Stock D16z6 in a 93 Si.
Changed the cap & rotor a few months ago along with the distributor o-ring to fix an oil leak.
It was doing the jumpy tach thing so I replaced the igniter which fixed the jumpy tach & seemed to make the engine a bit smoother.
Fast-forward about 1500 km & the tach is getting jumpy again.

Luckily the igniter has a year warranty on it so it's free to replace it but what would cause it to go bad so quickly? Is there something else I should replace so I don't destroy a third igniter?

Thanks in advance!

 

Bump.
Anybody?

 

it could be in the distributor itself

 

When you say jumpy do you mean the idle is hunting revving up and down say around 500 to 1500 rpm?

 

No, the tach needle jumps around when driving (up or down 1-2000 RPM & back in the blink of an eye). When it happens it doesn't seem to affect engine performance. Idle is fine.
It happens mostly when accelerating above 3k RPM though occasionally I'll see the tach needle twitch while cruising on the highway 2500 - 3000 RPM. As the problem gets worse over time the RPM that it happens at seems to get progressively lower.

The car is a manual & the clutch isn't slipping (besides the needle moves way to fast for that). I'd describe it more as a twitch than a jump actually.

It was doing it with the old igniter & getting progressively worse so I changed to a new igniter which cured the problem completely (which confirms to me that the igniter is at least partially to blame) and now a bit under 2000 km later it's back.

I've been through the posts here on this subject here & checked the few things mentioned (missing spring/contact to the coil in the distributor cap & missing plastic shield between the rotor & the guts of the distibutor) but neither is the case.
The white grease stuff was applied to the back of the new igniter between it & the metal piece it's mounted to (I assume some sort of thermal paste/heat-sink deal) and all wires are firmly attached.

I guess it could be a fluke & I just got a defective part but with my luck that's doubtful.

 

mine's been sorta doing the same thing....but it eats coils instead. i've gone though 3 and a different distributor. the weird thing is that i macguyvered a dx distributor on it when it left me on the side of the road and it's ran fine ever since.

 

Poor wiring causes components to wear out very quickly, I suggest you start with an examination of the wiring inside the distributor, and any other wiring that you have done along that same path.

Most common cause for a jumpy tach that I've seen is a loose BLK/YEL coil supply wire, causing the spark to go weak, and make the tach bounce around. Sometimes (but not always) a high load misfire accompanies this.