7A-GE 16v ITB's map/alpha-n

[86Spain]

Hello Everyone!

 

This summer I finished assembling a 7A-GE (1800cc block of 7A-FE and cylinder head of 4A-GE), wiring and mapping was to be made by a workshop that, after having bought the ECU and sensors link, invited me to find a plan B because they were too busy, so I am the plan B xD

By the way, it's a Link Storm G4X.

The engine has a ported cylinder head, 20v Black Top ITB's, high compression pistons, lightened connecting rods, all balanced and well measured, and now that it's time to move on to the engine management, I wanted to ask you:

After reading a lot, it seems that the best for a car with itbs that is used daily, what works best is a mix between Alpha-n and MAP, so for the map I'm mounting a vacuum manifold with check valves to the itbs.

The ECU has coolant temp, oil temp, oil pressure, MAP, TPS, IAT, fuel pressure, wideband and knock sensor, and the triggers come from the 24 tooth wheel and the second from the phasing wheel, which originally had 4 teeth and now only 1.

The ignition is now OK, we can adjust the advance and measuring with the stroboscope, it works perfect.

What I wanted to ask you is if you could tell me how or where to start learning about mixed maps, or how to call the maps that value map and alpha-n, or if it is a table with alpha-n and map correction or the other way around, or if it goes by percentages of tps or vacuum in the map.

 

I'm still learning, greetings and thank you very much!

[DerekAE86]

I wouldn't bank on you having a good enough MAP signal to use it for tuning. It'll be something you'll have to determine after you get the car running on a TPS only tune first.

Typically on ITB engines with a vacuum manifold the MAP signal is very noisy (can see the pulses from every cylinder firing) and its very low resolution.
Meaning it will go from high vacuum to almost none in the first few % movement of the TPS.

I have ITBs on my 4AGE 20v and here is a snippet from one of my logs where I do a short high acceleration squirt:

You can see it goes from creating 55kPa of vacuum in overrun rapidly down to only 5.5kPa of vacuum at only 10% throttle.
I only went to 85% throttle, but by only 30% the manifold pressure was already reading atmosphere so if you tuned off MAP/MGP the ECU wouldn't be able to tell the difference between 30% and 100% throttle.

I do utilize manifold pressure for other purposes like increasing fueling at idle and low load when I have AC on or high electrical load like fans.
And I use it as one of the parameters to determine when to turn on my VVT. It just depends what else your engine has and how in depth you want to go.

If you do want to pursue a mixed tuning method, I would recommend using TPS% as the axis on your Fuel Table1. Then create another table (a 4D/5D table) with MGP as the axis.

But I would keep this second table much lower RPM resolution (maybe 1000rpm steps) so you don't have heaps of cells to tune.
Then during the tuning process you'll need to figure out if there's situations at the same TPS% point your MGP reads significantly higher or lower which is making a difference to your fueling and adjust accordingly.

Say you tune the engine at a steady state with a certain amount of load. You get the fueling perfect at 10% TPS @ 3000rpm with MGP reading -5kPA for example.
But then you change gear/load/vvt/ac/something and even though you're still at 10% TPS @ 3000rpm the MGP reading has gone to -2.5kPa and your Lambda is now reading leaner.
Since you know your TPS% table is tuned at the previous steady state you can instead change the MGP table to increase fueling and bring your Lambda reading back to target.

[Adamw]

If you have an idle valve then the suggested strategy is to set the equation load source to MAP, use TPS as the load axis on the fuel, ign and lambda target tables.  This would be Alpha-N + MAP compensation.  The MAP compensation will then just happen in the background with no user set up/tuning required, the MAP is needed to compensate for any air going through the idle valve bypassing the throttles. 

If there is no idle valve then the suggested strategy would be to set the equation load source to BAP, with TPS as the load axis on the fuel, ign and lambda target tables.  This would be Alpha-N + Baro compensation.  This will give more stable AFR at idle and light loads than using MAP, but can only be used when there is no idle valve.  You do not need a MAP sensor connected for this application as the ECU has a baro sensor built-in.  

