Hi, my car has aslight mis and idle and if I bring it up to 2,500 rpm the car runs rough, I don't notice it when I am driving though.

Do spark plugs go bad with age? I have had them in there ( rapid fire) for 5 years, I have only put 2,000 miles on them though. cap rotor and wires have a little less. Thanks

 

Plugs or wires would be my first guess.

 

Plugs or wires would be my first guess.

 

in my experiance, plugs fail with mileage, and wires with age

 

Should I put any die electric grease on any of the contact points on the dist cap or rotor? I was told to do this. Is there anything I can use to clean them up inside? the cap is accel and the rotor is a msd. The gas always get stabile and I try to run a tank or 2 though it a year and I always store the car with a full tank.

 

With the car running, unplug a plug wire from the cap. If the engine idle changes then plug it back up. keep doing that till you find the wire where the idle doesn't change. then you have found the bad plug or wire. USE GLOVES if not, that **** hurts.

 

89 IROCZ is right on how to check for the misfire. Does your car come with an idle air controller (I appologize on my lack of carb knowledge)? If so you will need to disconnect it or it will compensate and increase air flow to bring the RPM back up to normal.

 

This test determines which cylinder is misfiring. A single cylinder repeating misfire can be caused by ignition sources such as a bad plug or wire, or from other sources such as a bad injector, loss of compression, or any other malfunction that is related only to one cylinder.

 

What is the spark plug/spark plug wire tester called? and where can I find it? thanks

 

Use a digital volt meter, check the resistence of each plug wire, I believe it's got to be lower than 50 ohms per foot.
Also, look under the hood in a dark place and see if you see any crossfiring or firing to ground, indicating a bad plug wire.
Spark testers, plug onto the spark plug and into the plug wire. You can then see if the spark is there, weak=orange, or good=bright blue.

 

And what does the spark plug tester tell you? if it is orange? bad wire? bad plug? thanks

 

Unless you're running MSD 8.5 or the new Moroso wires(MSD are 50/ft and Morosos are 40/ft you're looking between 300 to 1000 ohms/ft on good wires.Wires do go bad with age and AC plugs do have a tendency to go bad(the resistors in them fail with age but they have improved).You can use dielectric grease on the plug wire boots(both ends)keeps the boots from sticking to the plug insulator while providing a moisture barrier - same for the cap end of the wire.You can use the grease around the base of the cap where in mates with the dist body for the same reason.It's not as critical with electronic dist as it was with point dist.Have you changed the fuel filter lately?Could have trash in it.QJets have a bad habit of gumming(varnish)in the float bowl when they sit.When was the last time you cleaned your air filter?

 

The air filter is clean, the fuel filter is fairly new, it seems as if it is not as bad after changeing the module and re greasein the plug wires and clean the cap and rotor. I also wiped the spark plugs, I may try a new set of plugs and then a new set of wires at some point, everything has such a small amount of miles on them.

 

When you changed the ignition module did you clean it's mounting point in the dist and use the supplied grease(or as someone else posted you can get it from Radio Shack - it's different type of grease from dielectric if I remember right)?If you didn't apply this the module will overheat and begin to break down or fail completly.Plugs are such an easy inexpensive check if it wasn't for the PIA to change them in any F-Body(and my 4WD Jimmy is not much better).

 

If the miss is there at most any rpm, it's probably ignition, just at lower rpms then vac leak. High rpm only, suspect lean miss, bad fuel pump, filter or dirty injectors.