nj1266

iTrader: (6)

A friend of mine shared a flash with me. He tells me that it is possible to control boost with ecuflash w/o an MBC/EBC. I looked up the boost section of the flash and found the following changes from my stock rom. Could someone please explain these to me? I did a search and I still have some questions.

At the top are the modifed boost tables and at the bottom are my stock ones. From left to right:



Boost control load offset set @ 100 from 60 stock. Why? What does that mean?
Boost cut delay timer set @ what seems to be an arbitrary number from 1000. Why? What is it for?
Boost limit set @ 319. I understand that this one is maxed out, correct? What does 319 translate to psi?
Boost desired engine load 1, 2, & 3. I read that number two is the one that is changed but I have no idea why. And it is maxed out. Again why? Number 1 and 3 are only changed from 6000-7000 rpm and are set @ 140. Why this number?

I hope someone can answer these questions. If I ever flash my car I really do not want to use an MBC. If this does not work, then I will use my xede as a boost controller and flash the timing and AFR only.

jcsbanks

>Boost control load offset set @ 100 from 60 stock. Why? What does that mean?
This is added to the boost target to give target load.

>Boost cut delay timer set @ what seems to be an arbitrary number from 1000. Why? What is it for?
1000ms (1 sec) with the load over the cut and it will fuel cut.

>Boost limit set @ 319. I understand that this one is maxed out, correct? What does 319 translate to psi?
319 engine load. Low 30s PSI. I don't think engine load could ever exceed 319 though.

>Boost desired engine load 1, 2, & 3. I read that number two is the one that is changed but I have no idea why. And it is maxed out. Again why? Number 1 and 3 are only changed from 6000-7000 rpm and are set @ 140. Why this number?
Change them all together. 219.4 load target (159.4+60).

EvoAnthony

iTrader: (13)

So you're saying to change all the boost desired engine loads to 219.4?

nj1266

iTrader: (6)

Could you give me an example of how this works?
So basically the modified number is arbitray since it sets the cut to 1638.xx seconds. Am I reading this right?
This is scary What should it be set to to hit 22-23 psi?
Why the 219.4 load target? What boost would that get?

jcsbanks

I'm saying that 219.4 is the load target you get with the original table of 159.4 and the offset of 60 added together. I'm not recommending this as a target. So 250 might be sensible for a tame tuned pump fuel car - about 22 PSI depending on temperature and RPM but this is usually about right for the midrange on a stock MAF sensor/airbox. You could do this with a 100 offset and a 150 boost target.

255 fuel cut would be about 1.55 bar in the midrange, multiply my 14.5 to get PSI.

Yes the maxxed out timer for boost cut is set so that it never gets to cut the fuel (along with the 319 target that will never be exceeded).

nj1266

iTrader: (6)

I understand better now. So currently the setting is 259.4 (159.4+100 offset), correct? You believe that it is better to make it 250 either by lowering the offset or by lowering the boost desired load tables. Should I set ALL three tables @ 250 or only table #2?
Is the 255 fuel cut number you are referring to to be placed in the boost limit table? So change the boost limit table from 319 to 255?

Thanks a lot for all the help

KevinD

iTrader: (56)

no, leave the boost limit tables as 319.

jcsbanks

I prefer to have an overboost fuel cut so set it to about 20 above target load.

You need to decide what boost to run depending on your spec and octane. Work in bar absolute manifold pressure and multiply by 100 to get the approximate load at least for the midrange. So 1.5 bar boost is approx 250 load. At 6000 RPM, 1.5 bar boost is more like 235 load on my car.

I would set all three (or four) boost target and duty tables the same until they are fully described as to how they work. This works practically with what is known about the ECU at present.

RazorLab

iTrader: (8)

Remember you also need to change the restrictor to get a good level of control on the boost via the ecu.

nj1266

iTrader: (6)

jcsbanks,

So your advice to get 22-23 psi on 93 octane gas is as follows:

1. Set the boost limit table to 255 down from 319
2. Set ALL three boost desired engine load tables to 150 provided the boost control offset is 100. This will give a target load of 250

What should I do with the boost cut delay timer? Should I keep that 1638 375 number? Or use an "real" number? What do you have your boost cut set to?

Thank you very much

heyzeus11

iTrader: (12)

I think he was saying for the boost desired engine load set the mid range to about 150; but still let values taper up top(as he said 1.5bar in the mid-range is about 250=150+100, but at 6000rpms 1.5bar was about 235=135+100).

heyzeus11

iTrader: (12)

Going by what jcsbanks said, assuming you are setting your midrange desired load to ~250 (150+100); then since he recommended 20 over your desired load that would be ~270 for your mid-range for boost limit. Setting it to 319 pretty much makes it useless.

Evo_Jay

iTrader: (17)

NJ, theres a lot of info about the stock boost system here....

https://www.evolutionm.net/forums/sh...d.php?t=227006

nj1266

iTrader: (6)

So make the desired load boost tables look something like this. This is with 100 offset.

nj1266

iTrader: (6)

Yeah, I read that thread. But most are trying to control boost by removing the solenoid pill or resizing it. I want to set peak boost to 22-23 psi peak and let it taper to about 19-20 w/o removing the stock pill or using a modified one.

Is that doable given the tables I posted?