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Anthony
Anthony, Ford Technician
Category: Ford
Satisfied Customers: 11750
Experience:  ASE Master Automobile Technician with over 20 years exp.
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98 ford explorer. code p0304. cylinder 4 misfire. Checked plug,

Customer Question

98 ford explorer. code p0304. cylinder 4 misfire. Checked plug, ok. Replaced coil pack. drove car and it is still running rough. plugged in again and found new code, po354. Where do i go now?
Submitted: 7 years ago.
Category: Ford
Expert:  Anthony replied 7 years ago.

Hello! Welcome to justanswer!

 

What is the eighth digit of you vin number?

Customer: replied 7 years ago.

The 8th digit is L as in larry. Don't know if this makes a difference, but this is a suv that belongs to a fire department.(may have a police package) Oh ya, i made a mistake, its an expedition not an explorer.

Expert:  Anthony replied 7 years ago.
Ok, I still need the eighth digit of the vin though.
Customer: replied 7 years ago.
The 8th digit is L as in larry
Expert:  Anthony replied 7 years ago.
Ok, can you verify if the #4 spark plug is firing?
Customer: replied 7 years ago.

i'll get back too u on that

 

Expert:  Anthony replied 7 years ago.
Ok, sounds good.
Customer: replied 7 years ago.
pulled coil out and checked for spark. there is no spark at the coil.
Expert:  Anthony replied 7 years ago.
Ok, try switching it with another coil and see if spark returns at #4. Use the #3 coil. What happens?
Customer: replied 7 years ago.
will do
Expert:  Anthony replied 7 years ago.
Ok, let me know what you find. I'll be here.
Customer: replied 7 years ago.

all right. i a little bit forward too. ur original question, the answer is yes. new coil to #3 coil this time and in-line-spark checker lit up. ( so new coil is good. and obiously #3 coil wiring is good.) which leads me to my next question. we checked for voltage at all coils on that bank, 1 wire in each of them has 12v w/ ignition on. the other doesnt and we tested them to see if the went to ground w/ an ohm meter. (it read open.)

What next?

Expert:  Anthony replied 7 years ago.

Ok, at #4, what is the voltage to ground (engine block) with the key on for the red wire?

Customer: replied 7 years ago.
The wire has 12 volts. in fact they all have 12volts in one wire.
Expert:  Anthony replied 7 years ago.
Ok, if thats the case, you have a bad engine computer. Do you need the instructions on how to change it?
Customer: replied 7 years ago.
where is it? 2morrow i will switch it out w/ one of the other 3 suvs (same yr.) we got.
Expert:  Anthony replied 7 years ago.

Ok, see the file below:

 

CLICK HERE FOR PDF FILE DOWNLOAD

Customer: replied 7 years ago.
Anthony, i switched the computer out w/ its sister car. NO CHANGE. coil #4 still is not firing.
Expert:  Anthony replied 7 years ago.
Ok, then you have to trace the wire from #4 back to the computer and see where its broken.