 

7 hours ago, 86Spain said:

so for the map I'm mounting a vacuum manifold with check valves to the itbs.

There should only be a check valve between the manifold and brake booster (if there is a booster), definitely not between the vac manifold and engine.  

[Vaughan]

7 hours ago, 86Spain said:

After reading a lot, it seems that the best for a car with itbs that is used daily, what works best is a mix between Alpha-n and MAP, so for the map I'm mounting a vacuum manifold with check valves to the itbs.

As far as I am aware there would be no purpose for check valves from the ITBs to the vacuum manifold especially if you are wanting to use that vacuum manifold for a MAP reference. You would obviously still want a check valve/one way valve between the vacuum manifold and your brake booster (if fitted).

7 hours ago, 86Spain said:

What I wanted to ask you is if you could tell me how or where to start learning about mixed maps, or how to call the maps that value map and alpha-n, or if it is a table with alpha-n and map correction or the other way around, or if it goes by percentages of tps or vacuum in the map.

Set the 'Equation Load Source" to "Load=MAP" and then setup the Fuel and Ignition tables to have TPS on the load axis. It is a good idea to have the TPS values increase in a non linear manner such as 1, 2, 5, 10 etc as you will see the largest variations in air flow/fuel requirements around the smallest throttle openings.

Setting the Equation load source to MAP means that it will apply a MAP correction over the top of the rest of the fueling.

[atlex]

Hola de Emporda (Catalunya)! Mi motor passear el ITV facil, y lambda es en control pero no necessitas por es un coche sin catalizador.

Typically the 4AGE ITBs have only two map source ports - one on cyl1 and one on cyl4 - as well as a big port on cyl4 to run the brake booster.

You could tap the 2nd and 3rd runners for more and then attach them to a vacuum distribution block to try and get more accuracy but it's not worth it and most people don't do this.

Don't be confused with the ports that are closer to the throttle body itself, those aren't any good for a vacuum. I don't know what those were for. They're almost at the blade rather than properly behind it, so aren't any good.

My 4AGE ITB tune (it's a Mazda B6 motor, RS Aizawa 'kit') runs with a TPS load axis only, the MAP is hooked up but it is just there as it is also the reference for the FPR.

It's perfectly good as long as your TPS is giving valid, repeatable numbers.

For added benefit you can go 'hyper fine' on the low TPS parts of your fuel map - 0%, 0.5% 1%, 2% 4% - the difference in flow between 70% TPS and 100% is minimal, the relative difference between 0% and 1% is huge.

That said I'm actually looking to find a way to get a more accurate TPS on there than the Toyota Stock one. If anyone has ideas / knows of an adapter ? I'd love to run a hall effect rather than wipe type TPS.

P.s. I'd love to go 7AGE, I've got a 7AFE block in my 4WD Carib and this would be one of the paths to glory for that car.

[DerekAE86]

29 minutes ago, atlex said:

Typically the 4AGE ITBs have only two map source ports - one on cyl1 and one on cyl4 - as well as a big port on cyl4 to run the brake booster.

This is the case for a 20v head. But when using the ITBs on a 16v head you can't use the standard 20v "manifold" that has the vac ports, brake booster port and vacuum chamber.

So you have to put vacuum ports in each of the runners and collect that in an external vacuum manifold to feed to the booster, map sensor and fpr.

[86Spain]

thanks to all of you for such a quick responses!

so BAP + alpha N is the way to go, no need for map sensor

 

yes, all itbs are connected to a vacuum block, the itb adapter has nipples after thottle butterfly so they have vacuum there. Plugged to the brake booster (with check valve) and oem 4age 16v fuel pressure regulator

 

i would like to ask where to start looking for a base ignition table or a base map to have a reference or starting point, and where can i find info on how to set up link knock sensor on the link software, as there is absolutelly no info about it 

 

 

As before, thanks in advace guys! much appreciated

[atlex]

Check your messages, I've sent you an example ITB map for the same ITBs but different motor. It has the knock and decent fuel/ignition tables to make a good starting point.

