* Transmission Issues: This is the most probable cause. The symptoms strongly suggest a problem with the automatic transmission (assuming it's an automatic, as manuals don't "change gears" in the same way). Possible culprits include:
* Low Transmission Fluid: This is the easiest and cheapest thing to check first. Low fluid can cause slippage, poor shifting, and ultimately stalling. Check the fluid level and condition (it should be pink/red and not burnt smelling).
* Transmission Fluid Filter Clogged: A clogged filter restricts fluid flow, leading to similar problems as low fluid.
* Worn Clutch Packs/Bands: Internal components of the transmission wear over time. Worn clutch packs or bands can cause slippage and inability to engage gears properly. This requires a transmission rebuild or replacement.
* Torque Converter Problems: The torque converter connects the engine to the transmission. A faulty torque converter can cause slipping and stalling.
* Valve Body Issues: The valve body controls the fluid flow within the transmission. Problems here can disrupt shifting and cause stalling.
* Solenoid Problems: These are electromagnets that control the fluid flow in the transmission. A failing solenoid can prevent gears from engaging.
* Engine Problems: While less likely given the description, engine issues could contribute:
* Ignition System Problems: A faulty ignition coil, distributor cap, rotor, or spark plug wires can cause misfires or complete engine failure, mimicking a transmission problem.
* Fuel System Issues: A clogged fuel filter, fuel pump failure, or problems with the fuel injectors could starve the engine of fuel, leading to stalling.
* Electrical Problems:
* Transmission Control Module (TCM) Failure: The TCM controls the automatic transmission. A malfunctioning TCM can cause erratic shifting and stalling. This is more likely in later model years with more sophisticated electronics, but it's still a possibility.
* Speed Sensor Issues: An inaccurate or failing speed sensor can confuse the transmission control system and lead to problems.
Troubleshooting Steps:
1. Check Transmission Fluid: This is the absolute first step. Low or dirty fluid is an easy fix.
2. Inspect for Codes: If your Probe has a check engine light (CEL), get the trouble codes read using an OBD-I scanner (compatible with a 1989 vehicle). This can provide valuable clues.
3. Listen for Unusual Noises: Unusual whining, grinding, or banging noises from the transmission area strongly suggest internal transmission problems.
4. Test Drive (carefully!): See if the stalling occurs under specific conditions (e.g., accelerating, decelerating, turning). This can help narrow down the potential causes.
If you are not experienced working on cars, it is best to take your Probe to a qualified mechanic, especially if you suspect transmission problems. Transmission repairs can be expensive. Accurate diagnosis is essential to avoid unnecessary costs.
