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-   -   Drive for 10 minutes and vtec wont work. (http://www.jdmcity.com/showthread.php?t=22379)

4DRLX 05/06/2012 04:35 PM

Drive for 10 minutes and vtec wont work.
 
so heres the deal. ( SORRY for the long post )

it all started when my oil pressure unit ( low oil psi ((back of block)) snapped or something. not sure how it happened, but the entire wire got ripped from the unit and was no where to be found behind the intake manifold.

during this time my oil light would stay on.

car still drove perfect and vtec hit everytime.

time passes and gets to the point where vtec would work for 10 minutes of driving or so and then i would climb the tach and vtec would cut in and out. try hitting it again.. no vtec.. keep climbing tach and itll pop code 22

so i replaced my pressure switch

and it still was the same.
-----
now today i read that you can jump the solenoid and pressure switch wire together to fool the ecu into thinking it always has pressure. i did this because it was a easy way to "delete" the vtec control system.

once i did this it instead pop'd code 21 for the vtec solenoid....
so i call up a local shop and buy a vtec solenoid with the housing and it had the plug in the pressure switch spot.

now my car is tuned on chrome so i figured i could always disable my vtec pressure switch and the solenoid altogher.

so thats what ive done i put the new solenoid on and reburned my chip with the pressure switch and solenoid disabled, drove for about 15 minutes and go to hit vtec and it goes in and out of it.. try again and no vtec at all.

so this all leads me to believe that my problem isnt with my solenoid or pressure switch since it behaves the same with them disabled.

hoping the pros can chime in here as im really getting sick of this.

btw the vtp and vts delete was a temporary thing to test a theory, i wouldnt leave it like that. which is why im trying to figure out this damn puzzle.

hope some one can help.

H22APWRD94 05/06/2012 07:55 PM

Re: Drive for 10 minutes and vtec wont work.
 
Check your oil pressure. If it is too low (which the pressure switch checks) it will not engage vtec because there actually is not enough physical pressure to engage the pins. Takes around 35-36 psi of pressure to engage the sliding pins in the rockers.

4DRLX 05/07/2012 09:19 AM

Re: Drive for 10 minutes and vtec wont work.
 
why would my pressure drop after driving?

H22APWRD94 05/07/2012 11:19 AM

Re: Drive for 10 minutes and vtec wont work.
 
Quote:

Originally Posted by 4DRLX (Post 287174)
why would my pressure drop after driving?

When oil warms up, it becomes thinner. Thinner oil moves easier depending on bearing and pump tolerances and creates less pressure. It sounds like it is borderline. Put a pressure gauge on it and see what you are looking at for pressure. You should see 50+psi at 3k rpm after engine is at normal operating temperature. A minimum of 10psi at idle after engine is warmed up.

Dj Technick 05/07/2012 03:25 PM

Re: Drive for 10 minutes and vtec wont work.
 
Do as he says!

http://t3.gstatic.com/images?q=tbn:A...Oczjvd1upPFLaj

4DRLX 05/07/2012 10:55 PM

Re: Drive for 10 minutes and vtec wont work.
 
the bolt on the top left of the head is the one i use to check pressure correct? unscrew the bolt and screw pressure guage in.

H22APWRD94 05/07/2012 11:27 PM

Re: Drive for 10 minutes and vtec wont work.
 
That should give you pressure.

4DRLX 05/08/2012 12:06 PM

Havnt had a chance to check it out but after an oil change it seems alot better vtec hit every time today. I would still like to hook up a oil psi guage in the car but im a little nervous about mechanical ones, since i dd this and wouldnt want oil on my work clothes.

one_slow_ej 05/08/2012 02:46 PM

Re: Drive for 10 minutes and vtec wont work.
 
sounds like it was low on oil, if an oil change fixed the problem.

H22APWRD94 05/08/2012 04:24 PM

Re: Drive for 10 minutes and vtec wont work.
 
Quote:

Originally Posted by one_slow_ej (Post 287390)
sounds like it was low on oil, if an oil change fixed the problem.

That was my thought Sean, or possibly just some old, old oil. Screaming around with low enough oil pressure that VTEC won't engage is bad for an engine.

Gimpster 05/09/2012 09:54 AM

Re: Drive for 10 minutes and vtec wont work.
 
Every VTEC based motor I've had ... very sensitive to oil level. Even slightly dented oil pans have nailed me before too. It was very rare I had a working VTP sensor on any of my swaps (would get broken off in transit) so I just always disabled it in the ROM :)

4DRLX 05/13/2012 10:41 PM

Re: Drive for 10 minutes and vtec wont work.
 
wasnt the oil, because it still does it.

H22APWRD94 05/14/2012 01:13 AM

Re: Drive for 10 minutes and vtec wont work.
 
Quote:

Originally Posted by 4DRLX (Post 288152)
wasnt the oil, because it still does it.

Have you checked the oil pressure yet. That is the only thing that can physically keep it from engaging. Also, pull off your solenoid assembly and check to make sure that filter is clean.


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