So I bought a 91 Civic with a 94 GSR swap. Vtec will only work if directly connected to a toggle switch and will bog in and out of vtec at around 6k +. Always done this since I've had it. Any ideas? Things changed/checked. Oil is fine. Rewired vtec and other sensors. Changed vtec selonoid. Tried other virgin/chipped ecu's. Running str8 pipe, so no cat. And only CEL on throwing is 6 Engine coolant temp sensor, and thats because it's not plugged in. Things that I think can cause the problem. Preety bad dented oil pan. Don't know the condition of either oil pump or oil pick up. And maybe fuel, even tough fuel gauge reading 50 at idle. Please help..