Accel Enrichment, Supercharged EF six cyl

[JayGow]

Can someone please point me in the right direction.

Having trouble finding a balance with accel enrichment. At higher rpm it's fine, but at lower rpm it seems to want to hold peak enrichment way after I need it to taper off, and it's frustrating me big time.

Screenshot explains it better than I can.

Cheers.

 

 

[Brad Burnett]

try cutting "Accel hold" in half

[JayGow]

Ok so I have worked out that it has nothing to do with accel hold.

It seems that the initial tip-in value is held until the TPS ROC drops. 

So for example if I feed throttle on from 1000rpm giving me say 60% enrichment at tip-in, that 60% addition continues all the way to 100% throttle. By the time I'm at 70% throttle and close to maximum boost then adding 60% accel enrichment is just way too much fuel.

By the time I'm at 100% throttle I've got so much added fuel that afr's are in the low 10's, and no power until it clears.

This may not be as much of an issue for turbo'd cars as boost/load usually climbs after throttle so additional fuel would still be commanded. But my boost/load climbs faster than throttle opening, so I always see peak load long before full throttle. 

So, what I need to be able to do is have accel enrichment follow the accel load correction table as throttle position or load increases, rather than hold initial peak value until ROC drops.

 

Edited June 17, 2017 by JayGow
Clarification of term

[Adamw]

Hi Jay,

Sorry I missed your post here the other day.  I had a bit of a play around on the simulator myself and can reproduce a similar effect to what you are seeing.  If I continuously increase throttle from a small TP, the load correction table doesnt seem to pull the enrichment down as TP increases like my logic would expect it to.  

Im not sure yet if this is expected behavior and it was just designed to operate that way for a reason or if there is actually a problem with it.  We dont get too many reports from tuners about it not working right though so I suspect it must work ok for most.  I will get engineering to take a look at it but the main firmware developer is away this week so its not going to be a quick reply.

[JayGow]

Thanks for checking it out.

 

I have been experimenting with the accel enrichment settings over the past few days to see if I can find something that works with my setup but so far I haven't been able to get it right.

Not sure if it has something to do with the low velocity of the ports in the falcon head, or just that my engine setup is fairly unique having a large positive displacement supercharger on the 4.0L six, but it seems to need a fairly long enrichment duration which reduces as throttle position increases. 

I'll keep playing with it until I hear back from you. I tried switching to MAP based load correction today but it just isn't fast enough, so I'll go back to TPS tomorrow and keep trying.

Cheers.

[JayGow]

Ok, so I came across another potential issue today.

One of my aux outputs, aux8 didn't activate today, even though all conditions were met. (It did eventually activate after a few seconds, but by then it was way past required.)

Thankfully it was my boost control which I only use to give it a bit of a curve at lower rpm, so the table was zeroed at the time anyway.

But, it is a bit of a concern to me as if it had been aux7 that hadn't turned on instead of aux8, it could have potentially caused some major damage to the engine.  

Logging frequency for aux8 is 5Hz, aux7 is 10Hz. 

[Adamw]

Can you email us your map and log from above, include a link to this thread so we know what it is about.  I will have a play on the sim and see if I can find or explain the issue.  

[Brad Burnett]

I'm more curious as to whats going on in that log....

Full throttle, constant boost pressure, and rpm is decreasing at the last little bit of the graph.

[Steve]

Yeah. Thats weird.

[JayGow]

Haha it does look strange.

There is a gear shift in there (auto) at which point it broke traction. The drop in rpm is it hooking up again.

The flat boost curve is because positive displacement supercharger.

[JayGow]

Email sent. Thanks Adam.

[Adamw]

I have already replied to Jay via email, but for the interest of any that may be following along this thread, the reason that Aux 8 is turning "off" (or not turning on) in those screenshots above is there was a critical piece of information missing.  That missing information was the Aux 8 DC table had zeros in it in those regions - so even if the activation conditions have been met, when you have a PWM output with a DC of 0% it is effectively (and logged as) "off". 

It would be nice to be able to log %DC one day to make this easier to visualise on a log...

[JayGow]

Thanks for the reply. I did say in my post that the table was zeroed at that point but normally still shows as on in my logs.

At least I know it's working. Thanks for checking it out.

And yes! I would love to be able to log the DC of outputs. I have mentioned that before in another thread. Hopefully it can be added in a future update.....

 

Also still struggling with the accel enrichment holding peak value as TP increases. I need a lot of accel fuel on initial tip-in to prevent lean spikes but having it hold initial value until full throttle is just too much. Everything I have tried to correct it just results in not enough enrichment on tip-in, resulting in big lean spikes and hesitation.

This is my daily driver, and weekend track car. I really want to get it right.

I know you are still working on it Adam, and I appreciate your time. Thankyou.

In the mean time, if anyone has any suggestions on what I can try or maybe what I am doing wrong here, please let me know.

 

Thanks all.

Jay. 

 

 

Edited June 27, 2017 by JayGow

[Ducie54]

Could you post a log file Of runs using different settings?