I have a 99 si..... B18C1 bottom end with a B16A2 head...... Boosted........
Car started running strange above 4000 rpm....Crapping out like your hitting rev limiter.

Put in a dizzy out of a GSR and it ran great... But the tach after 4000 rpm would wig out and fall to 0

Bought a brand new dizzy for a A2 head and the car runs perfect but the tach dont work now..... When you first start the car the needle moves once and thats it. I tried another cluster and it didnt change a thing.

Its got a OBD1 P-72 with a jumper. Running Hondata s300.... When we hook the laptop up to the ecu and run the car, its showing the rpm perfectly. Over 4000 also.

So I cant figure out why the tach isnt working.

Am I loseing it from the ecu to the tach?????

Please help if you can cuz its driving me nuts.............

 

Check ur VSS it may be bad.

 

Check the blue tach wire at the rear of the cluster. Alternatively, the cluster tach is bad.

(VSS is for mph not rpm)

 

I tried another tach and it didnt change

 

Could be a bad tach wire (blue) between the distributor and cluster.

 

Correct.

 

Do u have the CPK sensor hooked up?

 

The CKP sensor must be hooked up, otherwise the engine would not run. However, you reminded me that the tach signal for 99-00 Civics is sent from the CKP sensor to the ECU, which then delivers the signal to the cluster on the blue wire.

 

Engine can run without CPK but will run like crap. But there is a way to buypass CPK sensor.

 

I think you mean CKF sensor behind the lower timing belt cover. The CKP sensor in the distributor is needed for the ignition timing and firing of the fuel injectors, so the engine won't run without it.