2001 Dodge Neon Stalling

Tiny
BILLKROPP
  • MEMBER
  • 2001 DODGE NEON
Engine Performance problem
2001 Dodge Neon 4 cyl Automatic 278000 miles

Vehicle is a 2001 Neon 2 Liter 16V SOHC 278,000 miles.
Runs relatively well I guess I mean it runs. Recently began having problem of car fells like it wants to stall while idling. Stop at traffic light or stop sign especially with AC running. Stalled once in neighbor's approach. Had vehicle tune up. Month and a half stalled again. Had dealership replace idle air control motor, clean throttle body and fuel injection service, oil change and trans fluid/filter change. Couple weeks after repair vehicle stalled at stop with AC running. Vehicle runs but has low idle and feels like it wants to stall when AC is on. Been turning off AC and/or vent when stopped at stop sign or stopping in traffic to try preventing stall. Have stopped a few times with air on low and did not not stall but engine seemed like it wanted to.
Seems to perform most poorly when idling or going slow 25 miles or less - street driving. Beginning to wonder if accelerator cable isn't performing properly like loose or worn and causing incorrect fuel flow. Does the acceleration cable and pedal just give the engine fuel or does it also control amount of fuel flow?
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Tuesday, August 3rd, 2010 AT 12:50 PM

1 Reply

Tiny
CARADIODOC
  • EXPERT
Hi billkropp. Welcome to the forum. The accelerator cable has nothing to do with idle speed. There is a mechanical stop for the throttle valve. From there, the Engine Computer controls idle speed by opening up an air passage around the throttle valve with the automatic idle speed motor, and increasing the length of time the injectors are open. That varies the amount of air and fuel.

If there is a history of the battery being recently run dead or disconnected, "minimum throttle" must be relearned before the computer will know when it must be in control of idle speed. Until the occurs, stalling at stop signs will be a common problem.

Being so intermittent will make this problem hard to find. One approach is to drive the car with a scanner connected that has a record / playback feature. When the engine stalls, the record button is pressed. Because the live sensor data passes through the scanner's memory, the recording actually starts a few seconds before the button is pressed. Later, the data can be played back while you watch for a glitch in a sensor reading.

You can also watch "inputs / outputs" with the scanner. Of particular interest is "idle steps". The computer can command the automatic idle speed motor to any of 256 steps. As the steps increase, the motor turns a threaded rod which retracts the pintle valve to open the air passage around the throttle blade. Step number 32 is typical with the AC turned off. What's important is the step number when the stalling occurs. If it is lower than normal, the computer is not commanding an increase in rpm, usually due to a faulty sensor reading. If the number is high, the computer sees the low rpm and is trying to bring it up but something is not responding.

There's an easy way to tell if the automatic idle speed motor is working. When you start the engine, there should be an "idle flare-up" to around 1500 rpm, then it should come right back down to normal. That proves the motor is working and the computer has control of it. That flare-up will not occur if minimum throttle needs to be relearned.

Caradiodoc
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Tuesday, August 3rd, 2010 AT 2:41 PM

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