Distributor cap is sparking...
 

I just changed my spark plugs, my plug on piston 1 was only screwing 1/2 way in so i just took it and got it re-tapped and put in correctly. my car was still running very rough (which was what i previously thought to be caused by the spark plug only sitting 1/2 way in). I had my hood opend and i heard a poping noise (kind of like ticking) then i looked at the distributor cap and there was a spark on the outside aching between two of the spark plug wire inputs...would this type of thing cause the car to run poorly? i checked and the cap didnt appear to be cracked at all so i dont know why it would be doing this. Anyone have an idea of whats making my car run rough (hesitation, bad idle..) and whats wrong with the distributor cap?

YES!

Now, it's either the cap itself or the plug wires are arching because the insulation is worn through near the boots... It's probably the cap though. Replace it. How old are the wires? You might want to replace them too.

Rod.

Wires are about 3 months old, they are looking to be in good shape, although the sparking wasnt on the rubber part of the wires it was actually on the distributor cap. Im about to take a run up to discount auto and pick up a cap and see how that goes.

::Edit:: Just changed the distributor cap and im still haveing a total lack of power and hesitation and all that crap still. Could it be the rotor is bad as well?

Yeah, It's your cap. From what I know, the dizzy cap is a particularly common source of grief on the Z31. Even the best cars have their little quirks.

Rod.

i just changed it though and its still giving me problems

::Edit:: this wouldn't be like an air/fuel ratio thing would it?

Is the cap still sparking or is the car just still not running right? If the cap is still arching then its not an air/fuel problem. I'm not saying you dont have an A/R problem, but that it wouldnt be related to the cap arching like that. If it's still arching and you just replaced the cap then go ahead and try swapping the wires. Even if they are only 3 months old, that doesn't mean they're not defective.

Cap is fine now. Just took it to a shop and had them look at it. He says im getting no compression in my second cylinder on the left side (if your looking at the engine from the front), i think its cylider 3 if remember correctly? he said that it may not have been working because of a fouled plug, i just changed that and still nothing. I called and asked how much the problem would cost to fix the compression problem and he gave a rough estimate of $800.....

Hmmm, Me = Skeptical. I'd get a second opinion.

AZ-ZBum or one of the other hardcore Z31 guys might have better insight here than I do, or have an idea what the problem may be.

Rod.

I checked my wires (the one going to the "compression issue cylinder" the wire was pulled back inside the insulater so i pushed it forward again so that it would have a good connection, started up the car, it ran a bit better than before but still having issues. I can smell fuel on my exhaust fairly prominately. I went to run the ECU codes but i couldn't find the "Test selector screw" so i wasn't able to run the codes.

You don't say what brand you got to replace them or what brand you are using.

For the cap and rotor, get Nissan parts only.
For the plug wires, get NGK or Nissan only. (or magnacore if you feel like spending the $$$)
For plugs, get regular NGK's only.

Hmm... You retapped what? The cylinder hole? Uhh... Did you helicoil it first? Did you clean out the cylinder before putting in a new plug?

plugs are all NGK's, cap is standard from Discount, wires are same thing.

Retapped the Cylinder hole, umm, i didnt do it i took it to get done. Whats Helicoil?

Would you suggest running a pressure check?

The only thing that will cause sparking is substandard wires or cap or rotor.

Replace them with the parts I mentioned.

the sparking problem is gone now after i replaced my Dis. cap. but my car still runs really rough and i can smell gasoline on my exhaust exessivly

Compare the installed height of the spark plug in the rethreaded hole to the other sparkplugs and make sure its about the same. If the spark plug isn't reaching far enough into the cylinder then you could be getting incomplete combustion which would not only cause a fuel smell through the exhaust but it would also mean that cylinder is not producing full power (or any power) which would cause a rough running underpowered situation.