Got a track related question? I'll try to answer.

[wrbrz?]

Originally Posted by CSG Mike

I'd be surprised if OFT can't log the high pressure fuel pressure rail; it's available in OBD2, and can be read by even the most rudimentary OBD2 device.

Correlating fuel level + high pressure fuel pressure, will give us a clue on what the actual cause is.

If you're tracking your car, I *really* recommend you get EcuTek. It is light years ahead of OFT in terms of features and performance.

I have some OBD2 logged data now.

The below PDF is of one session where I let the fuel level drop a little lower (we were only running 4 timed laps per session yesterday). Turn 12 and the subsequent straight are highlighted in green.

In the second last lap of the session, the fuel rail pressure briefly drops from ~3000 to ~900.

Before the session started, I had 85% fuel remaining and one lap later, after it ended, I had 72% remaining.

[CSG Mike]

Originally Posted by wrbrz?

I have some OBD2 logged data now.

The below PDF is of one session where I let the fuel level drop a little lower (we were only running 4 timed laps per session yesterday). Turn 12 and the subsequent straight are highlighted in green.

In the second last lap of the session, the fuel rail pressure briefly drops from ~3000 to ~900.

Before the session started, I had 85% fuel remaining and one lap later, after it ended, I had 72% remaining.

Can you log FLI?

After you do that, lets filter out all the data that isn't WOT, and then we can sort by FLI and HPFuel Pressure, and determine if there is a correlation there.

That'll help us determine if you have a fuel delivery issue.

[wrbrz?]

Originally Posted by CSG Mike

Can you log FLI?

After you do that, lets filter out all the data that isn't WOT, and then we can sort by FLI and HPFuel Pressure, and determine if there is a correlation there.

That'll help us determine if you have a fuel delivery issue.

Sorry, I'm not really sure what FLI is.
I logged the Fuel Level and Fuel Rail Pressure though.

Wish I could just upload the Excel doc, but I've made the changes as best I could.

For some reason, the way Torque interprets data, the 'Accelerator Pedal Position' and 'Relative Throttle Position' have a maximum value of 44/45% and 69% respectively.

I have removed anything below 20% (which looks to be around 50%) throttle position and sorted by the Fuel Rail Pressure.

The second and third line are clearly the result of starvation in my eyes, as that's exactly where I experienced a power cut on exiting the corner.

[TommyC]

Originally Posted by CSG Mike

225/45/17.

Not because of fitment, but because you'll get better respone out of the tire.

Why not 235/40R17? Seems like the best of both worlds (and actually what I plan on running on my 17x8 wheel, but haven't purchased the track rubber yet so I could still be persuaded). Slightly wider with a slightly smaller sidewall should still provide great feel. More tire options in that size as well.

[CSG Mike]

Originally Posted by TommyC

Why not 235/40R17? Seems like the best of both worlds (and actually what I plan on running on my 17x8 wheel, but haven't purchased the track rubber yet so I could still be persuaded). Slightly wider with a slightly smaller sidewall should still provide great feel. More tire options in that size as well.

that's fine if you can deal with shorter gearing, and a thinner sidewall which puts the wheel at more risk.

[CSG Mike]

Originally Posted by wrbrz?

Sorry, I'm not really sure what FLI is.
I logged the Fuel Level and Fuel Rail Pressure though.

Wish I could just upload the Excel doc, but I've made the changes as best I could.

For some reason, the way Torque interprets data, the 'Accelerator Pedal Position' and 'Relative Throttle Position' have a maximum value of 44/45% and 69% respectively.

I have removed anything below 20% (which looks to be around 50%) throttle position and sorted by the Fuel Rail Pressure.

The second and third line are clearly the result of starvation in my eyes, as that's exactly where I experienced a power cut on exiting the corner.

FLI is fuel level indicator.

Can you send this to me tab delineated?

[TommyC]

Originally Posted by CSG Mike

that's fine if you can deal with shorter gearing, and a thinner sidewall which puts the wheel at more risk.

