Need some Megasquirt tuning help please

gsmith660 · 12-29-2010, 12:01 PM

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

flat6pilot · flat6pilot's Garage

I had/have a similar problem on my MS-II. First start of the day...or extended periods between starts. Otherwise it's fine.

My idle runs best about 12.5 or 12.7. So I shoot for that or a little less (11 and under is getting too rich) and compensate for the WE calculation.

I watched the AF/R table at start-up and bumped the tabled up to increase richness a bit at that location. (As you probably know, a log is very helpful here) It seems this part of the table combination is only used during start-up (high MAP, low RPM) I had to re-balance the WE table to compensate. Still working on it myself but it has improved.

You should upgrade to the MS-II. I've noticed it's much smoother running all over because of the increased 12x12 tables. It idles nicer too as I was able to add one of the table lines at my exact MAP/RPM range for more accurate adjustment.

gsmith660 · 12-29-2010, 05:00 PM

I have a 12x12 map with extra and once I get past this hiccup my AFR runs rich in the 11-12 range I just cant figure out why it gets the rpm jump then bottoms then comes back up with decent AFR's and tapers off until warm I am trying to figure out what is driving this it only lasts for a few seconds on each cold start. I am thinking it has to be one of the other enrichments because they are all over and above the VE table and when warm I have a great idle very smooth.

TimT · 12-29-2010, 05:17 PM

What kind of cranking advance do you have mapped? what about advance sub say 700 rpm? Idle advance?

gsmith660 · 05:43 PM

Quote:

Originally Posted by TimT

What kind of cranking advance do you have mapped? what about advance sub say 700 rpm? Idle advance?

I dont know I think it is around 10 deg. but I will look you may have something. I checked and the advance is at 9-10 deg. below 700 rpm.

TimT · 12-29-2010, 07:32 PM

Most people pay attention to the advance table for the power hp torque range.....

Your ignition advance table for cold star/warm-up/ idle is very important for a easy starting engine...

gsmith660 · 12-29-2010, 07:33 PM

Quote:

Originally Posted by TimT

Most people pay attention to the advance table for the power hp torque range.....

Your ignition advance table for cold star/warm-up/ idle is very important for a easy starting engine...

Open to suggestions where should it be?

gsmith660 · 12-30-2010, 05:57 AM

Ok I leaned it out in the idle area of the ve table and upped the cranking enrichment ant 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.

flat6pilot · flat6pilot's Garage

Sounds like your real close.

What numbers do you have for AFTERSTART ENRICH (amount and time) and the WARMUP ENRICH % (for current OSA temp)?

You can always increase the ASE time a little longer if you haven't already. Sounds like you need to get the transitional overlap closer and you'll have it.

I know on the MS-II (using current firmware) it has an ignition COLD START menu where you can adjust the advance for starting. Works like the START-UP ENRICHMENT where it only uses this table for a few secs after the motor cranks and starts. I think it may run off MAP...I can't remember. Not sure what the MS EXTRA looks like though.

gsmith660 · 12-31-2010, 04:34 PM

i am real close to having it dialed in I upped the cranking pulsewidth way to much and flooded the motor so I put it back to original settings and then upped it .5 ms and it almost started (took 2 trys) now I upped it 1 ms total my ASE settings range from 140 to 190% and it is almost starting and idleing without any interaction from me.

flat6pilot · flat6pilot's Garage

Interesting. What's your prime pulse COLD PW (mine=10) and prime pulse HOT PW (mine=1) numbers?

gsmith660 · 01-01-2011, 05:06 AM

3.6 hot and 13.6 at 0 deg.

gsmith660 · 01-01-2011, 06:24 PM

Thanks for the ideas I think I have cold start pretty close now it's 23 deg. here and it fired and died then I had to crank for maybe 2 sec. to get it to start and it came up to 1600 rpm and stayed there no stumbling no backfires.

gsmith660 · 01-03-2011, 04:22 AM

After much tweaking of the cranking pulse width and after start enrichment I have a motor that starts right up 3-4 cranking cycles and idles smoothly at 850-900 rpm after 2-3 min. all at a temp. of 25-35 deg. now we wait till spring to tweak the warmer settings. Thanks everyone for your ideas and help.