Speed Density on Evo ECU

[scheides]

Monday update, the part throttle cruise either has gotten worse or I'm noticing it more. I am going to turn my async table back down to stock and see if that makes it better or if the increments I made to the EGR timing advance table make any difference either (I'll try that next).

I unplugged my stock MAS/MAF tonight w/o issue. No CEL, no stumble (did it while car was running), nadda, just plain awesome! Does anyone know if the MAF Scaling and associated tables actually do anything anymore?

Thanks a ton JohnBradley and Bryan@GST Motorsports for sharing your setups with me. JohnBradley's (Ref1, Ref2) is something to strive for, perfect fully tuned 1:1 VE tables, definite beauty to that! Bryan@GST, well, my tables look damn near identical to yours, although I did make a bump near the bottom to try and get some of my midrange load values to line up to my previous maf-based tune. However, our SD RPM VE tables are not so close, I feel like mine are globally down 15% from your or so. I have yet to idle or cruise in full open-loop but the car idled way rich and fuel trims were full -12% negative w/o setting these values in the middle of this table (1000-3000rpm) in the 67-70% region. Anyone have any idea why that might be? Ported head, cams?

I have timing very very close to where it was before and the car feels fantastic. Boost is low 24psi, right where I want it, nice and conservative. I'm nearly ready to flip the alky on except for a few problems: thanksgiving (traveling), rain, and snow in teh forcast. Sigh.

[scheides]

oh, I forgot! Any ideas on what to do for an intake when I delete the mas?

I'm thinking of simply bolting one of these to my standard buschur intake:
http://www.perrinperformance.com/pro...gory=3&model=2

[Kracka]

How do the EGR settings play into all this? I'm a bit lost on that considering you don't even have EGR on your car.

[jrohner]

Originally Posted by scheides

Monday update, the part throttle cruise either has gotten worse or I'm noticing it more. I am going to turn my async table back down to stock and see if that makes it better or if the increments I made to the EGR timing advance table make any difference either (I'll try that next).

I unplugged my stock MAS/MAF tonight w/o issue. No CEL, no stumble (did it while car was running), nadda, just plain awesome! Does anyone know if the MAF Scaling and associated tables actually do anything anymore?

You probably have a better tune now, which is why you notice the stumble more now. It was the same way for me. When it was too rich I didn't notice it, but when I got the AFR's stoich (I want to run much leaner than stoich) it got much worse. I mostly only notice it at around 50-55MPH. I don't usually go that speed, but on a new road near my house they changed the speed limit (for the 3rd time - 45, 55, 50) and it's now 50MPH.

The MAS scaling should still matter, as the way they have the SD set up is to mimic the MAS.

I wish they had the SD set up like hak has ds-map / jackal set up. My new Holset powered 1g runs so awesome. I think 1G's have the best driveability (and idle) to begin with, and they did an amazing job setting up the SD.

[scheides]

Originally Posted by Kracka

How do the EGR settings play into all this? I'm a bit lost on that considering you don't even have EGR on your car.

Despite actual EGR being deleted, there is a subroutine that increases timing off of your timing map while you are at cruise, basically to improve fuel mileage. If you log your car, you'll notice that the timing values while cruising will hover around 40, while the max timing values in your timing table are 38 (on a stock rom). There is a full timing table that allows you to select rpm and load points and how much timing advance you'd like this EGR timing function to add. I don't think it will automatically add 100% of the values in this table, but progressively add some and pull some as needed to keep things running nice and efficient.

On the same note, there is an actual timing table for the cold start/cold coolant temp. It modifies the stock table up to these numbers (they're all negative, right in the cruising area and 0 everywhere else), and the table that we have been messing with over the last year or so (dropped the middle values from 256 to 200, 128, 100, etc) are a reference to this table and the percentage up to which it should be used. Just more ways to tweak tweak tweak!

Anyways, I tried fulltime open-loop and it did not help the 2000-2700rpm studder/jitter problem at all. I tried afrs from 15.5 down to 12.9 w/o any difference (other than it smelled like gas a lot more LOL!). I want to elaborate on this, it is not really THAT bad, it is just a mild 'nervous' feeling the car has in these rpm ranges while cruising steadily. It is really the last thing I do not like with this speed density conversion. My AFR, timing, boost values are all perfect and the car rips on pump gas.

Time for alky

[scheides]

Loaded up alky/alt-map stuff last night and tested it this morning. Fuel is spot on, high 11's just perfect. Timing however, is pretty far off, 4-5°. Thankfully they were LOW, otherwise I might be crying right now Going to have to adjust the scaling a little to bring it up to where it should be.

