warrenoliver

Went on a short trip this weekend and started having pretty severe hesitation on long uphill grades while in overdrive. The Check Engine light came on several times. I was able to avoid the problem by shifting out of overdrive and getting the RPM's above 2K. My OBD reader said I have a "Cylinder 7 Misfire". How do I diagnose this properly? I don't want to just replace the COP and the plug. BTW, the plugs and the COPS were changed by a shop prior to my purchase of the the truck. It currently has about 128K miles on it.
I do not know if the COPS and plugs are Motorcraft but I will check tomorrow when I get a chance. Is there a way to test the COP? I plan to examine the plug and add some dielectric grease to the contact. Short of throwing parts at it, is there a way to narrow down the problem?

Thanks

joe mcmillan

Switch COP #7 with another to see if misfire continues and whether code follows the position switch.
Also take a look at FPDM above the spare tire. If it is corroded or cracked, replace ASAP.

warrenoliver

I swapped the #6 COP and boot with the #7 and took it for a long drive along the same route that caused me trouble previously. It ran great! Used the OBD reader for the whole route and caught a total of 12 misfires total - only 1 for cylinder 6 and none for cylinder 7 the rest seemed randomly distributed among the other cylinders. I am not sure what this tells me.
When I removed the COPS and boots, they seemed to be in very good condition. I did put some dielectric grease on the distal end of the boot when reinstalling.

techrep

iTrader: (1)

So... what brand COP was it ?

warrenoliver

Crap! I never thought to look at who made the darn thing. I am 99.9% sure they are not MotorCraft since they and the plugs were replaced at my request by the used car dealer when I bought the truck 8 months ago.

warrenoliver

Just pulled a COP and could find no identifying marks so I don't know which ones I have. As I said before, I doubt they are Motorcraft since they were changed by the used car dealer prior to purchase. I see they put in Autolite plugs so I am sure they went the cheapest route. Where can I find the best deal for Motorcraft COPS? I have already purchased SP515 plugs.

Thanks

Aeromech

Let me ask you a question. You say you went for a drive with your OBD reader hooked up and counted several misfires. Were these misfires you felt and set the dash light or does your reader give you real time info? The reason I ask is that my 2006 F150 bucks sometimes under load in OD with RPM low but the check engine light never comes on and it doesn't set a code. That makes finding the problem difficult. Please share what tool you are using because I'd like to have one and my birthday is coming up. Thanks

warrenoliver

Aeromech,
I do not feel the misfires when it shows me I occasionally have a single one, I can see the OBD reader has captured a misfire. When I have had significant misfires that cause the bucking, the Check Engine light does not come on immediately. If it keeps misfiring, then the light begins to blink but it disappears after a few minutes. If you hook up an OBD reader, it will tell you that you had a misfire and you can then tell which cylinder it was.
The OBD reader I bought was a cheapo OBD reader from Amazon. Once I had it, I downloaded the TorquePro app for my Android phone ($5.00), connected via bluetooth and was able to monitor real time info.
Hope that helps.

techrep

iTrader: (1)

Get the Autolite plugs out of that motor...and buy some decent COP's

Aeromech

Thanks Warren,
I have about a $100 OBD2 reader from Autozone that I use for reading and clearing codes but I'm unsure if I drive and leave it plugged in that it will somehow display misfires unless a code is set.

I also have a bluetooth reader that I can plug in and drive with using my iPhone to monitor things like RPM and other parameters. It will read codes and clear them as well but as far as seeing misfires as they happen I don't know that it works that way. I use two APPS for this, DashCmd and EngineLink.

I'd love to be able to see misfires as they happen