84 vette wont idle or stay running very long
 

i just bought a 84 corvette it will start but wont idle or stay running without revving the engine, once it warms up though it will stay running as long as your going down the road but still will not idle. above a idle it will run. but otherwise go dead at a idle. anyone have any idea what may be causing this, it is my first corvette please help

Probably have a bad idle control motor.

You may need to adjust the throtle position sensor, I think that is the officeal name. But it is located on throtle body, on the opposite side from where the throtle cable is mounted. Should have 2 wires in one connection plugged into it. You will need an ampmeter to ajust it. Sorry I don't have my manual handy to get the specs.....but that fixxed my 86.

84 Corvette Crossfire Injection
 

Might want to check the C3 forum for the '82 Corvette which has the same Crossfire Injection system.

Also, having a partially stuck open EGR valve will cause that problem.

Throttle Position Sensor (TPS)
 

The TPS sensor will affect idling as well as above idle power curves & fuel economy.
On the rear TBI there is the TPS sensor just above the valve cover with 3 wires coming out of it.
I use 3 jumper wires to connect the harness to the sensor from a Sun Pro Sensor Tester that I have. Mid-America Corvette sells the TPS adapter also.
With the engine off/ignition on, put your voltmeter's red lead to the center wire and the voltmeter's black lead to the bottom wire which is the ground terminal. The voltmeter should be one that is used to check transistors to prevent damage to the ECM.
The voltage should be around .525V
If it is not, loosen the 2 torx head screws enough to move the sensor with a slight drag. Move the left side of the sensor up or down to bring the sensor within the .525V range & re-tighten the torx screws while holding the sensor in place as the .525V will change if the sensor is not held in place.

Good to get one of those OBD1 GM ALDL code readers which are inexpensive and available on eBay.
If your Check Engine light goes on, one of the engine sensors are out of tolerance and the trouble code is stored in the ECM. Engine sensors are the CTS (Coolant Temperature Sensor), IAC valves (Idle Air Control Valve- one in each TBI), MAP sensor (Manifold Absolute Pressure), O2 Sensor (Oxygen Sensor), EGR valve, TPS sensor.
After plugging in the ALDL code reader, the first code to come up which is normal is Code 12. The trouble light will blink once then twice to designate "12". After that there is a slight pause, then if there is a trouble code, the Check Engine Light will blink out the code.
GM OBD1 trouble codes are published readily on the internet.
If your Corvette has over 60K miles, I would definitely change the O2 sensor as it is over it's life expectancy and controls the air/fuel ratio and a bad O2 sensor will cause the engine to idle poorly as well as poor overall engine performance & poor gas mileage. With a bad O2 sensor, the ECM no longer controls the air fuel mixture and cannot correctly pulse the fuel to the TBI injectors.
A leaking diaphram in the EGR valve or an EGR valve that is stuck open due to carbon build-up will introduce air directly into the Crossfire intake and cause a lean mixture to starve the engine.

I also purchased an OBD1 ALDL to USB interface cable to connect to a WinXP laptop to read the sensor voltages while the engine is actually running. The interface cable also comes in handy for a ECM chip re-programming using a GM 1227747 ECM. Free software is available for the WinXP/Vista/Win2000 operating system.

Hope this helps.

Tuning the Crossfire EFI
 

Here's a good step-by-step instruction on tuning the Crossfire EFI:

http://www.corvettefever.com/techart...ing/index.html