Rough Idle On 93 W/351

Capt Buck · May 15, 2004

Still having problems with a couple cylinders not firing all the time at idle, resulting in a miss. It idles Ok on startup then when it goes to normal idle, the missng starts. It all started after we did a full monty tuneup including fuel injector service, new plugs and wires, cleaned the TB,changed the fuel filter,etc. I installed a MSD TBF ciol and am waiting for a set of 8.5mm wires to try that. The truck runs like a bear under accelaration and at high speed. Any ideas? Also as a side note: I can buy a complete set of 24lb injectors for our Mustang for $225, but injectors for the 351 are $50.00 a piece, does this sound right?

Justshootme84 · May 15, 2004

Sometimes you need to disconnect the battery to reset the ECM or computer. Aside from that, did you clean/replace the IAC valve? And I don't know what the prices are on the injectors, but that does sound high at $50/each!

Capt Buck · May 15, 2004

Yes, I did an adaptive relearn by depowering after cleaning the IAC. It's not like the idle thing is really affecting the way the truck acts, but it's staring to bug us that it idles worse after the tuneup.

Raven · May 15, 2004

You change the cap and roter also? .. when you replaced the wires are you sure you put then in the right order almost soundslike you have acouple of them mixed up and going to the wrong spark plug. I would double check that.

Capt Buck · May 15, 2004

Yup, changed the cap and checked the wires about 657 times. My mechanic also had the truck for two days and did everything over just to make sure. The truck does run better overall and the fuel milage got better and it pulls our 20 ft boat like nothing now, just idles like crap.