Tuning supercharged C7 - Weird issues

[Andy@A&A]

Running it on the dyno after building our 1st system. I expected some issues and it didn't disappoint It has crazy KR even though I've turned the knock sensors way down and even added some Torco. I'm sure it's not real. It had 10 degrees of retard throughout a good portion of the run. I set the maximum retard at 2* just so I could run it through.
At about 5200 RPM the throttle drops to 64% and the car just craps out. It drops from 500 RWT to 300 RWT in just a few hundred RPM. It feels just like bad plugs or wires but I don't see any evidence of an actual misfire.
Air fuel is reasonably close and doesn't make any huge swings when it craps out. I was thinking I may have fueling issues but that doesn't seem to be it.
In the 2nd log I set Max KR at zero and bumped the timing from 10* to 14*. It did the same thing, although it dropped the throttle sooner and even more than before.
Anyone have any ideas on what to look at ? I'm kind of lost at this point.
Disregard Run file R9. I just can't figure out how to delete it.

[yonson]

R9 looks like a N/A log.

Engine Diag/General your Max Airflow vs. RPM is still stock this could be causing your throttle to close.

[Andy@A&A]

R9 looks like a N/A log.

Engine Diag/General your Max Airflow vs. RPM is still stock this could be causing your throttle to close.

My error. I had 2 folders of logs, 1 NA and 1 with the blower.
Thanks for letting me know.

I had P0068 enable at 10,000 RPM. I didn't think it would look at the other tables with this disabled altogether. I guess I shouldn't assume anything with this new stuff. I'll change it and see what happens.
Thanks

For clarification of the issue, it does close the throttle but that would be a smooth loss of power. This thing just falls apart on the dyno. It farts and craps like it was so rich or lean that it would barely run. The wideband doesn't show this however.

[JnJSpdShop]

Andy are you hitting a torque limit?

[mowton]

Andy,

We are just getting into our C7 and learning the new tuning process so please don't take this as gospel....my initial guess is the throttle blade is bouncing all over especially when you hit the point where the pedal demand drops from 84% to 64% (or was that the driver?). The MAF airflow and cylinder charge values are bouncing around while the RPM and MAP remain constant.... I would log the ETC position (or desired position) to see if this is true. Also maybe Driver Pedal Power (power request from Driver Demand table), Predicted Axle Torque Command (Commanded axle Torque after limiting) and Predicted Engine Torque (commanded engine Torque after limiting). Still reading and taking notes on E92/78 operation so it would then appear that the Torque based elements (numerous) might be intervening based on the new found torque.

Sorry no better help but I'll keep reading and learning Good Luck

Ed M

[Andy@A&A]

R9 looks like a N/A log.

Engine Diag/General your Max Airflow vs. RPM is still stock this could be causing your throttle to close.

That didn't fix it, but Thanks.

Andy are you hitting a torque limit?

It may well be that, but I don't see where.

Andy,

We are just getting into our C7 and learning the new tuning process so please don't take this as gospel....my initial guess is the throttle blade is bouncing all over especially when you hit the point where the pedal demand drops from 84% to 64% (or was that the driver?). The MAF airflow and cylinder charge values are bouncing around while the RPM and MAP remain constant.... I would log the ETC position (or desired position) to see if this is true. Also maybe Driver Pedal Power (power request from Driver Demand table), Predicted Axle Torque Command (Commanded axle Torque after limiting) and Predicted Engine Torque (commanded engine Torque after limiting). Still reading and taking notes on E92/78 operation so it would then appear that the Torque based elements (numerous) might be intervening based on the new found torque.

Sorry no better help but I'll keep reading and learning Good Luck

Ed M

That'll take me some time to figure out how to even log that stuff. If that stuff is logged, I'm not sure what is available to actually solve the issue. I thought I'd played with all the TM tables. I hope there's not something in the background that is not available for editing.
Thanks, Andy

[black06g85]

just taking a quick look (no idea with the new lt1 motors) but I know with the lnf (cobalt) di you were stuck around a max of a 5.5ms injection window. from that log it looks like your up around 9.5ms. Anyway to control fuel pressure up top (again not sure on the lt1) with the lnf cars you could up the commanded fule psi up top and change the angle of injection a bit to gain a little more leeway with fueling with some big boost.

as for the throttle closing, I"ll have to look at that later tonight, we had the same issues with the di cobalts in the beginning too.

