Tuning Help Needed: 3L with MS2 PMO ITB twin plug EDIS igntion

flatspin911 · 07-08-2011, 10:07 AM

I have read various posts on this formum and see there are various guys running Megasquirt systems successfully with their 911. I was hoping to tap into some of the collective experience tuning my system

My setup:
Megasquirt 2 V3.0 Hardware with V2.883b sw
Megatune tuning Software on PC

Car:
72 911 RS clone with:
3.0L with 10.5:1 pistons
Webcams
EDIS twin plug ignition
PMO ITB Fuel Injection

First season
I started with twin plug EDIS controlled by MS2 and Weber 46 Carbs.
Spent time tuning the Ignition map, runs great!
I know engine is good and igntion system works great

Second Season
Added PMO ITB Fuel injection with Innovate Wide band sensor

After some time I got it to idle OK.
Will go down the road but on the very rich side 10:1 AFR
Also when accelerating goes lean and sputters.
I need to tune the acceleration enrichement section and then the overall map

I am struggling with this tuning.
I was going to use the auto tune mode of the Megatune but had heard that Tuner Studio is the way to go.

My questions:
Should I continue with Megatune or switch to Tuner Studio?
Should I be using version V2.883b of the embedded sw or MSEXTRA
What are usable settings on the Acceleration Enrichement page (TPS with MAP?)

Anyone share their experience here?

I will post pics of the setup, wiring and plumbing experiences

Yarko

jpnovak · 07-08-2011, 10:29 AM

I run the MS2-Extra 3.1 code. Works well.

What you need to do is have someone drive the car while you tune. If it is running that rich just pull fuel away.

Tunerstudio is much more user friendly compared with MegaTune. It is worth paying the license fee to enable the VE Analyze live function. Simply set target AFRs for your VE table and start driving. the PC will adjust (up or down) the fuel levels until the AFRs match your target. I still prefer to tune manually, especially when starting out, as it is faster and can be more accurate.

What cams are you running? I could send you my VE table but it would likely be much different than yours.

I have my car tuned for MAP only (speed density). There are some tricks to setting up the VE table values such that they scale within the usable MAP readings. This will depend on your plumbing of the vacuum lines and what cams (duration and overlap) are doing to create reversion and prevent a good vacuum signal.

I always start by shutting off all accel enrichments and tuning the VE table until the car runs very well. Then establish transient response by adding in some AE settings. FYI - even with ITBs I need VERY LITTLE AE correction once the VE table is tuned correctly.

flatspin911 · 07-08-2011, 10:46 AM

Thanks for the reply Jamie

I have read your various threads and you have been one of the inspirations for me to persue this project.

Signing up to Tuner Studio today - thanks for the suggestion.
Not sure what is difference with MS2-Extra Vs what I am running.
Is it more compatible with the TUner Studio?

CAMs Webcam: 140/102

Send VE Tables - at least I can compare relative values.
Sent you email

Yarko

flatspin911 · 07-09-2011, 02:32 PM

Downloaded TunerStudio and bought registration liscence.

Turned off Enrichment.
Got a helper to drive and spent some time with VE Analyze Live and "auto tuning" the VE table. Nice tool - very easy to use! Very intuitive. Especially like the graphs beside showing the areas affected and how.

Running sweet now! Definetly more driveable than with the webers. No spitting and farting on decel etc.

Will take a longer drive tomorrow and more VE table tuning.
Focus on WOT and Decel
Decell very lean - off the map lean - perhaps need to tweek AFR table.

So far did not add any Accell enrichment. Seems to not need it. More fun for a later day.

Would be happy to share VE table if interested.

Jamie
Thanks again for your help and experience!

Yarko

DUK · 07-09-2011, 02:43 PM

How many squirts are you running? I just had the same problem with decel lean and went to 2 squirts alt. and it cleared it up.

If your map is right you shouldn't need all that much accel enrich.

flatspin911 · 07-09-2011, 02:47 PM

Running 6 squirts Alternating.
Will try 2 and let you know - Thanks DUK

DUK · 07-09-2011, 02:52 PM

I guarantee it will fix the decel. Plus will help almost every wherr else. Don't forget to do a new map and ve analyze, as the fewers squirts will mean higher numbers on the map.