Note: Allpar does not take responsibility for the veracity of any information or opinions here, does not claim expertise, and is not responsible for any consequences. Please proceed at your own risk.
If your car is fuel injected, first check for error codes in your computer.
Most stalling issues in fuel-injected cars come from:
For non-fuel injected cars, most stalling issues can be traced to the carburetor or timing settings. A good tune-up with high quality wires, rotor, and distributor cap can often permanently solve stalling. For other ideas, visit Valiant Varieties
or our vintage car repairs page.
Dirt and water can get between any sensor and the wire leading back to the computer, so first check the contacts for each sensor. Sometimes, you can buy a kit which replaces just the part of the wire near the sensor. You can also make a temporary fix by buying the end of the wire from a junkyard and splicing it on.
Measure the resistance of the ignition wires and replace any which exceed roughly 15k ohms. If the rotor appears to be worn (on cars with distributors), replace the rotor and cap. Check the resistance of the ignition coil (if there is just one): the primary should be about 1.5 ohms whereas secondary will be a few kilo-ohms.
Fuel injected with automatic transmission: Pull diagnostic trouble codes. After the "55" has been flashed, move the transmission gear selector from Park to Neutral to Reverse/Drive. The power loss light should flash indicating that the computer is seeing changes in the neutral safety switch. If no changes are seen, the engine may bog when switching gears because the idle anticipation will not work. Injector base pulse width is also partially controlled by this switch.
Fuel injected: Check to ensure that there are no TPS related diagnostic trouble codes (DTCs). In an EFI engine, the TPS serves as an "electronic" accelerator pump. If the TPS circuit is not operating, the computer will not be able to react to sudden changes in throttle setting.
Check fuel pressure against factory specs. If this is TBI, pressure should be 14.5 psi +/- 1 psi.
Measure the voltage from the + side of the ignition coil to ground -- it should be within a few hundred millivolts of battery voltage (the positive side also goes to the fuel pump; the entire circuit is fed by the ASD relay in the computer/power module). Check spark plugs; the gap on the Champion RN12YC sparkplugs is 0.035”.
Clean the coolant temperature sensor connections with television tuner cleaner, since these will often corrode and cause the computer to see an abnormally low temperature (and thus flood the engine).
Carbureted engines: If you have access to an oscilloscope, check the primary side of the ignition coil; the pulse width (burn time) should be between 0.85 ms and about 2 ms (my Le Baron has between 1.9 and 2.1 ms). The pulse during the burn time should be flat; if it’s tilting upward, then you have either excessive circuit resistance or lean misfire. The firing voltage (spike) should be around 200 volts; if it’s substantially less than that, then either you have a short someplace in the secondary ignition system or the primary has excessive resistance.
Assuming you’ve done all the above, connect a high impedance dwell meter to the mixture control solenoid. Set the meter for the 6 cylinders scale. With the engine in closed loop, the average dwell should be 30 degrees (50% duty cycle on the m/c solenoid). See the FAQ for further details.
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