[Andy@A&A]

That's interesting. The thing is that it does not go lean at all. I really don't think I'm having a fueling issue.
There are a couple of tables under "Driver demand" that look like they may do something. There is a warning that states "modify this table at your own risk" I'm hesitant to do anything with them.
Anyone have experience with these?

[mowton]

That's interesting. The thing is that it does not go lean at all. I really don't think I'm having a fueling issue.
There are a couple of tables under "Driver demand" that look like they may do something. There is a warning that states "modify this table at your own risk" I'm hesitant to do anything with them.
Anyone have experience with these?

Andy,

Those are the tables I was speaking about. Read the E78 tutorial in the HPTuners Help file as it incorporates the same Torque based tuning methodology as the E92. That helped me a lot in explaining the whole Torque model and how it controls the Throttle, spark and fueling. Unfortunately, I have not had a chance to play with the tables though. I did see the PIDs I spoke of in the PID tables so I believe they are available. Interestingly the tutorial says you should only have to modify the 100% pedal tables for the most part. Even at 60 I need to stay in school

Ed M

[black06g85]

That's interesting. The thing is that it does not go lean at all. I really don't think I'm having a fueling issue.
There are a couple of tables under "Driver demand" that look like they may do something. There is a warning that states "modify this table at your own risk" I'm hesitant to do anything with them.
Anyone have experience with these?

commanded afr looks to be very rich. di motors you need to stay in the 12.6:1 range as once you get that rich bad things start happening (looks like a commanded of 11.2:1) stock motor lnf cars we were runnin a 12.6-12.8 afr on pump gas with a little meth injection at 34psi on big turbo setups and they ran like animals.
also take a look into that fast torque limit table.
that's about all I got for now, will look through the tune a bit more this afternoon when I have a chance.

[Bluecat]

Andy, I would imagine your problem lies in the driver demand. If you have even used the torque model stuff to hold a FI car back on the gen IV stuff, the way the ETC reacts looks very similar. Neat that the pedal relation to engine output is tied to "power" and not "torque" though. Guess that has to deal with how the blade position is more relevant to power than torque on a gas motor. Just more common to seeing this logic tactic implemented on a diesel. The Ford guys already have to look at it this way.

Regardless, if full pedal is supposed to mean "500" HP to the ecm, there is a point its going to hold you back. I think the warning listed with those tables is more relevant to the danger of run away cars. Its probably not that you'll end up with a bricked piece of hardware. Id imagine at some point your going to have to increase the numbers in the 100% area on those tables, like you would with any other vehicle that uses a system like this.

[Area47]

you're most likely out of injection window. back the afr off to 12.0 and drop the timing and see what it does. Whats fuel pressure doing at the hpfp?

[Phil'sC5Vette]

Three great minds in this thread Ed, Andy, and the Cat, I don't know the answer, but I know when to listen and learn.
I saw howard at Redline get a C7 into the mid 10's already but it was H/C. He may hope in

[Andy@A&A]

Andy,

Those are the tables I was speaking about. Read the E78 tutorial in the HPTuners Help file as it incorporates the same Torque based tuning methodology as the E92. That helped me a lot in explaining the whole Torque model and how it controls the Throttle, spark and fueling. Unfortunately, I have not had a chance to play with the tables though. I did see the PIDs I spoke of in the PID tables so I believe they are available. Interestingly the tutorial says you should only have to modify the 100% pedal tables for the most part. Even at 60 I need to stay in school

Ed M

I did play with those some today and got the throttle to stay open past 6200.

commanded afr looks to be very rich. di motors you need to stay in the 12.6:1 range as once you get that rich bad things start happening (looks like a commanded of 11.2:1) stock motor lnf cars we were runnin a 12.6-12.8 afr on pump gas with a little meth injection at 34psi on big turbo setups and they ran like animals.
also take a look into that fast torque limit table.
that's about all I got for now, will look through the tune a bit more this afternoon when I have a chance.

