Can anybody help me out? My caravan's engine is acting weird. The engine would shut off randomly and when you restart it, it will start but you will need to step on the gas pedal for a while before releasing otherwise it will shut down again. And when I'm driving at trafic stops it will stall when I release the gas pedal. This would happen randomly sometimes every other day sometimes once a week. :( This has been going on for quite a while and it starts to drive me crazy. I've sent it to repair shop and they said maybe its the electrical system and they've change the wiring and the "black box" on the top of the engine and it still is the same.
StandOnCliff
09-01-2008, 09:05 PM
If no vacuum leaks are present.Two parts come to mind. A throttle position sensor or an automatic idle speed motor. Tps sensor is the cheapest to try and can't hurt if this vehicle has high mileage. The AIS motor is more pricey. Pulling and cleaning the AIS and it mounting location can fix the problem sometimes. The TPS can be checked with an ohmmeter. Put one lead of the ohmmeter into the center prong of the throttle position sensor and the other probe put into either outer prong. Turn ohmmeter on to read resistance. Move throttle slowly up and down and watch the sweep of the needle on the ohmmeter (digital ohmmeters don't work well). The needle should move fluently with the movement of the throttle. Any spikes or glitches with the needle and it's going bad. The AIS motor has basic tests that can be done to it also. Disconnect the electrical connector from the AIC valve and listen carefully for a change in the idle. Connect the AIC valve back up and turn on the A/C and listen for change in idle. When the vehicle is cold the AIC valve should vary the idle as the engine begins to warm up and also when the A/C is turned on. If there are no obvious signs that the AIC valve is working, continue below. Use a voltmeter and test for voltage to the AIC valve with the ignition key on(engine not running). Backprobe the AIC valve electrical connector and check for power on the purple or purple with a white tracer wire. It should have 12 volts. The yellow wire should have 12 volts also. Both should also remain having power with vehicle running, but voltage will fluctuate. If no power is present at either one you have eletrical issues. If all power checks out. Unbolt the AIC motor and leave it connected electrically. Turn the ignition key to ON (engine not running) The pin on the AIC motor should retract(pull in). If it doesn't it's bad. No further testing is possible without a scan tool. Here is both in the picture. The other thing is a sensor going bad. Is the check engine light on? Are you stalling as your moving down the road or just when idling or dropping to idle and coming to stops? If your stalling out while cruising down the road it could be crank or camshaft sensors going bad. Failing fuel pump or pressure regulator can be added as possibilities. Fuel pressure checks would verify this.
insight
09-02-2008, 01:52 AM
Hi, thanks for the reply. My van is stalling when i'm coming down to idling or just idling or just started the engine or whenever i release the gas pedal.
StandOnCliff
09-02-2008, 04:55 PM
If you haven't changed the fuel filter and air cleaner in a while. You might want to start there, for piece of mind and fuel economy. Otherwise look into the AIS motor, it sounds like thats what could be failing. It should run high idle when cold, come down in idle as it warms up. It should also change it's idling pattern when A/C is engaged. It also governs the idle so it doesn't stall when you come to stops or let off the throttle suddenly. There is also the possibility that the temperature sensor is stuck in the warm position. Usually if that is the case the check engine light usually comes on, or you notice it runs fine warmed up and like crap cold.
