Logging for VE Tune and Car go into Limp Home Mode

[Chalky]

Logging at lower speeds is ok. Problems arise when I try and hit upper RPM in MAP 90-100. Log was fine for the most part up until reduced power mode.

Any suggestions?
TIA.

[purrvert]

If you are setting 1514 code increase table C6101.

[Chalky]

No codes. I completed one log and had copied and paste into the VE File. I tried to do some blending to smooth out the graph. I am assuming I must have gone to far with the blending. Still trying to understand why I bumped the VE table by 15% when I started tuning.

[purrvert]

No codes. I completed one log and had copied and paste into the VE File. I tried to do some blending to smooth out the graph. I am assuming I must have gone to far with the blending. Still trying to understand why I bumped the VE table by 15% when I started tuning.


Increase is to assure you don't run lean. You are probably moving more air than predicted in C6101, hence limp mode. Do a search on 1514.

[Chalky]

Thanks Purrvert:

I just changed 1514. We'll see what happens!

[superls1]

Thanks Purrvert:

I just changed 1514. We'll see what happens!

You can multiply the entire table, C6101, by some percentage and it will usually prevent this problem. Did you do this or disable P1514? The description of the P1514 DTC indicates:




The PCM uses the TP, the BARO, the IAT and the engine RPM in order to calculate an expected Mass Airflow rate. The PCM compares this value to the Mass Airflow value and the speed density calculation in order to verify the proper throttle operation.


Just curious, but does anybody know the exact definitions of each formula?

[Chalky]

I disabled 1514.

[blandmiller]

Here is the Excel formula I use for calculating air density using a 6th order polynomial approximation (accurate to >0.5%). 'O18' cell is dew point in degrees F. 'O19' is air temperature in degrees F {IAT}. 'F19' is barometric pressure in Torr (Torr=mmHg="Hg*25.4).

=1.2929*273.13/((O19-32)*5/9+273.13)*((F19*25.4)-((6.107799961+((O19-32)*5/9)*(0.4436518521+((O19-32)*5/9)*(0.01428945805+((O19-32)*5/9)*(0.0002650648471+((O19-32)*5/9)*(0.000003031240396+((O19-32)*5/9)*(0.00000002034080948+6.136820929E-11*((O19-32)*5/9)))))))*((6.107799961+((O18-32)*5/9)*(0.4436518521+((O18-32)*5/9)*(0.01428945805+((O18-32)*5/9)*(0.0002650648471+((O18-32)*5/9)*(0.000003031240396+((O18-32)*5/9)*(0.00000002034080948+6.136820929E-11*((O18-32)*5/9)))))))))/(6.107799961+O19*(0.4436518521+O19*(0.01428945805+ O19*(0.0002650648471+O19*(0.000003031240396+O19*(0 .00000002034080948+6.136820929E-11*O19)))))))/760*0.06242796058

Ooops, the result will be in '#/cf' (pounds per cubic foot).

[redhardsupra]

where and how did you get this formula?

[blandmiller]

I am a design engineer for a vacuum pump manufacturer. We deal with Boyle's law every day.

[redhardsupra]

oh really? we need to talk... ;)

[blandmiller]

I just edited my earlier post. The accuracy of the equation is greater than 1/2% not 0.05%.