3.0L Megasquirt w/ EDIS: Headers running at different temps?

[FABombjoy]

Unless you set up the lambda delay table for your engine/exhaust, VEL (autotune) will frequently make adjustments based on measurements at the wrong point in time.

You can use formulas to constrain it to only adjust on low TPSdot / RPMdot / MAPdot to limit changes during steady states. Or bring a friend that will turn it on and off at strategic points in the map and then interpolate.

[jangell]

My extremely limited understanding of tuning is that I want to hit AFR targets by adjusting fuel (via the VE table) at a given MAP. Which it seems like is exactly what auto-tune does. But I can understand it being tricky if you're accelerating and decelerating a lot. It seems like it would be easier for it if you're holding at a particular throttle position and engine load.

My AFR table is auto-generated, because I have no idea what it should be otherwise. It seemed like auto-tune would get me at least part of the way there, and I could tweak it after that. But I admit that even their own docs say that it works "to an extent." Luckily there are restore points and I can just reset the table if I screw it up too much.

Some Googling found people having good results with auto-tune, but some people saying they don't like it, but not so much saying why they don't. I found some notes on setting it to only tune above 1200 RPM or so so that it doesn't mess with your idle, and some mentions of adjusting the lambda delay to make it less aggressive, but I haven't found a good "how to" on it yet.

Of course, first I have to get it running again...

-- Joe

[dn010]

Hey Joe, before your next go: in ignition settings - ignition options, set your input capture to rising edge instead of falling edge and give it a try. Maybe this is your whole problem.

[Spittybug]

Hey Joe, before your next go: in ignition settings - ignition options, set your input capture to rising edge instead of falling edge and give it a try. Maybe this is your whole problem.

I concur. I am set up rising edge, going high.

[jangell]

Will do. I think this may be one of the settings I copied from Josh, but I did get the impression that rising edge was more common. Thanks!

-- Joe

[dn010]

Will do. I think this may be one of the settings I copied from Josh, but I did get the impression that rising edge was more common. Thanks!

-- Joe

Per the Megamanual, EDIS needs to be rising edge / going high. It says if it is incorrect "you can experience timing drift with rpms or misdetection of missing teeth on a missing tooth wheel", mis-detection seems like what you're experiencing.

[jangell]

Not sure how I missed that -- I've already made the change on my laptop for when I go to the garage this weekend. Thanks!

-- Joe

[Drive Stainless]

The rising edge vs falling edge is a complicated issue and depends on the circuit that is being used for input.

If you have the v3.57 board, this is what Matt Cramer (DIY Autotune) says:

Use "Rising Edge" if using the following combinations of jumpers on a V3.57:

JP1 on 2-3, J1 on 1-2
JP1 on 1-2, J1 on 5-6

Use "Falling Edge" if using this jumper combination:

JP1 on 1-2, J1 on 3-4

On my 3.0L EDIS setup, I use "falling edge."

[jangell]

I do have a 3.57 (MS2357-C) with MS2-Extra 3.3.3 loaded (well, that's what's printed on the label; I never updated it beyond that).

I popped off the case, and JP1 is on 2-3, and J1 is at 1-2, so it looks like I do want rising edge.

Thanks!

-- Joe

[dn010]

Well, updates?