07 zo6 H/C/I

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05-06-2012
z0sleeper

07 zo6 H/C/I

Hey All,

I'm looking for a very choppy idle but when I lower my timing/idle/overspeed settings, exhaust poping after 2400rpm in between shifts. Let me know what you guys think.

P.s Car made 607/533 dyno jet

Thanks.
05-07-2012
z0sleeper

wow really nobody knows?
05-07-2012
IDRIVEAG8GT

Need a bit more specific description. The exhaust pops between shifts? Sounds like DFCO or a lean issue.
05-07-2012
z0sleeper

under normal driving anything higher then 1500rpm backfire/minor poping sound. Do you see anything wrong with my file? Should I data log it?

Thanks
05-08-2012
IDRIVEAG8GT

Quote:

Originally Posted by z0sleeper

under normal driving anything higher then 1500rpm backfire/minor poping sound. Do you see anything wrong with my file? Should I data log it?

Thanks

Haven't been able to look like it. It sounds exactly like DFCO because it enables anywhere above 1,500 rpm. You'll find the adjustments in the cutoff section.
05-08-2012
z0sleeper

This seems to only happen when car warms up, can I try enable 2500rpm and disable 1200?
05-08-2012
IDRIVEAG8GT

Yep you can try that. If it still does it, the problem is clutch fuel cutoff. P.S. I would not leave the rev limit at 7,400 rpm. That's too fast even for LS7 lifters. About 7,200 is max.
05-08-2012
z0sleeper

Quote:

Originally Posted by IDRIVEAG8GT

Yep you can try that. If it still does it, the problem is clutch fuel cutoff. P.S. I would not leave the rev limit at 7,400 rpm. That's too fast even for LS7 lifters. About 7,200 is max.

Thanks man,

I posted up my data log drive from today. Didnt change the dfco yet. Let me know what you think.

Any idea why my car dieseling when shut down.
05-09-2012
IDRIVEAG8GT

Quote:

Originally Posted by z0sleeper

Thanks man,

I posted up my data log drive from today. Didnt change the dfco yet. Let me know what you think.

Any idea why my car dieseling when shut down.

Lol yes I do. How to fix it, I still am not sure. Something about the TPS reopeninf to default before the car dies.

Will look at log later.
05-09-2012
z0sleeper

I did a shut down log today tps goes from 18% to 28% on it own.
05-10-2012
IDRIVEAG8GT

Quote:

Originally Posted by z0sleeper

I did a shut down log today tps goes from 18% to 28% on it own.

Exactly and that is what causes the dieseling. I really don't know, nor does hardly anyone know how to fix it. :eek:
06-17-2012
Michael_D

Is there a way to decrease DFCO rate? I'd like to reduce it a bit, if possible. I'm not a big fan of popping every time I lift the throttle. My AFR jumps to 21 when it engages. That seams a bit too aggressive to me.
06-17-2012
edcmat-l1

Quote:

Originally Posted by Michael_D

Is there a way to decrease DFCO rate? I'd like to reduce it a bit, if possible. I'm not a big fan of popping every time I lift the throttle. My AFR jumps to 21 when it engages. That seams a bit too aggressive to me.

Set your DFCO entry and exit timing to something like 15 or 18 degrees. That will remove almost all the popping.
06-17-2012
LSxpwrdZ

I have found most dieseling is caused by wrong injector data. I have a procharged c6z in the shop right now that had 85lb fast injectors which I don't personally have the data for. The car was extremely hard to start and when you shut it off it would keep running for a good 5 seconds. Put a set of stock injectors in it fired the car up nearly like stock and shut off like stock. So with that said getting the fuel shut off when the engine is supposed to shut off is key to keep it from dieseling. The gen4 stuff seems like they are more touchy on that than older gen3 stuff.

