Idle Airflow w/ and w/o clutch engaged

[phuz]

Actually I'm wrong. I answered that without actually checking and thinking about it. I'm used to my turbo cars where that is not the case. Yes, it's open venting charge pressure.

I forgot to note earlier that if I simply "blip" the throttle as the RPMs are falling, it resets the STIT to zero and the stall never occurs.

[edcmat-l1]

Actually I'm wrong. I answered that without actually checking and thinking about it. I'm used to my turbo cars where that is not the case. Yes, it's open venting charge pressure.

I'd recommend you check and make sure. There's a reason I asked. Some of your symptoms point to that. Even your idle looks like it is probably being force fed air. I wouldn't doubt it's closed or at least partially closed. Especially if you never changed the spring or cut it down. With a lopey cam the lower manifold vacuum normally means you have to modify the BOV so it'll be wide open at idle.

[phuz]

I'd recommend you check and make sure. There's a reason I asked. Some of your symptoms point to that. Even your idle looks like it is probably being force fed air. I wouldn't doubt it's closed or at least partially closed. Especially if you never changed the spring or cut it down. With a lopey cam the lower manifold vacuum normally means you have to modify the BOV so it'll be wide open at idle.

Yes, I did, and it's venting, but that makes me wonder if it's venting as much as it should be because of the cam's low vacuum. A&A already uses soft springs, but I believe they are designed for stock vacuum levels.

[edcmat-l1]

Yes, I did, and it's venting, but that makes me wonder if it's venting as much as it should be because of the cam's low vacuum. A&A already uses soft springs, but I believe they are designed for stock vacuum levels.

I agree the A&A BOVs are setup right for most cars.

If you have access to a hand vacuum pump like a Mightyvac an easy way to test is check your airflow numbers in your scanner, then pull the vacuum hose where it tees into the manifold. Have someone pinch it shut with needle nose pliers and it'll keep it open when you pull the hose off. Hook up your vacuum pump and apply 20 inches of vacuum and compare your idle numbers. Other than that, physically get to it and do a visual. I still would do a vacuum pump test. You'll be able to see the difference in the data if you are able to open it more.

[phuz]

I agree the A&A BOVs are setup right for most cars.

If you have access to a hand vacuum pump like a Mightyvac an easy way to test is check your airflow numbers in your scanner, then pull the vacuum hose where it tees into the manifold. Have someone pinch it shut with needle nose pliers and it'll keep it open when you pull the hose off. Hook up your vacuum pump and apply 20 inches of vacuum and compare your idle numbers. Other than that, physically get to it and do a visual. I still would do a vacuum pump test. You'll be able to see the difference in the data if you are able to open it more.

Good idea. No hand pump, but I've got a good venturi I use off my compressor that'll pull 25" no problem.

I've made a slight revelation based on some other threads and that is the adaptive idle will not kick in until both throttle cracker & throttle follower are zero. Because I had the throttle cracker table zeroed out, adaptive idle was kicking in as soon as the follower finished it's routine, so it was starting early. I added very small numbers to the cracker table (not enough to actually affect airflow) which prevented any premature STIT values and every stop I made it idled out nice and smooth.
Attached is that log and current tune and the three idle warmup logs starting at 117F. (VCM Scanner kept stopping the log so I had to restart)

[edcmat-l1]

Funny how you haven't made a revelation about your injectors not functioning properly. As long as you don't straighten that out the rest will never work correctly. If you can't control your injectors correctly at idle your VE will never be right. You'll always have a richer than should be condition when returning to idle. Because your VE won't be right your idle air numbers can't be right. But keep chasing that adaptive idle. Keep adjusting the VE to match your idle air. Sounds like you really got it figured out.

[phuz]

Funny how you haven't made a revelation about your injectors not functioning properly. As long as you don't straighten that out the rest will never work correctly. If you can't control your injectors correctly at idle your VE will never be right. You'll always have a richer than should be condition when returning to idle. Because your VE won't be right your idle air numbers can't be right. But keep chasing that adaptive idle. Keep adjusting the VE to match your idle air. Sounds like you really got it figured out.

You've given me a couple pointers that I greatly appreciate, but by and large you are a pretty negative person and I am kindly asking that you refrain from responding to my posts (in ALL my threads) from here on out.

[edcmat-l1]

You've given me a couple pointers that I greatly appreciate, but by and large you are a pretty negative person and I am kindly asking that you refrain from responding to my posts from here on out.

Call em like I see em. And I had intended on dipping out.

[gtstorey]

Ah, the worst insult in modern life, being negative (aka being direct or telling the truth without blowing smoke up someone's butt).

[Alvin]

Call em like I see em. And I had intended on dipping out.

He's got at least two guys with decades of experience who do this daily telling him things he doesn't want to hear.

There is some people you just can't help.

