ignition advance's effect on idle speed?

matt_fulghum · Post by **matt_fulghum** » Mon Jun 19, 2006 4:13 pm

My car idles at a stable 14.4 AFR or so now, with great vacuum (28 kPa on brand new rings!) but it runs at about 1470 rpm. I noticed that the spark advance at that point in the spark map I'm using is around 20 degrees!

I figure I could help keep the speed in check if I drop down the advance to something more like 14 BTDC or so, but I was looking for advice on this?

I'm running I think the latest v2.5 MSII code, with an MSD 6A box, if it helps at all.

matt_fulghum · Post by **matt_fulghum** » Mon Jun 19, 2006 4:33 pm

yeah, I cranked it way open to see if it would help the car start, now that I think about it. I'll close it up a little later.

Another thing, although I don't know if it should go in this topic... The car idled stably for around 12 seconds, and then just died. The afterstart enrichment had long since gone and all, it didn't seem to have any good reason for why it croaked. Any ideas? I could post up the log if you'd like.

matt_fulghum · Post by **matt_fulghum** » Mon Jun 19, 2006 4:40 pm

well given that it's 91 degrees out atm, I figured that the warmup enrichment would be pretty minimal by this point. Also, the AFRs seemed pretty stable throughout the time it idled. Whatev. I'll post up the log. Gimme a second.

Although, on the note of temperature sensors, I can't seem to get the sensors to read exactly the right temp... I don't know if that's because I'm inputting the wrong resistance values, or because the engine bay is getting steamy in this weather. Well, I'll let you guys toss suggestions my way when I post the log up.

matt_fulghum · Post by **matt_fulghum** » Mon Jun 19, 2006 4:42 pm

Here you go... The idling period is right at the end, I turned off the MS right after it died.

matt_fulghum · Post by **matt_fulghum** » Mon Jun 19, 2006 5:08 pm

ah... I was looking for the battery voltage log and I couldn't find it. No wonder

If you think I should go to the 2.6 code versus the 2.5 code I'll pop over, no problem. Is it stable enough do you think?

Alright, lemme get that stuff done, and I'll get right back to you.

matt_fulghum · Post by **matt_fulghum** » Mon Jun 19, 2006 5:29 pm

heh, I found another potential factor... when I unplugged the Megasquirt, it knocked out the crimp on the spade terminal I have running from the VB921 to the MSD box... maybe the wire was loose before? I'll recrimp it and see if it and the latest code help at all.

matt_fulghum · Post by **matt_fulghum** » Mon Jun 19, 2006 5:36 pm

btw, for your reference, the 2.672x7a code from the beta code page isn't burning right. It fails verification. I'll pop over into linux and recompile and tell you if it works right then.

edit: or should I go for the 7b code in the 2.672 discussion thread? ever figure out the comm dropping weirdness?
edit again: I went to the latest Downloader and it burned fine.

matt_fulghum · Post by **matt_fulghum** » Wed Jun 21, 2006 9:35 am

well I put the new code in... a bit of weirdness, and had to change the thing in common.ini to not drop comms. Anyway. I plugged that code in, and tried to start... it's a no go... but I imagine part of that is because it dropped to 7.3 volts at one point in time

I imagine that's way too low to actually get the thing running?

It's a fairly new optima battery... Any suggestions?

Logs attached.

edit: also, yesterday when it fired up, I DID have it hooked up to the battery charger on "start". Maybe my grounding's poor or something, and that's making it weird?