Miss
Thread Starter
3rd Gear Member
Joined: Feb 2005
Posts: 515
From:
Miss
Alright boys i am in need of wisdom. I have a 96 cobra with a kenne bell supercharger on it. My number 6 cylinder has a miss to it. I have changed the plug, wires, Coil and fuel injector. It seemed to get better but is still there. I am growing fustrated and cant seem to figuare it out. I need help!!!!!!!!! Any advice would be appreciated.
Thanks
Paulstang
( Could the crank sensor do this by chance)
Thanks
Paulstang
( Could the crank sensor do this by chance)
2nd Gear Member
Joined: Oct 2006
Posts: 245
From: Baton Rouge La.
RE: Miss
It could be a number of things and I would need some more info like is there any noises coming form the cylinder.Was the old plug fouled out with fuel or oil. Is burning oil. Is the exhaust poping when you get on it.
1. I would run a compression test on the cylinder in question.
2. Run compression test on the remaining cylinders to see if there is a difference.
3. The reason why I say this is because of that monster (Kenne Bell) you have sitting on top of the motor. Sounds like you mave have"droped a cylinder or piston" (meaning bad rings)however any one likes to say it, but can`t be to sure without more info. Hope this helps
4. You could have floated a valve that would also foul out the plug and give it miss.
1. I would run a compression test on the cylinder in question.
2. Run compression test on the remaining cylinders to see if there is a difference.
3. The reason why I say this is because of that monster (Kenne Bell) you have sitting on top of the motor. Sounds like you mave have"droped a cylinder or piston" (meaning bad rings)however any one likes to say it, but can`t be to sure without more info. Hope this helps
4. You could have floated a valve that would also foul out the plug and give it miss.
Thread Starter
3rd Gear Member
Joined: Feb 2005
Posts: 515
From:
RE: Miss
I am not hearing any noise from the cylinder. It is only missing at low rpms like idle. I do have a hesitaion when i get a load on it like 3rd gear and give it gas. The injector i changed was really shot like everything on top of it was bad and torn up i changed that and it was alote better but i still have a miss.
3rd Gear Member
Joined: Jul 2006
Posts: 706
From: New Orleans, LA (westbank)
RE: Miss
Well if the fuel injector was tore up, make sure to check the injector harness and connector at that injector, it might not be firing the injector properly.
I've seen the injector connector overheat and melt inside, but you couldnt tell until you unplugged the connector from the injector and looked at the contact pins inside the connector, they were full of melted plastic.
I've seen the injector connector overheat and melt inside, but you couldnt tell until you unplugged the connector from the injector and looked at the contact pins inside the connector, they were full of melted plastic.
Thread Starter
3rd Gear Member
Joined: Feb 2005
Posts: 515
From:
RE: Miss
well i checked my compression and its at 90 pounds. My car isnt using any oil and runs better in higher rpms just at idel it misses . I was thinking that i may have a bad valve spring. What do you guys say rings or valve springs.
3rd Gear Member
Joined: Nov 2006
Posts: 516
From: Frederick, MD
RE: Miss
HEY!! i have the same problem with my 02 KB GT. i dont know too much about cars but when i got my car dynoed today and he said i have a miss. not sure what cylinder but same thing as u when u shift to third and get on it right away it doesnt go for a sec and then kicks in. so i will keep checkin this thread or if u find out PLEASE pm me some advice. thanks!
Thread Starter
3rd Gear Member
Joined: Feb 2005
Posts: 515
From:
RE: Miss
Ill let you know but i hope you dont have the same problem i do. I did a compression test and my #5 cylinder is at 130 psi while my #6 is at 90 psi. my plug on my 5 looks good maybe a little rich while the #6 looks like is a going a little lean i think i have tracked it down to a valve spring so this weekend i am taking the valve cover off and seeing which one is bad. Does anyone know any tricks to tell if its the ring or valve spring? im pretty shure its the valve spring but it would be nice to know.
Thanks
Paulstang
Thanks
Paulstang
2nd Gear Member
Joined: Oct 2006
Posts: 245
From: Baton Rouge La.
RE: Miss
1.Your going to have to disable the car from firing up.
2. Pull the valve cover.
3.Have a buddyturn the motor over and watch the valves. If it is the number six valves, you`ll noticed the difference in how they move. look for the rocker arm not togo up and down all the way like the rest of the rockers. Check to see if the rocker appears to be in a bind, this means you have a valve stuck open or closed and since you said the pluged looked lean it sounds like the intake valves or valve is stuck closed. If this is true you going to have to investigate in to what cause the Valve or valvesto get stuck in the first place, so your not rebuilding heads twice and a motor once!
4. If you can`t tell with your eyes you can also measure the travel distance of the springup and down with a small slide ruler just compare it to the rest of the valves on that head. Just use a known point on the bottom ofeach valve spring. You can calla ford dealership and talk to one of the mechs and they might be able to tell you what the travel distance is or get a Chiltons manual onyourCobra of that year( if the make one)and it will also tell and give you a step by step guide with pics on what to do.Also you can`t do this by using the ignition, you`ll have to get that same buddy to turn the crank by hand with a socketwrench at the crankshaft pulley.Hope this helps!
2. Pull the valve cover.
3.Have a buddyturn the motor over and watch the valves. If it is the number six valves, you`ll noticed the difference in how they move. look for the rocker arm not togo up and down all the way like the rest of the rockers. Check to see if the rocker appears to be in a bind, this means you have a valve stuck open or closed and since you said the pluged looked lean it sounds like the intake valves or valve is stuck closed. If this is true you going to have to investigate in to what cause the Valve or valvesto get stuck in the first place, so your not rebuilding heads twice and a motor once!
4. If you can`t tell with your eyes you can also measure the travel distance of the springup and down with a small slide ruler just compare it to the rest of the valves on that head. Just use a known point on the bottom ofeach valve spring. You can calla ford dealership and talk to one of the mechs and they might be able to tell you what the travel distance is or get a Chiltons manual onyourCobra of that year( if the make one)and it will also tell and give you a step by step guide with pics on what to do.Also you can`t do this by using the ignition, you`ll have to get that same buddy to turn the crank by hand with a socketwrench at the crankshaft pulley.Hope this helps!