Hello

I did my minimal idel set today. I got the hot cam so I hade to adjust the idel screw some so it dident died.
After that I looked at my TPS volts and it showed 0.63V, to much! But I cant make it any lower, cause if I do my minimal idel setting also gets to low and the car dies. To keep my car idle with the IAC disconnect and the car in op temp. The lowest I can set the idle screw before the car dies is when the TPS is att 0.63 V.. Is that ok?

And yes the IAC is in its lowest position.

 

If you are adjusting the TPS to .63Vdc at normal idle speed, i.e. ~750RPM, that is a little low. At 750RPM I would expect to see around .70-.75Vdc.

If you are getting .63Vdc at base idle, i.e. with IAC pintel extended & 450RPM, that is fine.

 

with my stock cam I could set my base idel to around 450 rpm. With my new cam I must set it to around 750 rpm. But then the TPS volt increase also ( of course) is that ok?

 

Devil you'll be fine. I idle at 900 RPM and have it set to 0.68v without any issues. You can set it to whatever you want, it just takes some playing with. :)

 

thanks :)

 

Dude I know exactly what your dilema is. You read the tech tip here on the forum...no offense to whoever did it. :jester

You have to set the min idle, with the screw that moves the blades. Then your done with that screw. The tech tips, at least the time I read it, made it should like you then use that same screw for the TPS adjustment. When really there are two screws on the TPS itself that need to be adjusted to set that. You should never have to adjust the min idle screw after getting the IAC set.

Although I shoot for an IAC asjustment at idle of about 20-30 counts. This limits the amount of air the IAC can add, and keeps the car from hunting for idle. If you have the TB blades closed too far, and the IAC counts are high like 50-70 then you will get the pulsing idle, that people describe. I wrote a very good post on how to properly set the min air, and the effects it has on the idle quality. I wish we had a sticky section....HINT HINT.

With the proper settings your car should idle no problem at 500 RPM without stalling. I can take my desired idle down to 450 with the romulator and with the 610 lift mech cam and it will idle....soundy pretty hairy and the whole car shakes, but it won't stall.

if you have any problems let me know. I can probably help. Remember the ECM is what command the idle, the IAC is what is basically a controlled air leak, allowing air into the engine., You want 80% of that air coming from the TB blade and the other 20% from the IAC. If its the other way around, then you will get a surging or stall problems etc.

L8r :cheers:

 

Did you mod the TPS sensor so you can adjust it?

You have a 90 or 91 right?
They are not adjustable. I could not get my new one to work out volatge wise, so I drilled the mounting holes bigger and now I can adjust it.

You set the voltage on the TPS sensor by moving the sensor, not by turning the min idle screw on the drivers side.

I set mine at .58 or so at my 850 idle...

The 90's ecm, from what I have learned on here, is not so sensitve about the .54 volts. it looks at the min and max values and sets itself? :confused:
Thats what I have been told, yet I still set it to .54-.58.

If you go too high or too low on the TPS voltage, it will set off a code and the check engine light will turn on, mine has done it, that is why I drilled out my sensor to make it adjustable.


[Modified by bill mcdonald, 12:51 PM 6/6/2003]

 

I got a 91.

I can adjust my TPS, not much only aroun -+0.05volts.

My car idles very good at around 800rpm with my new cam. My IAC counts ar around 40.
The TPS volt should be linear , right? So if I set my minimal idle at 700rpm, the TPS shoudlent read 0.54 , if I set it to that the TPS volt curve isent linear.
What I really should do is to set my TPS at 0.54V at 450 rpm, and then dont really car what the tps is at 800rpm..

 

tt

 

If you can only adjust it by .05 volts then you have a bad sensor.

 

:confused:
2 questions.

How are you adjusting it?
Did you drill the mounting holes bigger so you can rock it back and forth?

 

no I just forced it with the stock holes. And that is not much... :(

 

I thought just hte LT1/4 TPS units were non-adjustable? Hell slot yours and MAKE it adjustable. :)

 

what should the TPS be at WOT?

 

Look at your ECM and you should see a value for something like "% throttle to activate WOT". Mine is 69%. So you take 69% of the 5 volt reference line and get 3.69v. So anytime my ECM sees over 3.69v on the TPS it goes into WOT (power enrichment) mode.

 

Yeah I had a long debate a while back with another member, I though it was adjustable since mine was on my 90. well the TPS died and I got a new one, and it was not adjustable.
So I went ahead and slotted the mounting holes with a drill.

Now I can adjust it as I please, which is what I have been trying to tell Devil Fish to do.

 

there must be a reason my GM took away the adj TPS?