2000 Dodge Stratus Misfire, Stalls, Spits and Sputters.

Tiny
MKCOCONUTS
  • MEMBER
  • 2000 DODGE STRATUS
  • 108,000 MILES
Pretty much as the subject says, it misfires, stalls, spits and sputters real bad. You can hold the pedal to the floor while in park and the car won't climb past 2000 rpm and will eventually die. If you don't give it any throttle, it'll die. When we do keep it running for a bit, it gets worse and worse on how it idles. Originally, it was pulling a P0171 code and a few EVAP leak codes. They were cleared to see which would come back. The O2 sensor has been replaced, but the car still has the same symptoms, but no codes have been brought back on. I've been thinking possibly the TPS sensor or the fuel pressure regulator if there isn't a problem with the fuel pressure itself. I'm usually good with diagnosing and fixing vehicles, but this one has me at a loss.
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Thursday, October 10th, 2013 AT 9:58 PM

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Tiny
CARADIODOC
  • EXPERT
MAP sensors used to be a high-failure item and they often caused the symptoms you described when they had just started to fail but weren't bad enough to trigger a fault code. I'm not a fan of replacing random parts but you might want to try a new one or pick up a used one from a salvage yard. Don't overlook a vacuum leak since MAP sensors measure intake manifold vacuum.

You didn't say which engine you have. If you have a single camshaft four-cylinder engine, the dowel pin between the cam and sprocket can shear off and the sprocket can turn a little. When the camshaft is late by the equivalent of one tooth, the Check Engine light will turn on and there will be a fault code "cam and crank sync". At two teeth, the Engine Computer will shut the engine down to protect the valves. Before it gets to one tooth, the engine will not have the proper response but there may be no fault code set.

The TPS might cause a little hesitation but that's all. A momentary glitch in the signal voltage will be detected by the Engine Computer which will set a related fault code. Even with a hard failure and a fault code, it won't cause what you described.

I don't think fuel pressure is the cause either. Some GM engines won't run when fuel pressure is down just a few pounds, but my '88 Grand Caravan runs 50 pounds of pressure and it will still run fine as low as 20 pounds. I drove with a fuel pressure gauge attached to the radio antenna for over a year while chasing an intermittent problem. That's how I learned how it runs with the wrong pressure. GM also had a huge problem with leaking pressure regulators but I've only read about that on a Chrysler product once. I've never heard of one having low fuel pressure caused by the regulator.

You may need to connect a scanner to view live data to see what the Engine Computer is seeing and reacting to. When there's no fault codes and the cause of a running problem isn't obvious or easy to diagnose, a visit to an engine performance specialist can be less costly and faster than trying various things.
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Thursday, October 10th, 2013 AT 11:22 PM
Tiny
MKCOCONUTS
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Thanks for the quick response. It is the 2.4 DOHC I4 btw. There are two vacuum hoses that need replaced. One I know has to do with the PCV, the other isn't too bad of shape but I'm not 100 percent sure what it is part of yet, but I've never seen vacuum hoses have that kind of effect, high idle yes, but not stalling and sputtering. I will have to look into the MAP sensor as it was one theory that slipped my mind.

I plan on using a better scanner than mine later today to allow me to view the live data. As far as codes, there are none to speak of any more. The light hasn't turned back on and there aren't any stored. That or my code reader isn't picking them up.

The thought of it jumping time was a possibility that came to mind, but again, I would figure that the light would have triggered by now. Also, before the original codes were cleared, the vehicle had a very hard time starting and sometimes wouldn't. Now, it'll usually start, but acts almost as if one or two of the spark plug boots weren't connected.

Unfortunately, with this being my friends car and a few months old issue, it is hard to describe how exactly the problem came to be. She said it started acting this way after a trip to visit a friend.

One of the reasons I'm leaning toward a fuel issue is because the O2 sensor was picking up a lean condition. Something had to have been preventing enough fuel from entering the cylinders or somehow too much air is getting into the engine.
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Friday, October 11th, 2013 AT 12:02 AM
Tiny
CARADIODOC
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The lean issue would also result from a vacuum leak. A much less common cause is an exhaust leak ahead of the front oxygen sensor. In between the puffs of exhaust gas flow, the momentum creates little puffs of vacuum that can draw in outside air. The oxygen in that air is detected as running too lean too long. The computer will try to correct that by dumping in more fuel but there will still always be that extra oxygen.

The mixture can only be adjusted up or down about ten percent based on oxygen sensor readings. It rarely gets to those extremes, but even then the engine will run reasonably well. The clue would be in the fuel trim numbers on the scanner. If they're high positive, the computer is adding fuel, most likely in relation to what set the lean code. If the numbers are high negative, the computer is subtracting fuel from the pre-programmed calculations. Then you have to determine if that is because it sees a too-rich condition from the O2 sensor or in response to other sensor readings. The MAP sensor has the biggest say in how much fuel is needed. All kinds of symptoms can occur when the fuel metering calculations are based on incorrect information from him.
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Friday, October 11th, 2013 AT 1:02 AM

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