Megasuirt tuning

gsmith660 · 12-29-2010, 11:02 AM

I have Megasquirt I MSNS-extra on my turbo motor controlling EDIS and the only issue I have is cold start. It has to crank a while to start and is real lean and after a couple sec I get a jump in rpms and it goes rich then the rpm drops and it goes lean again for about a second then the rpms come back up and the AFR richens up and it sounds like it is going through the warm up enrichment routine. Can anybody steer me in the right direction to smooth out these two lean spot on cold start and also it seems like it only the first start of the day or if it has sat for several hours between starts. Thanks for any ideas you can give me to start with. I use megatune 2.25

sjf911 · sjf911's Garage

Cold start is the hardest thing to tune. It is too easy to get it too lean or too rich and it is difficult to tell because the WB isn't registering accurately. I think the best thing to do is start with cranking pulse width on the lean side and gradually increase until it fires quickly even if it dies immediately. After you have it catching well during cranking then work on after start enrichment in the same manner. Then you can work on the ASE taper last to merge it in with your warm up enrichment.

gsmith660 · 12-29-2010, 12:51 PM

I will have a try, with that I have a question is anybody using the AAR from their CIS system to give extra idle air at startup?

drmatera · 12-29-2010, 01:56 PM

gsmith - is your VE table tuned well in the idle region? Are you using Tuner Studio or megatune?

I have a nice a/f table I can send if you use TS.

sjf911 · sjf911's Garage

Quote:

Originally Posted by gsmith660

I will have a try, with that I have a question is anybody using the AAR from their CIS system to give extra idle air at startup?

I used the AAR for a while with MS2 as it was more predictable than the stepper but ditched it for the 3-wire PWM valve stock to the 3.2 when I converted to MS3+MS3X. The AAR worked fine but the plumbing was awkward.

gsmith660 · 12-29-2010, 02:44 PM

Quote:

Originally Posted by drmatera

gsmith - is your VE table tuned well in the idle region? Are you using Tuner Studio or megatune?

I have a nice a/f table I can send if you use TS.

Yes it seems to be tuned well I have a good stable idle when warmed up and I use both tunerstudio and megatune they both have advantages.

gsmith660 · 12-29-2010, 02:45 PM

Quote:

Originally Posted by sjf911

I used the AAR for a while with MS2 as it was more predictable than the stepper but ditched it for the 3-wire PWM valve stock to the 3.2 when I converted to MS3+MS3X. The AAR worked fine but the plumbing was awkward.

How does the PWM work and I bet I cant use it with what I am using right now can I?

sjf911 · sjf911's Garage

I know you can run a PWM 2-wire with MS2 directly and a 3-wire with a resistor to ground on one lead but I don't know if you can with MS1.

gsmith660 · 12-30-2010, 03:01 AM

Quote:

Originally Posted by sjf911

I know you can run a PWM 2-wire with MS2 directly and a 3-wire with a resistor to ground on one lead but I don't know if you can with MS1.

Thanks Steve

gsmith660 · 12-30-2010, 06:00 AM

Ok I leaned it out in the idle area of the ve table and upped the cranking enrichment and the after start enrichments alot and it fired up almost immediately and then died once then fired up and stumbled for a sec. or 2 then came up and idled good. I may be on to something thanks for the help.

drmatera · 12-30-2010, 06:18 AM

One thing I noticed with my car is that it likes a bunch of ASE cold or hot. Not sure if it's because the engine is air cooled and wall wetting is an issue.

How much ASE do you have? on a cold day i'm up around 600%. I've been told by tuners that some cars require up to 800% ASE to stay running after initial start-up

gsmith660 · 12-30-2010, 06:21 AM

I am only like 40% at most

drmatera · 12-30-2010, 06:42 AM

crank, start and warm-up can be confusing. Some add a percentage and some multiply. ASE multiplies. If you have 40% then the MS gives the engine 40% of the VE table value. If you want 40% more you need to put in 140%

gsmith660 · 12-30-2010, 07:03 AM

I just looked at tunerstudio and that is correct it is 140% I up some of them and lowered the cranking pulse width as what I raised them to flooded the motor I had to pull the relay and shut the fuel pump off to get the car to start.

drmatera · 12-30-2010, 07:08 AM

yeah, on cranking pulse you should start very low and slowly bump it up till the engine fires..

remember

cranking pulse - fires engine - (if it dies within a couple seconds move to ASE)

All cranking does is fire the engine

gsmith660 · 12-30-2010, 07:23 AM

Thanks I just figured that out when I could really smell gas the pulse widths are now back to what they were and I will now play with them in small increments.

gsmith660 · 12-30-2010, 07:46 AM

bumped up my cranking pulsewidth by .5 ms and see where that is after it cools back down started right up luke warm (100 deg. clt temp.).

gsmith660 · 12-31-2010, 06:15 AM

I am making progress bump after start enrichment about 20% and I got it to fire and idle on its own after the third try so I will keep bumping it in small increments until I get it to start and idle on its own. This is exactly why I did this project it is a tremendous learning experience and has been great fun!

JohnJL · 01-01-2011, 06:10 AM

Sorry for the hijack, but I am also running EDIS and have coil/plug wire issues. What EDIS coil are you running and what plug wires?

gsmith660 · 06:28 AM

No problem I am running the stock coil that was sent to me from Boost Engineering - Advanced Engine Management and the wires are MSD wires for a mustang cobra I got from Summit I think in the future I will look for wires that have the beru boots on them.