CRX W/b18c, No CEL's, VTEC works great untill the engine is fully warmed up then the VTEC no longer engages untill I let the engine fully cool down. I changed the temp sensor and VTEC selonoid. Any Ideas? Thanks!

 

Im having the same problem with my H22a. Keep me posted and ill keep you posted. Its probably and oil pressure issue. I just don't know exactly how to fix it yet but I'm working on it.

 

definitely oil pressure, oil thins out as it heats up.

 

get an oil pressure gauge and put it on and monitor the pressure, seen this happen plenty of times

 

Here's my answer.

Your ecu is tuned to run at maximum performance under normal circumstances, and normal circumstances is a fully warmed up motor.

The engine runs differently as it does cold as opposed to warmed up. When it's colder, the vtec engagement point might be optimized if it were set to a lower rpm, but since your ecu was factory tuned for a fully warmed up motor, it's going to engage vtec later, thus making it more obvious in the change with exhaust notes. If your pre vtec lobes max out at 3k, and your vtec is at 4.5k, the jump between non-vtec to vtec is greater.

but..... when it's warmed up, the vtec engage point is optimized, and so the vtec engagement is less noticeable. So your pre vtec lobes max out at 4.5k, and vtec occurs at 4.5k, making a smoother transaction.

This is assuming that your basing your knowledge of not having vtec from the change in exhaust note.

 

No there is just no crossover in my car. Lol We actually found metal shavings in the screen in the vtec solenoid gasket when we pulled the solenoid off. The machine shop didn't clean the head out properly when they rebuilt it. Thats my story. We have to pull the head, see if there is any internal damage and if anything needs replaced the machine shop is going to pick up the tab. We are also going to pull the oil pan and inspect the bottom end and flush it out with some fresh oil as well to ensure there are no metal shavings in the bottom end.