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Twin BF150and VTEC

P

PaulBF150

Contributing Member
Here is the situation: One Engine which engages the VTEC Overheats. The other engine fails to engage the VTEC mode but does run upto 5K RPM without overheating.

So could the engine that is not energizing the VTEC be causing strain on the engine that does energize VTEC then overheats?

I been chancing the Overheating issue and not the other engine that doesn't go into VTEC mode.

Looking at the engine w/o VTEC working i do have oil pressure and solenoid confirmed to operate when I swapped it on the other engine. I guess I might be stuck wiht pulling valve cover for more inspection.

Really at a loss here, any guidance is greatly appreciated.
 
The short answer to your overheat is no, it should not overheat even under full load and sister engine not running at all, so you have a problem with the cooling system there. The question of Vtec is another issue, how do you know it's not engaging, are you certain that engine is getting enough rpm? Vtec should engage at 4200
 
On the engine that overheats I can hear the VTEC engage and feel boost of power. That does not happen of the sister engine. It runs to about 5K

I read that the ECM collects data points on oil pressure, RPM and throttle position. I have oil pressure (no alarm and engine runs at 5K) The RPM seem to exceed the 4200RPM, Throttle has to be open otherwise wouldn't have 5K RPM. ECM will get upset when I disconnect the Solenoid, so I must have signal. Whether the driver in the ECM is good, I will see on next ride.

So, I was planning to place 16-ohm resistor on the connection to the ECM (to make it happy), meanwhile connect the VTEC Solenoid to I believe 5VDC will do it and switch it on manually when RPM is up there. See if it goes?????
 
Have you checked the basics, compression, fuel pressure and missfire test under load? I have never known these motors to require any modifications from standard. There's usually a simple solution to problems like this. If your vtec wasn't functioning you would have an alarm and check engine light on.
 
Well during the test run with my temporary modification didn't seem to work as expected, however with VTEC basically diabled I could only achieve 3,500 rpm. When I reconnected it and ran the engine, I did hear something different, but it did rev up to about 5k. So maybe it is working, I just don't hear it as the other engine does it.

I guess we can put this one to bed, or see what Dr H. reports when I get it next week.
 
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