I ordered some 80lb Siemens injectors for this car just because I know the data on them and the QC seems much better on them than the junk EV14 FAST injectors. I don't think the particular FAST injectors we had ever actually closed when pressure was on them. They seemed to leak down pretty bad.
06-17-2012
Michael_D

Quote:

Originally Posted by edcmat-l1

Set your DFCO entry and exit timing to something like 15 or 18 degrees. That will remove almost all the popping.

Thanks Ed! I'll give that a try.
06-17-2012
realcanuk

Quote:

Originally Posted by LSxpwrdZ

I have found most dieseling is caused by wrong injector data. I have a procharged c6z in the shop right now that had 85lb fast injectors which I don't personally have the data for. The car was extremely hard to start and when you shut it off it would keep running for a good 5 seconds. Put a set of stock injectors in it fired the car up nearly like stock and shut off like stock. So with that said getting the fuel shut off when the engine is supposed to shut off is key to keep it from dieseling. The gen4 stuff seems like they are more touchy on that than older gen3 stuff.

I ordered some 80lb Siemens injectors for this car just because I know the data on them and the QC seems much better on them than the junk EV14 FAST injectors. I don't think the particular FAST injectors we had ever actually closed when pressure was on them. They seemed to leak down pretty bad.

I agree. I know of a few cases of dieseling where changing the injectors (to ones with known good data) has solved the issue.
06-17-2012
MikeOD

Quote:

Originally Posted by edcmat-l1

Set your DFCO entry and exit timing to something like 15 or 18 degrees. That will remove almost all the popping.

ZR1 DFCO timing tables cure it...they're even higher. I put in the numbers from the ZR1 and I have literally no popping at all in DFCO.

Whoever said his AFR is going to 21 and that's too agressive...that's just what your wideband maxes at...your AFR is going to just air when you're in DFCO. The injectors turn off. The popping noise is residual fuel blowing up in the pipes because there's not enough spark advance to light it off in the chambers...or it's crappy injectors not closing well...either way, with enough timing, it'll all happen in the chamber and you won't hear the popping.
06-18-2012
edcmat-l1

Quote:

Originally Posted by MikeOD

Whoever said his AFR is going to 21 and that's too agressive...that's just what your wideband maxes at...your AFR is going to just air when you're in DFCO. The injectors turn off. The popping noise is residual fuel blowing up in the pipes because there's not enough spark advance to light it off in the chambers...or it's crappy injectors not closing well...either way, with enough timing, it'll all happen in the chamber and you won't hear the popping.

That's exactly right.
06-18-2012
Michael_D

Quote:

Originally Posted by MikeOD

ZR1 DFCO timing tables cure it...they're even higher. I put in the numbers from the ZR1 and I have literally no popping at all in DFCO.

Whoever said his AFR is going to 21 and that's too agressive...that's just what your wideband maxes at...your AFR is going to just air when you're in DFCO. The injectors turn off. The popping noise is residual fuel blowing up in the pipes because there's not enough spark advance to light it off in the chambers...or it's crappy injectors not closing well...either way, with enough timing, it'll all happen in the chamber and you won't hear the popping.

Ya, I understand what's happening. I just didn't know it was a complete shut off.

I understand the DFCO entry tables, but the exit tables are confusing. Mine (stock tune settings) are all negative from 0 RPM to 3072, then 0's the rest of the way. -10, -10, -10, -8.5, -5.5, -3, -1.5

DFCO entry was +10 across the entire RPM range. I moved these to +18 and there is less popping, but I still have some.

For DFCO exit, do I want to move those numbers to +15 - or so??
06-18-2012
edcmat-l1

Quote:

Originally Posted by Michael_D

For DFCO exit, do I want to move those numbers to +15 - or so??

Set the DFCO exit to +15 or so.
06-18-2012
Michael_D

Quote:

Originally Posted by edcmat-l1

Set the DFCO exit to +15 or so.

Wow, cool....no more popping with your recommended settings. At least it's at a tolerable level, perfect. Thank you sir. Where do I send the check? :D