Is there a parameter that specifies the position of the Oxygen sensor? E38

[Highlander]

is there a parameter that specifies the distance from the engine for the oxygen sensors?

This is very very important when adding headers and achieving a more smoother tune.

I have not seen this on the Efilive calibrations, but I've seen it on fords.

[swingtan]

Not as far as I know. As you've probably found, the further away the O2 is from the head, the slower the response to fueling changes. This can induce some "hunt" as the RPM follows the CL fuel cycle. If you get the fueling spot on ( between +2% / -5% trim ) then it should be fine. The other thing to look at in the E38 is {B1101} through to {B1108}. I believe that the ECM will alter it's CL fueling strategy in idle mode to compensate for the lower gas speeds even in stock form.

Simon

[Highlander]

There has got to be a parameter for it as LS3s have the sensors located very near the exhaust port and the z06 has them farther down the stream. Yet both cars w-o headers will achieve a PERFECT afr at idle with the stock cam of course and no radical afr swinging if at all.

Ross can you look into this?

Thanks

[swingtan]

Got any examples of the swinging?

With a stock log I just checked, there is about a 3 second cycle time with an L77 ( 6lt with AFM and auto in gear, idling ). STFT's were almost "0" for this data.

My car on the other hand, L76, manual, 220/224 @114 4>1 long headers, can take up to 6 seconds to cycle, but where the trims are very close to "0", the cycle time drops to about 3.5 seconds.

I don't think the cycle time is only affected by the distance from the port, but also the amount of STFT correction involved.

[swingtan]

I've had a play with {B1101} through {B1108}, Ireally htink you need to ensure "CL Idle Mode" is being used. I'm assuming that the ECM knows that the idle gas flow will be much slower than when crusing, so it changes it's CL behavior to suit.

Here's an example of CL Idle mode off....

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And here's one with CL Idle mode on....

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Simon.

[Redline Motorsports]

Fords have a parameter like that called "transport delay"...its a tabled based on ms....we usually have to raise it between 10-15% to control what you are talking about.

It has to be in there as its most certainly a calculated time to control pulse width from feedback..

Howard

[Highlander]

I know... i've been playing with the close loop mode table and it shows some change, but not the one you would expect.

[Ira]

I have no idea if there is any truth to this, but the only reason I can imagine needing that information is if they're using widebands that are fast enough to pick up the individual cylinder pulses and using individual cylinder adjustment.

Ira

[Highlander]

Needing this information will make larger cams not "swing" when the car changes AFRs... AFRs will vary in a sinusoidal way from 14.0 to 15.5 or so. It will make the car change power drastically and you would have to drop timing and KILL it in order to avoid it, and there goes your fuel consumption!

STFT will react depending on the calculation it makes. On the LS1 pcm which we have control over the multipliers and base adders and using a road runner, there is practically NO way to solve this.

THe only way is to run FULL open loop and with the big climate changes we get here, its just not an option on a customer's car.

[Meister]

Needing this information will make larger cams not "swing" when the car changes AFRs... AFRs will vary in a sinusoidal way from 14.0 to 15.5 or so. It will make the car change power drastically and you would have to drop timing and KILL it in order to avoid it, and there goes your fuel consumption!

STFT will react depending on the calculation it makes. On the LS1 pcm which we have control over the multipliers and base adders and using a road runner, there is practically NO way to solve this.

THe only way is to run FULL open loop and with the big climate changes we get here, its just not an option on a customer's car.

You can increase the time it takes to go closed loop and there is another parameter for temp for heater (forget the name off the top of my head). These two changes help dramatically

There are other things to consider that Fords have control of including HEGO tip temp change, exhaust flanges will change temp as well, etc. maybe this is available in GM

[swingtan]

You can increase the time it takes to go closed loop and there is another parameter for temp for heater (forget the name off the top of my head). These two changes help dramatically

There are other things to consider that Fords have control of including HEGO tip temp change, exhaust flanges will change temp as well, etc. maybe this is available in GM

That will only change when CL mode will begin, it will not change the "reaction time" of the ECM from a fueling adjustment to when the O2 sensor sees the change.

CL Idle mode does however seem to meet some of the needed criteria. If you look at the images I posted earlier, you can see the CL Idle mode does not command as big a swing in AFR's as normal CL mode does. I've played with the settings and had "CL Idle" mode active at normal cruise speeds to prove it can be done, and it works OK. I think it might mess with LTFT's though ( only an assumption at this stage ). I've also played with dynamics, timing corrections and throttle air flow corrections and have a rock solid idle at 650 RPM (M6) with the 220/224@114 cam. In fact it's probably smoother on the logs traces than the stock idle was and does not hunt with the CL cycling.

Simon.

[etmotorsports]

13968

13969

I tuned a 2012 corvette with long tubes the only problem the headers seam to cause is at a cruise here is a datalog of the run on the dyno, i cruise for a little while at 1800-2000 rpms and you could feel a surge on the street you don't notice it as much but sometimes it is there. I am sure it is form the stft adjustment. I thought it was from the o2 being farther from the cylinder head but if you look at the tune in the ve table it is on the border of a zone i believe and you get a large change from -14 to 0 or 4 % i think that could be the issue will try to tweek that later. The idle seems to have no issues but it is a stock cam.

[swingtan]

Easy test.... just force it into OL mode and retest. I bet the light surge is still there even with the O2's turned off. Let me know if that's the case.

Simon

[etmotorsports]

Swingtan

It will be a week or so before i can drive the car again and that will be at the track so i will not be able to feel it there. If the surge is still there what would that mean? I can't think of what it would be.

[swingtan]

If it's not fuel trims, I'd be looking at dynamics or idle integral steps. Try dropping {B1844} (coast down ) by 50% for starters. You will need to get your min idle air correct though, or you may end up with a hanging idle.

Simon.