Tech Area

High Idle on 2M4

Question: I have an intermittent high idle (2200rpm) on my 84 2M4 auto. It doesn't matter if it's hot or cold when it does it but it is intermittent. I can turn the engine off and restart and then sometimes it will go away. The engine light comes on but the computer doesn't set a code - just the normal 12 code. I have replaced everything on it 4 months ago - cap, rotor, plugs, wires, fuel filter, air filter, and coil. Is it the IAC?? EGR??? TPS???

Answer: 1st suspect would be a bad throttle cable. 84-86 L4's had a problem with it wearing through by rubbing against the decklid after it's factory valve cover clamp broke.

Next would be sticking linkage bellcranks (that the cable attaches to).

3rd would be a loose accelerator pedal. Neither of these would set a code, since the ECM would just think thats where the engine was throttled to. Don't think you need to "throw" parts at the car.

Disconnect the throttle cable in the engine compartment (a bear to do and you'll probably have a few "bruises") and feel for absolute smoothness of movement. Then check for unimpeded bellcrank movement. Make sure the pedal is firmly attached to the firewall. Let me know if none of the above cures your problem as there are a few other remote things that can cause this, but these are the most prevalent.

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