Billiumss

iTrader: (11)

For many years, people have been tuning boosted cars with the standard 1bar VE set ups in the stock computer. Now that HP Tuners is offering 2 & 3bar VE tables, tuning boosted cars should be easier.

Here's my question:

Say I have a single turbo on my 2001 F-Body that is running 7-10lbs of boost. I upgrade to the 2 bar setup so I can fine tune my VE table for the boosted parts. Once I am happy with my SD tune using the 2 bar, can I switch it back over to closed loop mode and use the MAF?

Would I have to get a new MAP sensor for 2 bar?

Basically, can I have the best of both worlds, have an expanded VE table to help with boost fueling while getting good fuel economy by using the MAF and using my O2s to provide me with a constant/average 14.7 A/F when cruising around.

My best guess would be yes since the 3.8 SC engine has boost and run a MAF all the time from the factory.

What do you guys think or is this how it is done anyways with either the 2 or 3 bar setups?

Thanks for your comments and suggestions in advance.


Bill

SRPerformance

Small point: SD still uses close loop mode (unless you disable it) MAF is only used under 4000rpm.

gametech

iTrader: (1)

The maf is used above 4000rpm. That is why your motor goes lean when forced induction maxes out the maf. I still prefer to just go closed loop sd.

gameover

Our 2bar SD enhancement is to be used in SD mode only (which still runs in closed loop using your O2's).

Tuned correctly there is no difference in economy using the MAF or SD.

You need a 2bar MAP sensor for 2bar.

Chris...

RedHardSupra

iTrader: (1)

hey, gameover,
are we gonna get cool extra functions with the SD enhancment like the custom OS from EFI? (i'm not trying to start anything, i just wanna know, ppl been asking me)

Billiumss

iTrader: (11)

Do you tune it any different than a regular SD tune?

What would be your steps in correctly tuning a 2 bar SD tune?

Say you aim to set your part throttle cells for 14.5 A/F and your in closed loop SD mode, your Ltrims will stay slightly negitive and lock at zero when you go WOT?

Also, the O2's will still command 14.7 A/F during part throttle even though there is no MAF?

What 2 bar MAP sensor would I use, do you have a part number?

Does HP Tuner have a write up on how to tune the 2 bar SD enhancement?

Any detailed info you can provide will help me understand all the benefits of the 2 bar SD enhancement...

Thanks...

Bill

RedHardSupra

iTrader: (1)

from what I gather (never tried though myself, as i refuse to pay extra money for a product that has a subscription fee, as i don't know what i'm subscribing to if i have to pay extra) some tables that are based off MAP just get extended from 105kPa to 210 or 315. this is how you 'explain' boost to the engine.
another good thing about the extended SD would be having the dual spark capability, as normally when you go to SD you lose the High octane one, and just run off one.

soundengineer

iTrader: (16)

you will tune a 2 bar SD the same way you tune a normal SD tune...with a little more caution to steer away from deadly knock...especially at higher MAP values.
teh 02's always command 14.7...yes...without a MAF too(its still closed loop after all unless you put it in open loop
and they will ALWAYS pull the fuel back to 14.7 even if you set up your fueling in your VE to be at 14.5.....
GM has a 2 bar Map they sell...I know a few other companies have them too..I'm sure a sponsor on here has one that they sell

benefits of 2 Bar SD:
retain dual spark tables in SD mode
no need to reconfigure tables in teh tune to "mimic" teh 2 bar setup like you would need to with a 1 bar MAP

gameover

Software update service has been free since Apr 15.

WS6FirebirdTA00

iTrader: (33)

not trying to steal the thread but how much harder is it to use standard OS to tune a boosted application?

gameover

it's okay as long as the MAF doesn't max out. Once it does you need to wing it on the PE table.

For SD forget about using the std OS for boost.

Chris...

WS6FirebirdTA00

iTrader: (33)

ok thanks

Blackbird

Not necessarily. It's being done at Synergy right now.

98 Camaro with an STS running 9psi right now working there way up to as high as the turbo will take them and there is NO maf on that car.

Being done with the Stock PCM and HP Tuners and the owner Rick's know-how.

gameover

the thing is that sure you can run it on the stock VE table but once you hit boost you have to compromise, you have one line of the VE table for all your boost airflows. Its fine if you can handle rich mixtures at part-boost (if your setup/driving style allows) or if your boost isn't gonna change, or if you are a guru at setting up vac regs and fuel return lines.

With a 2/3 bar OS you can tune the VE table for different boost settings and then just change your boost controller/pulley without fear of running lean/rich, having to retune or make major changes to the fuel system.

Blackbird

not if you put a 2 bar map sensor in the car and work some magic

I should clarify in my above post. Stock 98 PCM, 2 bar MAP, no MAF, SD tune.

soundengineer

iTrader: (16)

yeah...there are a bunch of tables to half to make it work.....it just takes time....
but it can be done

Billiumss

iTrader: (11)

How? Please explain....

Billiumss

iTrader: (11)

That is good to know. So if you can still have closed loop without a MAF, then what is the benefit of having one then if fuel economy will stay the same?

Some say that a MAF doesn't work until 4k rpm's, well I disagree. If you rescale the whole MAF table, your Ltrims change at part throttle.

Could anyone explain how the 3800 SC systems/tune works, they have boost and use a MAF. I figure if GM did it in the 3800 SC cars, then why can't we do it in ours?

gameover

excellent question! the main reason being that with a MAF you can make a lot of changes (like bolt a supercharger on at low boost) and the tune will stay pretty good. WIth SD you need to retune it for any intake, camshaft etc. changes.)

below 4k, MAF + VE + TPS + MAP are used to determine airmass during non-steady conditions (MAF is used if MAP is steady). Above 4k MAF is used only.


The V6 system is a lot simpler, it doesn't use the complex algorithm of the V8s to perdict airflow, it is much more trusting of the MAF. It only uses the VE if the MAF gets way outta shape. The thing with a V6 is that because you only have 6 cyls instead of 8 you have ~25% more headroom before the MAF becomes an issue (meaning you can run higher boost before the MAF maxes out).

In either system you can use the MAF but once it maxes out you only have the PE table to "wing it" on the fuel. ie. setting the PE to command a richer AFR than normal because the airflow side of the equation has maxed. For the V8's, a 2 or 3bar SD mod is not too hard to code (just extending tables for the most part) but on the V6's there are other limitations on the VE table due to the code structure.

soundengineer

iTrader: (16)

well..a 2 bar map sensor that outputs the same total voltage that a 1 bar does would mean the VE table would be half resolution as 50 would now mean 100 and 100 would now mean 200.....

hows that for a start and an example