idle question

jasonlee · 06-30-2006, 05:22 PM

Just replaced my cap, rotor, and plugs on my 82 SC yesterday, and now at idle it seems to lope or fluctuate. Not very much maybe 25 -50 rpm, but noticable. What's the problem...is my timing off because of the new rotor? How do I fix it? Any help would be appreciated.

Thanks,

2.7RACER · 07-01-2006, 04:47 AM

J,
A new rotor doesn't change your timing. Rotating the distributor in the slot will change timing. Did you remove the distributor?
Same heat range plugs? How about the plug gap?
You can always put the old rotor and cap back on for comparison.
Is it fully warmed up?
Is the idle rpm around 900? I wouldn't get too nervous about it.

jasonlee · 07-01-2006, 06:50 AM

Doug,
I didn't remove the distributor, only the cap Plugs are the same heat range Car only jumps at idle when fully warmed up. Maybe the gap on the plugs is off. Maybe I should pull th plugs and re-gap. Any thing else it could be?

Thanks,

2.7RACER · 07-01-2006, 03:55 PM

Jason,
I went back and looked at your SC. Nice ride. I like the Baby seat in the back.
Going back to your idle, I would tug on each plug connector to be sure they are fully seated. Should be a little click when it's fully on.
Recheck the fit of the cap on your distributor. There is a little notch it sits in when it's right.
Double check the wires into the cap and coil. Any question, pull and reconnect it.
At night, look into your engine compartment and look carefully for any sparking from your plug wires. This just isn't visible in daylight.
Stock ignition, plugs should be .028".
If nothing seems to work, I'd put the old distributor cap on and see if there is any difference.
Wouldn't hurt to look inside the new cap, looking for any carbon tracks.
I'd also pull the rotor and see if things are clean and freshly oiled.
Drop some oil on the little felt pad in the center of the rotor shaft.
Maybe even lift the felt pad and drop oil below it then replace the pad.
Then grasp the shaft and rotate it back and forth. It should move freely about 15 degrees.
Any rust or corrosion might mean removing the distributor and doing a thorough cleanup.
Not to worry, just make a note of where the distributor rotor is pointing, better yet, take a pic with your digital camera.
Put a timing light on number one and check for a stable spark, no jumping around. Then check for a smooth advance up to 5,000 rpm. This will give you a clue if the distributor is OK.
If you don't have a timing light, call your local auto parts, some loan out these things. They might even have a sale going for a decent one.
Bottom line, your ride must be reliable with a little one in back.
Hey fellow pelicans, Vancouver is gorgeous this time of year.
Good luck,

jasonlee · 07-01-2006, 06:28 PM

Thanks for the comments about my ride. I get lots of comments about the baby seat. Looks like I will be rechecking all connections and will re-gap my plugs. I will also double check the cap and rotor. I will let you know how it turns out.

Thanks,

jasonlee · 07-04-2006, 06:42 PM

update, well I pulled all my plugs and checked the gap. All to spec at 0.028, pulled all the plug an ignition wires and reinstalled. Checked rotor and cap. All is good. Idle is still hunting. Seems to surge all the time now. Interestingly enough, I checked the gap on my old plugs they were gapped at 0.034. They also looked good, no heavy carbon build up, pr burning, no oil. It ran fine before, I guess I should have left it alone. Any thoughts?

jasonlee · 07-05-2006, 06:09 AM

bump....any ideas what could be cause the problem. Please help.

Por_sha911 · Por_sha911's Garage

I always go back to "What was the last thing I did before problems arose?"
-Check to make sure you didn't disturb any other wires when you did your tune-up. Did you disconnect the O2 Sensor or maybe disturb the distributor green wire (look for worn area).
-Try putting the old plugs back in. It will only cost you some time while doing so, see if any of the new plugs are fouled). If that fixes the problem you may have a bad new plug or consider regapping the new plugs.

jasonlee · 07-05-2006, 07:55 PM

I will have to go back in and check it out. Problem arose when I decided to change out the rotor, cap and plugs. I guess in retrospect I should have followed if it isn't broken, don't fix it mantra. I will be doucble checking everything tomorrow morning. My original plugs we gaped to about 0.034, and I gapped my new ones to spec at 0.028. I have pulled the new plugs once already, and they looked fine. Maybe I should just stick the old stuff back in.

2.7RACER · 07-05-2006, 10:16 PM

Jason,
Did you look at the ignition with a timing light? Was it correct? 5 degrees BTDC. Thats to the right of the Z1 mark about 1/4". Was the mark stable? Not moving back and forth at idle?
As you accellerate the engine the mark should appear to move left indicating the ignition advance is working.

Don't do anything below until you have checked the timing with a light.

If the above is OK, ignition is not the problem.
Check for intake air leaks. Make sure all the little hoses are connected.
The O2 sensor can be affecting the idle. Find the O2 wires, follow them to the connector and disconnect the connector. Might be two connectors from the O2 sensor. Disconnect both. One is the signal the other is the heater voltage.
If the O2 sensor is the problem the idle should stabilize. But it could be the mixture and the O2 is trying to correct it.
Leave the O2 sensor disconnected to adjust the idle mixture.
A slightly rich mixture can cause the idle to hunt.
You'll need a long 3mm allen wrench, the T handle type are easiest to use. The mixture control screw is accessed through a small hole above the intake box between the fuel distributor and the rubber air duct.
The screw is located on the control arm for the fuel distributor. You can see it if you remove the air filter.
CAUTION, a little goes a long way here. CCW leans the mixture. Try turning 1/8th turn. Do the adjusting with the engine off. Remove the allen wrench from the screw before attempting to restart. Don't try to adjust with the engine running. Moving the arm causes the fuel distributor to change the fuel flow to the injectors. If a second 1/8th turn CCW does not do the job, this is not your problem. Return the screw to it's original position. Remember no big adjustments here.
If the idle smooths out, reconnect the O2 sensor. Both connectors.
If the problem comes back, the O2 sensor may be bad. You can run with the O2 sensor disconnected. You likely won't pass a smog test.
Beyond this advice we are getting into the bowels of the CIS system and there are others much better at this than I.
Have fun and Good luck,

jasonlee · 07-06-2006, 12:30 PM

thanks for all your help. Car is running like a top. Stopped by my mechanic this morning, just need to adjust the mixture, and fine tune a little. Combination of o2 sensor and the mixture. Thanks again for all your help. Once again I am a happy boy.

Thanks,