AFR readings

moggy240

Insurance Valuations Officer
Staff member
Club Member
Well my new lambda sensor arrived and it won't calibrate so tried it in my mates mx5 and the same . Going to keep looking to see what I can find .
 

jonbills

Membership Secretary
Site Administrator
Mine arrived but I haven't tried it. My controller doesn't need calibration with new sensors, in fact, come to think of it, I thought it was one of the defining characteristics of the LSU 4.9 that it has its own internal reference and doesnt need calibration?
 

moggy240

Insurance Valuations Officer
Staff member
Club Member
I have to power up the gauge with the sensor disconnected to clear it and then connect the sensor and power up for a 30-60 to fresh air until calibrated and then I can fit it to the exhaust and use it.
 

johnymd

Club Member
Mike - I think that is the process for all the ones I've seen. I don't bother with my portable gauge as the sensor is already in the exhaust and I cant be bothered to remove it. The controller still goes through its 60s startup calibration phase but I don't run it in clean air. Still gives exactly the same readings though.
 

moggy240

Insurance Valuations Officer
Staff member
Club Member
Ordered, hopefully a genuine bosch lambda sensor for £57 which should come for the weekend was looking at the Inovate kit and they offer no warranty on the lambda sensor which shows how sensitive they can be.
 

johnymd

Club Member
After talking with a friend of mine about how much these widebands have come down in price he pointed out that the good ones hadn’t. The Bosch ones are apparently not as tolerant/reliable as the ones used by innovate or life racing. They do the same job but may not last long. The 4.9 is the common one used on oem’s like seat among others. Try using these with high octaine fuel and they will be dead in less than half hour. I watched 2 die on a dyno with an l series engine.

I guess you get what you pay for. The better ones are still over £120 for a reason.
 

jonbills

Membership Secretary
Site Administrator
Innovate sell Bosch sensors, just at a high price, although I suppose its possible Bosch make different quality sensors for different use cases. Life use NTK(NGK).
 

johnymd

Club Member
Sorry Jon, yes your right. I think my innovate came with the NTK ones as that’s what I have in the 3 cars.
 

johnymd

Club Member
I may swap my NTK a cheap one to see how it lasts. I can then always put the NTK back if it fails.
 

moggy240

Insurance Valuations Officer
Staff member
Club Member
Well my new £57 sensor has calibrated so that is good. So will fit it over the weekend and see how it runs,should be ok .
 

AliK

Vehicle Dating Officer
Staff member
Club Member
On this topic, having just replaced the same sensor on a friend’s Audi A3 TDi a couple of weeks ago, I learned that you can bring old ones back to life by heating up with a gas torch. (You also need the hands of a child to work on that engine)!

Apparently they get “clogged” up with soot inside and once you burn it off, they go back to normal. There’s a YouTube video of a guy who gets his glowing red and shows how it comes back to life with a Volt metre. I kept the old one to try the same when I get some time.

In this scenario a bosch one from GSF was only £70 (with discount code) so it made sense to just replace it for a reliable commuting car.

Edit: the gsf Bosch one looked identical to the one that came with my Innovate AFR. Also here’s the link to the YouTube thing I was referring to (there are many more claiming the same):

 
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moggy240

Insurance Valuations Officer
Staff member
Club Member
Interesting, might try this as I have couple spare.
Out of interest I did a little test by installing the lambda sensor without calibrating first, ran it for a bit, then calibrated it and ran it to see what the difference would be. Not much difference but uncalibrated it was showing at the most only 1.0 out. But I still need to get a proper tune done but going to do that after japfest at donnington, I am happy to run it rich at the moment.
 

AliK

Vehicle Dating Officer
Staff member
Club Member
Now that my car is back together again, the tuning tinkering obsession is starting to niggle me again.

For anyone else thus inclined, here is a great article that explains things simply buy with good detail ...

https://www.aa1car.com/library/air_fuel_ratios.htm

I hadn’t realised how much the ethanol content affected the target AFR!!!


And a great video tuning a modern Z but the principles shown on the dyno are excellent! Obviously a modern head design etc is capable of tolerating much leaner AFRs but the principles of the difference in power by AFR hold true for our L series engines too. How lean or rich you run comes down to how cool you want to run and what you are doing with your car. For example: Racers tend to run down to 11.5 for WOT for the cooling effect but they don’t care as much about engine longevity either.

 
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