LSA Boost Pressure gets Clipped After a Period of Time in Same Trip.

[1bad68ls]

I have a ZL1 engine (Manual trans) with BTR stage 3 cam, 30% overdrive on the SC pulleys, ID1050x injectors, minor porting and headers in a 2nd gen Camaro. I tuned the MAF and VVE tables and I have the car running and idling well. I am now tuning the power output for the added hardware.

I went into Virtual Torque and bumped up the last row of the tables by ~46% and interpolated the tables. In the Torque Management section, I disabled ALL methods of torque management (Other than [Oil Starvation]), and I increased all the boost limits to 200% in the Supercharger section.

THE ISSUE: When I go on a "trip", the first one (or two) WOT hits will commands Engine Torque @ over 1000 ft-lbs and delivers ~625 ft-lbs. MAP goes to ~205 kPa and I get incredible acceleration and a hell of a smile on my face.... however during the same "trip", when I go WOT again, my MAP gets clipped at 125 kpa throughout the rest of my "trip". When I am clipped, I notice by [Engine Torque] is now the same as my [Delivered Engine Torque] at ~625 ft-lbs. I do not understand why my MAP is now getting clipped at 125 kPa (I did several WOTS again and MAP still is clipped at 125kPa) or why my [Engine Torque] is now lower than the start of my "trip". It appear that I am being managed by Torque control.. but I thought I disabled all of it??? Any suggestions for where to look?

I am including a screen shot where the MAP go to ~190-200kPA (2nd graph) during the first half of the plots. You can also see the Eng Torque jump to >800 during this timeframe... HOWEVER in the 2nd half of the plots, you can see MAP getting clipped at 125kPa and now the Eng Torque nearly identical to delivered torque. I assume the torque control is limiting my MAP. Does anyone have suggestions to remove this 125kPa map limit?InkedScreenshot 2020-09-29 214901_LI2.jpg

Thank you!

[jsllc]

Post tune and log if you want help and unless you have some new way of increasing TQ without air you should put the Virtual TQ back to stock. Higher lift longer duration cams will reduce TQ down low at idle and may increase some at very high MAP and air flow values but it will be closer to 5%. No mod made will increase TQ by 46% at a given air value.

[1bad68ls]

Thanks JSLLC,
I agree with your comments about TQ down low. I am driving the SC 30% faster than stock with the BTR stage 3 (aggressive lift) cam and I expect the torque would significantly increase above ~1200rpm to the rev limiter. I agree the torque tables are likely too high, however my goal was to get the max power out of the engine and fine tune the torque tables after I get it on a dyno.

When I increased the torque tables, the car laid down significantly more power... and I was hitting over 205kPa MAP (for a while until it was clipped to 125 kPa)... therefore it suggests modifying the torque tables is in the right direction.
I appear to be in a catch 22 because I would like to get the car on a dyno to better tune the torque tables, however I am unclear how I can get the max power to the dyno if the torques tables are regulating the power of the car (by clipping my MAP at 125kPa)?
I am attaching my current [work in progress] tune. I appreciate any feedback on how to remove the 125kPa clip.

[RobZL1]

I think your problem is probably the P0101, P0106, and P0121 codes- they need to be disabled at higher boost. I'm guessing you are getting that code and maybe don't see it if you don't have a CEL installed with your swap?

I would also fix your VVE. It is doing some really odd things at higher MAP values. Extend your axes out to 200 or higher if you don't see the problem in your VVE editor. You probably also need to disable or raise the threshold on your P0068 test.

If increasing the torque tables increased power output, then I think it was masking something else that was actually the root cause. I've never heard of the torque tables doing anything to increase WOT power in a Gen 4 application.

[1bad68ls]

Hi RobZL1,
Thank you for the great input. I will take a closer look at the codes and see if they were set during the trip.... which may be the root cause of the MAP clipping.

Regarding the VVE table, I spent a ton of time tuning it in and you can see in the table that my engine is producing harmonics at 3 specific RPMs. The largest is at 2600 rpm (all loads), second at 1600rpm, and a smaller harmonic at 1000 rpm. I believe the harmonics are airflow related... likely due to the 30% overdrive on the blower, however I was able to tune in lambda to around 2% for the whole table. I will look at extending the VVE table to ~200kPa.

I am still learning the torque tables and trying to understand the value of tuning them for a manual trans vehicle.
Thanks again for the help.

[1bad68ls]

I think your problem is probably the P0101, P0106, and P0121 codes- they need to be disabled at higher boost.

RobZL1,
You are right on the money! I had two codes that popped:
- P0106 - Manifold Absolute Pressure/BARO Sensor Range/Performance
- P1101 - Mass Airflow Sensor Out Of Self Test Range

It appears that HPTuners does not make available the calibrations to allow users to adjust the self test limits for these codes.
Question: How do I disable (or calibrate the self test range) for these? Or... do I need to go into [Engine Diag] and uncheck [SES Enable] and set the Error Mode to [No Error Reported] to keep the ECM from clipping my MAP at 125kPa?

Thanks again for your help!!!

[1bad68ls]

After reviewing a few other tunes and the [Engine Diag] area, in the [Airflow] tab, others have:
1) Set the min ECT to outside the operating range in the [P0101, P0106, P0121] section.
2) Increased the MAF fail high frequency to 16,000Hz
3) Set the [P0068] Enable RPM outside the operating range
which I assume will resolve the P0106 & P1101 codes that I am getting.

Do you believe this will resolve the 125 kPa clipping issue?
Thanks!

[Wildctsv]

Well did this fix your problem I feel like I ran into the same problem

[LukeyB]

Id like to know as well. I don't like turningoff codes I dont need to