i've been rebuilding my '97 gsr(from a wreck) and ran into a new problem. i've just about got everything back together and running well...until now. Here's the problem: When v-tec engages (around 57-5900, I'm assuming a little late, b/c it's stock and hasn't ever been tuned...150k miles) the tach needle jumps from 6 to 7000 and kind of bounces around. At the same time the needle jumps the check engine light, on the dash, start surging/flashing. The only reason the CEL is on is, b/c the o2 sensors are not installed. Important fact: the car still pulls hard throughout the entire powerband, so I'm assuming v-tec is still working. The car has been running well for a couple of months, since i put it back together. this just came out of the blue. Any thoughts? Thanks.....

 

I'd get the o2 sensor(s) installed soon. You're probably running very rich without them. As for the tach, did you try the general tune-up stuff? Plugs, Dist. Cap, Rotor, etc.?

If the car seems to run ok, it might just be a wire/ground issue with the tachometer. I'm not sure how to check it with a volt meter. Mabye somebody else could suggest that?

 

Yes, the car still runs well. i'm going to check the tach ground and other wires, b/c this problem didn't happen the last 2 days. thank you for your input.

 

Look up my post on my Tach jumping issue... It was a lose ground wire, could be your problem too!
Good luck...