WHEN I GIVE IT GAS IT START TO MISFIRE
Misfires are caused by one of 3 things-gas, spark, or compression-one of those is the problem. For gas, check the fuel pressure and see if it is at the right pressure for your car. Low fuel pressure will cause misfires. If pressure is good, it could still be an injector problem, like a clogged injector. If low pressure, suspect the fuel pump or the fuel filter.
For an ignition spark problem, check your spark plugs. Pull them out and inspect them for broken or cracked plugs, check the spark plug gap, check for oil fouled plugs. You may be able to isolate the misfire to a cylinder or two by the plugs condition. A misfiring plug or cylinder should show more black, sooty deposits than the other plugs. A normal firing plug will have a tan or brown colored insulator on the end with very little deposits. If the plugs are okay, clean them a bit if needed, and check for spark on the spark plug wire ends with engine cranking. Buy an inexpensive spark tester, or hold each spark plug wire metal end terminal 1/4 inch from a ground on the engine block, while cranking the engine. Wear a heavy glove to avoid getting shocked. Check that every cylinder is getting a strong blue spark to eliminate ignition as a problem. A weak, yellow or orange spark is an ignition problem, possibly a bad coil, or other ignition part.
If spark and gas is good, you may need to check engine compression. Any cylinder that has significantly lower compression than the other cylinders will cause a misfire, and set a misfire code. You should check for any trouble codes in the engine computer. A code reader or scanner would have to be connected to the diagnostic connector under the dash. What is "significantly lower" compression? About 15-20% less compression. Say you checked and had 150 psi compression in most cylinders. If one had 20% lower compression ( 150 X 20%= 30 psi, 150 -30 =120 psi, or same as saying 150 X 80%= 120 psi.), a condition like that can cause a misfire. I hope I have made sense here. Good luck, and post back what you find, or if any questions.
Apr 10, 2014 |
1998 Ford Windstar