My buddy's got a OBDI GSR motor in a Del Sol. Vtec hits at about 5500rpm but it doesnt hit as hard as it should... the power is all there before VTEC but it doesnt really pull any harder after 6000 rpm.... what could cause this?

 

Is your ECU stock? Perhaps the air/fuel ratio is messed up once your engine hits VTEC. Either that, or his engine may not be engaging VTEC at all.

EDIT: Agreeing with the posts below, this is assuming there is in fact a problem with his VTEC. If he's just not satisfied with it, he should upgrade the valvetrain and go with some Skunk2 Stage II cams.


Modified by BlackoutVTi at 5:51 PM 5/23/2007

 

The VTEC engagement on a GS-R is 4400 RPM, and the secondaries open at 5750. Neither will really "hit hard".

 

16sec quarter mile is NOT fast

 

its got a 2 step computer and the VTEC is hitting... but its hittin at 5500.. secondary butterflys are removed

 

well if you remove the secondaries and you still running the stock gsr manifold, there is your problem. get a skunk or blox manifold

 

VTEC is either on or off, there is no in-between.

 

The GSR manifold uses the Butterflys within it, acts as a secondary (comes first tho) mechansim so increase airflow. I really dont see the use for it persoanlly, but yea, it wont seem to hit that loud. Also, keep in mind for any other motor ( maybe this one from the OP's as well) If you have an aftermarket Manifold, that too will change the sound of the VTEC engagment, sometimes even muffling it, because you are changing the way the air is resonating within the Manifold, therefore it wont seem to hit as loud sometimes. Depends on what manifold you are running, either OEM spec or Aftermarket.

 

when vtec is loud or lol "hitting hard" somthings wrong.

vtec is not suposed to "'hit hard" or be loud.

as far as the IAB's you guys, stop removing them, your cars are not strip cars, them damn things are there for a reason, like for low end power. get your iabs to close when vtec opens and youll get your "hitting hard" vtec, lol

EDIT, i mean open, not close, lol, sorry


Modified by THC07 at 9:55 PM 5/23/2007

 

You removed the secondaries?

Gsr ecu's are known for lighter vtec engagement, if you ask me I think it's easier on your valvetrain.

Vtec either engages or it doesn't there's no "light engage or kind-of engagement"

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by THC07 &raquo;</TD></TR><TR><TD CLASS="quote">when vtec is loud or lol "hitting hard" somthings wrong.

vtec is not suposed to "'hit hard" or be loud.</TD></TR></TABLE>

x 10,000

 

i wonder, at what oil psi does vtec engauge?

does vtec engauge at the same oil psi, b16 as to a b18c?

 

VTEC is engaging.,... the car doesnt pull after 6000 rpm... it just wont pull any harder

 

Dang, here I thought VTEC was the next nitrous..

Maybe ignition or something with the ECU?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Racing rice &raquo;</TD></TR><TR><TD CLASS="quote">Dang, here I thought VTEC was the next nitrous.. </TD></TR></TABLE>

x2 lol

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ProjectTib &raquo;</TD></TR><TR><TD CLASS="quote">VTEC is engaging.,... the car doesnt pull after 6000 rpm... it just wont pull any harder</TD></TR></TABLE>

you might have a timing issue. or the ecu is not liking somthing at 6000 and starts to pull timing.

 

alright ill try puttin in a stock GSR ecu... and chek the timing. thanks for all your help guys

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by THC07 &raquo;</TD></TR><TR><TD CLASS="quote">i wonder, at what oil psi does vtec engauge?

does vtec engauge at the same oil psi, b16 as to a b18c?</TD></TR></TABLE>

It's not about what "oil psi" it engages. What it is about is a MINIMUM oil pressure that needs to be met so that VTEC can engage.

 

did you calibrate your butt dyno? tryied a different pair of underware?

bring your car to a REAL dyno..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EE_Chris &raquo;</TD></TR><TR><TD CLASS="quote">

It's not about what "oil psi" it engages. What it is about is a MINIMUM oil pressure that needs to be met so that VTEC can engage.</TD></TR></TABLE>

do you happen to know what that minimum is?

im not following what your saying. can you elaborate?

 

just make sure your oil is topped up

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by THC07 &raquo;</TD></TR><TR><TD CLASS="quote">do you happen to know what that minimum is?</TD></TR></TABLE>

Looking in the 96-00 Civic Helms, it appears to be &gt;57psi.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by THC07 &raquo;</TD></TR><TR><TD CLASS="quote">im not following what your saying. can you elaborate?</TD></TR></TABLE>

I can see my wording might have been a little confusing. To clarify, oil pressure is what ultimately pushes the locking pins out to make VTEC happen. However, as a first line defense to making sure there is actually enough oil pressure to push those pins, you've got the VTEC pressure switch. If that switch doesn't see &gt;57psi, the ECU will never try and activate the VTEC solenoid....because it sees the VTEC pressure switch is saying there's a problem.

You asked:

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by THC07 &raquo;</TD></TR><TR><TD CLASS="quote">i wonder, at what oil psi does vtec engauge?

does vtec engauge at the same oil psi, b16 as to a b18c?</TD></TR></TABLE>

So you see, VTEC doesn't engage at a particular oil pressure - it engages at a particular RPM. It would have been wrong of me to say "It engages &gt;57psi" because the only thing tied to that number is the pressure switch, which by itself does not engage VTEC.

Are the pressure switch limits the same for a B18C - I dunno. I've only got access to the 96-00 Civic Helms.

 

I gotcha.

thanks, awsome elaboration

 

my freind had an ecu that didn't open up as loud as mine in my gsr hatch.so we swapped ecu's because mine opened up hard.when we swapped his opened up like mine would,and when i had his ecu, mine sounded like his car.I also say it has to do with the exhaust system

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Padawan &raquo;</TD></TR><TR><TD CLASS="quote">The VTEC engagement on a GS-R is 4400 RPM, and the secondaries open at 5750. Neither will really "hit hard". </TD></TR></TABLE>

x2, the OP's friend should just get a chipped p28 along with an aftermarket IM or chipped p72 with his stock IM to eliminate the secondary butterflies. If vtec is indeed engaging and working properly, then doing the following changes should allow vtec to be more noticeable.

 

if its a bone stock gsr dont expect too much outta it. if you want your vtec to hit loud get a short ram intake and a obx filter. then move vtec to like 3k and then bamm you hear it for 5000 rpms