Just got a JDM B18C put in my 1993 Civic Si
-engine has 50,000 miles/82,000km
-used P72 ECU and modified my stock Si harness
-no CEL comes on
-car ran well the first few days but could not tell for sure if the VTEC was activating
(ie no great change in performance compared to my buddies 99 Si(R) (B16A2)

Now the car sometimes misses at idle and while driving and lacks power.
-changed the dist. cap and will replace rotor and plug wires as soon as the dealer gets them in.
-fuel filter is nearly new

Any ideas anyone?
rotor/cap/plug wires?
timing?
fuel/injectors?
What is the optimal octane for JDM engines?

 

They can run on 91 octane (I tired it out because i couldn't find anything else and I was about to run out of gas.

 

anybody else?

 

i am having the same problem with my B18C, check if the secondary is opening up, the little metal 'pole' will actually move when it engages under the vacuum thingy, here is a link with a pic.

https://honda-tech.com/zerothread?id=265558

 

ttt

 

are you using the JDM ECU as well? the civic one works, but its not perfect. Use the JDM unit and be sure to hook up the knock sensor and AIB sensor.

The Civic ECU gave no CEL either, but ran really rich and sluggish.

After i changed to the JDM ECU it ran Beautifully.now i can feel the Vtec engaging.

 

Changed the plug wires with NGK blues. Car now runs perfect. Thanks