M20 Misfire (Please help....)

[Finn]

So I did a cylinder leak down test of the one cylinder which is suspect. The result was that it leaks pretty bad. This leads me to believe that I have a burnt valve which doesn't seal completely. I could take the head off and inspect it, but I think its time to take the car off the road and prepare for an engine swap. I don't have enougth time to deal with it now so I have to go back to my old rusty trusty Saab. :(

[Infamouscrew02]

Wow, im having the same issue. If i dont floor it i can rev very well all the way to 6500 rpms. But if i put the pedal to the floor then right at about 5000 rpms it misses like crazy. Really uncool.

Ive checked almost everything you guys have checked and still am having the problem. I'm going to try and tighten my exhaust bolts, valve cover bolts, and oil pan bolts. Maybe somewhere in there its creating a vacuum leak. Also am going to try and run my car with the o2 sensor unplugged to see if that helps at all.

[structured]

I posted previously that I was experiencing the same type of misfire. I just fixed it.

See here: http://www.r3vlimited.com/board/showthread.php?t=147102

[beemerhog]

try driving with diagnostic cap off for a few minutes see if that helps.

[iamsam]

try driving with diagnostic cap off for a few minutes see if that helps.

what would that do? doesn't the diagnostic cap have jumpers in it that jump several pins?

[quikveedb2]

I posted previously that I was experiencing the same type of misfire. I just fixed it.

See here: http://www.r3vlimited.com/board/showthread.php?t=147102

dude! hero status! i'm heading home in a bit to check my vibration dampener for play but what we've all been describing for the past few weeks seems so similar, and the timelines of the deterioration of the motors function so close i can't imagine that there is any other factor that could be causing the exact same problem for so many cars. if this works for me this'll be one of the most epic fixes i've ever been a part of.

[iamsam]

dude! hero status! i'm heading home in a bit to check my vibration dampener for play but what we've all been describing for the past few weeks seems so similar, and the timelines of the deterioration of the motors function so close i can't imagine that there is any other factor that could be causing the exact same problem for so many cars. if this works for me this'll be one of the most epic fixes i've ever been a part of.

please let us know if it works for you too.

[quikveedb2]

will do!

[Quailane]

Ok, so I got home from the beach last night and went to work on my car today. Guess what? The toothed part of my harmonic balancer can be moved around! Too bad I spent so much time on the car already. At least it has its valves adjusted and a new distributor. I'll try to JB weld mine back together.

[Infamouscrew02]

So here is my issue that ive been dealing with:

Floor the gas pedal and my result is this:

http://www.youtube.com/watch?v=mXRrftIKm0Q

Press the gas pedal and keep it from the floor and I get this:

http://www.youtube.com/watch?v=O6Fhvmyauqg

Also what is this button thing under the gas pedal? It actually compresses in.


It's driving me insane when it misses.

[structured]

Ok, so I got home from the beach last night and went to work on my car today. Guess what? The toothed part of my harmonic balancer can be moved around! Too bad I spent so much time on the car already. At least it has its valves adjusted and a new distributor. I'll try to JB weld mine back together.

FYI, I got my used balancer for $50 shipped from a board member. You could probably find a similar deal. The part is like $400 new...

[Sirotto]

Add another ground from teh valve cover to the common ground on the shock tower. Have you metered teh AFM. Make sure the values are smooth with the opening of teh barn doorin the AFM. The ground under the engine on the drivers side can also be the issue. Just taking it off or looking at it will not fix any problems. Remove the groundning strap completely from the car and take a wire brush to it. Keep brushing untill it it clean. Then take alcohol and clean it again. Now take teh wire brush and clean both contact points including the bolt that connects them. After you are all done with that move to the trunk. Remove battery and repeat cleaning to the negative cable. Starp and locations, add the valve cover ground and try that. If that still doesnt work you can do the pinout test according tho the bentley manual.

[SpecM]

Add another ground from teh valve cover to the common ground on the shock tower.

why?

[Quailane]

So, how is the vibration dampener supposed to align to the crankshaft? I know the location of the missing teeth is vital, but where does it go in relation to top dead center?

[structured]

There should be a pin on the crankshaft flange and a hole in the hub of the damper. This forces you to put it on the correct way. If you can't see that pin, something is wrong.

EDIT: Just realized that you are the one who wants to jb weld it together. If you look at the pictures in my other thread, you should be able to approximate how the two pieces align. I would assume that this needs to be pretty exact though. If not, your car will "think" that the timing is off.

EDIT AGAIN: You can't see the location of the missing teeth in the other thread. I'll see if I have a better picture.