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Lambda reaction time from "free air" to Lambda 1 and vice versa

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I changed my lambdacontroller from a haltech platinum wb1 sensor with lsu 4.2 to a elite wb1 with lsu 4.9.

After changing I saw some strange behaviour of this controller.

You can see that on my attached images:


Time from lifting the throttle to showing free air takes 9 (nine!!) seconds.


Time from free air to show correct lambda value again 4.5 seconds.

The old controller was by an order of magnitude faster than that. Haltech send me a new unit but it has exactly the same behaviour.

Has anyone the same controller and made the same experiences? I dont even know how I should tune transients with this controller.



Attached Files

thats interesting have you been in contact with there tech support ?

Hi Ross,

I was in contact with them and they told me that this is the normal behaviour of this Controller.( I sent them my logs and Logs from Different controllers as comparison) In my opinion this is not normal. I have used zeitronix, different innovate and AEM Controllers. None of them where this slow! Yesterday I asked them again and I got this answer: "We had figured this is expected behaviour as the sensor does not read an immediate change in lambda."

So what would you do now?

This slow reaction of the controlled renders it useless for me, and I think for many other people too. Any other guys here with the same Controller?

Im not convinced that your log really shows an issue. Why would you expect the lambda to read "free air" instantly just because you lifted off? There will generally still be a small amount of combustion going on during over-run conditions and with the throttle closed there is not much mass flow moving through the exhaust system so depending on many factors there can be a significant transport delay.

And in the "delay 2" screenshot where you have marked the 4.5S delay, the top graph shows the fuel load was only 0.2% for that entire area, so again this is still in over-run conditions with closed throttle, low RPM, an likely only a small amount of unstable combustion going on.

Does it respond quicker if you lift off quickly from high boost/high RPM then apply throttle again quickly?

A more valid test would be to hold the engine steady at medium load/medium RPM and make a step change to the VE table and note how long it takes for the Lambda to show the same change.

+1 for the step change test. That is the only valid way to determine Lambda response to the exhaust system mass flow. The delay between the combustion event and the first sensor response may be mostly due to the transport delay in the exhaust system -- all related to the mass flow rate (so higher RPM, or higher load will have less delay, and low RPM, low load will have longer delays.

Out of curiosity i did a short check what it's like with my setup, running a Link G4+ Fury with onboard Lambda.

In overrun conditions it is only 0.125s from the last "correct" Lambda value to "free air/max Lambda".

The other way round with engaging injection after overrun, it is 0.175s from "free air/max Lambda" to "correct" reading Lambda values.

Assuming the numbers i get are pretty common, i would also be really concerned with the behavior of the Haltech controller in comparison.

Attached Files
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I can't do steady state tests by the lack of a dynamometer.

But I checked the delay with higher RPM to test if it is faster with more mass flow. (The O2 sensor is directly after the turbos, and if it also interesting for that case: its a rotary engine)

Deceleration in overrun condition(engine state is in the log) takes in that case 10 seconds to "free air"

From overrun to actual lambda it took about 3 seconds. I think mass flow isn't the problem here. I assume that a rotary engine @ ~3000 RPM generates enough mass flow.

I noticed this whole thing in the MLVHD when my histograms were falsified by this behaviour

Additional I have logs from the same car with exactly the same setup but with a different lambdactontroller:

under 0.4 seconds to max-lambda/free-air

Max-lambda to correct read lambda 0.4 seconds.

Attached Files

You keep saying "free air" -- but the exhaust will not have free air (ie. 22% oxygen) unless then engine hasn't been run for days, or a fresh air supply has been pumped into the exhaust.

Your graphs do not show the relavant channels. RPM & TPS have are not the cause of Lambda changes, only the amount of air (ie, MAP value) and fuel that are combusted. So, please include a fuel volume, fuel pulse width, injector duty cycle, or similar, so we can see the delay from when that changes to when the Lambda changes.