Just wondering if I can track down a short by pulling 1 spark plug wire at a time while it is running,its a 92 SSEi that I'm looking at,which has a miss to it at idle and under load,the guy told me it was the plugs and wires that were bad so I want to try this procedure.I'm new to the board and have been doing some searching on the subject but I didn't find what I was looking for.It also has a exhaust manifold leak....any help would be appreciated...Thanks

Sometimes all you've got to do is wait until dark, start her up, and open the hood. Follow each plug wire with your eyes and look for arcs.

If you don't see any visible arcs, another method is to wrap some bare copper wire around a screwdriver (the big kind with square shafts work best, since the wire won't slip off as easily) and then wrap the other end of the wire around a (clean) ground point. Your screwdriver will then be a better ground than whatever the wire'* arcing to, and if you trace the wires (gently!) with the tip of the screwdriver, you might be able to draw an arc from a bad spot in the wire to the screwdriver.

One safety note about your suggestion, though -- you say you have an exhaust manifold leak. Keep in mind that if you start pulling plug wires while the car is on, the fuel in that cylinder obviously won't get burned, and unburned fuel vapor may begin to build up in the engine compartment through that manifold leak. Combine that with an arcing plug wire (or the one you disconnect) and you may create an explosion hazard. :?

-b

Good point,never thought of that,I'll give your suggestion a try though,see what I come up with.Great forum,lots of info!!Thanks

use the techinfo procedure for checking to see if you have any codes. if not, do the plugs and wires. The O2 sensor would come next, followed with an airfilter.

A general rule of thumb:

If you don't know how old your plugs and wires are, change them. Factory wires are only good for about 50k miles. Are yours gray, and numbered for the cylinders? If so, change them.

And the advice above follows. Full tuneup. O2 sensor, PCV, fuel filter, air filter, and check/change that SC oil!

thanx will, i new i was forgetting to tell him something.

My technique for testing wires is to spray them with water. If it runs fine while it is wet, then they are fine. But again it they are still numbered (original) change them and the plugs (for the cost).

Thanks again,I might buy this particular car so I'm not sure how long the plugs and wires have been in,they look kinda old,spraying them with water won't work in this situation because it already has the miss,idiling and in driving range.I'm gonna take a good look at it tomorrow.The car has been off the road since about 2 years.

Just pulling each plug and looking at them is probably the easiest and the best diagnostic tool you can have....especially it you could take digital pictures of them and post them for this site...

If you are really concerned about buying this car, do a combustion test. As long as each cyclinder is within 15 percent of each other, then it is fine mechanically (without crankshaft knock that is).

I had a former GM service manager tell me that whenever they had a 3800 come in with a misfire, they automatically changed the plugs, wires, coils, and added some fuel system cleaner... Then they charged about $400 for it...