I just did an mpfi swap on my 89 civic cx.

I noticed that after about 4000+rpm the tach starts to get real bouncy. As in the tach starts to wander around after 4000 rpm.

I changed the gauge cluster and still the same problem.

Any suggestions?

 

check ur dizzy. my buddies hatch woulkd pull great until he got in upper rpms. 4000+ then it would like missfire kinda and u could see the tach kinda bounce everything is did that. he open up his dizzy cleaned it out and it turned out he ignitor connections were loose. so he tighted all the stuff in the dizzy down the clips on the ignitor n such and got a new rotor n Cap and his car was running great spent 25 bucks instead of 150+ for a new dizzy..

 

Yeah, mine did that too. Come to find out the rpm signal wire in the dizzy was not connected to the terminal. It was just sitting next to it. Reconnected it, and all was well.