Misfire on cylinder #3 - P0303 DTC

[Race Red Boss]

Hi All,

Anyone dealt with a misfire problem on their Cobra? Mine started to act up today as I was on my way to the golf driving range. Definitely could tell something was up....car was running rough and down on power.

From the little reading I've done, coil pack and/or wires and/or plug can be a common issue, or possible fuel injector problem.

Let me know if you've had this issue and how you successfully trouble shot it.

Thanks!

 

[Sn951997SVT]

If I may ask,what plugs and plug wires you running?

 

[ashleyroachclip]

This is for the 98 in your signature ?

 

[Race Red Boss]

Yes, this is for my 98 Cobra and the wires and plugs are original factory....approx. 68K miles on the car.

 

[Sn951997SVT]

I would start with the spark plugs, then move on to the plug wires.

Then check your coil packs and fuel injectors.

Sometimes it takes a bit of troubleshooting on these cars.

Good luck buddy!

 

[Tillerman77]

Recommendation - use OEM wires, coil packs & plugs. My 97 developed a misfire about 69K and the wires were the culprit. New OEM plugs and wires went in and misfire was gone. Many folks have tried the "sexy" FRPP wires only to continue to have misfire issues. BTW, my coil packs were fine.

 

[Race Red Boss]

Recommendation - use OEM wires, coil packs & plugs. My 97 developed a misfire about 69K and the wires were the culprit. New OEM plugs and wires went in and misfire was gone. Many folks have tried the "sexy" FRPP wires only to continue to have misfire issues. BTW, my coil packs were fine.

Thanks. I am going with the 9mm FRPP wires as I saw a lot of positive reviews on them from other Cobra owners. Fingers crossed they work out...but if they don't, I'll buy an OEM set. I am putting in the Motorcraft OEM platinum plugs.

Given all the heat under and the age have finally caught up with the wire for #3 cylinder. I'll post in this thread how things go with the new wires and plugs and hopefully like you....the problem will be solved.

 

[Tillerman77]

Hope they work for you.

 

[Miked232]

Hi All,

Anyone dealt with a misfire problem on their Cobra? Mine started to act up today as I was on my way to the golf driving range. Definitely could tell something was up....car was running rough and down on power.

From the little reading I've done, coil pack and/or wires and/or plug can be a common issue, or possible fuel injector problem.

Let me know if you've had this issue and how you successfully trouble shot it.

Thanks!

My 97 had the same code. One injector is clogged and the spark plug boot separated from the wire. I can only assume it’s one of the two


Sent from my iPhone using the svtperformance.com mobile app

 

[Race Red Boss]

My 97 had the same code. One injector is clogged and the spark plug boot separated from the wire. I can only assume it’s one of the two


Sent from my iPhone using the svtperformance.com mobile app

Wow, two issues at once...that makes for some fun troubleshooting. Was the injector and boot issue on the same cylinder....or different ones? My code is specific to cylinder #3, so I'm assuming I'll find the problem related to the wire/plug/injector or coil pack port associated to #3.

Just waiting for my new 9mm FRPP wires and Motorcraft plugs to arrive from Summit so I can get to work on it.

 

[Miked232]

Wow, two issues at once...that makes for some fun troubleshooting. Was the injector and boot issue on the same cylinder....or different ones? My code is specific to cylinder #3, so I'm assuming I'll find the problem related to the wire/plug/injector or coil pack port associated to #3.

Just waiting for my new 9mm FRPP wires and Motorcraft plugs to arrive from Summit so I can get to work on it.

Same cylinder. I just cleaned the injectors and replaced the o-rings. And got new wires


Sent from my iPhone using the svtperformance.com mobile app

 

[Race Red Boss]

Good news, swapped out the plugs ( motorcraft) and wires (FRPP 9 mm) and she's back running better than ever.

If any of you still have the original plugs and wires in your car and have over 60K on them, I highly recommend a refresh.

Thanks again to all for the input.

 

[IA-SteveB]

Glad you got it worked out. I had the exact same problem on mine at the same mileage and it was the spark plug wire.