Questions and Answers
Plymouth Voyager Poor Fuel Economy?
Q. Dear Vincent, I have a 1990 Plymouth Voyager with a 2.5 liter engine and manual 5-speed transmission. It only has 103,000 miles on it. I believe it is fuel injected. It does not have ABS but does have excellent A/C and cruise control. There are a couple of things that bother me. One, it only get 16 MPG on average. All the estimates I can find say it should be getting between 22 and 28 mpg.
I have checked the air filter and changed the oil as well as made sure all the tires were properly inflated but no luck. My Maintenance Required Light is on. I am wondering if it is an oxygen sensor that needs to be replaced?
The second thing that bugs is that it is pretty cold blooded. It takes several minutes to get going even when it is not very cold. It hesitates and stutters for approximately the first five minutes it is driven. I also noticed that there seems to be a lot of back spray from the tailpipe when I first start it up leaving a streak on the pavement but it does not smoke that I can see. What gives?
Matt
A. The Maintenance Required Light (EMR) is for the emissions system. On certain models, this Emission Maintenance Reminder System is incorporated into the engine controller. The controller stores vehicle mileage into its memory every 8 miles, then at 60,000, 82,500 or 120,000 miles it will illuminate the EMR lamp. When the indicated mileage is reached or the EMR lamp is on at all times. So I doubt it has anything to do with the problem.
The black smoke coming from the tail pipe when it's first started and cold would make me think of a leaking injector or a bad Coolant Temperature Sensor (CTS).
You can put a fuel pressure tester on the engine, start it up and let the fuel pressure stabilize and then shut the engine off. Watch the fuel pressure and see if it drops or slowly bleeds off. If it slowly bleeds off, restart the engine and let the fuel pressure stabilize. Then shut it off and quickly pinch off the feed and return fuel lines. If it still slowly bleeds off, and there are no leaks, the injectors are leaking down.
To check the CTS, you can hook up a scan tool to the engine after sitting over night and see what the CTS temperature is. It should be within a couple of degrees of ambient air temperature. If not, replace it.
Of course a good tune up, new spark plugs, spark plug wires, distributor cap and rotor will help a lot. Checking and adjusting the ignition timing is important and often left out of a tune up these days. It is fully adjustable on your engine. Your driving habits affect fuel milage as well so look, realistically, at the way you drive and see if there are things you can change to get more miles per gallon.
Here are a couple of articles you may find useful.
Additional Information provided courtesy of AllDATA