The sidewall is 3% shorter and overall diameter is 1% shorter compared to 215/45. I think it will be OK.

225/45 will actually be taller/less responsive than 215/45.

[EAGLE5]

Originally Posted by TommyC

The sidewall is 3% shorter and overall diameter is 1% shorter compared to 215/45. I think it will be OK.

225/45 will actually be taller/less responsive than 215/45.

Probably not less responsive because of the stretch of the narrower tire and the wide wheel. All that really depends on the specific tire and stretch, I would think.

[CSG Mike]

Originally Posted by TommyC

The sidewall is 3% shorter and overall diameter is 1% shorter compared to 215/45. I think it will be OK.

225/45 will actually be taller/less responsive than 215/45.

Negative Batman.

Check out the load ratings on the tires you run. Most 225/45/17 and 255/40/17 tires in the EHP category are assumed to be driven hard, and have a stiffer sidewall than their counterparts.

[wrbrz?]

Originally Posted by CSG Mike

FLI is fuel level indicator.

Can you send this to me tab delineated?

Yeah, sure thing.

Is this the right format? I'll send it to the info@csg email too.

[Fish Eagle]

Originally Posted by TommyC

Why not 235/40R17? Seems like the best of both worlds (and actually what I plan on running on my 17x8 wheel, but haven't purchased the track rubber yet so I could still be persuaded). Slightly wider with a slightly smaller sidewall should still provide great feel. More tire options in that size as well.

I've run both sizes quite a lot on track, and I prefer 225/45R17 - got better feel, and quicker.

[CSG Mike]

Originally Posted by wrbrz?

Yeah, sure thing.

Is this the right format? I'll send it to the info@csg email too.

It looks like you're getting the starvation in a straight line? The accelerometer data is no calibrated, so I can't say for sure.

Fuel level in the tank is at least 3/4, interpolating, so there's no reason you should be getting fuel starvation.

Are you on an aftermarket fuel pump? The CSG car runs on E85 at times, and even boosted and around 400hp, we don't have starvation issues.

Do you have a log of the fuel pump voltage?

Your tuner would be the best one to diagnose this; if they don't have experience with the platform on the track, this may be difficult.

[wrbrz?]

Originally Posted by CSG Mike

It looks like you're getting the starvation in a straight line? The accelerometer data is no calibrated, so I can't say for sure.

Fuel level in the tank is at least 3/4, interpolating, so there's no reason you should be getting fuel starvation.

Are you on an aftermarket fuel pump? The CSG car runs on E85 at times, and even boosted and around 400hp, we don't have starvation issues.

Do you have a log of the fuel pump voltage?

Your tuner would be the best one to diagnose this; if they don't have experience with the platform on the track, this may be difficult.

It's a stock fuel pump. Should I be looking to upgrade to an aftermarket one?

It happens pretty much immediately after straightening out, so yes it is in a straight line.

I am full throttle through that corner, not sure if that makes any difference.

Unfortunately not. I don't have the PID for that.
I'll try and find it before this weekends track day.

Thanks for taking the time to look at the data.

[CSG Mike]

Originally Posted by wrbrz?

It's a stock fuel pump. Should I be looking to upgrade to an aftermarket one?

It happens pretty much immediately after straightening out, so yes it is in a straight line.

I am full throttle through that corner, not sure if that makes any difference.

Unfortunately not. I don't have the PID for that.
I'll try and find it before this weekends track day.

Thanks for taking the time to look at the data.

I don't know if there is a PID for the fuel pump voltage, but it is variable depending on the fuel demand of the engine.

The thing here is you're WOT as you're coming out of the corner, not after you're straight, and the fuel delivery is fine for a bit before it briefly sputters, and then resumes.

I want to know why the fuel pressure momentarily drops. The rest of the log indicates that combustion is still happening, so it means there's a cut in the fuel delivery, and picking up air on a stock pump at 75% tank is not very likely, given where the actual pickups are.