Misfiring problem at cruising speed
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Joined: Apr 2007
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Misfiring problem at cruising speed
Hey, guys! Heres the deal. I have a 87' with a heavy 406 with all the goodies. The problem I'm having is a slight skip at crusing speed. I'm very intuned with my car and I can tell when its not counting off on eight. I have recently just changed the gear ratio from a 3:75 to a 4:11gear. With the change, my cruising rpm has raised a little, but to me it enhanced bad qualities of a misfire when listening to your exhaust at 2400 rpms. I've just installed new msd wires and plugs, but the skipping is still there and the gas milage has really gone south. I was wondering would the auto x-ray scanner be at all helpful in locating this misfire or any other tools that you may know of.
Thanks
purplehayes
Thanks
purplehayes
Safety Car
Joined: Jan 2006
Posts: 3,566
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From: Mt Laurel NJ
St. Jude Donor '06-'07
Hey, guys! Heres the deal. I have a 87' with a heavy 406 with all the goodies. The problem I'm having is a slight skip at crusing speed. I'm very intuned with my car and I can tell when its not counting off on eight. I have recently just changed the gear ratio from a 3:75 to a 4:11gear. With the change, my cruising rpm has raised a little, but to me it enhanced bad qualities of a misfire when listening to your exhaust at 2400 rpms. I've just installed new msd wires and plugs, but the skipping is still there and the gas milage has really gone south. I was wondering would the auto x-ray scanner be at all helpful in locating this misfire or any other tools that you may know of.
Thanks
purplehayes
Thanks
purplehayes
Let us know what happens.
Randy
Last edited by RandyJ75; Apr 27, 2008 at 10:07 PM.
Team Owner
Joined: Mar 2001
Posts: 54,124
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From: Cincinnati, Oh USA
Initial advance may be set too far advanced. Also, at night, with the hood lights off, look for sparks along each plug wire and then check each plug wire with an ohmeter. Look at the condition of your plug wire looms, replace any that are broken or missing. These looms keep the plug wires from touching metal. All ignition wires have microscopic pinholes in them and if touching grounded metal will spark through these pinholes.
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When checking the injectors with the ohm meter, what should the voltage read. The wires are but the enginge comartment is tight, some of the wire are laying on metal items. When checking the wire for cross fire, I use a bottle of water to spray the wires to help me locate jumping sparks . This has always worked in the past. I have not check the dist. cap and rotor yet, they could be suspect as well.
