Misfire code found the problem

[tjl006]

Well after my secound dyno run I had been getting random misfire codes. So I replaced the plugs, got deal on coils(thanks musclmerc) replaced them. Code was still coming up, I also found the car hard to start after it was warmed up. So today i did a compresion test cylinder #8 80 psi, #7 190psi,#6 190psi,#5 190psi,#4 220psi,#3 210psi,#2 210psi and #1 210psi. Added some oil to the number eight cylinder no change in the compression, suspect its a valve issue what do you guys think? what should be my next course of action?

[bawazir]

how many miles on the car?

[Zack]

Very sorry to hear. Sounds like a valve issue indeed.

If I had any cash to my name Id buy the car in the state its in.

[ImpalaSlayer]

sorry to hear that Tom. if you decide you want to rebuild, i have a cobra short block and a pair of heads here.

[musclemerc]

Valves are the likely culprit. Sorry to hear this about your MM. Build it stronger!

[LeoVampire]

With our engine's it is difficult due to how deep the spark plugs go into it.

Get an old spark plug and snap off the porcelin and then hallow out the electrode so you can see through the treaded end of it.

Take an air hose fitting and weld it to a long hallow tube and then weld the other end of the tube to the left over spark plug hallow end.

Screw it into the spark plug hole and then attach an air hose up to it and put pressure to it.

With a ratchet and socket on the Crank turn the engine to open and close the valves until you find out what set of them are leaking in that cylender.

If it is the rings you will feel air comming out the dip stick tube btw.

[FordNut]

With our engine's it is difficult due to how deep the spark plugs go into it.

Get an old spark plug and snap off the porcelin and then hallow out the electrode so you can see through the treaded end of it.

Take an air hose fitting and weld it to a long hallow tube and then weld the other end of the tube to the left over spark plug hallow end.

Screw it into the spark plug hole and then attach an air hose up to it and put pressure to it.

With a ratchet and socket on the Crank turn the engine to open and close the valves until you find out what set of them are leaking in that cylender.

If it is the rings you will feel air comming out the dip stick tube btw.

There is no need to rig up some jake-legged contraption to do a leakdown test. Any shop worth their salt should have everything it takes to connect compressed air to the spark plug hole and do a leakdown test to determine if it's intake valves, exhaust valves, or rings. Or even head gaskets, but I don't think that's the issue here.

[LeoVampire]

There is no need to rig up some jake-legged contraption to do a leakdown test. Any shop worth their salt should have everything it takes to connect compressed air to the spark plug hole and do a leakdown test to determine if it's intake valves, exhaust valves, or rings. Or even head gaskets, but I don't think that's the issue here.

Plus it allows him to confirm what a shop may tell him and make sure he is not being railroaded.

[tjl006]

The compression tester I have allows you to hook an aircompressor to it to pressurize the cylinder. I did it and couldnt hear any leeks. But I didnt turn the crank over either. Also should I be worried that one side averaged 190psi and the other 210psi?

[FordNut]

Not really, but the one dead hole is a problem. Connect a valve to your compression tester, pressurize the cylinder and close the valve. Use a stopwatch to time the pressure drop and listen for the air to flow out the exhaust or intake. You may need a mechanic's stethoscope to hear the air flow.

[Black_Out]

Mechanics stethoscope - $2.99 at harbor freight :D

[bawazir]

sorry to hear that Tom. if you decide you want to rebuild, i have a cobra short block and a pair of heads here.

what happened why are you selling it? i thought your going to swap that in your MM?

[CanadaMarauder]

Same codes and problem on my Aviator..Burnt Valve on #8 and started pitting #7.. Sad down fall of the 32v

[LeoVampire]

Same codes and problem on my Aviator..Burnt Valve on #8 and started pitting #7.. Sad down fall of the 32v

Does the Aviator have the same coolant flow problem our engine's do?

The mustang has okay coolant flow through the passenger head but not on the drivers side head is that the same situation on the Aviator seeing those 2 cyl are on the same side?

[Dennis Reinhart]

Well after my secound dyno run I had been getting random misfire codes. So I replaced the plugs, got deal on coils(thanks musclmerc) replaced them. Code was still coming up, I also found the car hard to start after it was warmed up. So today i did a compresion test cylinder #8 80 psi, #7 190psi,#6 190psi,#5 190psi,#4 220psi,#3 210psi,#2 210psi and #1 210psi. Added some oil to the number eight cylinder no change in the compression, suspect its a valve issue what do you guys think? what should be my next course of action?


If it is a 03A it is the head, so depending on the miles you may just want to consider a reman 03 Cobra motor, if you plan on adding a S/C since the Cobra is 9 to 1 if not stay at 10 to 1. I feel you are in the 4 to 6 k range with install, or you can try and find a clean used Marauder or Mach 1 motor for half that.

[Kennyrauder]

I guess we all have issues. Some owners seem to get hi miles especially ones in the 125 K mile range or more. I hope my 46 k mile Marauder goes for a long time. Question... for everyone... instead of doing the 4.6 again, why not do a Fomoco 460 crate or at least a 351 crate? What are your thoughts? How would I have to change my ECM & all the other Stuff? I hope this is a good conversation point. As always , ... GLAD to be a part here. Best Regards Kenny.