JDM D15B in a 92 Si with stock wire harness and P28 ecu. I ran a 17 flat at the track Sunday and my friend rode with me (small guy, little extra weight.) He said he didn't hear any vtec crossover so when we got back to our town, we tested it by doing a couple pulls as it sat and then unplugging the solenoid. Exhaust and motor sounded the EXACT same both time, only difference was I had CEL's with it unplugged.

I realize that it's a single cam but everything about the car felt the EXACT same with vtec plugged in or not. The solenoid is the one that came on the motor and, for some reason, it has both the pressure and the solenoid plugs...

I have no CEL's with it plugged in, which is why I'm on here... I have no idea what to check... My friend suggested cleaning the mesh screens inside, and I'm also considering putting on a solenoid from my original Z6. Any other ideas?

 

Speedo work?

 

Sometimes... Forgot to mention that when I unplugged the solenoid it threw the code for the VSS (code 17) too... The original plug was corrorded and I cut the wires and twisted in a new plug... The speedo sometimes jumps around, but I don't have a code...

 

Problem solved. Vtec needs a sound speedo to read.

 

Figures... So how to I get to a sound VSS? I'm really leaning towards the wires being goofy since it still reads sometimes and isn't it rare for the VSS itself to go bad? What's the best way to fix the wiring?

 

Either cluster, wiring to cluster, VSS plug, or VSS. Swap a knwon good VSS and see what it does, hit the plug with a good amount of cleaner, or just swap it out, follow wires to cluster and repair when needed. If none of that fixes it, new cluster.

 

I was just about to ask if the cluster would cause the problem... No codes, cruise control works and the other gauges work...

 

does the cluster actually affect vtec though?

 

i didnt think the cluster affected vtec... but myabe who knows. Vtec also wont hit if ur low on oil.

 

possibly a bad v tec solenoid.

 

But there isn't a CEL for that unless I unplug it

 

Solenoid's can do that though. Act fine but not work. But the VTEC system in these cars works as long as the speedometer unit is fully functional. So, you need a good cluster for it to work. It works off the VSS AND the cluster. But yes, the solenoid can act fine and not work, I didn't think of that.

 

I'm gonna go with the cluster then cause I forgot to mention that when the speedo is jumping or stuck at 0 I can hit the dash right above it and it starts working.

 

I Usually dont feel vtec when I had a y8. I mean it sounds nothing like a B or a K. If you disconnect and feel no difference idk but all sohc vtec I drove i never really felt a big difference when vtec come on

 

Yeah, but I at least heard it when I rode with my cousin. She has a 98 civ ex automatic, bone stock.

 

No it does not.

The VSS signal is split; it goes to the ECU, cruise control unit (if present) and to the speedo gauge in the cluster. VTEC will still engage if the speedometer gauge isn't working or if it isn't getting a signal. VTEC will not engage if the VSS isn't working.

VTEC needs signals from these sensors:

VSS
TPS
RPM
Coolant temp
Knock sensor
Oil pressure

That's off the top of my head, maybe missed one.

 

Oh, thought it needed a signal from the cluster. Knew it needed it from the VSS however.

 

VTEC is easier to hear without modifications.

 

oil preasure check it make sure you have oil trust me, if you dont have enough oil or its low there will be no oil pressure which vtec needs oil pressure to hit.

 

actually, if the plug was corroded, then the sensor was corroded as well, ive had the pins on the vss break off before and do the same thing this kids car is doing. get the top off of a speed sensor.
free at junkyard

 

The problem with the VSS was that the center wire was completely corroded through and broke apart. The other 2 were fine. Fixed the broken one and now the speedo reads just fine. Not sure about vtec though... Still feels the same.

It's not the oil. It's filled and I cleaned the solenoid gasket screens (both of them) even though they were completely clean to start with aside from being covered with clean oil (from taking it apart and the solenoid was filled with good oil).

Could the ECU be the problem? It is socketed for a chip (no chip in it now) because it used to be boosted. Is it possible that the guy I bought it from made it so that the chip controlled vtec instead of the computer?

 

what ecu do you have

 

would throwing code 1 (o2 sensor, I know whats going on) cause v-tec not to work???

 

P28, I put that in the first post, lol. I ran a p08 for a little bit but when I got into higher rpm it felt like it was just falling on its face...

 

Test the VTEC solenoid by giving it battery voltage and listen for a click. Search for the procedure if you need to.

Even if you're not getting code 21 the solenoid might still be bad.