[chris_mac]

G'day

I've noticed a strange thing happaning to rev while driving. tacho jumps up and down about 200-400 RPM usually jst after shifting to higher gear. I have no idea what can it be. fuel problem (pump or carby?), coil. it is not noticable for passanger, car doesn jerk, I can't really feel it through accelerator pedal, however I feel the RPM jump throgh gear stick. Anyone have any ideas, what that can be?

Thanks

Chris

[kenn]

Sliping clutch?

[chris_mac]

no clutch is ok, I changed it for the heavy duty one last year.

[royce]

I have heard a few people comment their tacho did this just before the ignition module died

[Rockhopper]

royce wrote:

I have heard a few people comment their tacho did this just before the ignition module died

This is a common occurence on quite a few makes and models of cars just before the module craps itself. The early magna's and Camira's were renown for it. It might go for a while longer yet, but it's better not to take the chance.

[joeblow]

i also had a customers car do this....turns out the 8mm bolt to lock the dizzy was loose.

[chris_mac]

thanks, what is that ignition module? Is it dizzy or something else? Is it expensive?

[chris_mac]

I forgot to mention that I have vitara 1.6 carby engine in my sierra, I guess that this dosn't matter in this case.

[Rockhopper]

I'm not 100% sure because I've never even had my distributor cap off yet, but I think the module on a Sierra or Vitara is located inside the distributor. On some other types cars they are bolted on the side of the dizzy, and some other models again are fitted away from the dizzy somewhere else in the engine bay eg 5 litre Holden VN-VS. They're not hard to replace, and even though it has probably just clapped out over time, when you replace the module, check out the rest of the ignition components are ok. Things such as high ignition lead resistance, can put an extra load on the module and cause it to fail prematurly.

[chris_mac]

thx for help. I checked all cabels around dizzy and coil and found one coming from dizzy to coil nearly broken. I soldered it and everything is ok.
cheers