i have a problem with vtec engaging after i put a turbo on my b16. it worked fine before i put it on then the day i took it for a ride with the turbo it just flew past the vtec crossover point. another thing is...when the downpipe is disconnected from the turbo, vtec will work again but when its connected again it stops working. ive checked oil pressure and wiring a few times and it is alright, could this be a sensor causing it to not work or what? any advice is appreciated, thanks!

 

I had a problem with not enough oil pressure to the vtec pressure sensor when I install my turbo reroute your lines or possibly run a resistor in the feed line what an feed are you running

 

see the thing is if i disconnect the downpipe from the turbo right now the vtec would work again, but thats just not a practical thing to do. yet when i put it back on the vtec wont work again so its bc of this that i have ruled out oil pressure and any wiring issues. its crazy

 

This makes no sense to me
Thinking

 

Sometimes when you're boosted, you won't be able to hear it engage. Are you throwing any codes ?

There is no reason why when you take off a downpipe it'll work again. Take your car to a local shop, and have them hook up a diagnostics on it. That will say right there if your vtec is engaging or not, whether or not you hear it.

 

Are you driveing to to be sure that the vtec is working or revving and listening for vtec with the downpipe on and off because the downpipe should not make a difference unless there is something I am not taking into consideration any other factors you are changing

 

i have had that done already and it threw codes for my knock sensor and air control valve, but the vtec worked before with those codes, it was just after i put the turbo on it stopped. yeah tell me about it...it makes no sense to me either.and the only thing that disconnecting has an affect on is the o2 sensor...could it be something with that (i have already installed a new one about 1000 miles ago)

 

yeah i can hear the vtec with it off its very crisp so i know it works with it off and when its back on the revs just fly past where it would crossover without crossing over...and not having vtec with turbo SUCKS

 

So what codes are you throwing when the downpipe is connected?

 

knock sensor and air control valve...same with the downpipe off. and the same when the turbo wasnt even on the car.

 

run a thicker oil, 20w50...the turbo is heating your oil and thinning it out...when I first had this problem at the shop, I when through everything related to vtec switched everything out, wired direct, etc... it would work a couple times then crap out... end up being the oil.

 

Have you checked w/ something simple as a test light, if vtec is working??? raise front wheels off the ground and run car in second gear... see if the test light that is tapped into VTEC solenoid lights up. Simple enough. A lot of turbo VTEC engines dont seem to notice when VTEC engages. I would think the car would not fly past the engagement if VTEC was not working. That and your check engine light would be on w/ codes 22 and/or 21. VTEC oil pressure switch-and VTEC solenoid codes.

Absubtle
PA

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EVIL TYPE R &raquo;</TD></TR><TR><TD CLASS="quote">run a thicker oil, 20w50...the turbo is heating your oil and thinning it out...when I first had this problem at the shop, I when through everything related to vtec switched everything out, wired direct, etc... it would work a couple times then crap out... end up being the oil.</TD></TR></TABLE>