P0068 and REP

[Rusty35]

Looking for a little help.
I bought a used ZL1 camaro with some mods, shortly after it started going into limp mode with code P0068 and sometimes also p012b.
I have looked for vacuum leaks, replaced MAF sensor, super charger inlet pressure sensor, throttle body, and accelerator pedal, with no luck.
So I decided maybe its in the tune so I purchased HP tuners Pro suite and am now trying to educate myself with very little luck.
Setting the P068 enable rpm to 8000 stops the limp mode issue , but I would imagine I still have an issue, and I still have the P012b .
Mods
Long tube Headers , cat delete
Roto Fab intake
PRC ported heads
Cam (unkown)
9.55 Lower pulley
Unkown injectors (850 scribed on the side of each injector)

[johnny_boii]

Go under engine diagnostics and disable the test for the code P0068. I also disable P0101, P0106 and P0121

[Rusty35]

Go under engine diagnostics and disable the test for the code P0068. I also disable P0101, P0106 and P0121

Thanks for the reply.
I have disabled the P0068 test, I was just hoping to understand why or what the issue is and I still have the P 012b code.

[johnny_boii]

It happens when the actual airflow exceeds the predicted airflow.

[jsllc]

This is difficult to clean up. Partly because you do not have access to all of the tables needed. There are new ones coming that will help with the issue but depending on all the mods and the tune it takes some work to clean up.

[Rusty35]

Thanks for the input.
Any thoughts on the P 012b code, it seems to happen at any rpm under light or no load, should I just turn of the DTC for it also?

[mowton]

While I may agree about disabling the P0121 test (no tables available) I do disagree about simply turning off tests that we have the ability to try and tune. The P0068 is one of those tests.

I recommend setting up a Graph based on the editor table and log the apprpriate parameters to establish the levels you are seeing so you can use them to update your table. When reviewing the log, hit the Plus sign (+) to show you the highest value you attained in your log and add 10-15% to that to repopulate your table. May have to hand smooth the area's you didn't collect data against. As a note, you would disable the test during your tuning session and then re-enable when done.

This way you maintain the protection intended for a runaway throttlebody. Of course if you are pushing more than the max, then you have no other choice but to disable.

Attached is a sample of the graph to use. HP Tuners has given us a few good tables to work with for other DTC's Like P154, P2102 etc.

Ed M

[Rusty35]

Thanks Ed
I appreciate the pointers and agree I would really rather find the problem if possible,
And the other code I have is P 012b not 0121, and I have a feeling the two are somehow connected.

[GHuggins]

You most likely won't be able to increase the limits to pass the test - your already exceeding the airflow and the P012b are the test parameters getting added that we don't have access to at the moment... As long as you don't increase the throttle safeties themselves beyond 14ish% it will still have runaway safeties... As for the map codes - you'll have to set the 3 for the P012b and the boost test including the high volt map test to disabled or no error... Only way your going to be able to drive it...

[Rusty35]

When you say exceeding the air flow what are you referring to, the P 0068 happens sometimes as low as 9 g/s but always between 3800 and 4000 rpm and at part throttle almost never at full throttle , and the P 012b happens at idle to 2000 rpm.

I think I am wrong about the 9 g/s, looking at the log that was probably after it went into limp mode, closer to 100g/s when it happened,

[mowton]

Thanks Ed
I appreciate the pointers and agree I would really rather find the problem if possible,
And the other code I have is P 012b not 0121, and I have a feeling the two are somehow connected.

I agree with Greg on the P012b. Log the airflow and post, lets see how close you get to the 512 g/sec limit. Based on the limited log data, you did exceed the stock value at 3000 (143 g/sec vs 140) but see you have changed those values. Did you change them after the REP or did the REP ocurr with these changes? Make sure its not the MAP delta as well. That is harder as I don't now a way to log that. Also you can use the Freeze Frame feature in the Scanner to see the PCM parameters at the point of the failure.

Ed M

[GHuggins]

I guess it could be scanner lag, but I've had them within 100 and still have this issue - I always wound up having to disable the test... Altitude will change everything too due to making more boost, quicker throttle ramps and so on - I always had to disable it...

[Rusty35]

You guys are a little above my pay grade, when you talk about 512g/sec limit where or what are we talking about.
When you say I changed the values Im not sue what you mean I don't think I changed anything in the log and I haven't touched the tune.

[Rusty35]

I have I think three logs of the P 0068 happening where I can pin point when it happened,and twice as many where it doesnt happen at all and runs on up to 11 psi and red line.

[mowton]

I have I think three logs of the P 0068 happening where I can pin point when it happened,and twice as many where it doesnt happen at all and runs on up to 11 psi and red line.

OK post them please, Your tune is not stock for that table.....I thought maybe you changed it. It has been increased quite a bit. Attached are the stock and your current tune tables.

Next time you get it to fail, go read the DTC from the scanner (hit the engine icon) with the key on and after jotting them down, activate the Freeze Frame feature to collect the status of the PCM parameters at the time of the fault. You can copy the freeze frame information and paste to a word or text file.

Ed M

[Rusty35]

I will find some more logs, in the log I posted in the op it happens at 00:45.325, I was logging the accelerator pedal mode and you can see where it goes to "Limited".

[Rusty35]

Here are some more logs where it happens.
In 0068 2 I cant pin point exact but it happens at about 00:01:02.115 mark.
In 0068-3 it happens at 00:01:49.224
And in the last log I was trying to make it do it and it wouldn't.

[mowton]

I don't see anything obvious that would trigger the P0068 based on these two logs....they are at low rpm 3700/3800, MAF air is very low <90 g/sec, MAP delta seems within the current settings etc.

Is the P0068 the only DTC you have?

How long were you driving the car after you got before the REP began.....Did you run it when you were looking to buy it. Trying to determine if its the tune or something mechanical.

I would also set the PE (Power Enrichment) MAP setting to 85 kPa...you have very little pedal and only 15 kPa for MAP enable now. And not that it should be active in your OS, set the PE delay to 0 as well...belts and suspenders as I call these types of changes :-)

Sorry couldn't be more help...

Ed M

[Rusty35]

The car didn't do this until the next day after I bought it.
I dont regret buying it, the car runs very good and I am pretty sure its not a major mechanical issue.
The car does seem to do it more when it is fully warmed up and been driving at least 15-20 minuets.
The P 0068 is always between 3800 and 4000 rpm.
The only other DTC is the P 012b that happens mostly at lower rpm.
There are a few things in the tune I wonder about.
In the Gain vs Cylinder table 1 cylinder has be changed to 1.0400 where the other cylinders are un changed.
Zone 23 in the Manifold switch open VVE table is odd looking to me.

I will eventually figure it out.
I appreciate you guys taking the time to have a look, probably would be an easy fix if you had the car in person.

[mowton]

Rusty, get it to fail and then retrieve the Freeze Frame information as I stated above.....Also fix the PE MAP to 85 kPa and set delay to 0.

Ed M