I have a doubt that my vtec is not working.
So I opened the wire going to the vtec solenoid.

And hooked it up to my Fluke Scope.
When the engine is runing. I get a clean +12.8 Volts d/c waveform.

I then rev the engine from idle to redline the +12 Volts stays on.

My question is simple.

a. Does the solunoid see +12 volts till the Vtec is switched on. Or does should the wire be dead till the vtec on RPM and then see +12 Volts.

b. I have a CEL. I know that my o2 sensor is not working. It has a problem with the O2 sensor. And Im working on installing my WB sensor which should be done in a day or two. Will the O2 sensor not working in some way effect the vtec.
This is the video of the Cell. It would seem to confirm my doubt about the O2 sensor.
http://www.youtube.com/watch?v=WWLcpU1AVpg

c. What are the conditions that must be met for the Vtec to work.
I heard that oil pressure must be 50 PSI. Is there something else like wheel speed or Coolant temp which is preventing my Vtec line from cycling.

 

Are you trying all this in neutral? The car will have to be moving for vtec to function.

Vtec requires that the vehicle be moving (I can't recall exactly how fast but it will function in 1st gear), it also requires that the engine be at normal operation temperature, and it also requires that there be a certain amount of oil pressure.

 

Dude pull the cels and if one is vtec solenoid or pressure than ur **** dont work. But do as eg said and try rolling and hitting vtec first cause it wont work at a stand still and it wont look for pressure either, meaning the cel wont come on if vtec isnt suppose to b coming on cause ur at a stand still or ur not up to operating temp, low oil pressure, etc...

WB sensor?

 

Thanks for clarifying that.
So it would seem that the solenoid gets +12 Volts when the Vtec is off.
And when the vtec kicks in it cuts the 12 Volts.

Yes I was trying all this with a cold engine with engine in neutral.
What I did find strange though is that even in Neutral with the wire hooked up and not hooked up. The engine sounded the same. I found this strange.

The reason for posting the video was because I dont know how to pull a cel.
the best I could do was the video.

Will try this again with the engine in gear. Will hook up a bulb to the Vtec wire and see if it switches on and off.

WB=Wide Band. No point replacing the crappy NB sensor when you can put in a WB for the same kind of money. Honda wants 18K for a NB sensor. For that kind of money I can put in a WB which will help me tune better.

 

Do u have some way to control fuel? so u can put that wb to use. Search how to pull cels its simple. all u need is a paper clip and under the glove box is two plugs one is a two prong plug and u need to jump it with the paper clip and the key in the on position. Then read the codes, the cel will flash. A short flash is one and a long flash is ten

 

Hey guys the video is the CEL Light Blinking.
The paper clip is easy. Figuring out the long and short bit. Is where I get confused. And why I posted the video. (Isnt that why people post their videos ?)


Second simple question nobdoy has answered. Is does the Vtec on by default and the 12 volts removed to activate it. Or is it no 12 Volts and then the 12 volts is supplied to activate ?

 

Im not really sure never diagnosed it that way I just use the cel. You can too

 

lol ok then this is the last time Ill bother with trying to make a video.
Will figure out the vtec bit too.

About the tuning bit. Sure you can tune anything from a cheap FPR to an uprated pump to larger or smaller injectors can be used to tune.
Or you can just play with the WB to NB simulated output numbers to get the ECU to pump less or more gas.
I normally dont touch an engine till I get a a WB onto it. Its a great tool.

 

If the CEL is on the ECU may be running in closed loop mode, preventing Vtec from working. I suggest fixing the CEL then testing the car while driving.

 

What? closed loop has nothing to do with vtec working or not. All factory ecu's run in closed loop and most "chips" "maps" delete 02 sensor input so theyd all b running in open loop. Whenever I order base maps, Im always sure to tell them to not delete o2 sensor input cause it trims fuel maps accordingly at lower vacuum and rpms.

 

I meant to say limp mode. I have experienced several DOHC swaps where Vtec was not activating due to a CEL, after the CEL was fixed and ECU was reset it worked. May not be the same for SOHC, just sayin...

 

Cant say if its in limp mode or not. Cause its pretty fast. Blows most of the other cars on the road. Jumps off the 7200 Rev Limiter easy in each gear.

I have my WB in. Now to figure out how to fool the ECU into not giving me a heater open / short code.

Ideas given to me run a 5watt bulb on the heater circuit. Power the WB from the heater circuit etc.

The ECU is getting a Propha NB signal. But the CEL stays on cause the two heater wires are not hooked up.