Orinawak

Just wanted to report on something I noticed tonight while doing some tuning. I've been tuning the I value of my EGO control, and so far it looks like it is oscillating less. There are three things I did notice that seem a bit odd, that maybe you guys could help me with.

1.) When cruising and using light throttle, it looks like my AFRs will sometimes go lean, almost like the car is trying to go into decel fuel cut. In the attached log, this can be seen from 129.472s to 134.085s, 181.626s to 186.313s, and 278.444 to 291.355s. Is there a setting I can play with for this, or is this normal?
2.) It looks like my EGO correction is trying to correct my AFRs while my car is going into decel fuel cut. This can be seen from 150.162s to 153.908s when going into decel fuel cut. Before, the car would very quickly go to the leanest condition in decel fuel cut (22.4 on the gauge). Now, the car seems to linger around 17 to 18 to 19 AFR before going full lean in decel fuel cut. Seems like my EGO correction is trying to correct it while in decel fuel cut. Is this normal, or is there something I can adjust to account for this?
3.) Sometimes when shifting; not always, my AFRs will lean out to between 15.3 to 16.0. Is this normal as well while shifting?

Thanks for any help! I know the log is long, so I tried to point out key areas that I noticed while going through it a bit.

HowPrayGame

Add fuel in the lower cells its hitting when it goes lean


Try lowering your Over-Run fuel cut delay from 2.0 to 0.7 or so, I only delay it to 2-3 seconds when I feel like being a ricer and making my exhaust pop. Then it won't hit the 20 kPA cells for longer than a few milliseconds. When you shift your car will hit the bottom cells, so fatten up the VE there as well if you want it to stay around your target AFR.

Orinawak

Thanks, I will make these changes and see how it goes! Out of curiosity, are the pops that occur due to the longer delay bad for the engine? I've always thought that the lean condition would be bad for the engine, but I guess it depends on load as well if I'm not mistaken.

HowPrayGame

Probably yeah, I have all of my VE cells under 19kPA set to 30 across the board and my Fuel Cut Delay to 3 seconds, as well as the 10 degree column in my timing table, and it probably isn't very good for my exhaust valves. When I was running the OEM Computer with this exhaust it also popped on over-run at higher RPMS ( I am assuming when it was running open loop ) so I suspect it isn't that much of an issue.

Not sure how OEMs do it.

deezums

iTrader: (3)

lol at MS3 VVT control.

You've got the same bug I do, log results go insane while in overrun fuel cut. Check out engine states. 1320 seconds Engine idling 3? Not supposed to happen. It's either a logging bug or something JSM did is wiping **** out it's not supposed to. The way he shoved the latest EGO corrections in I ain't surprised.

******* garbage megasquirt. Full of bugs. Full of half completed code, never to be finished.

I would post that log over on Megasquirt forums, and if you don't mind say" Deezums says Hi, JSM."

Orinawak

Thanks! I'll play around with the VE table and then the fuel cut delay. I kind of like the pops, but I don't want to prematurely destroy my engine, haha!

Ahhh I see, thats interesting. I'll post it over there. I'll pass your message on too. I have been talking to someone who knows much more than I do when it comes to ECU tuning, and he does not like Megasquirt at all...he says there are much better ECU solutions out there. I was just looking for ease of use, and it seems MS is the go to in the Miata community.

Orinawak

I decided to try going out on a drive with no computer and just see how the car behaves. I noticed that now when coming back to Idle from a higher RPM, the car is now dipping again, and the AFRs go lean (17.0 to 19.0) before the RPM jumps back up slightly again. I did not take a log since I didnt have the computer, but I can reproduce the issue and log it and upload the log along with my tune later. The only things I changed was I ran VEAL on WUE before driving, and then increased the fuel VE under 20kpa to hopefully keep it from leaning out while shifting, and changed some of my accel enrich graph values. Still getting the lean condition during light throttle application, but I didnt address that too much yet. I will attach my tune and a log later, but that is what I am experiencing so far.

Orinawak

Here are the logs for the conditions I'm experiencing as well as my tune. The first log (return to idle dip and lean) is the one where when going back to idle, the RPMs dip and AFRs go lean. I had this issue before, but it was cured and is happening again. You can see this occur from 2.266s to 11.139s. You can see at 4.262s and 16.886s where my idle RPMs drop to below 700.

The second log is during startup, I have noticed my AFRs are lean for 5-10 seconds before going back to around 14.7. Not sure what is causing that since I did not have that before either, so just thought I would throw a log in for that as well. Thanks for any help again, you guys are very helpful! If I didn't have your help, I would have probably ripped the Megasquirt out by now and thrown it at the wall!

HowPrayGame

Lean hot starts - Fuel gets hot inside fuel rail due to returnless fuel system of NBs, to work around increase ASE Taper to look like a U (left graph) so when the ASE Taper ends its where it normally hits 14.7 (either due to EGO or the hot fuel all being used)


The idle dip looks like lockout settings for closed loop idle/the engine states Overrun MAP threshold not being exact, I am not running engine states but the MAP goes from 15.3 at minimum (2.1s) to 20 (3.3s) and then 3 seconds later the car enters closed loop idle (status 2 = 128) as the idle goes up to 1100 rpm, then it settles down to target. Your car is a bit different from mine as below 20 kPA I am not on the throttle, on some logs you uploaded your car is in the low 18s-19s, maybe try lowering the over-run MAP threshold a little bit, 15 or 16 perhaps? I can't tell what the right value would be but I suspect the car stays in over-run too long. It also goes real lean so more idle VE fuel may be required on the 20 kPA region from 700-1200 RPM, it not going lean should help the dip as well. May want to turn off progressive fuel cut for Over-run Fuel Cut first to see what happens.

