Looking for 20V 4ag ignition map

[gunni]

No ,

why do you think that?

[rob@vems.co.uk]

OK that makes sense.  But still can't let me use SD for lower RPM and alphaN for higher RPM.  This is ultimately what I'm looking for I think.

You want AlphaN down at low RPMs where the MAP signal is noisy, and SD further up once the pulses even out.

[sly]

That is what the OEM did.(run MAP down low and TPS for the rest) I want to do the same for my alfa too.
For idle the motor has a small log plenum and works like a plenum motor down low and idle.
but as you lift off then the reading can go to hell. On my alfa spider the problem is the vents in to the ITBs from the tiny plenum get venturi like so the MAP numbers get strange depending on how the air flow is going past the vent. one moment it can be blowing in the vent giving more PSI then is, there then the next change to a venturi where the PSI is much lower then real.
I could and did run MAP on the spider. but the maps had a lot of ups and downs. And the EGO worked overtime. I put the vents in the best place I could. I placed notches in line with the shaft of the butterfly. where the air speed is the slowest. The stock ports for idle bypass where the worst as there were right on the out side and had big time venturi affects.

I am guessing the 20V may have the same problems.  but getting good MAP on idle is very easy on a ITB car. you just need the idle plenum and take the reading from there. The idle plenum is also what keeps the balance as the butterfly's never seal the same when all the way closed. even the smallest of scratches makes a big difference then.

[Denmark]

I hvae run a blacktop on pure map,
And the only problem i had was if was was going to hold a high speed with partial throttle, that was fixed with running a very fast ego corretion, as it had to lean out fast, otherwise it would make a bug as it would run really rich lambda 0.7

The take of was the oe take of to the map sensor ,and the is normal engine vakuum, no problem at all..


/Skassa

[rob@vems.co.uk]

AlphaN blending uses TPS at low RPM and MAP at high:
http://www.vems.hu/wiki/index.php?page=GenBoard/UnderDevelopment/AlphaN

When I did the mapping on a 20V I used SD because of the plenum signal - but it was poor in two areas: the difference between 1% and say 5% TPS opening was vast, and the difference between 75% and 100% was a few kpa, but I got it evened out okay using very small steps from 95kpa, fuelling from closed throttle was always a pain though.

The professional calibrator (who works for an OEM) who then mapped the car, put it onto AlphaN blending and got a spot on map that's in use on about 5 different cars used for drift and road driving - which is why I recommended it.

This is the reason that many OEMs use MAFs - they meter the airflow regardless of throttle type, and use the TPS for acceleration enrichment.

They say that we can technically use MAFs on this system by replacing the TPS input with the MAF output - I've never seen it done though.

[Grant]

OK, so the guy you know overcame the issue you had with small throttle openings by using alphaN @ small TPS, and switching to map above there and it seemed to work? 

What RPM do you recommend I switchover from AlphaN to SD? 
Also,
1. Do you have any idea what I might be having trouble with getting fuel cut to come on full time?  Under what seem like the same conditions (similar RPM, CLT temp, MAT, and 0 TPS) fuel cut will happen 1/4 of the time or so, and the rest of the time it will not.  I've been fiddling with megatune for a while now and am stumped.  Maybe it's a bug from using strictly alpha-n?
2.  Any idea why when I sloooowly tip in the throttle at low-load, lower RPM (3% tps, 2500 rpm) I keep getting spikes of extra fuel, before EGO leans out to the desired lambda?  MAT % is like 0-1% extra enrichment, Accel enrichment is nearly nothing in the first few default DV/DT bins. 

Thanks for any help 

[rob@vems.co.uk]

The answer for all of this can be found in the maps, PM IrishTwinCam on here, he's got all this info stored away he's a walking reference for all 4A-GE related info.

IIRC the blend point was around 3500rpm for alphaN and 2500rpm for SD.

As for fuelling - what firmware is this on again?  I think you'd really benefit from the newer ones with dTPSvsRPM mapping

[gunni]

If you have pulsation in the map signal then you´ll need to dampen that.

Especially if you have good pressure readings at low throttle angle. Then you should have the same at higher throttle angle.
If not then putting in a damper as can be found in most aftermarket boost controllers should dampen the signal.

The place where all the ITB´s connect together and then to the ecu, this is where you can redesign it´s size to create a smoother signal.

I´d rather go Alpha-N with map compensation , and the reading for the map would be infront of the itb´s.

[Grant]

Ok Rob, I'll be sure to PM him.

For blending...I'm a bit confused, since there is only one map to reference from, how do you figure out what values to input if KPA was a reading for TPS position below 2500, but becomes actual vacuum above 3500?  How would you map out 3000 rpm if the two load designations are conflicting?

Is there a way to have two separate maps to reference from that I'm not seeing or something? 

This is on 1.1.44alpha2, but I'm OK with upgrading to anything that is stable.  Daily driver at college ATM.

[Grant]

Gunni,

When you say AlphaN with map compensation, that's what we're talking about as well right? AlphaN below a certain rpm, then SD above it?

PS, map readings are fine on this engine, it's a factory ITB engine so they did their homework.  Seems stable at most RPMs.  The trouble is, as Rob mentioned, The map readings are usually very high or very low, not linear at all. 

[gunni]

No what I´m talking about it using Alpha-N only for all the fuel.
But then adjust for any ram-air effects or different atmospheric pressure by measuring the pressure infront of the ITB´s runner.

If you have a smooth map signal all around , then you can adjust the scaling so that the trouble area has better resolution
say

Kpa axis , 20,40,45,50,55,60,65,70,75,80,90,100

But hybrid alpha-n is probably the best solution though. , Low rpm is alpha-n and low intake pressure, higher rpm´s and higher intake pressures where they are stable you run MAP.