I'm taking baby steps, and it is just amazing to me how much power 2° of timing adds on alky, the car just feels like it is waking up! 2-3° left to go. I'm working out what I want to do for a new intake, and still contemplating a new COP ignition setup before I throw it on the dyno for shane to dial it in.

[turbotalon1g]

Do you have some kind of freq flyer miles with shane?
I need to get in there when I get home.
Glad to hear its working out, very cool

[scheides]

I wish. I pay just as much as anyone else Discounts are nice, but I'd rather pay full price and know they'll be there whenever I want to go back.

[scheides]

Got alky dialed in today, car rips again! virtual dyno room puts me right back where I was, around 420whp on evoM comparator mode. I had to mess with the load scaling to get timing where it was, but seems pretty good now!

So, I have 2 pending issues:
-knock on spool-up, or tip-in. I'll try messing with the tip-in table, but I haven't logged a lean condition yet and timing seems ok, so not sure what the deal is.
-2000-2800rpm jitter. Still searching, hoping to log it and find a work-around.

Just wanna say thanks to everyone that helped me get this far, I am SO happy with the new speed density setup, it is absolutely amazing.

[scheides]

Well we've been trying to tack down this jitter problem. Basically IPW bounces back and forth when it should be more steady. Today mrfred unraveled one piece of the puzzle:

Originally Posted by mrfred

I've been putting some time into trying to figure out this issue, and there are a couple of areas where I can provide some clarification:

1) You guys may already know this, but the name "MAF filter" is somewhat of a misnomer. This value is used to calculate a weighted running average between the old master load value and the newly calculated master load (from the MAF). The formula goes like:

MasterLoad = [MAFfilter*MasterLoadOld + (256-MAFfilter)*MasterLoadNew]/256

2) SD master load is inserted in place of MAF master load further down in the master load calculation subroutine, so SD master load is not affected this weighting calculation, and thus any changes in the "MAF filter" value have no effect on the SD master load.

However, in looking a little further just now, I do see that there is a flag that gets set at the end of the subroutine where the weighting value is determined. The value of the flag is dependent on whether the weighting parameter is above or below 200. This flag doesn't affect the master load calculation, but it does affect some of the calculations for the fuel pulse width. This is the best candidate that I've seen for causing the jittery IPW issue. I'll see if I can look at it further this weekend and perhaps come up with a patch to test it.

EDIT: Having thought about it a little more, it should be pretty easy to test this. We can create a 1D table for the over/under value, and then set the over/under value to 255. Another over/under value to try would be 0. This value is below all the possible weighting parameter values. For the 9653 ROM, the address of the over/under value is 0x162C. Its a word length value, so use uint16 for the scaling.

So, I'm gonna try:

<table name="MAF Pulsewidth reset (test)" category="Speed Density Tuning" address="162c" type="1D" scaling="uint16"/>

Unfortunately I'm gone till sunday night :P

More info on this subject here, we started a thread dedicated to it:
http://forums.evolutionm.net/ecuflas...ml#post7747496

[scheides]

Wow, reports are already coming in that setting this to 255 solves the jitter problem! Can't wait to try it out

[Matt D.]

Is there any reason that I should not do this to my car as soon as possible? Based on everything you've said it seems like it would cure my drivability issues and cold start idle.

[scheides]

For me to do this safely I have a wideband and have been logging logging logging my car under all driving conditions and openly accepting the fact that ultimately I could do more harm than good during this process. without a wideband, a trip to the dyno is really really necessary to get this done, and I'm sure it'd be more time than a standard tune although it isn't much more work than dialing in injectors and standard maf scaling it does take some time.

The other thing to remember is that if your volumetric efficiency (VE) changes at all, you need to brush up your fueling. If you put a few parts on and make a bit more power, you'll be running lean, as this whole system is built around specific scaling for the engine's current VE.

I'd say its worth having a wideband in the car (they're cheap now) and owning a logging cable so you could plug it in and verify all is well now and again, but I would say if shane is willing to do a tune on it I'd be willing to help anyone get converted and make sure everything's ready to rock.

Parts list:
-IAT sensor
-uprated MAP sensor, JDM/EvoX 3.3 bar or the Omni 4 bar
-wideband (LC-1 or similar)
-tactrix cable

Once I make sure all is dandy with my car I'm willing to let people check it out for themselves, I think it is absolutely worth the effort.

