Hey Guys,

I've got some questions about AFR systems. For those of you who have them, what system/brand do you have? What do you like/dislike about it? In hindsight, what recommendations would you make? I like the idea of a handheld system over a permanent gauge, but this is where I hope you guys will school me on the pro's and con's of both systems. I like the idea of having a bung that I can install a sensor in wired to a handheld device when I want to tune. Then remove it and stick everything in the toolbox when I'm done.

So all of you guys that have AFR systems, let me know your thoughts and knowledge.
Thanks.

 

I have a AEM wideband, it works quite well. I bought cats with O2 bungs built in. Good part, they had plugs included. I like having the gauge built in, but I am sure any gauge could be made temporary.

 

I was looking at AEM. Looks pretty nice.
You've got me really curious. Why did you put cats on your car?

 

I prefer the smell of exhaust through catalytic converters for one. Also this style of cats won't restrict flow hardly at all. Plus if smog laws get stupid, along with the SEFI I am adding, I would pass with flying colours. You never know.

 

I’m kind of an in-betweener: using a late model (75-up) qjet with a wideband 02 sensor to tune it. Works well.

Can recommend Innovative Solutions DLG-1 (dual exhaust) to read how what you’re doing the carb is related to optimal AFR or Lambda.

Fun to see what the carb in does in real time from an O2 sensor perspective at startup, idle, cruise and WOT. Huge leap in my tuning outcomes, if not my abilities.

Just today for example, I caught that the car on cold-start was wildly lean (meaning maladjusted choke). The carb is new, so I’m still dialing it in. Nothing went wrong, it’s just tuning time.

Without the O2 sensor I’d never have known if it were rich or lean on startup. I just would have known it was wrong.

I might add cats one day if CA eventually requires it (a possibility), but by then maybe batteries will be good enough that I’ll have switched to electric like Neil Young…

Or not.

Cheers
cf

 

Happy with AEM here. Have used it in my cars and tuning for other people. One of those things that once I used it, I couldn’t be without.

​​​​​​….

 

Don't kid yourself. The spot check smog tests only verify that the OEM system is operating at one or two conditions. That's why a visual inspection is also required. The test assumes that if the car passes at the one or two test points, AND if all the factory equipment is in place, then the system will operate as intended. This is a compromise for practicality. Manufacturers are required to certify emissions under the complete range of driving conditions, which takes weeks, specialized test facilities, and hundreds of thousands of dollars. No home-brewed system is certified and won't be accepted under any emissions laws without full certification testing. This is what importers of grey market cars used to have to do. This is also why states like Calif allow you to swap in a newer engine so long as you include ALL of the factory emissions equipment in the OEM certified configuration. The GM E-Rod crate motor was also specifically EPA certified for swaps like this and comes with all that emissions equipment.

 

Your comment on preferring the smell of exhaust through cats made me laugh. Lol. I love the smell of burning racing fuel.

 

Yeah I wish, regular is 158.9 per liter, 10 percent Ethanol. The 91 Premium I currently run, 1.75 per liter, no Ethanol at least. Race fuel, I don't want to know. Exhaust just clings to me, even after a short start up, even with the garage door open.

 

Yeah, I'm thinking it will be the same for me. Anything that gives me more information for fine tuning things, I like.


Oh I don't run it. I'm in the same boat as you. Pre-Covid it was about $8.50 a gallon for 110. Now it's probably $14 or more. Way too steep for this kid. And of course, my motor doesn't need it. I just like the smell of it.

 

I have been using this on my’72, for about the last 4 years. Best of both worlds. My IPhone is the gauge, both handheld or in my phone caddy.

 

That looks very interesting. Unfortunately I can't get on their site. It must be down right now. Is it bluetooth?

 

i have am autometer AFR gauge in my 63 Catalina. Originally used it to tune the holley that I was running, but now have switched over to a proflo 4 efi and have the gauge sensor on one bank and the efi sensor on the other. Gives me a quick visual to see that it's doing what it is supposed to i guess. It has worked well for the 3 years since I installed it.

