4.0 Doing crazy weird things
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Freshman User
Joined: Aug 2004
Posts: 26
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4.0 Doing crazy weird things
I just recently replaced the IAC Valve on my 94 ranger cause the idle was surching high at start up, i haven't noticed any problems since i just put it on yesterday, i figured it was about time to replace it when my idle was still staying at 2,000 rpm at a stop light. Im not too sure if its misfiring or what is going on but i will have a steady 600 idle and it will drop sometimes then when i have it in park i rev it up to about 1000 rpms and it shakes and vibrates but when i go above the 1,000 rpms it seems fine and i drop it down again and it has a rough idle down i guess you could say. My dad and i looked at it and the wire for the cylinder 1 was pulsating and we replaced the wire and it was still doing it but i pushed the wire down real good on the plug and it wasn't pulsating much anymore. Im just stumped should i go buy all new plugs and wires or could it be something else. Also another question is if the IAC valve wasn't the problem what else could it be, i was thinking the TPS but would that throw a code if it went bad?
Post Fiend
Joined: Feb 2003
Posts: 6,940
Likes: 2
From: Eastern WA
Is there a CEL? If so codes on your EEC-IV system are easy to pull. Details on how to do this (three ways and two do NOT require use of a scanner) are in the Ranger forum. A bad plug wire (internal degredation/failure) will initially result in a miss on a cold engine that goes away as the engine warms up. As the wire burns further internally, the miss continues when the engine is warm. You can check for a bad plug wire with an ohm meter. Of course, you can also pop the hood when dark and look at the wires for any arching, but given the heavy insulation used for over a decade now, any arching will be due to a cut or burnt wire. This assumes that the connections at the coil and plugs are in good condition. BTW, you shouldn't have to struggle to install a plug wire. Do make sure that a small amount of dielectric grease is applied inside the boot prior to installation as this keeps moisture out and eases removal in the future. Buy no sensors on a whim; prove they are bad before purchase.
Posting Guru
Joined: May 2002
Posts: 1,574
Likes: 1
From: Phoenix
Since you can manipulate the issue by pushing on the plug wire (and not getting shocked) I would concentrate on that area. 1) is the plug in good shape? 2) is the wire connector tight on the end of the plug? Use a pair of pliers to squeze a round crimp around the metal conector. Sometimes, even a new wire will not crimp around the plug tight enough.
Also - what plugs do you have? Some have screw on tips and if you lost one, the wire will never connect properly to the plug unless you push on it physically.
Also - what plugs do you have? Some have screw on tips and if you lost one, the wire will never connect properly to the plug unless you push on it physically.
