Close
Van has a constant miss
1999 Mercury Villager

Van has a constant miss

(1999 Mercury Villager)
one code reader said cylender 4 misfire, so i changed plugs. still missed. my mechanics reader said random misfire, he said change wires, i did. still misses. is there a coil pack? should i look there?
2 answers & 0 comments
Popular Answer
on December 17, 2010
First you need to find out why #4 cylinder was missing, was it a plug, a wire etc? It could be a lean condition, so I would check your Long Term Fuel Trim, that can cause a random misfire, or a leaking intake manifold. Make sure that your Long Term Fuel Trim is not above 9% for either Bank 1 or Bank 2, if it is, you may have a vacuum leak or a defective Mass Air Flow Sensor or other things. I would also do a compression test just to be sure that the engine is still tight, you want to see at least 150 psi in all cylinders.
Sign in to reply
Oil Leak Diagnosis
$88 - $111 Learn More
on December 17, 2010
First you need to find out why #4 cylinder was missing, was it a plug, a wire etc? It could be a lean condition, so I would check your Long Term Fuel Trim, that can cause a random misfire, or a leaking intake manifold. Make sure that your Long Term Fuel Trim is not above 9% for either Bank 1 or Bank 2, if it is, you may have a vacuum leak or a defective Mass Air Flow Sensor or other things. I would also do a compression test just to be sure that the engine is still tight, you want to see at least 150 psi in all cylinders.
Sign in to reply
on March 19, 2012
Try the distributer cap and rotor. Could also be a bad injector (of somthing else in the fuel system) or something mechanical. Run a compression check on the cylinder.
Sign in to reply

Similar Questions

View answers to similar questions from RepairPal's community of auto experts and enthusiasts.
I have changed the plugs, wires and coil and the van still runs horrible. when you are accelerating it runs very...