Throttle Position Sensor showing only 90% at WOT?

[SVO MkII]

I use the Track Addict app for HPDE. When reviewing the detailed data log, I'm seeing that Track Addict is only showing the throttle opened at 90% when the pedal was firmly to the floor (nothing wedged between it and the floor). I realize this could be an anomaly caused by the app not properly interpreting data from the ECU. Is there a way to verify that the throttle is actually 100% open at WOT? This is when I miss mechanical linages :(

Sponsored

 

[steve0s550]

I use the Track Addict app for HPDE. When reviewing the detailed data log, I'm seeing that Track Addict is only showing the throttle opened at 90% when the pedal was firmly to the floor (nothing wedged between it and the floor). I realize this could be an anomaly caused by the app not properly interpreting data from the ECU. Is there a way to verify that the throttle is actually 100% open at WOT? This is when I miss mechanical linages :(

When doing all my WOT datalogging for my protunes it always showed 100% throttle position but throttle plate never was more than 90%....2 different PID's on the log.

 

[Cobra Jet]

When doing all my WOT datalogging for my protunes it always showed 100% throttle position but throttle plate never was more than 90%....2 different PID's on the log.

So what is holding back the throttle plate in the TB from not being open 100%?

 

[Coyote Chase]

When thottle position (pedal) is at 100%, your actual thottle plate position or ETC Angle, is only at 81.98 degrees.

 

[Coyote Chase]

So what is holding back the throttle plate in the TB from not being open 100%?

The ECU controls the actual thottle plate position and when adjusting the position of your thottle plate, it considers more than just the command it is getting from your thottle pedal, for example, your desired boost level and your actual boost level, etc.

 

[Dana Pants]

Same here. Don’t overthink it.

 

[Scootsmcgreggor]

That’s normal it will never go beyond 90%. And if the turbo is creating more boost than demanded the Ecu will close it further to achieve the desired manifold pressure.

 

[Elamcup]

What is the Blow Off Valve and the Waste Gate doing when the throttle is closing back to reduce power?

 

[Scootsmcgreggor]

It’s super complicated but essentially the Ecu is always working to achieve a torque target and uses all manner of controls to achieve it. So in the case of the throttle closing to limit manifold boost pressure the wastegste duty cycle will increase as well to drop boost pressure as well. But the throttle can accomplish this much faster so it closes first then the wastegate opens more. BOV is not usually used to bleed boost while under load.

 

[Coyote Chase]

It’s super complicated but essentially the Ecu is always working to achieve a torque target and uses all manner of controls to achieve it. So in the case of the throttle closing to limit manifold boost pressure the wastegste duty cycle will increase as well to drop boost pressure as well. But the throttle can accomplish this much faster so it closes first then the wastegate opens more. BOV is not usually used to bleed boost while under load.

Interesting! Can the thottle plate be adjusted to increase boost?

 

[Scootsmcgreggor]

Interesting! Can the thottle plate be adjusted to increase boost?

Well a better way to do that would be to increase your torque/boost target. The throttle closing should only be used for overboost conditions. But funny/sad thing is some tuners appear to use it as a crutch. Getting wastegate duty cycles on these motors dialed in well can be difficult and time consuming so I’ve seen tunes that seem to over boost by design and just let the throttle plate regulate how much boost makes it into the intake manifold. Not ideal as the turbo is then overworked and producing hotter air than it should be.

 

[SVO MkII]

Well a better way to do that would be to increase your torque/boost target. The throttle closing should only be used for overboost conditions. But funny/sad thing is some tuners appear to use it as a crutch. Getting wastegate duty cycles on these motors dialed in well can be difficult and time consuming so I’ve seen tunes that seem to over boost by design and just let the throttle plate regulate how much boost makes it into the intake manifold. Not ideal as the turbo is then overworked and producing hotter air than it should be.

This is very interesting. I assumed the boost control from the ECU was much more sophisticated than the old days, but really didn't know exactly how much more. The only other turbo car I have had experience with is my son's '86 944 Turbo (951). The 951 is such a simple, old school turbo set up. You basically put different strength springs in the (Tial) wastegate, and then control it with a knob, that reads manifold pressure. It is pretty cool though, with the wastegate dumping to atmosphere. It blasts!

 

[Coyote Chase]

My boost level peaks at 3 or 4 K rpm, and then fades slowly, as the RPMs increase. Is there anything electronic, that can be changed? I'd like the boost to peak closer to the rpm red line.

 

[SVO MkII]

My boost level peaks at 3 or 4 K rpm, and then fades slowly, as the RPMs increase. Is there anything electronic, that can be changed? I'd like the boost to peak closer to the rpm red line.

Are you still running the stock intercooler? If so, that must be changed out for a larger one. I run an all stock motor with a bigger IC, and my boost holds at 20-22 psi up to almost 6K.

 

[Scootsmcgreggor]

My boost level peaks at 3 or 4 K rpm, and then fades slowly, as the RPMs increase. Is there anything electronic, that can be changed? I'd like the boost to peak closer to the rpm red line.

Well that's because the stock turbo is so small. It can't flow enough air at higher boost pressures near redline so it drops off a bit. Also exhaust manifold pressure is very high (1.5-2x boos pressure) so depending on your setup exhaust manifold pressure can be so high it starts to push the wastegate open.

Sponsored