1. Home
  2. Automotive Technologies
  3. missing with fast idle?

missing with fast idle?

I cleaned the contacts on the distributor cap and rotor and now the engine is missing and won't come down off fast idle. Maybe I was a little too enthusiatic with the sand paper and widened the gap between the cap and rotor contacts which could explain the misses. But my Haynes troubleshooting guide doesn't say anything about fast idle being caused by faulty ignition. I can only imagine the computer may be holding the throttle open to compensate for the faulty ignition. The misses would leave unburned fuel in the cylinder(s). Does that sound logical?

Its a 14 year old car (clean low milage Ford Festiva). Parts are getting scarce. I have a 4 day wait for a new cap, lots of time to contemplate a diagnosis. I've lifted the air filtre and checked hoses and throttle linkages in case I inadvertently disturbed something. I had changed the PCV valve at the same time I "cleaned" the distributor contacts but I checked the valve and the hose connections, and even tried putting the old PCV valve back on with no improvement.

--

------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage:

formatting link
warning: non-freenet email must have "notspam" in subject or its returned

Reply to
William R. Watt
Loading thread data ...

You cannot get away with cleaning the newer distributor caps.

The old ones had brass posts, those could be cleaned. The new ones with the white metal posts just arc out all over the place after a clean.

Sandpaper also will leave junk behind, so no matter the type of cap it will miss. I used to use emery paper or a sharp blade to clean them back when they were cleanable.

I am not sure if the miss will turn on fast idle, could be or a vacuum line is loose under there somewhere.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

"William R. Watt" wrote:

Reply to
Mike Romain

thanks. some of my car repair books are pretty old. the contact on the rotor looks like brass.

Tried spraying. No change. Computers sure complicate things. It would be nice to have a flowchart for the computer program.

I do have a replacement rotor. Its just the cap I have to wait for. So I replaced the rotor. There was a change in the rythm of the missing and the idle speed came down somewhat. Hopeful that the new cap will get things running smoothy.

--

------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage:

formatting link
warning: non-freenet email must have "notspam" in subject or its returned

Reply to
William R. Watt

It was reported here that I should not have attempted to clean the aluminum contacts on the distributor cap. Today I replaced the cap and rotor with new ones and the engine has come down off fast idle. The engine is running almost as smoothly as it did before I attempted to clean the contacts on the cap and rotor, which was nice and smooth. I drove the car

20 km today to let the computer reset its parameters if it needed to. The engine is running a bit rough. I rechecked the ignition timing and idle speed today. I plugged a vacuum guage into the vacuum delay hose on the distributor to check the eninge and its mostly steady 21 Hg but drops to 20 Hg from time to time, and wavers back and forth 1 Hg at times. If I listen closely I can hear a slight variation in the engine idle speed. If I hold my hand at the exhaust pipe I can feel an ocassional collapse in exhaust pressure. Its intermittent, not steady. I'm not used to the engine acting this way. Does that sound like something which would case the car to fail an emissions test?

I've alread cleaned and gapped the plugs. They were in good shape. The car was running fine after that was done. The only other thing I know how to do myself is check the valve clearances. The manual says only do that if they are making "excessive" noise.

--

------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage:

formatting link
warning: non-freenet email must have "notspam" in subject or it's returned

Reply to
William R. Watt

If you have an emissions system charcoal canister, lots of them have an air filter on the bottom most folks forget to change. If dirty it can affect the idle.

So can an EGR valve that is starting to get sticky.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

"William R. Watt" wrote:

Reply to
Mike Romain

--

------------------------------------------------------------------------------ William R Watt National Capital FreeNet Ottawa's free community network homepage:

formatting link
warning: non-freenet email must have "notspam" in subject or it's returned

Reply to
William R. Watt

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.