MicroSquirt.com read only forum (Jan.15,2018)

PLEASE HELP!
I am trying to get a decent tune on my megasquirt II. I had a narrow band o2 and could get wide open throttle to run fairly decent, but I could not get it to idle correctly. I recently installed a LC-1 wideband. I calibrated the sensor from 0-5v, changed the config file and updated settings in megatune. I can now get the vehicle to idle great, but it coughs and backfires in the exhaust on accell. When I accelerate it goes full lean, I have tried to richen it up in the ve table, no help. I pulled a plug - plug is black indicating it is running rich. I read through the manual and found a section where it says it will show it is running lean if it is running extremely rich. So i tried leaning it out - made condition worse. I am new to tuning, so I may be doing something wrong. From what I understand, I set up a AFR table and try to set ve table so ego correction stays at 0. any help would be greatly appreciated,

What I have - 388 sbc, brodix 200cc runner heads, holley stealth ram intake, 58mm t/b, 24lb injectors, stock hei remote coil, 280/290 duration 488/510 lift cam.

I have included my msq file - I have not taken a datalog yet - can't drive far enough to do any good.

thanks again,
Jason

(1) You say the plugs are sooted, which as you state suggests rich.
(2) You state the LC-1 is indicating lean.
(3) You have enrichened VE.

I guess (and i'm no wideband expert) that it's going so rich it ain't burning (hence the rough-running) and there is therefore excess O2 in the exhaust, giving the sensor the impression of lean. There is some stuff on the http://www.megasquirt.info site about this effect (i think).

Try taking you VE back to your starting point and going leaner (obviously with extreme caution)

Hope this is of use.

Sorry you've already tried this, i didn't read your post properly - i'll shut up now!!!!

I agree, its a classic problem, a rich misfire makes the O2 show dead lean and it tells MS to piss in even more fuel. Get the entire range runnable if not perfect and then turn on the EGO correction, it cant work miracles, especially correcting mega rich problems. You need to err on the lean side before first test of the O2 system but tune with caution as lean can be bad (VERY) for the engine if you work it hard.


Jon

I think may be what was causing my problem is that I have also turned up my accell enrichments to max, thinking it was going lean. I will disable the accell enrichments, turn off ego correction and try leaning it up more from there. Thanks for the help - I will post how it went tommorow.

Thanks,
Jason

I agree, its a classic problem, a rich misfire makes the O2 show dead lean and it tells MS to piss in even more fuel. Get the entire range runnable if not perfect and then turn on the EGO correction, it cant work miracles, especially correcting mega rich problems. You need to err on the lean side before first test of the O2 system but tune with caution as lean can be bad (VERY) for the engine if you work it hard. Jon
-------------------- m2f -------------------- This post is at: http://www.msefi.com/viewtopic.php?p=135514#135514 -------------------- m2f --------------------


Posted by email.

I think may be what was causing my problem is that I have also turned up my accell enrichments to max, thinking it was going lean. I will disable the accell enrichments, turn off ego correction and try leaning it up more from there. Thanks for the help - I will post how it went tommorow. Thanks, Jason
-------------------- m2f -------------------- This post is at: http://www.msefi.com/viewtopic.php?p=135527#135527 -------------------- m2f --------------------


Posted by email.