[scheides]

mrfred's MAF airflow reset tweak works! At cruise, at any speed (specifically 1800-2800rpm) the car drives SMOOTH AS SILK! I will be logging over the next few days to verify nothing else is changed but I'm confident that this was something that only affected airflow levels at cruise.

I'm now fully sold on speed density. This has completely transformed the car into a new level of smooth on all things that previously set the car apart from your average car that already has a smooth idle, steady cruise, and keeps everything that makes it an evo

[jrohner]

I'll have to give it a try again then. I'm also going to give ceddy's 98-99 DSM speed density a try (ordered an openport 2.0 cable the other day), which is based on the same thing.

[scheides]

Check back here this week, there's a change that mrfred gave us to try that might actually work better to accomplish the above issue w/o affecting some of the accel enrichment stuff (which the original hack may or may not have affected, but better safe than sorry). I'll post my findings

[scheides]

http://forums.evolutionm.net/7753333-post44.html

fix#2:

<table name="Scaling Factor for Transition Load" category="Speed Density Programming" address="1630" type="1D" level="1" scaling="uint16"/>

Put fix#1 back to 205 (or leave it stock if you haven't done it yet) and set fix#2 to 0.

fix#1 was SOOO SMOOTH it left my car feeling like a caddie! I was initially so impressed, I was blinded by the fact that what this fix did was actually make the car lethargic under 160load. It's too bad, because it was so nice Fix#2 brings back quick response and leaves the car nice and smooth, probably the best solution for 99% of everyone that would want to try this and not touch any other tables.

Here's an excerpt from mrfred about what the two fixes do:

Originally Posted by mrfred

You are welcome to use either fix if you are not having any driveability issues. Here's a rundown of the situation:

For uncompensated loads of < 70, the FPW calculation subroutine wants to use the following formula to scale the base fuel pulse contribution to the total fuel pulse:

BFPW scalar = (MasterLoadW +/- C*DeltaMasterLoadW)/2048

where "+" is used when the load is increasing the "-" is used when the load is decreasing. The "W" means the values are scaled by the fuel pulse width warmup up compensation table, aka MAFMULTWARMUP.

When uncompensated load is >= 70, then the code wants to use this formula for the base fuel pulse scalar:

BFPW scalar = MasterLoadW/2048

For reasons that aren't clear to me yet but are surely in the details of how the master load is calculated in low load conditions, a car in MAF control seems to do ok with this scenario, but a car with the SD patch does not like the DeltaMasterLoadW contribution.

Here is what the first fix does:

1) It forces the code to use MasterLoadW/2048 at all times for the base fuel pulse width scalar.

2) It changes the method for calculating the min load change needed to induce a SyncLoadAccel contribution to the total fuel pulse width. Compared to the factory setup, at low loads, the min load change required is increased, and at high loads, the min load change required is decreased. Thus the car may have a little more hesitation during load change at low loads (below 160 load), and may be a little richer during load change at high loads (above 160 load).

The second fix just forces the use of MasterLoadW/2048 at all times.

Without knowing how much SyncLoadAccel contributes to the total fuel pulse width, the second fix seems the safer route to go. However, if you are happy with AFRs during load transitions when using the first fix, then its ok to use.

What ultimately may be the best solution could be the use of the second fix in combination with access to the tables that control the min load change required to induce a SyncLoadAccel enrichment contribution. These min load change values for SyncLoadAccel contributions may be causing the jittery response that you feel with the second fix. I plan to post those tables in my advanced fuel control options thread later this week.

I'm going to run on fix#2 for a few days, see how I like it, and go from there. Might try a combo of the two or maybe dig deeper, but for your basic bang/buck speed density setup, fix#2 (Scaling Factor for Transition Load=0) is IMHO the way to go.

[rose0529]

Got to drive this car last night with the #2 fix on it. Felt very good! I had ridden with scheides just before the speed density set-up and this is a vast improvement. It had a rock solid idle and cruising seemed nice.

[jrohner]

Looks like I gotta order another GM 3-bar MAP sensor (robbed it off my 2G for my Holset-powered 1G that's running speed density) so I can give my SD rom another try with this change.

[scheides]

Do it, you will like it I ordered a new filter to delete my MAF today from perrin. It has a 3.125" inlet and is 95%+ the surface area of the old one but will bolt straight to the existing 3" intake pipe already on the car. I've had the MAF unplugged for a week or so now, no need for it anymore