I had this problem a few months ago and never figured it out, it just went away. Well, now it’s back. I have a factory gauge cluster with tach. What’s happening is my tachometer is lagging behind my engines actual RPM’s. The best way I can describe it is it seems like the needle has extra weight on it or is in a bind. Before, when I was going 70 mph, I would be reading about 3200-3500 RPM’s. Now, it’s about 2100. If I go WOT, it will finally jump and read almost all the way to redline, however, it hit the rev limiter at 7500 instead of around 8000-8200. I don’t know how to check the gauge itself or unit that sends the signal.
Where is the sending unit for the tach? Will this affect when vtec engages?
Any idea’s are welcome. Thanks

 

check for any lose ground wires in your eng bay..and ummm no it wont effect "VTEC"

 

dude check your distrib. Its probably the ignitor. Thats what mine was, but make sure you put the dist, back on right. Dont want to try to start your car and jump 2-3 notches on your timming. Late.

 

OK, I went out at lunch and cleaned all my ground conections under the hood. I took all the plug/connections apart and cleaned them. Same thing. Is there a way to test the Ignitor? Or what about testing the gauge itself?

 

the only way is to get one that works. It didnt work when you took apart the dist. and cleaned it.

 

This thing has been wracking my brain. Well, I took out the gauge cluster today and took the tach out also. I put some machine oil on the shaft holding the needle, put it all back together and it works now... Perfect. I don't know if it was from taking the connections apart and putting them back together that did it or the oil. Either way I'm glad.