Would a distributor going bad cause the tach to read incorrectly?
The reason I think its the dist. is because when I checked the timing, at idle it was at 0 degrees,at wot it was at 0 but at half it was about 4 degrees btdc. That was with the wire diconnected on the passenger side. During driving, it runs fine but from a slow start, it starts knocking and having a blackish smoke come from the exhaust. The ecm threw the code for the ignition module but I have already replaced it after the code flashed. Also its throwin a code 13 every once in a while.

Any help would be appreciated

`91 rs tbi
bone stock

 

have u replaced your coil anytime?

the blackish smoke is a fuel issue with your valves... Probably a seal going bad, but nothing I would think causing your tach to read bad.. That could be a faulty connection, bad gauge, and like you said the distrib but I guess unlikely.

 

I was starting to look into replacing the coil. Would it be best to go with a OEM or aftermarket?

 

But wouldn`t the coil pickup the signal from the dist or how does that work. The distributor had rust underneath the rotor, that made me think that was it also.

 

well regardless, if there is rust present its for sure time for a new cap, wires, rotor install...i'm not sure how your coil is, but mine is on the cap of the distrib...OEM would be just fine, matter of fact some aftermartket are just junk and some can fire to much of a boom..oem ac delco..

i believe the module inside the distrib gathers the coil signal n the tach wire reads from that which remind me to tell you to go through the coil wires and look for any cuts/burns... Check your grounds, could be a simple power feed problem.

perhaps your circuit board is fried as well, yikes =[