From knowing nothing to having a Thunderbird supercharger on an m20b27i

[Victell]

Awesome. Congrats on the progress so far.

[ak-]

Cold start, the car should idle a little rich around 11 to 12.
Once getting up to proper temps it should bounce from 14 to 15 and back.

[Ether-D]

When stone cold, it starts out idling at 10.9 then you can watch it step up as it warms up. 11.2, 11.4-5, 11.7-9, 12.2-3, then leveled out at 12.6ish.

Now, I did tell the megasquirt that it has 33# injectors instead of 36# which is what these are called. I can see that making it run a bit rich as the ecu tells them to pulse a bit longer than they should because it thinks they are smaller than they (maybe) are. But that's no big deal. A little rich is fine for now. I also heard a small amount of pinging going uphill at low rpm a couple times, but that could partly be the regular gas that's still in it. So any real world experience and/or tips for getting her dialed in are very appreciated. Even little things. Thanks fellers.

Anyone know how to get my idle to go down a bit? How to mess with the idle PWM settings or what those numbers mean?

[george graves]

What are you measuring AFR' on? When tuning, richer is better. Unless your soooo rich that you have gas going into your oil, but I doubt that you have that going on - BMW piston rings are much better then most. So not at lot of blowby. Did you get a wideband?

[Ether-D]

Yep got a lc-2.

[Q5Quint]

If it pings pull back timing in those spark bins. If it is too rich (why do you need 10:1 at idle? Does it idle better? I feel like my old beast used to idle best a little lean... at 15:1 or so?

Do a logged drive and autotune to the afr table you set keeping it rich 12:1 or so while in the power areas for safety. If you feel 'ping' or are scared pull timing back from the timing map.

Not sure what idle sensor you are using but the tuning instructions for both are here: http://www.megamanual.com/ms2/tune.htm

Changing from 33 to 36lbers should literally mean dropping your req fuel value to down like 8% or so. A single value in MS changes this.

Currently your fuel map would be 8% rich if it was tuned for 33s and you put in 36s, but your afr map that megasquirt uses to adjust the fueling would pull it down to the values you put in that table, EXCEPT for areas under that map (usually 2000rpm ie idle). That is why your idle is so rich and everything else that started 8% rich just tuned itself back to exactly what you had in your afr map.

You can leave the req fuel the same and just tune down your idle fuel map, or restart with the same 33lb map and tune down the req fuel 8% (what I would advise).

Edit: how does your spark map compare to other turbo/supercharged spark maps? Is it an aggressive max hp on 93 octane dyno tuned spark map? A de-tuned street version of that map?Knowing where that came from is kind of critical. Also because I want to compare the one I have heh.

This was my old turbo tune from ms1extra. It is a de-tuned version of somebodys turbo map from e30tech many moons ago. It could probably go up 5-10deg in some areas but I wanted to be 'super safe' as it was a street tune that was already shredding a stock clutch.

[Ether-D]

So the tune is mostly Whodwho's base tune that comes with the whodwho ms2. I've adjusted the idle pwm somethingerothers to get the idle down and told it that I have 34# injectors and that's about it. I've driven it about 2 miles. I've stepped on it a few times and the AFRs stay real good when getting on it. I didn't hear any pinging this time.

[The Dark Side of Will]

Changing from 33 to 36lbers should literally mean dropping your req fuel value to down like 8% or so. A single value in MS changes this.

Currently your fuel map would be 8% rich if it was tuned for 33s and you put in 36s, but your afr map that megasquirt uses to adjust the fueling would pull it down to the values you put in that table, EXCEPT for areas under that map (usually 2000rpm ie idle). That is why your idle is so rich and everything else that started 8% rich just tuned itself back to exactly what you had in your afr map.

You can leave the req fuel the same and just tune down your idle fuel map, or restart with the same 33lb map and tune down the req fuel 8% (what I would advise).

Why do you advise that? While it's possible to tell the computer that he's running pretty much any injector flow rate and tune around it in the VE tables, why bother? Put the right injector flow rate in and then you don't have to remember later what you lied to the computer about.

[Ether-D]

Well, the main reason I told it 33# is because I read that the "36#" were actually 33# in disguise. But that was on the interwebz so it must be 100% true. I will up it to the right amount once I'm not scared of going lean.

[The Dark Side of Will]

They can be both if the flow rating is quoted at different pressures. GM's of the era run 3.5 bar fuel pressure, but Fords run 3.3 (I think), so if swapping injectors among systems with different rail pressures, you need to rate accordingly. Even the same manufacturers run different pressures at different times. I thought BMW's ran 3.5 bar for most apps, but the S54 and I think S62 run 5.0 bar.

What fuel pressure are you running?
Converting injector flow among different pressures is easy, but the relationship is NOT linear. You can google "injector flow calculator" or something like that and find out lots of info on it.

[whodwho]

You should be able to find the flow on the injectors by the part number use the figures for 43.5psi pressure, post up the number if you are not finding solid figures.

You will want to adjust your req_fuel over just altering the VE table, other settings are based on req_fuel as well.

If you are finding it is lean overall then raise the req_fuel, if rich then lower it. You ultimately want your VE table bins at 100 and at your peak torque to be close to 100.

What is your air temps like when stone cold? 10 AFR is a bit rich, I would try starting around 11.5ish after you get the req_fuel set and VE table dialed in around idle set when all warmed up and running about 14ish at idle.

***And remember this is a startup tune and in no way should you be flogging it before getting it dialed in!!***

[The Dark Side of Will]

Changing from 33 to 36lbers should literally mean dropping your req fuel value to down like 8% or so. A single value in MS changes this.

Currently your fuel map would be 8% rich if it was tuned for 33s and you put in 36s, but your afr map that megasquirt uses to adjust the fueling would pull it down to the values you put in that table, EXCEPT for areas under that map (usually 2000rpm ie idle). That is why your idle is so rich and everything else that started 8% rich just tuned itself back to exactly what you had in your afr map.

I @$$ume from this that MS "thinks" in terms of AFR rather than in terms of Lambda, as an 8% change in fuel flow is an 8% change in AFR, but is NOT an 8% change in Lambda.

[Ether-D]

***And remember this is a startup tune and in no way should you be flogging it before getting it dialed in!!***

Not flogging. Paying close attention to AFRs and being 99% very gentle. 1% experimental medium to heavy footedness.

[Ether-D]

"0280155737. These injectors are commonly referred to as 36# from L67 supercharged engines but flow more close to 34 lbs/hr @ 2.5 bar or 43.5 PSI"

I have them in the MS2 as 34#.

[The Dark Side of Will]

2.5 bar is not 43.5 psi... typo?