I've read some posts from here and They are roughly the same about TPS voltage.

BUT the Haynes manual gives 2 different voltages to look for at idle depending on the use of a scan tool (datamaster) or a volt meter?

Does anyone have an explination for this except that haynes manuals suck...

I want to set up the tps and TB up for the smoothest Idle possible and have the proper range for max HP. The TPS is adjustable and It is on a 52MM holley. I have it set on .76v now, the haynes manual says @.8v with a volt meter but 1.2 to 1.4v with a scan tool!!!!

What is up,

 

The TPS has a wide range it wil work with in .3-.9 (At idle) and as long as your not throwing a code it should not affect idle quality. I never set mine above .5 (.43 from the factory and thats good enough for me) Some get confused because with the old TPI systems the TPS voltage was a lot more critical but the LT1s ECM will auto adjust as long as it falls with in specs. If you have poor idle I would be looking at the IAC rather then the TPS.

 

Yes, I have though about that also, I'm adjusting the throttle blades idle screw position at the same time so I can't narrow things down, I have a very evident whistle at idle, Have you heard any similer reports about the BBK throttle body doing that.

 

The BBK throttle body is widely known for its "whistle". Many have had success in reducing or eliminating this fake supercharger by filing/grinding down the IAC port edges. They are razor sharp from the factory. Rounding these over helps to reduce the noise.

 

The TPS voltage should not be any different, whether you are measuring it with a scan tool, or directly from the sensor with a volt meter.

 

That is exactly my point about the haynes manual...It seemed very strange to me. Has anyone found a good starting point adjusting the TB blades screw, (measured distance) and TPS voltage at idle that keeps the idle nice and AFR at optimum without over working the IAC valve counts?

Oh for those of you who have recent data master files on a 383 lt1, at idle what are your tps voltages and IAC counts at @1000 rpm?

 

When I had the BBK I took the IAC housing off and smoothed out all the IAC pasages and it realy helped the Jet sound quite a bit. To set the throttle blades I disconnected the IAC and set the idle to 650 RPMs, Shut the car off reconected the IAC and reset the IAC idle, using the steps I have listed below

My idle, via tuning is set at 900 RPMs and my TPS voltage was .42 at idle and the IAC pos is 108. At 1125 it is .53 and the IAC is 119. Have you reset the IAC yet?

On the 94 corvette THe IAC set procedure is ( I usaly have to do this a couple of times.)

1. Depress accelerator pedal slightly.
2. Start engine and release accelerator pedal, run engine for 5 seconds.
3. Turn ignition “OFF” for 10 seconds. D. Restart engine and check for proper idle operation.

 

The LT1 engine isn't very sensitive to the TPS voltage setting. As long as it is between 0.20-0.90V with the blades closed, the PCM will baseline that voltage as "0%" TPP, and prorate up to a 100% TPP value approx 4V higher than the closed throttle voltage. The position of the TPS, as long as it is within spec will not affect the A/F ratio... the PCM controls that using feedback from the O2 sensors. TPS voltage does not affect idle speed or change the IAC setting.

Rather than adjust the TPS voltage, its best to start with the blade stop screw. Move it out slowly and open the blades until the IAC motor bottoms out at "0" and the idle speed starts to increase . Then start backing off until the idle speed returns to the correct value (800rpm in the M6, 650rpm in neutral in the A4) and check to make sure the IAC counts are in the range of 20-50. Then check your TPS voltage, and make sure its in the range of 0.20-0.90V. If it isn't you can slot the holes in the TPS sensor so it can be rotated. But unless you have gone to an aftermarket TB, adjustment is seldom needed.

 

Ok, that helps alot, I actually stumbled accross that fact today about the tps voltage being "learned" at start up as 0% while I was adjusting it. The iac counts is helpful too, for some reason I was under the impression that 120 at idle was the goal. Thanks for the help

 

You might want to read this for help with the scan data:

http://members.aol.com/InjuneerZZ/ScanMast.htm