87 Chevy TBI TPS/TPS % with TunerPro RT

[87ChevyV20]

I just got TunerPro RT and a Moates ALDL cable. I ran Ole Blister up to operating temperature to try and help with a high idle situation.

I noticed that the throttle position (TPS) reading and TPS % reading are a little weird.
The TPS voltage (I think that is what this value is) is .53 and the TPS % is 27

Am I correct in assuming that 27% means quarter throttle?

The engine RPM's are 900-950.

Should the 2 TPS readings be more relative?

.53 seems like a good value for an idling engine, or am I wrong about that?

 

[Ricko1966]

What is your TPS voltage at 1/4 1/2 3/4 and wide open?

 

[87ChevyV20]

Measured in TunerPro RT.
TPS value
TPS % value

Idle	.53 27%
1/4 Throttle	1.92 98%
1/2 Throttle	3.04 155%
3/4 Throttle	3.53 180%
Full Throttle	4.41 225%

 

[Vbb199]

You have the incorrect multiplier or possibly .xdf file.. theres always problems reading tps on these gm TBI's.

 

[87ChevyV20]

So, is the TPS % a value that the ECM uses or just a multiplier that TunerPro uses?

 

[Vbb199]

So, is the TPS % a value that the ECM uses or just a multiplier that TunerPro uses?

The ecm uses 0-100%

The multipler that tunerpro uses needs to be skewed.

 

[87ChevyV20]

But it uses the voltage reading, not necessarily a % scale?

Like the ECM knows .5 volts 0% ish and 4.5 is wide open throttle and everything else is linear from that.

 

[Vbb199]

But it uses the voltage reading, not necessarily a % scale?

Like the ECM knows .5 volts 0% ish and 4.5 is wide open throttle and everything else is linear from that.

Yes the ecm uses voltage in order to linearize the percentage displayed

 

[AuroraGirl]

Yes the ecm uses voltage in order to linearize the percentage displayed

it must determine closed by using the same base value that off-throttle reverts to, yes? kinda the same way fords "ratch" works

 

[87ChevyV20]

So, I don't necessarily need to worry about the % value in TunerPro, just the voltage.

 

[Ricko1966]

So, I don't necessarily need to worry about the % value in TunerPro, just the voltage.

Yes and yours looks good, maybe bump it to 4.5 on the high side let the low side land where it lands. But if you aren't getting drivability problems right now I'd call it a day.

 

[AuroraGirl]

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Verify that idle is at specified value.
Make all checks/adjustments with engine at operating temperature.

Fuel Injected Models: Disconnect harness multi-plug from TPS. Using three six-inch jumper wires, reconnect harness to TPS. With ignition on and engine not running, connect a digital voltmeter to terminals A and B of TPS harness. If TPS is adjustable, loosen the unit retaining screws and rotate the unit to obtain the specified value.

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