You can go pretty lean on overrun (15-30 kPa area), but if to go really lean, say higher than about 15 AFR, you'll get a lot of exhaust 'burbble.' Some people like this sound, so if you do aim for 16-17 AFR, or if it's not your thing, more like stoch - 15.

I have no burble

Correction, if you cut fuel completely, then you don't burble either, sorry!  And timing also matters some, but I'm less clear on the relationship there.

Burble is a fun word to say.   I am not seeing anything to far above 15-16 on the AFR, just by eyeballing it.   I haven't really done a deep dive on the data.  I am waiting for the header.  

There is some sort of sensitivity setting to do with the O2 sensor.   It has to do with the distance between the collector and the sensor.  I really don't want to play with that right now.  Not sure if that is something that you can play with on the Megasquirt.

Convention is 24" downstream from the exhaust ports.  You want it far enough away that gasses from all 4 cylinders have mingled and the EGT isn't so hot to foul the sensor, but not so far away that it takes forever to warm up and lags behind what is actually happening in the combustion chamber.  In all honesty though, I think a lot of this is more important for turbo and catalytic converter setups, and doubt a few inches closer or further will make much difference in the M10 exhaust stream.

I am experimenting with open/close loop.   I  had it set for 140 degrees for CL but it didn't like that,  Just wanted to see what it would do.   I have now set it for RPM,   So it will go CL for anything above 1200 RPM, just to see what the AFR's would do at idle.  The CL comp would normally cycle from -4 to +6 at idle.  I wanted to see what would happen on open loop.   It made little difference except when I let it idle down, about 40% of the time it would keep going to 100 RPM, lean out to 32 and then recover.  The only thing I am seeing is that it tends to overcompensate less. 

The header will be here by Tuesday or Wednesday, hopefully, I don't have to drag it to an exhaust shop after it goes in.  Attached is my current config file.  I am playing around a lot with stuff.   I think I may start a fresh file from scratch when I do the header. 

BMW2002 v 16.sniper

I have never felt so good to see a pile of pipes.  I have it just about installed. Everything is in and hanging loose.  Tomorrow I will snug up on everything and give it a run, hopefully, I don't have any leaks.  I will have to adjust everything down the line. The header extends back further than the old one, so I will have to push up the slip joint by the diff. 

On 11/18/2018 at 2:35 PM, AustrianVespaGuy said:

That guy's me, so thanks but yes I'll stand by those values for AFR targets!

Ok so the header is in, and it makes a nice sound, but I feel my targets are maybe too rich.  I am going to copy your tables into the sniper setup and see what I get.  Also now that I know that air leaks are at a minimum. I am going to start pinging Holley to see if there is something I am missing. 

For the life of me, I am not sure how it figures out my advance.  And the first question I will ask them is why on my data logs am I seeing flat points on the advance graph.  There is a way to set the baseline, which is 12 degrees at idle. But I am not sure what that really means, or even it applies to someone with a CD box ignition.  

The good news is that the reverse light fix was easy, and my power door lock was just a loose wire and the evaporator is back in, so I can now start tidying up wires.  Now if I can just nail this thing down I am a king. 

Flash update! the 02 sensor went for a s**t.  Luckily like the header, I planned for this.  I have a new OEM Bosch sensor in the parts stash the I got about 3 months ago.  Holley will cover this under warranty, I will keep it in the trunk for a spare.

This may be the source of my frustration with the car overrunning when decelerating to the point where it almost stalls.   I am likely not that lucky. 

I will let you know tomorrow.   

Ok the new O2 sensor is in, it is maxing out the learning at %50.  Not sure what to make of this,  but I will need to drive it to get the learning table down.  

At idle it does seem to be able to hold a lot closer to the target, so we will have to see how this shakes out. 

Where did you install it in the header? I think that Bosch LSU4.2 sensors don't like TOO much heat; I was killing about 1 a year in my car so put in one of these to help the situation; only been about a year so a little premature to tell but have a good feeling about it! NOTE: note sure if this issue also applies to the new LSU4.9 sensors too or not. . .

https://www.innovatemotorsports.com/xcart/product.php?productid=16148

It is not uncommon for the Holley sensors to go, much like the fuel pump.   I have a serious problem, and I can't tune my way out of it.   When I try to go CL, the compensation just is in this long parable. 

Tried for 2 hours to tune it out. It is like the AFR and the CL are not paying attention to each other, or are lazy. 

You can see in the attached log around Second spot 940 I turned off Closed loop, and things settle down. Turn it off and CL comp chases the AFR up and down.

Is the Closed Lopp compensation chasing the AFR?  or the AFR chasing the CL? 

Any help would be appreciated.   I have set the computer to go CL above 2000 RPM, but when I hold it at 2500, I get the same sort of cycling of afr and CL comp. 

I have completely disabled CL for now, so I can drive it, but It would be nice for it to tune properly. 

Sniper Log hunting idle.dl

On 12/23/2018 at 12:39 PM, AustrianVespaGuy said:

Where did you install it in the header? I think that Bosch LSU4.2 sensors don't like TOO much heat; I was killing about 1 a year in my car so put in one of these to help the situation; only been about a year so a little premature to tell but have a good feeling about it! NOTE: note sure if this issue also applies to the new LSU4.9 sensors too or not. . .

 

https://www.innovatemotorsports.com/xcart/product.php?productid=16148

It is installed about 6 inches past the collector.

Any luck reaching out to Holley for guidance? @Holley Tech