Both times it is 3 seconds after 20 MAP/kPA that the car enters closed loop idle, the car will sit for 2 seconds (set under Closed-Loop Idle PID Delay) before entering closed loop, at the appropriate Initial Value Table that is referenced, which is 29.4 IAC Duty % both times.

It may also just be the initial value table value not being high enough (what RPM does the car idle at with the idle valve test mode set to 29.4? If its 1100, then its fine. If its 700, then raise it till it is a few hundred above the target RPM and the dip should stop.

irodd

iTrader: (4)

here is your tune with the corrected engine state setting, injector voltage correction, speed and gears settings, etc.
also consider update firmware to 1.5.2rc13

Orinawak

Thank you! I will take a look at these settings. I figured I may have had to adjust the ASE settings for the lean hot starts, but didn't know how to proceed so thanks for the information there! I didn't know about that issue with the NBs. Thanks for the other information, I will take a look at it and see what adjustments may or may not work and let you know!

Thank you! I will give this tune a try before making any changes. Is that a beta firmware release? Anything I should know about using that firmware, or is it basically just like using any other?

Orinawak

Just an update; I tried the tune you gave me irodd, and when I started the car, the RPMs were fluctuating between 1300 RPM to 600 RPM, and my ignition advance would fluctuate from 7 degrees to 30 degrees of advance. The AFRs were consistently around 18.8 to 20.3 before the car finally died after 10-15 seconds. I then reloaded the backup I took of my tune before uploading that one, and started to make small changes.

The first change I made was with the ASE taper. Seemed to be okay, so I left that at the values that HowPrayGame, you show in your picture. Next I went and played around with the fuel VE table to see if I could get it to stop leaning out. After revving it slightly to around 2500 RPM and letting it drop to idle, it still would lean out, but only to around 15.1 to 15.2 AFRs. I then decided to try changing the engine state settings to the one in the tune you gave me irodd, with the exception of the overrun MAP threshold; I set that to 16kPA. I did the same test, but AFRs went up to 15.4 to 15.6 at that point. Added some more fuel, and it is still going lean around 15.3 or so AFRs when settling back to idle, but Idle RPMs do not seem to be dipping as bad as they were before. Still have progressive fuel-cut on; tried with it off but I didn't seem to see much of a difference. I will see how the car behaves again when the engine has cooled overnight.

I also did the test you mentioned HowPrayGrame with the IAC Duty %, and at 29.4 I'm at about 950-960 RPMs.

At this point, do you guys think I should just add more fuel until the AFRs aren't leaning out the way they are when returning to idle? Just trying to understand why its doing what its doing and what I can do to mitigate this. I will have to take it for a drive tomorrow and take a datalog to see if the engine state settings made a difference while driving as well.

HowPrayGame

Yeah its basically just adding fuel to the VE table to fix the leaning out when lifting throttle thing. My car does the opposite, it richens temporarily before my fuel cut kicks in when I lift the throttle. IAC Value is fine, dip should be heavily reduced with additional fuel and tuning other stuff, not the initial valve duty

Orinawak

Awesome thanks! I'll do some more tuning tomorrow and let you know how it goes.

Orinawak

So, an issue with cold start after the changes I made. On cold start, the car will go in and out of idle and decel. The ignition advance will go up to about 40 then drop back down again when it enters decel, and shoot back up as it goes back into idle. The RPMs also will stay around 2700 RPM and not go down as it should while in idle. Any tips on what I should look into tweaking to help smooth out this issue?

I have attached a log I took along with my CurrentTune.

HowPrayGame

Here's why



Change the engine state Slow Decel threshold back to -800, if its any less than that when you start the car and it settles to the target idle you will have issues. Since its -300 and it hits -440 here it exits slow decel and continues

I noticed some megalog viewer parameters I have missed previously, this should help determine what lockout setting is messing up if you have engine state issues. With your TPS lockout at 0.3% if you have any amount of noise it is possible your car may go in/out of closed loop idle. Look out for that.

Orinawak

Ahh I see thank you, I will change that. I will probably change my TPS lockout to 1% again as well to account for any noise. Where did you find those parameters in megalogviewer? Is there a view I have to toggle on to see that? Currently on mine I see the data points and their values, and then the graphs at the top with a tuning screen to the right, which I figure I can turn off.

HowPrayGame

Quick views

Orinawak

Oh thanks! I thought it was a different menu, just realized its on the side there...my bad. So I've been playing around with my tune a bit to help with the lean condition during return to idle. I added more fuel to my idle cells, but just enough that I would still hit my AFR target of around 14.7 at idle. I still notice a slight lean condition (anywhere from 15.2 to 16.0) when returning to idle. I tried adding more fuel, but my idle AFRs then drop to around 14.3 to 14.5 rather than the target of 14.7. Not sure if there is anything else I can do here?

I also decided to run VEAL against WUE, and after changing the ASE taper, VEAL decided to change all my WUE values to 100. Seems kind of odd to me, not sure if thats normal.

I'll upload my tune and a log of the slight lean condition on idle return; thanks again for staying with me and helping, I really appreciate it!

Orinawak

Quick question here. Should I be using the idle VE table? I was told to turn it off by someone else who I reached out to, due to it being not needed and redundant in their opinion, but now Im thinking using that table could help solve some of the issues I’m experiencing.