Lean cut engine protection

[MarcusP]

Is there a way to build a lean cut table.  Say if lambda is 5 or 10% above target etc?

[essb00]

Thing is, rich misfire or ignition misfire would also indicate lean lambda values and read by wideband.
If you plan to cut ignition you'd have all the more lean lambda readings and it will keep going until your conditions are no longer met or engine has stalled.

Best would be to properly tune, then aided by knock control.

[MarcusP]

Just now, essb00 said:

Thing is, rich misfire or ignition misfire would also indicate lean lambda values.
If you plan to cut ignition you'd have all the more lean lambda readings and it will keep going until your conditions are no longer met or engine has stalled.

Best would be to properly tune, then aided by knock control.

I was out tuning and it started acting weird...  Took the 3rd pull to realize I was dropping fuel pressure.  If I wasn't paying attention or if I didn't have the laptop plugged in I may not have realized.  It was a fuel pump issue not a tune issue..  Id rather have it cut so I know there is a problem VS not being sure.

 

Would like a 5000 rpm rev limit if I am more than 10% over target for example. 

 

[essb00]

2 minutes ago, MarcusP said:

I was out tuning and it started acting weird...  Took the 3rd pull to realize I was dropping fuel pressure.  If I wasn't paying attention or if I didn't have the laptop plugged in I may not have realized.  It was a fuel pump issue not a tune issue..  Id rather have it cut so I know there is a problem VS not being sure.

 

Would like a 5000 rpm rev limit if I am more than 10% over target for example. 

 

Then I guess it would be best to make a GP RPM Limit based on fuel pressure.

[MarcusP]

4 minutes ago, essb00 said:

Then I guess it would be best to make a GP RPM Limit based on fuel pressure.

So are you saying no I can't build a lean protection table?

 

[Vaughan]

3 minutes ago, MarcusP said:

So are you saying no I can't build a lean protection table?

You can but it won't necessarily do what you want it to unless it is very tightly constrained. One example would be letting of the throttle would cause it to go lean which would cause it to cut and then it would not be able to recover as the cut would be making it leaner. As essb00 suggested it would be better to focus on the things that would make it go lean rather than on the afr itself.

[MarcusP]

6 minutes ago, Vaughan said:

You can but it won't necessarily do what you want it to unless it is very tightly constrained. One example would be letting of the throttle would cause it to go lean which would cause it to cut and then it would not be able to recover as the cut would be making it leaner. As essb00 suggested it would be better to focus on the things that would make it go lean rather than on the afr itself.

I started playing with the GP rpm limit.  I used Lambda over MAP, Im going to set them at critical levels. .900 lambda vs 34 MAP is a 5000 rpm limit for example..  Im not looking for exact just worst case..  If its too picky Ill turn it off or increase the activation time, there are just too many variables that could make a motor go lean and at 9200rpm 30 lbs things go bad quick.  Id rather shut it down and keep the motor alive. 

[INSW20]

Here's how I have mine set up:

So I have two thresholds for lean cut, one for low boost, and one for higher boost.  Both have timers to give some wiggle room for gearshifts, although I'm trying to minimize that with accel enrich.  These are only triggered over 2500rpm and when in boost.  My RPM Limit Table 2 is a flat 2500rpm, so if this activates, it automatically cuts out until conditions reset or down to 2500rpm.  I also have a fuel differential pressure limiter.

[evo_gerard]

I've been playing with lambda 1 vs target afr. if its 1 afr point leaner than target for 1 second or more then it triggers  GP limiter.

still trying to evaluate how effective it is. could this strategy work?

 

 

 

[MarcusP]

So here is what I did to start.  Ill try some of the other options if this one doesn't work the way I hope.

 

On 2/16/2022 at 7:30 AM, evo_gerard said:

I've been playing with lambda 1 vs target afr. if its 1 afr point leaner than target for 1 second or more then it triggers  GP limiter.

still trying to evaluate how effective it is. could this strategy work?

Can you post a screenshot of how you have it set up? 

 

 

 

 

[evo_gerard]

21 hours ago, MarcusP said:

So here is what I did to start.  Ill try some of the other options if this one doesn't work the way I hope.

 

 

[MarcusP]

3 minutes ago, evo_gerard said:

 

I like that even better

 

[evo_gerard]

1 minute ago, MarcusP said:

I like that even better

 

to be honest, this was learnt via Evans performance academy. its not my creation lol

[INSW20]

I like that quite a lot.  Much cleaner than mine.  If I ever feel like what I'm doing is ineffective or overly complicated for what I need, will change to this.

[remski2]

I use 5D ignition for my AFR enging protection...

Active above 60% TPS.