98 civic tach help

[Im_Expired]

Cousin purchased my old 98 civic dx coupe from me as a rolling shell. It had the factory dx wire harness with a d16y7 in it. Manual conversion done, and an ex cluster swap.

The cluster worked perfectly fine when I parked it.

Now, he has a b20b swap and the cluster rpm gauge does not read properly. It bounces from 0 to about 4K rpm when we Rev the engine..... does know what could possibly be wrong?

Please and thank you for any advice.

 

[XpL0d3r]

Does the car itself run fine? It sounds like there could be an issue with the speed sensor. Corroded contacts maybe?

Is the CEL on?
What ECU?

 

[Mr.Baker]

Start looking at your alternator, distributor or VSS.

 

[Esotericimage]

What engine harness was used for this swap?

If it was the original one, then Im quite sure its the problem.

So i would look to make sure the wiring is in decent shape AND make sure it was wired properly for the swap since the pinouts are different for a B20

 

[Im_Expired]

We did the pin out for the b20 motor. The original harness was used. The engine runs fine. Problem here is, tach does not read unless you Rev the engine. The tach then jumps up to 4K rpm and back to zero... it's almost as if it reads the signal then loses the signal.

 

[Im_Expired]

No harness damage, no plugs are damaged. It's just really strange hoe it only reads the signal when you Rev the engine...then it drops signal right away.