus, below 750rpm, the mixture screw adjustment was not as crisp as at 780rpm.  Much soggier, on that particular QJet.

 

In general, I ended up close to the stated factory specs, but my method seemed to be better in actual practice.  When I developed this procedure in about 1972, it worked well for me.  BUT, single exhaust seemed to work better than dual exhaust, to feel the exhaust pulses.  "The smell test" still worked, though.  Never did perfect it with catalytic converter cars, though.  By that time, things were usually optimized better for OEM vehicles.

 

In those earlier times, the only meters I had were a good dwell tach and a vacuum gauge.  Never had too much luck getting the vacuum gauge to work as others claimed theirs did, but the dwell tach worked well.  At that time, the portable AFR meters were over $400.00 and NOT in my budget.  

 

At idle, the highest manifold vacuum should correlate to the highest idle speed with the mixture screws.  Seems like on the '66 Chrysler 383 2bbl Stromberg, the resultant AFR was in the 13s, but when the rpm was increased to 2500rpm, the needle on the Sunn AFR meter would quickly head to 14.7 and stay there.  BUT, if desired, the AFR could be adjusted to 14.2 (which the Chrysler CA-spec carbs would be set at), if a slightly rougher idle was desired.

 

Later, the affects of spark plug gap design were revealed.  I'd read of the Champion J-gap racing spark plugs.  I did that on the Chrysler and it seemed to have a little sharper off-idle response.  Later, when I found the NGK V-power plug handout (at the Toyota parts counter), wider spark plug gaps were "normal".  The V-power gap design was supposed to be better at firing leaner mixtures at wider gaps.  I considered that "better" as more of the flame kernel was exposed to the mixture, rather than being shrouded by the overhand of a perfectly-centered ground electrode of the spark plug.  On the Champion J-gap plug, the ground electrode only extended 1/2 the way over the center electrode.   The V-power and the later ACDelco RapidFire plugs also came this way, but 20years later.

 

After these designs were known about/discovered, the later Iridium spark plugs utilized the ".040 Fine Wire" design.  Look at the "First Start" lawn mower spark plugs and you'll probably find this same design (but probably not in Iridium).  A stronger zap for a quick start, I suspect, plus resistance to fouling from rich mixtures?

 

So, every little bit helps!  In the 1960s, one of the things was "spark plug indexing".  This was done with specific washers such that when the spark plug was installed in its hole, the plug gap would be facing in a particular orientation to the incoming mixture or particular valve.  It was something the high-level race engine builders did for a few more horsepower.  In more recent years, I don't recall anybody going to those lengths, which might not be as necessary with high-power ignition systems as it might have been in earlier times.  PLUS, these same things could be addressed in the original machining of the spark plug threads (on the cylinder head and the plug itself).

 

NTX5467

 

[EmTee]

Spark plug indexing on race engines was also done in some cases to ensure no contact between the ground electrode and the piston dome at TDC.

[buick man]

… yeah I will check the AEM sites and see what they have to offer …oh and  nice stroll down memory lane NTX ...