cannot accelerate up to highway speed
Thread Starter
arctic cat
Joined: Apr 2015
Posts: 3
Likes: 0
From: minneapolis mn
cannot accelerate up to highway speed
2005 F150 FX4 5.4 9100 miles.. When trying to accelerate up to freeway speed around 3500rpm motor starts pinging then CEL starts to flash and i start losing power and will not accelerate anymore until light stops flashing and then i can slowly accelerate up to speed. I hooked up my scan tool,showing misfire on #5&6.I started out by changing COPs on 5&6, cleared codes drove it still have same problem same code.So next i changed all 8 plugs(3 broke, lisle tool 65600 works great and is easy to use to remove broken plugs 
)but still no change and actually it seems to run worse.So next i decided to swap the two new COPs over to 1&2 &old ones from 1&2 to 5&6 to see if i got faulty COPs,cleared codes drove it still same problem,still showing misfire on 5&6
.Next i ohm the injectors all very close to equal,thinking maybe clogged injectors i swap 5&6 over to 1&2 to see if misfire follows but no still same problem still showing misfire on 5&6.BTW i have also changed fuel filter,fuel pump driver control module,cleaned MAF . Checked for vacuum leaks (because sometimes i get the lean bank 1 code but not always) i don't want to just start throwing parts at it.Thinking on taking it to dealer now, dont know what else to do 
former member
Joined: Jan 2014
Posts: 3,092
Likes: 857
2005 F150 FX4 5.4 9100 miles.. When trying to accelerate up to freeway speed around 3500rpm motor starts pinging then CEL starts to flash and i start losing power and will not accelerate anymore until light stops flashing and then i can slowly accelerate up to speed. I hooked up my scan tool,showing misfire on #5&6.I started out by changing COPs on 5&6, cleared codes drove it still have same problem same code.So next i changed all 8 plugs(3 broke, lisle tool 65600 works great and is easy to use to remove broken plugs )but still no change and actually it seems to run worse.So next i decided to swap the two new COPs over to 1&2 &old ones from 1&2 to 5&6 to see if i got faulty COPs,cleared codes drove it still same problem,still showing misfire on 5&6 .Next i ohm the injectors all very close to equal,thinking maybe clogged injectors i swap 5&6 over to 1&2 to see if misfire follows but no still same problem still showing misfire on 5&6.BTW i have also changed fuel filter,fuel pump driver control module,cleaned MAF . Checked for vacuum leaks (because sometimes i get the lean bank 1 code but not always) i don't want to just start throwing parts at it.Thinking on taking it to dealer now, dont know what else to do 
Vlad
Last edited by MGD; Apr 28, 2015 at 10:16 PM.
former member
Joined: Jan 2014
Posts: 3,092
Likes: 857
Good morning;
One can only wonder... low oil pressure, faulty follower/arm... The valve drops into the cylinder, and ... oye.
As Techrep suggests, there's not much that's cylinder-specific left to test -- COP/injector connectors,, harness, PCM drivers for the COP/injectors, compression tests, borescoping the cylinders....
Good luck, OP.
Regards;
Vladsky
One can only wonder... low oil pressure, faulty follower/arm... The valve drops into the cylinder, and ... oye.
As Techrep suggests, there's not much that's cylinder-specific left to test -- COP/injector connectors,, harness, PCM drivers for the COP/injectors, compression tests, borescoping the cylinders....
Good luck, OP.
Regards;
Vladsky
Thread Starter
arctic cat
Joined: Apr 2015
Posts: 3
Likes: 0
From: minneapolis mn
Brought the truck to dealer today,I was told my drivers side cat is cloged up.Makes since to me considering to problem has slowly been getting worse over the last few months,only cost $65.00 to find out.Now that I know I could have figured it out on my own with my scan tool by montering my o2 sensors,but I never even thought about it.$1300 estimate👄 I can get a walker cat for around $200 through Rock auto. I'm going to replace it and see what happens😎
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Thread Starter
arctic cat
Joined: Apr 2015
Posts: 3
Likes: 0
From: minneapolis mn
good news i took the cat off today and it sure was plugged up could not even blow compressed air through it.Started banging on it with a hammer **** started to fall out but not much,so i drove a long flat aluminum stake through it and broke through, it took a little while to break everything up using a screw driver through the 02 sensor hole to break up the big pieces so i could shake them out..got everything out of there re installed and now the truck runs great and no codes
i took the cat off today and it sure was plugged up could not even blow compressed air through it.Started banging on it with a hammer **** started to fall out but not much,so i drove a long flat aluminum stake through it and broke through, it took a little while to break everything up using a screw driver through the 02 sensor hole to break up the big pieces so i could shake them out..got everything out of there re installed and now the truck runs great and no codes
