Biochem

So in the tech article section there is an article about adjusting your TPS and IAC. I don't see an IAC on my q-jet. The only wires go to the M/C solenoid (top passanger side) and the TPS switch (front drivers side). Is that sensor only on TBI? If so, why is it under Carb tech articles?

Anyways, as for my TPS. The top wire reads a constant 5.0V, the bottom wire reads 0.0V. The middle wire will vary depending on the position of the throttle... it goes from 0.6V to about 3.78V (fairly linear). I think it should go from 0.54V to over 4.0V, but I cannot adjust the screw that hits the throttle bracket to go less then 0.60V without the engine stalling. And to do that, I have to screw in the screw on top of the carb (the one that hits a plate that rests on top of the primary rods inside the q-jet) all the way in. When it goes as low as it will go (TPS voltage), the car is in Park should it be?) and the rpms are barely 700rpms and it really wants to stall.

For now, I have the screw that hits the throttle bracket (fast idle screw?) so the rpms read 1000rpms in park and about 850rpms in drive, and the middle wire on the TPS reads about 0.74V. The car runs OK, but the idle is still a bit rough and I will see tomorrow when I first start up and it's cold.

I see a little screw of some type (looks like an allen wrench tip pointing towards me) that is in a little hole next to the TPS lever that hits the accelerator pump. Do I need to adjust that somehow?

Ed Maher

Biochem, i thought we'd been through all this a while ago with your TPS? Maybe i'm thinking about someone else. Anyhow...
#1, you don't have an IAC, so stop looking. From literature, apparently some CCCS cars had a fancy device for controlling idle speed, but i've never seen one.
#2, that little screw on the baseplate is not your fast idle screw. It's your curb idle screw. The fast idle screw is on the oass. side under the choke housing. The curb idle screw is for setting your regular idle speed. Set it wherever you like. 7-800 rpms is nice.
#3, do not adjust your TPS by using your curb idle screw. hehehe. That little hex head next to the acc. pump arm is the TPS adjusting screw. Yes you need a special tool to adjust it. YOu can get it at www.thexton.com (no time to look up the PN now.
#4, With the throttle closed the TPS should read 0.5V and should go to somewhere over 4V at idle. If yours doens't make it that high with the throttle wide open, it might be going dead. Honestly though, i wouldn't worry about it. Unlike FI cars, ours don't need to use the TPS much. They just act up when it isn't set to the right closed throttle value.
sorry, gotta run now...i'll post more later...ed

Biochem

Parts maybe, but not TPS and IAC stuff yet

#1 IAC... what IAC! Not looking anymore.

#2 Sorry, I get the names mixed up. Either way, unless my tach is off, I cannot go much lower then 1000 (in park) because the idle surges too much.

#3 Will look for that tool. I just adjusted the curb idle back to what runs the best for now.

#4 I had the carb re-built last November (before my engine) and the TPS was replaced. It does go up in voltage when I move the throttle bracket, just not from 0.5-4.0+ (only 0.7- 3.8V or so).

I think I need to adjust it... at least at the low end.