engine miss #4

[tspe2006]

i have a 95 lincoln town car. with a bad miss in #4. has spark gas and compression???????????PLEASE HELP!!!! codes read misfire in cyl #4 thats the only code. car has 168000 mile on a 4.6L over head cam

[corning_d3]

Have you installed a compression guage and checked it? Have you tested the injector? have you changed the plugwires yet?

[tspe2006]

Originally Posted by corning_d3

Have you installed a compression guage and checked it? Have you tested the injector? have you changed the plugwires yet?

yes checked compression put in new injector and plug wire is fine......??????.......pulled whole injector rail off unplugged both coils and turned over gas was shootin out of #4 injector. spark plug is new also......please help im stumped.....

[corning_d3]

what was the compression reading? Was the injector pulsing quickly or on steady? Have you tried another spark plug and wire?

[tspe2006]

Originally Posted by corning_d3

what was the compression reading? Was the injector pulsing quickly or on steady? Have you tried another spark plug and wire?

compression is 9 to 1 new spark plug new wire. new injector just tested it book says that the injector should be between 03 and 08 ohms on the two prongs on the injector itself its at 04 ohms. dont know how to check pulsing so i dont know.. thanks for the help.

[corning_d3]

Hmm, what about a new spark plug. Spark plugs have an internal resistor. Just by inspecting one visually, you can't tell if it's broke. Gapping a plug incorrectly can break one, also. Are there any small black spots or lines on the ceramic part of the plug? If so, the spark is jumping from inside the plug to the head or other ground. I'd replace the anyway to be sure, they're cheap....

[corning_d3]

Also, I don't recommend testing a plug with an ohm meter. It may show to be fine, but with 30,000 up to 50,000 volts running through it, it may arc somewhere else.

[tspe2006]

Originally Posted by corning_d3

Also, I don't recommend testing a plug with an ohm meter. It may show to be fine, but with 30,000 up to 50,000 volts running through it, it may arc somewhere else.

i didnt test the spark plug i tested the injector. the new injector is reading 4 ohms. the spark plug and wire are both new. i changed the spark plug again. still no changes. dont know what else to do. i was told that the egr is on the back of the motor and might dump into cyl. #4 so that might be the root of my problem but i dont know for sure if that will be it. will keep ya posted. thanks for all the info. any thing else please let me know!!!!!

[corning_d3]

Yes, the EGR can cause a miss. Try unplugging the vacuum line or wires(depending on model) and disconnecting the battery for a few minutes, then restart the vehicle. If it runs better, it's an EGR problem. One other thing, I'm thinking there may be a bad coil pack...

[tspe2006]

Originally Posted by corning_d3

Yes, the EGR can cause a miss. Try unplugging the vacuum line or wires(depending on model) and disconnecting the battery for a few minutes, then restart the vehicle. If it runs better, it's an EGR problem. One other thing, I'm thinking there may be a bad coil pack...

it worked thanks alot!!!! the info is greatly appreciated!!! wish i could buy ya a beer...haha, tspe2006

[corning_d3]

Just remember if it was a vacuum line, better plug it. An EGR valve can be expensive new(up to $150, some models). Salvage yards usually carry these fairly cheap. You really need your EGR system to work, because it reduces pinging, detonation, and heat in the cylinders. I'd replace the valve soon.