Fit engine voltage question

[cjsmith]

This past weekend I had a fuel pressure sensor go bad on my car. I replaced the sensor and raced Saturday, thanks to the Livingston's who had one I could use. The new sensor occasionally gave signals that the pressure was out of range on my dash. After the race, looking at my data I saw some fluctuation to the sensor readings every few laps. I checked all the connections, and looked at my ground and battery connections looking for anything that might be loose after the race. Nothing unusual was found. During Sundays race the car was off on power, it didn't feel tenable off but I couldn't keep the car in the draft. After the race I checked the data, saw my voltage readings which normal is at 12.9V +- and are reasonably steady were spiking up to 13.6 V during breaking and down shifting that I have never seen before on my data. I assume there is a voltage regulator in the alternator. Is it possible that the voltage regulator is cause of the voltage fluctuation ? For additional information. The voltage doesn't go below the 12.9 Volts, only spikes in additional voltage.

[Raceworks]

This past weekend I had a fuel pressure sensor go bad on my car. I replaced the sensor and raced Saturday, thanks to the Livingston's who had one I could use. The new sensor occasionally gave signals that the pressure was out of range on my dash. After the race, looking at my data I saw some fluctuation to the sensor readings every few laps. I checked all the connections, and looked at my ground and battery connections looking for anything that might be loose after the race. Nothing unusual was found. During Sundays race the car was off on power, it didn't feel tenable off but I couldn't keep the car in the draft. After the race I checked the data, saw my voltage readings which normal is at 12.9V +- and are reasonably steady were spiking up to 13.6 V during breaking and down shifting that I have never seen before on my data. I assume there is a voltage regulator in the alternator. Is it possible that the voltage regulator is cause of the voltage fluctuation ? For additional information. The voltage doesn't go below the 12.9 Volts, only spikes in additional voltage.

I'm assuming you checked both the battery ground and the two on the engine. I've only had one alternator go bad (and oddly it was a fairly new one), but I can't remember how we diagnosed it. I'll look at my data & see where they usually run at voltage wise.

If you haven't already remote-mount the pressure sensors. Mine are zip tied to padding on the frame & attach to their locations by -3 hoses. The OP in particular likes to break if it's direct-mounted to the engine block.

Check the tailpipe & see if it's running lean (light grey or white instead of dark grey / black). If it's lean check the fuel flow. Even the return line should have a steady stream & listen to the sound the pump is making. If the pump seems good check the filter. If you're running the XRP mesh filter that came with the kit get rid of it. They like to clog up once in a while and will mess up your day. I run an Aeromotive filter with the replaceable paper element.


Post script: another thing that may cause the voltage to get goofy is the master switch going bad. If that key gets a little loose or has dirt in it they can do weird things.

[Raceworks]

Looking at my data from both cars this weekend there's no voltage fluctuation at all and we got just over 14V the whole time.

[cjsmith]

Thanks Sam, I'll look into all of those options. I will probably order a new alternator to have one. I would have expected to see a higher
charging voltage but the base line values are consistent with other sessions in the past. below is a screen shot of what I'm seeing.

[Roux]

I'm assuming you checked both the battery ground and the two on the engine. I've only had one alternator go bad (and oddly it was a fairly new one), but I can't remember how we diagnosed it. I'll look at my data & see where they usually run at voltage wise.

If you haven't already remote-mount the pressure sensors. Mine are zip tied to padding on the frame & attach to their locations by -3 hoses. The OP in particular likes to break if it's direct-mounted to the engine block.

Check the tailpipe & see if it's running lean (light grey or white instead of dark grey / black). If it's lean check the fuel flow. Even the return line should have a steady stream & listen to the sound the pump is making. If the pump seems good check the filter. If you're running the XRP mesh filter that came with the kit get rid of it. They like to clog up once in a while and will mess up your day. I run an Aeromotive filter with the replaceable paper element.


Post script: another thing that may cause the voltage to get goofy is the master switch going bad. If that key gets a little loose or has dirt in it they can do weird things.

Is the Fit supposed to have a dark tailpipe? If so does that apply to all exhaust configurations? I have the Swift over the top pipe and it is light grey. I do not currently log fuel pressure but maybe I should

Thanks

Steve

Steve