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Stalling: repairs for Chrysler, Dodge, Plymouth, and other cars

If your car is fuel injected, first check for error codes in your computer.

Most stalling issues in fuel-injected cars come from:

  • Burglar alarms - often mis-diagnosed, and can include starting, then shutting off. Terra Sears was told that the fuel pump was at fault but he noticed the lights “strobed.” Resetting the system fixed it.
  • The Hall Effect sensor on cars made in the 1980s and up to the mid-1990s can fail and not set an error code. If the computer gets no data from the Hall Effect sensor, it will assume that the engine is not turning, and will not provide any fuel. This inexpensive gadget sits under the rotor on cars without distributorless ignition. A good first step on cars without distributorless ignition and not hard to replace, even for beginners. The pickup rotor can also be at fault; this can cause running then dying after about a minute.
  • The Auto Shutdown Relay (ASD) rarely breaks, but when it does, the engine stays off. It kills both fuel delivery and spark and can be triggered by a broken wire or short in another place -e.g. the fuel pump.
  • The MAP sensor measures air pressure in the manifold, is usually mounted on a fender in 1980s-90s cars, costs around $25, and is easy to replace. If your car won’t start, just unplug the electrical connection from the MAP sensor; if it then starts, replace the sensor. It, too, can act like a bad fuel pump.
  • There is a relay between the computer (PCM) and coil on the 2.2/2.5 TBI costs about $12. If it fails, mechanics may try replacing the computer (thanks, Ronald Knauf).
  • oxygen sensor (stalling)The starter relay is often misdiagnosed as the starter itself, the computer, etc. (thanks again, Ronald Knauf).
  • Fusible links: John Auto Tech wrote, "[on 2.2/2.5 cars, by the drivers side strut tower]. Give each one a [gentle] tug to see if one stretches like a rubber band."
  • Loose or dirty computer or battery connections - On vintage cars, check the hot wire going into the firewall plug... on the other side the wire goes to the fuse box then to the dash- when it goes to the dash it goes to the alt meter... it is a simple fix and one that should be checked. (It is also a good place for a fire - you’ve got loose hot wires and lots of loose insulation)
  • The idle speed motor can cause stalling when the engine is cold, but usually not when hot. This problem can affect newer cars.
  • Plugged exhaust (e.g. catalytic converter). F.J. MacFarlane wrote that many engines had/have two converters in series.
  • Clogged fuel filter or fuel line under the hood or in the tank. Similar symptoms can be caused by a weak fuel pump. There are two types of fuel pressure test: one which tests an instant of pressure, and a more sustained test. The latter can often solve stumble and stall problems that occur at highway speeds or under acceleration.
  • The speed (distance) sensor - see Ed Hennessy’s notes below.
  • Spark plug wires - Rosegate noted that a problem with missing cylinders was resolved by changing the wires. A dealer failed to solve the problem. You can do this yourself in ten minutes.
  • The oxygen sensor, usually easy to replace, can be damaged by bad gas or pollution from another bad part. Bad oxygen sensors can cause high idling, rough idling, stalling, lack of power, and poor fuel economy, not to mention excessive pollution. “An O2 sensor actually generates voltage and when active, varies between .5 and 1.0 V. which is rich/lean. It’s working ok if you see a wave between these numbers. If you see one steady reading the sensor is likely bad. Don’t forget the sensor must be hot to stard working.” - Wayne Moschella
  • Fuel line cracks - it happens, and they can be hard to find. Small, hard to see fuel line cracks can cause stalling and non-starting. Check not just the main fuel line but also delivery lines that feed individual injectors (thanks, R. Jake Carr).
  • Jim Zellmer wrote: a rubber elbow coming out of the rear intake manifold [may have a] crack that is not readily visible from the front of the car. The crack would open an cause a vaccuum leak big enough to shut down the engine.

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.

Stall at low rpm (by Bohdan Bodnar)

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.