[phuz]

He's got at least two guys with decades of experience who do this daily telling him things he doesn't want to hear.
There is some people you just can't help.

But don't trust the guy who is highly regarded in the tuning community with 35-40 years of tuning experience, right?

One thing that is very evident is that every professional tuner seems to have their own way of doing things (and that's fine. I'm a programmer and do the same).

[Alvin]

But don't trust the guy who is highly regarded in the tuning community with 35-40 years of tuning experience, right?

If he's so good.. why are you hear?

[edcmat-l1]

If he's so good.. why are you hear?

[edcmat-l1]

But don't trust the guy who is highly regarded in the tuning community with 35-40 years of tuning experience, right?

One thing that is very evident is that every professional tuner seems to have their own way of doing things (and that's fine. I'm a programmer and do the same).

That's fine as long as the end result is "proper". You do not have proper control of the injectors at low pulse widths, idle. It is clearly evident in the data logs. To continue to deny that is burying your head in the sand to the underlying issue.

The data is not setup correctly. I don't care how long your guy has been doing it.

[phuz]

If he's so good.. why are you hear?

*here

Because he's 90 minutes away and I'm trying to get advice from a general community to learn and fix this on my own. Is that not the purpose of this forum?

The individual being super critical looked at my tune and my logs and said that my injector pulse wasn't capable of getting below 1.8ms (2, it still bottoms out at 1.8 ms IPW. It actually gets to 1.8 and the trims continue to drop a few percent. Would like to see what the actual on time is with an o-scope. There's no way they're idling at stoich at 1.8 ms.), yet I posted logs even yesterday that showed the pulse as low as 1.40ms, so it's absolutely capable under my current injector settings.

Yes, Bill used a blended version of the injector data, but it's still very close, and with a minimum pulse at 0.8ms, there's plenty of room for trims to drop if they want to.
He spent 3 hours on it with most of that focus being the power portion of the map, and I've been doing the drivability quirks. For the most part, it's great, but there's still some areas I want to iron out.

Sorry if I pissed in your cheerios.

[SiriusC1024]

How are you able to look at a log and tell see that the offset is wrong? I know you mentioned PW. How would someone go about setting it up right? I'd take it for granted that the data is accurate.

[Alvin]

Ever heard of someone being an "askhole"?

You ask questions.. then when someone points out the problem or the underlining problem you respond with "well my guy has been doing it for 40 years and I trust him" what's funny is when you named dropped him it was a literal "who?" from me.

So if you don't want our answers.. go back to your 40 year veteran and get his take. simple! He doesn't take emails? BTW.. if he's such a rock star tuner.. why did he give it back with problems?

[edcmat-l1]

*here

Because he's 90 minutes away and I'm trying to get advice from a general community to learn and fix this on my own. Is that not the purpose of this forum?

The individual being super critical looked at my tune and my logs and said that my injector pulse wasn't capable of getting below 1.8ms (2, it still bottoms out at 1.8 ms IPW. It actually gets to 1.8 and the trims continue to drop a few percent. Would like to see what the actual on time is with an o-scope. There's no way they're idling at stoich at 1.8 ms.), yet I posted logs even yesterday that showed the pulse as low as 1.40ms, so it's absolutely capable under my current injector settings.

Yes, Bill used a blended version of the injector data, but it's still very close, and with a minimum pulse at 0.8ms, there's plenty of room for trims to drop if they want to.
He spent 3 hours on it with most of that focus being the power portion of the map, and I've been doing the drivability quirks. For the most part, it's great, but there's still some areas I want to iron out.

Sorry if I pissed in your cheerios.

It seems to be responding like we pissed in your Cheerios.

The trims take 30+ seconds to pull your narrowbands back around stoich. I can watch the activity at idle and know the data isn't correct. It does not switch quickly above and below stoich like a factory set of injectors would. That's what you're looking for. Factory looking injector behavior.

I'm trying not to be negative and just give you the facts.

[phuz]

BTW.. if he's such a rock star tuner.. why did he give it back with problems?

These aren't problems...they're minor quirks. And I paid him to work a specific portion of the map (see above response).
Now, if I left the dyno and it was running too rich or too lean and knocking under boost, I would've gone back in a heartbeat; but he did exactly what was asked and did it well.

I'm surprised you haven't heard of them TBH.
https://www.corvetteforum.com/forums...-dmv-area.html
https://www.google.com/search?q=%22s...t=gws-wiz-serp

Like I do with most things, I looked for negative reviews or comments about the shop prior to the visit, and came up empty. People, especially in the Corvette world, sing praises of their work. Some tuners, it's a lot easier to find a mixed back of positive and negative reviews.

[phuz]

How are you able to look at a log and tell see that the offset is wrong? I know you mentioned PW. How would someone go about setting it up right? I'd take it for granted that the data is accurate.

Are you asking me? Because I honestly don't know the answer to that question. That's why I'm here.