Misfire Problem
 

Ok, I've had a misfire for quite some time. I changed the spark plugs and wires. I've used a multi meter on all of those components and I still am having a problem. I tracked it down to cylinder #5. I unpluged the spark plug wire and it doesn't misfire anymore. You can just tell that it is missing that cylinder. So what would be my next plan of attaqck to get the mis out?

I just did a compression test on #5. I got 153 in 3 strokes. So I think that is good. My plug doesn't read when I ohm meter it and my wire going to that cylinder is 7.31 k ohm's.

What are you referring to as a misfire? I always thought of a misfire
as the air/fuel mixture not igniting....which would feel the same as
a plug wire being removed. But, you say it feels different with
the wire removed.

It is like a ticking noise. Like it is detonating to soon or too late.

Are you sure it's not an exhaust leak at the cylinder. An exhaust leak will sound like a tick.

How would I check for that?

Is it possible that you have too much valve lash? That could account for the noise and would explain why the noise goes away when you remove the plug wire. If so, the adjustment for it is fairly easy, though messy. Might want to consider having a good mechanic do it if you have not done it before because you can over tighten the rocker arms and end up burning your valve seats.

It is possible. I adjusted them in the first place. With the motor running. What a mess, took forever to get the oil burnt off my header wrap.

:iagree:

So, should I readjust that valve?

Justin you should go back and readjust all of your valves the way 427 Hotrod told you to do it.Post #8 of the 888 posts !!!

The valve was fine. Definatly wasn't to tight. The rest of the valves are good too.

try rerouting the #5 & #7 ignition wires. These two cylinders are adjacent to each other (obviously) but are also the only two cylinders that are consecutive in the firing order ( 1-8-4-3-6-5-7-2), this is known to be a problem at times on many cars. The spark from one wire affects the spark on the next pulse in the next wire.

So, you want me to move them away from eachother? They are all wireloomed up and not touching. But just to be safe, I can put them away from eachother. If this doesn't work do you have any other ideas of what it could be. I'm fresh out.

in the wire loom seperatoes they are also next to each other. at the least move the away from each other by changing their locations in the seperators and best case is to try to reroute both wires in some fashion to avoid as much as possible the #5 & #7 being close to each other. I know there are limitations how far you can keep the wires seperated but do what you can

Ok, I'll reroute them. But It is late to fire it up. What else could cause this ticking noise?

the wire moving is for the missing issue. don't have an answer for you on the ticking noise

Well, I'm assuming the ticking is the mis. Because it only happens when the spark plug wire is connected to the #5.

take the rocker arms from that cylinder and reset on another clyinder ,see what you get ,if its still happens i would check the lift of the rockers it may be a long shot but it could be a ...cam .

If you want to get rid of the tick and removing #5 does that -just leave the wire off !!!!!:rofl: Sorry couldnt resist.Justin did you get the backfire problem fixed?-------- http://forums.corvetteforum.com/show....php?t=1410195