That AFR sounds scary for a blower car. I'm used to shooting for 11.2 or so. I am going to try leaning it out, though. It absolutely hits a wall and starts breaking up at 5200. If I didn't have the wideband on it, I'd swear it was 9:1.

Andy, I would imagine your problem lies in the driver demand. If you have even used the torque model stuff to hold a FI car back on the gen IV stuff, the way the ETC reacts looks very similar. Neat that the pedal relation to engine output is tied to "power" and not "torque" though. Guess that has to deal with how the blade position is more relevant to power than torque on a gas motor. Just more common to seeing this logic tactic implemented on a diesel. The Ford guys already have to look at it this way.

Regardless, if full pedal is supposed to mean "500" HP to the ecm, there is a point its going to hold you back. I think the warning listed with those tables is more relevant to the danger of run away cars. Its probably not that you'll end up with a bricked piece of hardware. Id imagine at some point your going to have to increase the numbers in the 100% area on those tables, like you would with any other vehicle that uses a system like this.

I've bumped them up in the last few rows. It does seem to help with the throttle staying open.
Nothing seems to help with this wall I'm hitting at 5200, though.

you're most likely out of injection window. back the afr off to 12.0 and drop the timing and see what it does. Whats fuel pressure doing at the hpfp?

I haven't looked at fuel pressure. I'm looking at AFR and it's not going lean, so I'm assuming I'm OK on fueling.

Thanks for all the input.
I'll post a dyno sheet. You'll see that the wall I hit at 5200 is something totally different than the throttle closing.

[Andy@A&A]

This is what I'm hitting. I don't even see anything in the logs, at this RPM, that would cause such an extreme drop. AFR, although maybe a tad rich, stays stable, spark timing doesn't drop drastically.
What could be making it do this?
The attached log file correlates to this dyno graph.
I just don't see anything in the log file that changes drastically at 5200 RPM.
This is sort of uncharted territory as I'm pretty sure I'm the first to build a supercharger system for these cars. I think it's got great potential once I get this figured out. I'm just hoping somebody much smarter than me (most of you guys on here ) has an idea that I'm missing.

[SSUte01]

If spark is verified as being present and accurate and fuelling is verified by sideband then the only other option is air as in the ETC. Im not familiar with the PIDs available to you, but can you confirm that the ETC isn't closing assuming no wheelspin.

[kangsta]

You only have about 1deg timing at 5600rpm. Stop the KR and you will get the power back

[black06g85]

I"m sticking with overly rich. DI motors are designed to run leaner. IT was scary tuning the di 4 bangers at first, all tuning tells you to aim for 11.2-11.4 afr off the bat boosted, but you would be amazed at how much power was lost (and motors) at that afr.

[SultanHassanMasTuning]

please post your E92 config that you have built.

[Andy@A&A]

You only have about 1deg timing at 5600rpm. Stop the KR and you will get the power back

I actually should have posted a different run. All that KR is false. That's a whole other issue.
It's only got 5# of boost at that point and I have a whole can of Torco in it. If that was real KR and I turned it off completely, I'm pretty sure I would have blown it up by now.
I turned off KR altogether and it still hits the same wall.
I'm off to SEMA for a couple of days so I can't play with it until Friday.
I have some colder plugs coming for it. Nobody had a listing on the LT1 plugs. I have a 2014 Jeep SRT and the plugs, evidently, are the same. I just got another set of colder plugs for that to try. I'll feel safer with them in it.
If I were just looking at the dyno graph, I'd think a bad plug or wire or something. I don't see the O2s spiking lean, as I would expect from a bad misfire, though.
If it went pig rich at that point, the graph might take a big hit like that as well. But, again, the wideband doesn't show it.
I'm going to lean it out, as 06blackg85 has suggested and see what happens when I get back. I sure hope somebody makes pistons for these pretty soon. I may need them.
Thanks, all.