 

Wow! That is great integration into your dash. I love the look. Very clean. If there was a way to do something like that on a 69 Cutlass, I'd mount a permanent gauge. Unfortunately, the under dash gauge mount is the only option unless one gets really custom. I don't like sticking aftermarket gauges in the factory instrument locations. It looks really wonky at best.

 

If you’re having trouble finding the site try plxdevices.com .


The multi-gauge link provides the Bluetooth signal

 

I used FAST to tune the remove.
Works well.
https://www.jegs.com/i/FAST/244/170401/10002/-1

 

Is the single shown here adequate for tuning? I see there's a double too that's more expensive.

-Joe

 

The double is for R&L sides.
I assume both sides are the same as I run NA single plane manifold and run the single sensor.
You can buy the double and have the choice of single or double pending budget and needs.

 

I found this PE wideband, originally wanted the PLX but couldn’t find one.

Really glad I have a wideband now, help greatly with getting carb data.

this PE works like the PLX and transmits data to phone so no permanent instal required.
i had a bung put in each down-pipe. The unit just needs a positive and negative and install the O2 sensor and bang…in business…
I simply zip tied the unit to the brake booster area for temp use and put an end on that plugged into the hood light power wire and put ground on firewall. To operate I just turn parking lights on for power.

 

I drove my ‘66 Starfire this morning, wide-band O2 equipped. It runs just great, like you can feel the sensitivity of the tuned quadrajet with your foot.

Just to put it out there, at startup the Lambda was running .89 - .91 or so. Cold engine in rich mode as the choke does its thing thermomechanically. I’m reporting here, not advising, but thought it might help to put a number to a good warm up lambda reading. I’ll happily take criticism if you all think this is too rich.

As the engine warmed up on a cool grey day here, at idle I’m seeing lambdas of .96 or so, consistent side to side. Then it’s fun to watch part-throttle just to see when it’s at 1.00 which is some, but not all of the time. Going downhill with the throttle closed, lambda climbs to 1.08 or so, then when you put your foot in it, qjet style, lambda drops down to .78 or thereabouts.

I remember being curious about what others were seeing as their readings when I first got my sensors, so I’m hoping this little report helps any of the rest of you in your tuning.

Cheers
Chris

 

Are the bungs to be placed on the headers or after? and is 1 fine or do both pipes need a bung? I should probably get a wideband to tune after my motor goes in.

 

I’ve got more or less stock 2.5” pipes, not headers, but I had ‘em welded just in front of the firewall on the downward slope of my exhaust pipes. If your headers are off the car, that would seem to be the perfect time to weld the bungs in.

The general advice is to have the ends pointed downward so that condensation drips off and they don’t rust out. It’s mostly a matter of where you can fit them, but for th record mine are installed more or less flat. It’s a little wrong, but mine have worked fine for 5 or more years now.

If you have access to the Discovery Chanel (streaming), Engine Masters has an episode on this very topic. It used to be Hot Rod TV, but either way, Dave Freiburger did a study of these devices and some A/B testing. Most of those car shows are usually shilling something to get production money, and Engine Masters does a little bit too, but I found that wideband sensor episode worth a watch. It might be on YouTube by now too.

Cheers
Chris

 

I have one that i keep remote to move between cars. I wired it up with a cig lighter to just plug it in. It's a great tool to dial in a carb. There is lots of room for improvement even with a stock application.

 

I run an AEM. It does have a Lambda scale, but I leave it on AFR. Isn't 1.0 Lambda 14.7:1 stoichiometric? Seems lean to me.

 

Most recommended 1 to 10" after the collector and 18 to 24" of exhaust pipe after the sensor for a proper reading. One sensor is fine, mine would be within the recommended placement. It helps a bunch for tuning, a few turn of screws on Quadrajet changes the AFR a lot.

 

Depends on your combo, 14.7 cruising sounds fine to me. I also leave my AEM on AFR as well. I run about .90 to 1.05 crusing and about .88 WOT according to the Lambada scale.

