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Missfire detected on cyl 3 and 4 along with EGR valve codes

I am getting engine codes for misfire detection and EGR faults.

I replaced the spark plug wires and plugs. I also replaced the EGR valve. I added fuel injector cleaner and high test fuel with minimal results.



What is the cause for the misfire? What are the other possible remedies? Thank you.

hep me, hep me, I am competent but uneducated on some details.

I know I ain’t the only one workin on a ford. lol

What year?
How many miles?
What’s the maintenance history?

I’m gonna guess that the EGR valve is operated by a vacuum solenoid. Did you check that for operation?

Misfires 3&4…does this engine have a coil pack, two cylinders per coil?

What exactly are the codes?

Did you post in another forum section?

year 2000

mileage 153,000

coil pack? I do not know. I assume yes. your hint of onr coil derving two cylinders rises interest.

Codes: PO 401 EGR flow insufficient

PO 303 cylinder 3 misfire detected

PO 304 Cylinder 4 misfire detected

No previous postings on this vehicle.

Yup, it’s a three coil pack, two cylinders per coil. That would be my first suspect for the two misfiring cylinders.

I didn’t check to see if the same sector (coil) is for 3&4, but I’ll bet it is. You may want to check before spending the $100.

I will check to see if the EGR is solenoid activated. i know it is vacuum actuated.

Please clarify. Is the coil pack of 6 unitized or are the coils that serve 3 and 4 removable from the pack?

can i test the coils myself?

The vacuuum pulls a diaphragm that pulls the EGR valve open. That device is commmonly known as a vacuum solenoid.

It’s all six in one pack. Nonseparable. The only real way to test the individual coil is to see if you have erratic spark off of those two wires. You only need check one to find out if the coil’s bad. You could check using a spare plug or even a timing light, but unless it’s really cutting out when you rev the engine I’m not sure that will be definitive. Checking the spark pulses on an oscilloscope would be absolutely definitive, but my guess is that if you had that capability you’d have already done so.

Ok, The EGR may have a vacuum hose problem. I have already replaced the EGR solenoid.

I suppose I could get 75 dollar assessment performed by oscilloscope. I suppose i could perform a remove and replace the coil pack for around a hundred bucks. Either way I spend the money. Either way it will cost me twice if one fails to prove effective.

I am confident that you have led me down a sound path and i shall choose to maybe evaluate with diagnostic support and definitely replace the coil even if diagnostic is not used. I m unsure of the history of this vehicle but I have performed the tune up procedures for it along with a cam shaft synchronizer replacement. I am leaning toward coil. Thank you and i will beg you for your expertise at a later time. maybe a different topic.