Hello all. I've got a strange problem with my car. When my tps is plugged into my ccc quadrajet, my car idles like it has a lumpy cam, and it runs really rough until about 3000 rpm when it clears up. It's really slow off the line and runs very choppy under 3k. After 3k it clears up and takes off as normal.

Strange thing is if I unplug the tps it clears up. Car runs fine and idles smooth, however I've heard that this makes the carb run full rich which would explain why I get 11mpg on a stock 305. I was going to replace the tps in my original quadrajet but the whole carb needed work so I just replaced the entire carb with a rebuilt one from a carb shop (its a quadrajet E4ME same as before). The TPS on it is definetly new, yet it still does the same exact thing. Is the problem maybe in the wiring leading up to the TPS? I don't really understand whats happening here so any help would be great. Thanks guys.

Oh its a 1984 LG4 motor, Computer controlled carb.

 

You may need to adjust the TPS. To check this, you need a voltmeter and some wire. Run 12 guage wire from the TPS connector to the cable connector for all three leads. make sure that you have all wires connected and not grounded. You can then connect a voltmeter between the bottom two terminals. It should read .51 volts. There is an adjustment screw behind a plug that would need to be drilled out to get at it. I would say it is fine if the reading is between .46 to .56 volts. Other than this I can't think what would be causing this problem.

 

might try the o2 sensor. if its bad then the tps might be sending a good reading to the computer, but the o2 is messing everything up. When o2's go bad they usually cause a false rich condition, that would tell the computer to lean the mixture which would cause it to idle rough. I'm just guessing here though. Do you have any engine codes? The tps usually wont make too big of a problem unless its way WAY off. and just because its new doesnt mean it works or is adjusted properly. Especially if you got a rebuilt carb from a certain crappy retailer, Headache in Advance, Parts.