 

I believe 14.7 is the ideal cruise AFR for max mileage without being too lean. WOT I shoot for 12.5-13. Cruising at in the low 13s definitely makes the car more responsive but its all a comprise..

 

 

When I dug into the manual for my wideband sensors, I discovered that lambda is its native measuring scale, but it can be set for AFR or lambda. To me that means that they’ve put a translation map in the software to allow the user to choose either scale. That makes sense if you want to sell devices to people who speak either AFR or lambda.

I chose lambda for 2 reasons:
1) Going in, I didn’t know anything about either rich/lean scale, so the question was which scale to learn. Initially I went AFR, but then I learned that pure petroleum gasoline and alcohol/gasoline have different perfect combustion AFR’s. That meant that if I didn’t know quite what gas I was putting in the car, my calibration based on AFR could be wrong - rich or lean as the case may be.

2) Lambda seems to be the most direct measurement of O2 in the exhaust stream and since it shows rich lean as a function of O2 in the stream, I believe it is fuel-agnostic. It just tells you whether your cylinders have burned up whatever fuel you put in completely, or rich, or lean. If optimal AFR for gas and alcohol/gas is different, then you’ll have different targets for optimal tuning.

In the end, I suspect this is potentially distinctions without difference. These engines, carbureted or fuel injected, will run pretty well-to-great over a fairly wide range of rich/lean incorrectness. Over the past bunch of years, I’ve concluded these sensors really help you dial in carb tuning, but I think most of the gain is correcting gross errors at idle, part throttle, and WOT.

Once you get there, the engines run pretty well, then it’s really a matter of how much time you want to put in to get it as perfect as you want. Getting ever-closer is fun, but with mechanical carburetors like I have, even rebuilt, there’s only so close to lambda 1.00 you’re ever gonna get.

That’s why I posted the values above in case anyone is chasing their tail or looking to goals.

Cheers
Chris

 

Missed something about Dino-gas vs. Alcohol-gas. As i recall the latter must run “richer” due to the lower energy potential in the mixture. If I remember right the target AFR is more like .5 AFR richer than the traditional Dino-gas standards, owing to the dilutive effect of the alcohol. In short the alcohol contributes, and maybe saves oil, but it will get you fewer miles down the road.

On a related note, maybe we should let foreign alcohol producers sell us their gasoline additives to lower our price at the pump. Last I heard we’d protected our U.S. producers. Last week I paid over $7.00/gallon. Hmmm.

My cousin in Norway tells me their price equivalent cost is now $12.00/gallon. Yikes.

Chris

 

Yeah, Premium here right now $7.91 Canadian for a US Gallon or 2.089 per liter for 91 Ethanol free. And 89 is smack dab in the middle 199.9 and 5 percent Ethanol instead of 10 for 87 at 1.899. We basically produce all the heavy crude up here, we shouldn't be paying more for gas but we do.

 

I installed an Autometer wideband in my '69 about a year ago. I originally was looking at AEM but didn't like the unique/modern look of the gauge. The Autometer I use is the same style/type as the oil P and coolant T so everything matches. The style has more of a retro look that also matches the original factory gauges somewhat so nothing seems out of place.
Before I installed it, I also was considering not installing a permanent gauge but, rather, using it for tuning and then removing. After living with it for a year, I can honestly say the tuning never ends. I'm glad I can look down any time and see exactly what's going on. As mentioned, start-up, light cruise, transition, WOT - it's a real learning experience to figure out what the gauge is telling you. Also, with a carb and different seasons of the year, things fluctuate. Keep the gauge in the car and screwdrivers handy.

 

Depends on if you’re using pump E10 or non ethanol.

 

Mark,
If I understand you correctly, we agree on the fact that 1.0 lambda corresponds to different AFR’s depending on whether the driver is using Dino-gas or Alcohol-gas.

You know a whole lot more than me. If/when you have time & inclination, I’d love to hear your views.

Thanks
Chris