Raunch

Would the knock sensor cause this? What would prevent Vtec from activating? The ECU says that the Knock sensor is bad. What do you guys think?

junglerunna

Yes throwing the knock sensor code would not let vtec engage.

chrisCNL

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by junglerunna02 &raquo;</TD></TR><TR><TD CLASS="quote">Yes throwing the knock sensor code would not let vtec engage.</TD></TR></TABLE>

i do not agree. i work on many swapped that did not have a knock sensor and their VTEC engages fine. Swap you VTEC soleniod out with another and see VTEC works. Also check if the is a code 21 and 22 other that the code 23 for the knock sensor.

poison

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Raunch &raquo;</TD></TR><TR><TD CLASS="quote">Would the knock sensor cause this? What would prevent Vtec from activating? The ECU says that the Knock sensor is bad. What do you guys think?</TD></TR></TABLE>

NO!

Code 23 for Knock Sensor will NOT disable VTEC.

How did you do your oil line for your LS/VTEC? Please explain. Sounds like either you are not reaching 60 PSI for VTEC to engage, oil line wasn't routed right or not enough of it.

Could also be a bad VTEC solenoid/oil pressure sensor, or a break in the wire.

Chronic_SMOKE

is your speedo working, thats what caused my vtec to stop working

chidoks

check your wiring on your oil pressure sensor...and check your oil lines...it happened to me too...it turned out it was my oil pressure sensor that wasnt wired right

turtle-eg

Put a test light at the vtec solenoid wire and drive it to 5000k rpm (depending on your ecu) and see if the light turns on.... if it turns on then you know the ecm is activating it and the problem is either in the solenoid or oil pressure.

Hankish

im having the same problem. i wired it as shown by Katman, is there also a speed sensor? my speedo is working, so does this mean the speed sensor IS working/ conected?
Thanks
Hank

Hankish

this is in a 91 integra LS/VTEC. 94 block w /JDM obd 0 ECU. The car is also running CRAZY RICH. (plugs are BLACK w/carbon after just 1 trip around the block!) I have the 2nd o2 sensor wire just spliced off the first o2 (so there is really just 1 o2). do you think this is the problem? or just a bad o2? the only code is for the IAC...
Thanks

slixxracing

Well here's what I learn from past experiments with ls/vtec's. Sometimes it due to the brain that vtec doesnt engage. Use a friend's ecu or someone elses ecu and see if the problem still occurs. If not then you're problem is solved. Or you can just use a p28 ecu and it will eliminate the knock sensor problems. If you said you are running crazy rich maybe a p28 ecu can lower you pressure a bit.


Modified by slixxracing at 8:38 AM 11/8/2003

slixxracing

but first make sure you eliminate all the CEL's 1 by 1. Very important.

VtecDA9

To tell you the truth, you might just have to drive it a lil more if it's a fresh swap. It took mine a while to start engaging too, after a few days b4 it just started working. I mean, nothing was changed as far as wiring from the previous b16 motor... If anything make sure there is good oil pressure, enough oil etc... that damn external oil line just needs to get lubed up and ready to flow oil hahah. Then it's smiles from there if built right...

Cashflo

hook up a pressure guage on the head near the vtec solenoid... there should be a plug near the solenoid... then turn on the car to see psi.. or you can switch ecu's with someone to see if vtec will kick then... throwing a code 23 will not turn vtec off... i know cuz i drove with code 23... just check your solenoid by hooking up a wire from the solenoid to the battery... if it clicks then its still good... well good luck

Quiks66

The same thing was/is happening with my setup. I'm using a 98 GSR ECU and for a while my Vtec was not engaging. I could rev it up past the Vtec engaging point (4400rpm with this ECU) and it but Vtec would not engage and at WOT I would have a crazy 5500rpm rev limit. I was throwing a few CEL codes, both Vtec oil pressure switch and knock sensor, but I grounded out the oil pressure switch and took care of that one. I still don't have a knock sensor, which is OK but I have heard that not having a knock sensor sends your ECU into 'open loop mode' and uses different fuel maps and rev limit. Dunno if my Vtec is engaging now, but I'll post again tomorrow when I get on it and find out. Let me know how you're progessing with your Ls/Vtec and having Vtec engage

Quiks66

Well I believe Vtec is engaging, but it's very sensitive to throttle position. Also, the cams I'm using are so loud that Vtec operation sounds rather similar to normal driving non-Vtec. Need to take it to a track and really get on it to feel what I've got. Let me know how yours is going