[JSH]

A debate has risen between me and my tuner in terms of what SOI and eoi should be. Would you guys take a look at your data logs and let me know what your highest numbers are, and if it's cammed?

Mine are 392/207 at WOT with hpfp on 100+. I'm obviously spraying the exhaust valve for 32 degrees before TDC. The argument is that this will destroy the valve eventually.

[KingLT1]

The reason to advance SOI is if EOI gets too low. I would back the SOI down until EOI is around 180. That is what GM targets.

[JSH]

Originally Posted by KingLT1

The reason to advance SOI is if EOI gets too low. I would back the SOI down until EOI is around 180. That is what GM targets.

If I knew how to do that, I would. My current tuner does not tune SOI. Is there an EOI table with these values?

[Megahurtz]

In a perfect world your SOI would be no sooner than 360 and no later than 180. But you can push it past these values a little bit without issue.

You cannot tune your EOI. EOI is just a value that is determined by SOI, fuel pressure, and injector open time. So basically, you can only move SOI around to affect EOI.

[JSH]

Ok, so if I edited soi down to 380, eoi would fall 12 degrees? IPW is 4.9-5.0ms

[radz28]

Originally Posted by JSH

Ok, so if I edited soi down to 380, eoi would fall 12 degrees? IPW is 4.9-5.0ms

There's an alcohol modifier, too, that might influence this, if it's been changed. I think my stock tune was adding up to 15* for alcohol. I say this because if your tuner changed this (or others I'm not even knowledgeable of), it might not come down enough. Your IPWs look good though. Is that at WOT? I would make sure to watch the IPWs when you bring the SOI down. Maybe bring it down in little chunks of 5* instead of the wholesale 20*. Watch the RAIL pressure, too, because if you don't allow for enough SOI, the ECM could drive IPW up to try to meet fuel demand, and RAIL pressure could drop.

How did the SOI get to +400* anyways? Was that from past tuning? I'm not suggesting that's wrong, but it was interesting to see if jump that high. I know the ECM will, sometimes, push SOI to where it thinks it needs to be, under certain circumstances, so I was just curious.

ALSO - if you see what the WB is showing as a RICH condition when your SOI and IPWs are all crazy, that could be FALSE. That could very well be an actual LEAN condition in the chamber that shows as rich, because the fuel is injecting into the chamber, but pushed past the exhaust valve while it's still open, showing a RICH condition, when the chamber is actually LEAN. Just be careful. That's why I was suggesting baby steps with the SOI.

There is also a thread Josh' posted a while ago with some good testing and information. Also - check out Matt Sanford's YT channel. He's posted some free SOI information, too.

JMHO.

[Megahurtz]

Originally Posted by JSH

Ok, so if I edited soi down to 380, eoi would fall 12 degrees? IPW is 4.9-5.0ms

Yes. IPW would remain the same. I would lower it even more and not run SOI any higher than 370. With your EOI where it is, there no reason to back up SOI so much.

Basically at 392, you're injecting with 32 degrees of crank rotation left (32 degree before TDC) in the exhaust stroke and starting to spray fuel out of the exhaust valve.

[JSH]

Originally Posted by radz28

I've never run alcohol.

Your IPWs look good though. Is that at WOT? yes

when you bring the SOI down. Which table is this in?

Watch the RAIL pressure it's at 3000-3100

How did the SOI get to +400* anyways? 392. Previous tuner was 380.

baby steps with the SOI. The ECU must be setting the number because my current tuner doesn't tune for it

check out Matt Sanford's YT channel.

JMHO.

THanks

[radz28]

Originally Posted by JSH

THanks

I thought you said your rail pressure was dropping... My bad.

If I recall the last tuner, then I'm sure the SOI was set-up for the last combination perfectly fine. If it's at 380*, it's higher than stock (I think that's 356* or something in that area), so it seems like you have headroom, as Jason already said (and he would know).

[33908] is the alcohol table I'm talking about. It's probably already set-up for NO alcohol, but that was the table I was talking about.

Out of curiosity - why don't you go back to the old tuner?... It seems like he's got more knowledge, as I don't know why your current one doesn't do SOI, when, as my understand is, is so important.

[JSH]

When I was installing this new motor, Greg Kong suggested I try my current tuner.

Joe S. and KingLT1 tuned my previous 377 motor. I have no issues with either tuner. King's numbers are in my sig. SOI for both their tunes was around 375-380.

Joe S. asked me about my SOI a week ago. That's when my current tuner told me he doesn't tune for it which... surprised me.

LME will only say, "...try not to spray our exhaust valve that much..."

If it's just a matter of finding this fueling table and entering another value, I can do it, but surely lower SOI will affect other aspects of the tune.

I plan to test in Nebraska next Saturday - but only if I'm comfortable with SOI and the tune.

Originally Posted by radz28

I thought you said your rail pressure was dropping... My bad.

If I recall the last tuner, then I'm sure the SOI was set-up for the last combination perfectly fine. If it's at 380*, it's higher than stock (I think that's 356* or something in that area), so it seems like you have headroom, as Jason already said (and he would know).

[33908] is the alcohol table I'm talking about. It's probably already set-up for NO alcohol, but that was the table I was talking about.

Out of curiosity - why don't you go back to the old tuner?... It seems like he's got more knowledge, as I don't know why your current one doesn't do SOI, when, as my understand is, is so important.

[JSH]

I've adjusted them down to 373/181, IPW increased to 5.0-5.1ms, Lambda .848, no advance or spark events, and everything else looks normal

[Megahurtz]

The pulse width change is likely due to weather variances or airflow variances. SOI and EOI are just the start and stop of the injection event. The duration of the event is determined by the airmass calculations and commanded fuel ratio etc.

[JSH]

Originally Posted by Megahurtz

The pulse width change is likely due to weather variances or airflow variances. SOI and EOI are just the start and stop of the injection event. The duration of the event is determined by the airmass calculations and commanded fuel ratio etc.

I'll adjust SOI and EOI down to between 368-155 per your advice, thx

[JSH]

Mine's now at 370/175. 370 makes sense, but the 175... not so much. Here's a graphic to study on rainy days.