[DerekAE86]

On 9/12/2023 at 7:23 AM, Adamw said:

If you have an idle valve then the suggested strategy is to set the equation load source to MAP, use TPS as the load axis on the fuel, ign and lambda target tables.  This would be Alpha-N + MAP compensation.  The MAP compensation will then just happen in the background with no user set up/tuning required, the MAP is needed to compensate for any air going through the idle valve bypassing the throttles. 

I've been tuning mine with the source as BAP and tweaking here n there with a 4D table for Idle Valve% to help.

I would like to try changing the source to MAP but I assume that would require quite the adjustment to the main fuel table.
Do you have any tips that I could use to get it in the ballpark?

I assume there wouldn't be any difference to the fuel table for high TPS loads since you'd be reading pretty much atmophere already.
But the Idle/Low load ranges would change quite a bit.

I think I read that having source=MAP the fuel doubles for a doubling of the manifold pressure? So if it's already correct for 100kPa full load, at 50kPa idle for example would you halve the current VE%?

[KE30_3SGE]

On 9/12/2023 at 7:23 AM, Adamw said:

Apologies for hijacking this thread!

"If there is no idle valve then the suggested strategy would be to set the equation load source to BAP, with TPS as the load axis on the fuel, ign and lambda target tables.  This would be Alpha-N + Baro compensation.  This will give more stable AFR at idle and light loads than using MAP, but can only be used when there is no idle valve.  You do not need a MAP sensor connected for this application as the ECU has a baro sensor built-in."

Hi @Adamw, The details for the Alpha-B + Baro compensation sounds like my application (No idle valve, DBW ITB's on a 3SGE Beams, Naturally Aspirated, with flex fuel).  I just wanted a bit more clarification on not needing the MAP sensor. Can you confirm that the MAP is not required / is not part of the Fuel Equation when using BAP as the load source?

For context I've got a G4X Fury and a Link Map sensor and I'm just setting up the base map for the first start (once running it will get tuned on a dyno).  I'm using ALL the Analogue Inputs on the ECU at the moment, including one for the MAP sensor, however I'd ideally like to free one up.  I do have spare inputs on an Aim MGX Strada dash but I'd rather keep engine sensors isolated to the ECU and use the dash for chassis and suspension sensors.  I've not run this manifold and ITB setup before (BMW S1000RR ITB's on custom manifold) so I don't yet know if the MAP signal is usable / stable, but being large ITB's I'm guessing it wont have much vacuum outside of idle and very low load. If possible, ditching the MAP would also ease and simplify the vacuum plumbing; brake booster is managed by an external vacuum pump, and running fixed fuel pressure on the regulator with a pressure sensor, so I've tapped into the ITB's just for the MAP sensor vacuum.

 

[Adamw]

On 9/15/2023 at 6:45 PM, DerekAE86 said:

I would like to try changing the source to MAP but I assume that would require quite the adjustment to the main fuel table.
Do you have any tips that I could use to get it in the ballpark?

I assume there wouldn't be any difference to the fuel table for high TPS loads since you'd be reading pretty much atmophere already.
But the Idle/Low load ranges would change quite a bit.

I think I read that having source=MAP the fuel doubles for a doubling of the manifold pressure? So if it's already correct for 100kPa full load, at 50kPa idle for example would you halve the current VE%?

No easy fix, you really have to start again as there is little relationship between MAP and TPS with ITB's.  It will be mostly the rows less than about 20%TP that need significant adjustment but it will vary with RPM and idle valve position as well. 

 

14 hours ago, KE30_3SGE said:

Hi @Adamw, The details for the Alpha-B + Baro compensation sounds like my application (No idle valve, DBW ITB's on a 3SGE Beams, Naturally Aspirated, with flex fuel).  I just wanted a bit more clarification on not needing the MAP sensor. Can you confirm that the MAP is not required / is not part of the Fuel Equation when using BAP as the load source?

Correct, you likely wont need or use the MAP sensor.  I typically only use MAP if I have an idle valve, or if I have an air box that is either restrictive or gives a good aerodynamic "boost" then I would use it as an external BAP (connected to airbox).