Megasquirt Support Forum (MSEXTRA)

Looking at the EAE% at the bottom of this log in green:- What controls the taper from 22%-100% after a sudden lift? You can see it goes horribly lean for a considerable amount of time.

IF it goes lean after a lift, it means the MS thinks due to your settings that either there is more fuel coming off the wall during that condition than there really is, or that there is less fuel getting stuck on the wall in that condition than there really is.

My recommendation in that situation is to decrease the sucked from walls values in the areas where that event occurred... so if you went from 80 to 30 kPa, decrease the values in that area. Decreasing the sucked from walls values tells the ECU that less fuel is coming from the walls, so more needs to be injected.

You should decrease them a little bit at a time until you see the behavior you expect.

Ken

Okay lets get a little more specific...

The attached is a pic of me tuning EAE at 3,000rpm. I'm pretty proud of this as it's getting quite close to perfect on the rising map end, but the falling map is proving to be a challenge.

So the car is happily ticking along at 3krpm. O2 is stable at 14.7.

I smash the throttle to 100%, and there is a quick lean spike then O2 quickly settles at around 13.5. Is the lean spike avoidable, or just the limit of what's possible?

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After a few seconds I instantly 'chop' the throttle. O2 spikes rich then quickly goes way lean and stays there... Map drops from 100 to 15 in an instant. On the 'Sucked from Walls' table which end do I increase? 100 or 15?

Why does the EAE% take so long to return to 100%? The map holds at 15 for a considerable amount of time so what's determining the slope of the EAE return to 100?

milesinfront wrote: So the car is happily ticking along at 3krpm. O2 is stable at 14.7.

I smash the throttle to 100%, and there is a quick lean spike then O2 quickly settles at around 13.5. Is the lean spike avoidable, or just the limit of what's possible?

If you aren't using lag compensation then you'll probably get a lean spike when stomping the throttle. Even with lag compensation you may still get a very short lean-spike depending on the engine, manifold volume compared to engine volume, etc..

After a few seconds I instantly 'chop' the throttle. O2 spikes rich then quickly goes way lean and stays there... Map drops from 100 to 15 in an instant. On the 'Sucked from Walls' table which end do I increase? 100 or 15?

Most likely you'll want to start at the 15 side, but you'll probably have to change the shape of the curve between 100 and 15 as well.

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Why does the EAE% take so long to return to 100%? The map holds at 15 for a considerable amount of time so what's determining the slope of the EAE return to 100?[/quote]

I explained this in my last post. It will return to 100 when the amount of fuel going into the puddle on the walls equalizes with the amount coming off.. Your settings of the Added to walls in relation to the Sucked from walls setting at that kPa will determine how quickly it returns to 100.

As I said in my last post, if it's not returning to 100 as quickly as you think it should, and it's staying lean, then sucked from walls should be decreased or added to walls should be increased in that area. I would suggest starting with decreasing sucked from walls to tell the code that less fuel is being pulled from the walls, and to cause it to inject more fuel in that situation.

Ken

I am tuning this by datalog. What's the best activity to record in order to 'dial this in'??? I started off trying all sort of various conditions like small quick throttle movements up and down etc... I am now doing smooth increases from o-100% throttle and then 100-0% so the TP on the datalogs look like rolling hills with some flat area at the top. I then work my way up the MAP slope, adjusting EAE at each nearest MAP point.

This has been a slow and tedious task and the results, albeit positive, have been very slow...

Probably the hardest thing for me to understand is that EAE is active all the time. I'm having trouble understanding how it's not just 'activating' when there is a detected accel/deaccel event.

That t-shirt that said 'So advanced we can't tune it' is becoming less of a joke and more of a motto... ;)

yeah... i played heps with eae but have hard time to get it to behave perfectly... long story short, low to medium throttle openings it is ok, fast results in lean spike, even with lag compensation. and always rich when i 'cut' the throttle... i mean i can fix that but then 'accel part' doesnt work... aswell i'm having hard time getting cold eae to behave in any reasonable manner... I'm kinda frustrated as i spend significant amount of time anf fuel just driving up and down highway adjusting the settings endlessly...

i think the puddle size is crucial....

what you can try in megatune, set one gauge to 'wallfuel 1' and watch amount of fuels on the walls (or as ecu thinks it is), that will kinda give you a rough idea...

I'm tuning an M20 also. Mine's a C1 2.3 Alpina (Hot 323i)... I don't wanna give up, and I certainly don't wanna insult the code writers, but I feel like I'm chasing a rainbow. Just like you I've been driving up and down the street just burning fuel...

I've been keeping a written track of all the changes I've made, and so far I am still moving in a logical direction, so I suppose I should keep trying some more...

I'm in the same boat as you guys - but I think it's more my misunderstanding of EAE than any problem with the code itself. I'm also tuning an M20 (2.8l stroker) and have never had much luck getting accel enrichments right. Even the "normal" AE doesn't work very well for me - I decided to focus on dialing in my VE map and all other aspects of the engine, and fine tune EAE last.

I decided to focus on dialing in my VE map and all other aspects of the engine

You've gotta have a VERY polished VE map before attempting EAE as EAE is working constantly, not just on an 'event' basis...

the 'common denominator' here is that we all have problems with bmw m20 engine.... small plenum, very long runners... stock 325i cam is 253 deg with 108 deg lobe separation if memory serves me right... stock m20 injectors... they dont spray 'mist', rather they spray a 'stream', i suspect that has an effect on ae too... what AMAZES me is how the stock ecu is handling AE.. there's no map sensor, no TP sensor, there's flapper style afm, but that must have horrible response....

i tuned some other engines, it was so easy... just enable AE, and scale to match pw's, and it was sweet ass... this few we just got idling and enabled ae, and it had huge TB and i was thinking that never we'll never be able to tune ae, but no... 2 minutes later we were driving it without bucking and stumbling... m20 on other hand...

and scale to march pw's

What does this mean?

milesinfront wrote:

and scale to march pw's

What does this mean?

lol, a typo was supposed to be
"and scale to match pw's"

what i mean was that i took the default AE values and just scaled them down to match big injectors that were being used on that particular engine...

