Low idle speed...almost stalls

[Vito117]

Ok.....1993 ATX
136,000miles
I've tried resetting the idle speed.....someines it seems to idle perfect.....but
I notice that my idle speed is around 500rpms at times and the car will stall at times.
I ran the code (217)and it did say ignition coil 3 is bad. Do bad plug wires and bad coil cause stalls?
I know the plug wires and coil are original. Do I go ahead and change these and see a big differnence in performance?

 

[CharlieR]

Sounds somewhat like my problem see message below KOEO '93ATX code 551. You mentioned changing the idle speed. How did you do that? It was my understanding that idle speed was not adjustable and determined by the PCM (power control module) via its control of the IAC (idle air control)solenoid. I don't think changing the stop position on the throtle changes the idle. Any one else? Is idle speed (or cold idle speed) adjustable on the SHO?

 

[Vito117]

No I did the reset procedure as outlined in the SHO times.
You know....turn ignition over....turn off....turn on lights....let ist....blah blah blah....

 

[Mr Anonymous]

CharlieR, search the forum for 'idle speed reset', which allows you to force the PCM to re-learn its idle setting.

Vito, yes, a bad coil pack will definitely cause low RPM idle and stall conditions since two cylinders are not going to be firing with sufficient spark, if any at all. Bad plugs and wires could also contribute to the condition, but since you got a code for the coil pack, you can probably assume that it is responsible for the problem. AutoZone should be able to test the coil pack for free.

If they indeed verify your coil pack is defective, they sell the Wells version replacment for about $80 IIRC. If a new coil pack solves the problem, that doesn't get you off the hook for old plugs and wires -- at least install new plugs (Motorcraft AGSP32PP are the correct plugs for the SHO, don't waste your money on Bosch, Autolite, Splitfire, or any other brand plugs. The AGSP32PP plugs can be had from FordPartsNetwork.com for about $32 shipped, O'Reilly's carries them for about the same price if there is one near you (they're about $54 for a set from Ford). You should also eventually replace the wires (again with Motorcraft WR-4033 (MTX wires WILL fit your ATX) from FPN for $99), but if you're on a budget you can probably wait a little while longer.