Start, then immediate stall (by Bohdan Bodnar)

  • On a cold engine, read the coolant temperature sensor output and see if it agrees with the ambient temperature; they should be within around 2° F.
  • Measure the resistance of the secondary side of the ignition coil to one of the primary terminals. It should be around 8k ohms. If it’s more than about 12k, replace the coil. Primary side resistance should be around 1.3 ohms. If it’s above 2 ohms or below about 1 ohm, replace the coil. If you have other specs, use them, not these, which may be wrong for your car.
  • Stick a high impedance voltmeter from the switched battery feed on the ignition coil to ground and put the ignition key in run. For about two seconds, you’ll read something very close to battery voltage -- the difference should be < 500 mV. The positive side of the ignition coil is electrically connected to the fuel pump; this circuit is driven off of the autoshutdown relay inside the SMEC (Power Module, in my case).
  • Measure the resistance of the fuel injector + throttle body harness. It should be around 1.2 ohms. Resistance specs for this injector vary year-to-year. In general, the resistance is around 1 to 1.5 ohms. The harness introduces around 0.3 ohm extra resistance.
  • What is the condition of the spark plugs (clean, gapped correctly).
  • Measure the resistance of the ignition wires. Each wire should be, at most, around 10k ohms (Chrysler’s specs are lower than this). If any wire’s significantly higher than this, replace it. Is the cap and rotor okay (if it has them?)?
  • Connect a high-impedance voltmeter to the red wire on the MAP sensor and put the car in Run, with the engine off. You should read 5.0 volts. Now, read the signal return voltage, which should be around 4.9 volts (green wire, probably). Connect a vacuum pump to the MAP sensor and pump up a vacuum. The voltage should fall. If it doesn’t, replace the sensor. Examine the vacuum hose which you just disconnected; does it have a silicone gel visible? If so, then the MAP sensor’s falling apart internally. Check the hose going from the MAP sensor to the vacuum source for integrity.
  • Once you start the engine, the computer will lean the a/f mixture. The fuel pressure should be stable for several minutes. If it drops quickly, then something’s leaking (injector, regulator, or bad check valve in the pump).
  • There are two controls for the injector, one which fires the injector during startup and another which takes over controlling the injector approximately one second after start. The start circuit seems to have have much more current behind it than the ECM running feed. (I suspect to allow starting with a low battery where the ECM may not get sufficient voltage during cranking). When the plunger in the injector is sticking due to varnish build up, this start signal is able to operate the injector while the running feed from the ECM doesn’t have enough current (injector function is an electromagnet - more current=more pull on the internal plunger). It would start, but immediately stall every time. In my case I removed the injector from the car and backflushed it with cleaner. Most people may want to simply replace the injector(s).

Other possible stalling solutions

  • In the 1987 Plymouth Reliant and, likely, other cars of the era, there is a hidden connector in the power lead to the power module. From the top connector, closest to the fire wall, there is a red lead. Unwrap the binding tape from the wire bundle about 6 inches to expose an inline crimp connector (a factory kludge) which may be corroded and intermittent. (Vern)
  • Daryl Koehl noted that on the 3.3 V6 engine, there is a small plate that goes under the bolts that hides the problem. With the plate and flywheel removed you can see that the flywheel has sheared a complete circle around the entire set of bolts. You must remove the flywheel to see this.
  • Ed Hennessy wrote about someone whose Aries coughed, sputtered, and died sometimes when coming up to a stop sign - and sometimes recovered to a smooth idle: This is a classic symptom of a dead speed-distance sensor. The Hall Effect tends to fail only when hot and doesn’t usually matter if you stop or not. A bad speed sensor will stall the engine, but it will always fire right up immediately. You can check the sensor with an ohmmeter. Pull the sensor, and then connect the probes to the two terminals. You should see 8 pulses of zero resistance with infinite resistance in between. Anything else, and the sensor is bad. The LeBaron’s had 8 zero pulses, with relatively high (but not infinite) resistance in between.
  • seatiger noted that a bad steering pump could stall the engine when the wheel is turned, due to excess resistance.
  • A bad gas cap that does not allow venting can cause stalling, according to Jay Smith; one obvious symptom is seeing a deformed gas tank.

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