vtec probs, still!!!
Thread Starter
ThE_UnExPeCtEd
Joined: Sep 2008
Posts: 17
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From: central ohio
vtec probs, still!!!
ok fellas i have been trying and trying to figure this damn problem out and i still cant figure it out. its a 99 civic ex (daily driver), the problem im having is that when im under acceleration or even from a rolling start vtec will not engage until 6300 rpms, it was throwing a code but for a clogged converter i have since replaced the whole exhaust, o2 sensors, and ran a compression test on all cylinders in which all checked out fine. i have been told to check timing and to check the ecu. timing is fine and the ecu is new. so im stumped anybody with any ideas please fill me in before i decide to just swap the damn thing and get it over with. thanks in advance
Senior Member
Joined: Oct 2008
Posts: 254
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From: Sacramento
Its possible you have a bad VTEC Solnoid on the head I don't know much about it but that could be your possible culprit. I believe there are two solnoids but I a not sure. Get that checked or replaced and see if that makes a difference. Also another easy chek is your fuses and relays.
v-card member alpha
Joined: Oct 2006
Posts: 4,010
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From: Assplosion, NE
Assuming the solenoid is OK...
In order for it to switch over at the correct rpm (not even sure what that is on your year D16, on a D16z6 it's 4800rpm at WOT) it needs to be up to temp. (and for the ECU to know that via the sensor/sending unit), the manifold pressure has to be high enough (how it knows you're at WOT or close to it) and you need to be going fast enough, but I believe that's just 5mph for the cars with manual trans.
If for some reason your speed sensor wasn't working (no reading on gauge), or the MAP sensor wasn't getting the correct readings, or the water temp. wasn't high enough (around 160 I believe) or wasn't being registered as high enough to the ECU (at least not until you've floored it and gotten the revs up, see what I'm thinking...), those could all be potential causes.
Not a mechanic, just brainstorming.
In order for it to switch over at the correct rpm (not even sure what that is on your year D16, on a D16z6 it's 4800rpm at WOT) it needs to be up to temp. (and for the ECU to know that via the sensor/sending unit), the manifold pressure has to be high enough (how it knows you're at WOT or close to it) and you need to be going fast enough, but I believe that's just 5mph for the cars with manual trans.
If for some reason your speed sensor wasn't working (no reading on gauge), or the MAP sensor wasn't getting the correct readings, or the water temp. wasn't high enough (around 160 I believe) or wasn't being registered as high enough to the ECU (at least not until you've floored it and gotten the revs up, see what I'm thinking...), those could all be potential causes.
Not a mechanic, just brainstorming.
Thread Starter
ThE_UnExPeCtEd
Joined: Sep 2008
Posts: 17
Likes: 0
From: central ohio
well im pretty sure the y8 is suppose to engage at 5100 rpms maybe a little later idk, but one other thing i have noticed is when im accelerating real slow, once it trys to engage vtec it jerks and misses
. i think its time for me to tear it down before i boost it and figure the problem out even if this means time for a new motor. thanks again fellas
. i think its time for me to tear it down before i boost it and figure the problem out even if this means time for a new motor. thanks again fellas