Firstly what should the fuel pump voltage be at when scanning with Tunerpro. I am trying to diagnose a problem with a friends car and the volatges seem to be on the low side. His voltage starts off at 11.5 then gradually climbs up with time then sits at 12.5 then hits a maximum of 13volts for some time and then hovers around 12.9 to 13.1. Is that typical?

Is it normal for a MAF car to have readings of MAP voltages? Becuase in his data log he has MAf readings and then in another colom he has MAP vol readings but they hardly move 2.7-3 volts all the time. I have never data logged on a MAF car but I would have thought you have 1 or the other but not both. Just seems odd to me.

What is the recommended battery voltage? Again in ghis data log the volatges start off low then creep up but never go above 13.5 volts on average they are around the 13 volt mark. That also seems a bit low. His car is a 1989 TPI camaro. And the problem seems to be that the car is running rich. The O2 sensors readings are very bad too. The oscillation is very poor and this has been after a O2 replace.

I am thinking he is not getting enough volts in the system?

 

Battery voltage can vary based on conditions, charge system performance, etc. With a running engine, I would say a minimum of 12.5 volts should be seen at both the battery and the fuel pump. Usually there's only a slight difference between fuel pump voltage and battery voltage. If there is more than a couple of tenths of a volt, then there may be a relay or wiring issue between the battery and fuel pump.

If voltages seen with the engine running drop below 12v, there's a problem somewhere (battery, alternator, wiring, etc).

MAF and MAP voltages depends on the car. Any car you scan with TunerPro should only have one or the other, as far as I know. Only the newer cars had both (OBDII). Make sure you're not confusing one for MAT. Look up the .ds file for the vehicle and see what it should actually be.

13v is healthy for voltage.

Hopefully others will also chime in with their experience/opinions on voltages.

 

Thanks Mangus, definitely he is getting MAP volts table in tunerpro with a MAF car. He has both tables with values in the data log. I will have to ask him what he exactly did because I am not sure. But he has a grams sec table MAF and he also has a MAP volts table.