labatt50

i just bought a civic vx with the d15z1...
when i bought it, the car had 2 code, one for the laf sensor (wideband) and the other egr valve.

i bought a new sensor and i cleaned my egr valve and now i dont have any code.

since i always drive 85mph on the higway i noticed i lost mpg even tho i've change the sensor o2 and cleaned the egr valve. I was getting 42mpg and now only 33mpg. But what i am thinking is since it had codes... i think the vtec was not working so it was always on 8 valves thus giving me more mpg and now since the car has no code the vtec work and at 85pmh (~2900rpm)... its always on 16valves thus giving me less fuel economy...

Do you think because the vtec is alway on, i get lower mpg?
if yes... what way i could use to put the vtec crosser higher keeping my p07... and beside a vafc?

sorry if its not performance related but i really appreciate fuel economy these day... my other car is a cb7 turbo... and **** it really cost a lot on gas with 94octane

Froth

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by labatt50 &raquo;</TD></TR><TR><TD CLASS="quote">sorry if its not performance related but i really appreciate fuel economy these day...</TD></TR></TABLE>

85 is not exactly the most fuel friendly speed, cheaper than doing anything ECU related would to simply...slow down a bit. I'm not trying to tell you how to drive it just seems you have a constrasting train of thought on the subject.

labatt50

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

85 is not exactly the most fuel friendly speed, cheaper than doing anything ECU related would to simply...slow down a bit. I'm not trying to tell you how to drive it just seems you have a constrasting train of thought on the subject.</TD></TR></TABLE>

i know you are right on this point but since i got this car i slowed down from 100mph (accord) to 80~85 with the civic... it's just the fact that i dont want to cruise in vtec mode... since i think it burn more fuel

instrument

vtec kicks in at 29?

labatt50

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by instrument &raquo;</TD></TR><TR><TD CLASS="quote">vtec kicks in at 29?</TD></TR></TABLE>

i think it's between 2500 and 3000 but i'm not 100% sure...

fucjdm

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by labatt50 &raquo;</TD></TR><TR><TD CLASS="quote">

i think it's between 2500 and 3000 but i'm not 100% sure...</TD></TR></TABLE>
no vtec does not engage that early. WHat you are trying to refer to the motor jumping out of lean burn. which is after 2500 when it decides to run on 16valve as opposed to 8 valve

icedemon

VTEC engages at 2500rpm on a D15Z1. But it's not your conventional type of VTEC. It let you run on 16 valves instead of 8 but that is considered VTEC engaging on a VX motor.

Relic1

on a P07 VTEC switches over @ 2500 under heavy load and 3220 under light load.

more info on the VX version of VTEC...
http://www.leecao.com/honda/vtec/sohcvtece.html


if you're running 85mph, you're obviously not that worried about mpg.
If you are looking for mpg, slow down to 55-60mph, install a VTEC light and make sure your tires are properly inflated.