My tach gauge has been a bit screwy lately. Seems that when the gas is on the tach will sometimes become sporadic and jump up and down, but the engine doesn't rev any higher, only the tach goes crazy, so I'm guessing it's just some type of sensor (correct me if i'm wrong). If it is a sensor though, what is it called and where on the car is it located?

 

Are all your plugs firing?

 

As far as I can tell yes, I don't hear the car stutter when the needle freaks, so i'm guessing they are. I don't have a continuity light at the moment, but i'll pick one up tomorrow to be able to test for sure.

 

Just used a spark plug gap tester, and tested that all the spark plugs are creating spark. What's the next step?

 

Are they getting spark under load while you're having problems though?

 

I was wondering the same thing, problem being I can't quite get it to happen (sometimes for only a split second) while it's in park, only in drive. Is there any test for that?

 

So after doing some investigation (and getting some help from the guys over in Electronics). I found that even if I hook an external tach to my car, it even acts up, so it's no just the tach that's in the dash. It would be near impossible to hook up a spark plug gap tester while driving and see if every plug is firing at an uncertain interval (and i've pulled every plug, they didn't any reason to not fire, not even 1000 miles on them anyway). Is there an easier way to test this? or test something else that may also be the problem?