I don't want to even bother with EAE, never hear single person runing it perfect, I prefer AE

Good luck with that! Hope you make it

I don't want to even bother with EAE, never hear single person runing it perfect, I prefer AE

Easy tiger! I don't want this thread to become an EAE roasting session...

I like the theory and concept of EAE. I also think it has the potential to be far superior to AE. It just seems to be VERY difficult to get to the right numbers. So far for me it's been nearly as much work/time as building a VE table from scratch...

Hopefully I will get it 'smack on' in the end...
Hopefully my numbers will be 90% useful to other M20 tuners...
Hopefully I wont produce too much C02 in the process to make a noticeable difference to global warming...

mops wrote:the 'common denominator' here is that we all have problems with bmw m20 engine.... small plenum, very long runners... stock 325i cam is 253 deg with 108 deg lobe separation if memory serves me right... stock m20 injectors... they dont spray 'mist', rather they spray a 'stream', i suspect that has an effect on ae too... what AMAZES me is how the stock ecu is handling AE.. there's no map sensor, no TP sensor, there's flapper style afm, but that must have horrible response....

i tuned some other engines, it was so easy... just enable AE, and scale to match pw's, and it was sweet ass... this few we just got idling and enabled ae, and it had huge TB and i was thinking that never we'll never be able to tune ae, but no... 2 minutes later we were driving it without bucking and stumbling... m20 on other hand...

I think it might be more the design of the engine, rather than injectors and cam - FWIW, I have a schrick cam and aftermarket injectors - the problem is still the same though.

is it the injector firing order perhaps? the stock computer runs in semi-sequential - most of us are using simple batched or simultaneous fire. I think full sequential would give us a big boost in low-end tuneability. it doesn't help that my injectors are about 2x as big as they need to be!

I know matt860d had quite a lot of sucess with EAE - I don't know that he got it perfect, but it looked pretty good and he said it was very smooth. I tried using his #s for my engine, but it didn't help me at all.

as far as the stock ECU - from what I've learned tuning MS, I think most of the lag problems people get from the M20 are lack of proper AE, rather than the flapper AFM. it doesn't help, but now that I know for sure what an engine feels like when it goes lean on throttle tip in, I think the stock computer is somewhat to blame as well.

if I can get it to behave well enough below 3500rpm, I'd be happy as that's where I drive the most. Above 4k I don't really notice the lack of well tuned AE.

I'm probably being a little obsessive...

My car is driving almost perfect! I'm just trying to make the datalogs look perfect now...

My lean 'tip-ins' only drop the AFR to about 15-16, which is virtually undetectable to the driver. The only noticeable trait on the road is the excessive leanout between shifts. AFR's drop to the measurable limit of 18.3 on over-run between shifts. This translate to a 'jerk' when shifting to the next gear. Mostly prevelant when trying to drive slow and smooth...

Only other killer is EAE screwing up my idle. I wish it could be disabled at idle, but the theory is that if all is set properly, EAE can only help idle...

My biggest fear is getting to the point that my datalogs look perfect under all conditions, but the idle is stuffed and I still have to walk away from EAE. (I'll be asking really nicely for 'EAE disable at idle' option if that occurs...)

I used to get really bad idle oscillations when I had too big a change between 30-40kPa and 800-1000rpm, I adjusted the graphs so there was only a very small variation between them and the idles stable now.

Good to know!

milesinfront wrote:I'm probably being a little obsessive...

My car is driving almost perfect! I'm just trying to make the datalogs look perfect now...

My lean 'tip-ins' only drop the AFR to about 15-16, which is virtually undetectable to the driver. The only noticeable trait on the road is the excessive leanout between shifts. AFR's drop to the measurable limit of 18.3 on over-run between shifts. This translate to a 'jerk' when shifting to the next gear. Mostly prevelant when trying to drive slow and smooth...

Only other killer is EAE screwing up my idle. I wish it could be disabled at idle, but the theory is that if all is set properly, EAE can only help idle...

My biggest fear is getting to the point that my datalogs look perfect under all conditions, but the idle is stuffed and I still have to walk away from EAE. (I'll be asking really nicely for 'EAE disable at idle' option if that occurs...)

I'm obsessive too, so we both have the same disease ;)

I have the same lean tip in problem on shifts - I compensate for it by pushing the gas pedal earlier, before I let out the clutch. I can usually shift smoothly but sometimes I forget and I get a nasty buck. I think it's possible to tune this out with EAE - using lag compensation and very good settings. If you are gettinga big lean surge off throttle, perhaps sucked from walls needs to be decreased in that area?

as far as idle - ken doesn't approve of this method, but it did work for me. make sure your added and sucked from walls tables go all the way down to your idle rpm, and that you have two bins in that area. Then divide whatever values you have there by half - EAE is still active, but it's weakened enough that it won't cause oscillations in your idle. I had something like 50% for added and 45% for sucked at idle, and EAE stayed at a constant 99-100%.

diegom6 wrote:I don't want to even bother with EAE, never hear single person runing it perfect, I prefer AE

Good luck with that! Hope you make it

Every engine I've tuned on EAE runs great. so now you've heard of at least 3 very different engines running EAE no problem.

(Large v8, 4 cyl with ITBs, and a VW 1.8L with a small plenum and large runners).

Ken