2006 Chrysler PT Cruiser Poor Mileage

Tiny
KJHARTWELL
  • MEMBER
  • 2006 CHRYSLER PT CRUISER
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 76,000 MILES
My wife's 2006 Chrysler pt cruiser 4 dr sedan w/2.4L engine is getting poor mileage (approx. 17.8 mpg) as opposed to 24-25 mpg that it should get. We checked tire pressure, replaced air filter, changed oil and filter and put in new spark plugs ( factory recommended gapped at.040"). Tried putting in injector cleaner twice with no results. The check engine light is not on, so there is no indication of a problem with emission control etc.
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Tuesday, March 9th, 2010 AT 6:37 PM

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Tiny
CARADIODOC
  • EXPERT
Park on a slight incline, put it in neutral, and release the brakes. Does the car start to coast downhill on its own? If not, suspect a dragging brake. Look for one of the front wheels feeling hot after driving a few miles. Holler back if that's what you find.

Caradiodoc
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Tuesday, March 9th, 2010 AT 6:54 PM
Tiny
KJHARTWELL
  • MEMBER
The car rolls very easily. Also, I checked for vacuum leaks with starter fluid spay arround all vacuum hoses and found no leaks. Is it possible that the plug wires are bad?
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Thursday, March 11th, 2010 AT 10:14 PM
Tiny
CARADIODOC
  • EXPERT
You would notice bad plug wires as a rough running engine, and the Engine Computer would detect the misfires, memorize a diagnostic fault code, and turn on the Check Engine light.

Is it possible the cold winter temperatures are responsible for the lower fuel mileage?

Your mechanic can connect a hand-held computer called a scanner to read the short and long term fuel trims. If those numbers are high positive, it means the Engine Computer is requesting more fuel. If the numbers are high negative, the computer is trying to reduce the amount of fuel entering the engine.

One thing that can be hard to find is an exhaust leak before the catalytic converter. In between the pulses of exhaust gas, the momentum creates a tiny pulse of vacuum. That vacuum can draw in fresh air. The oxygen sensor will detect the unburned oxygen and the Engine Computer will mistakenly add fuel in an attempt to stabilize the mixture. No matter how much fuel is added, there will always be that unburned oxygen. Oxygen sensors only respond to oxygen, not fuel.

Caradiodoc
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Friday, March 12th, 2010 AT 2:47 AM

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