vtec issue ............help


colmbarr1988

New Member
Joined
Oct 31, 2010
Messages
95
on the graph it is down all over the place an no matter wat is givin it will not respond but wen vtec cross over it runs flat for about 1500 rpm den takes off
 


Vtec6000

Super Moderator
Staff member
Donator
Joined
Jun 5, 2007
Messages
6,224
on the graph it is down all over the place an no matter wat is givin it will not respond but wen vtec cross over it runs flat for about 1500 rpm den takes off

When you say new dizzy did you put a new one on or fit new internals? Posting the dyno sheet will help me understand what's going on better
 



tama666

VIP Member
VIP Member
Joined
Jul 24, 2009
Messages
6,294
What is your oil pressure reading?
What weight oil are you running?
Which brand oil filter?
 


freewilly

Member
Joined
Feb 21, 2008
Messages
242
have you open your ecu and look at it. Old capasitors have and will leak dielectrics and will "burn/eat" the pcb. This will also change the capasitance of the capasitors and will give the ecu false inputs. this will change a/f ratio and MAYBE vtec switch over.
 



colmbarr1988

New Member
Joined
Oct 31, 2010
Messages
95
have you open your ecu and look at it. Old capasitors have and will leak dielectrics and will "burn/eat" the pcb. This will also change the capasitance of the capasitors and will give the ecu false inputs. this will change a/f ratio and MAYBE vtec switch over.

this was happening on my stock ecu and my neptune demon ecu
 


Vtec6000

Super Moderator
Staff member
Donator
Joined
Jun 5, 2007
Messages
6,224
What was the fuelling like on stock ecu and now on the neptune ecu? is it going up and down or staying relatively consistent?
 


elchunk

KCCO
VIP Member
Joined
Dec 22, 2008
Messages
6,969
vtec is controlled by the following parameters, is it possible you may have a loose pressure sensor connection? or a wire in the wrong pin on your conversion harness?

oil pressure
oil temprature/coolant temp
vtec solenoid
vss
ecu
 


colmbarr1988

New Member
Joined
Oct 31, 2010
Messages
95
What was the fuelling like on stock ecu and now on the neptune ecu? is it going up and down or staying relatively consistent?
i done the clutch/lsd/header/cat back @ same time
so i ran in the comp clutch stage two ,
wen this was done (500 miles)
i had it dyno'd to see what i was making from the header and cat back and to have a tweek map done to receive full potential,
this was wen it became clear of the issue ,
fueling was needed but tots were tat a lil tweek would sort it out for the new header and cat back ,
but it would not peak over 171bhp the map showed the same issue on stock as it did on neptune ,
previous with a air box decat and map was 176bhp

after all the work in the original post still nutting has changed
today the clutch was changed and dyno'd but still no change

it is set to 6k rpm for vtec but no lift off till 7.5k rpm
so at this stage the only part of the car not changed is the bottom end???
could it be that the compression ring is blowing at the high rpm ,
and tat the oil ring is taking tat 1500rpm to rebuild compression and den takin off ??? its n ot use oil and its not blowing smoke,,,

so my issue is upon vtec .....????
i tink i will have the vtec cam locked out with the bearings and have it compression tested tat way to see if is down ?????
 

Last edited:

tama666

VIP Member
VIP Member
Joined
Jul 24, 2009
Messages
6,294
i tink was 65/75 psi
millers oil and honda filter which i always run

Do you have a oil pressure gauge? Do you see an issue at VTEC engagement on your gauge or data log? If you do, you may have an oil pump issue or a clog in the system. Gauges to the rescue.
 


Vtec6000

Super Moderator
Staff member
Donator
Joined
Jun 5, 2007
Messages
6,224
i done the clutch/lsd/header/cat back @ same time
so i ran in the comp clutch stage two ,
wen this was done (500 miles)
i had it dyno'd to see what i was making from the header and cat back and to have a tweek map done to receive full potential,
this was wen it became clear of the issue ,
fueling was needed but tots were tat a lil tweek would sort it out for the new header and cat back ,
but it would not peak over 171bhp the map showed the same issue on stock as it did on neptune ,
previous with a air box decat and map was 176bhp

after all the work in the original post still nutting has changed
today the clutch was changed and dyno'd but still no change

it is set to 6k rpm for vtec but no lift off till 7.5k rpm
so at this stage the only part of the car not changed is the bottom end???
could it be that the compression ring is blowing at the high rpm ,
and tat the oil ring is taking tat 1500rpm to rebuild compression and den takin off ??? its n ot use oil and its not blowing smoke,,,

so my issue is upon vtec .....????
i tink i will have the vtec cam locked out with the bearings and have it compression tested tat way to see if is down ?????

The leak down test would have indicated if the compression rings weren't sealing and you would definitely have oil usage if that was the case. What ex. manifold have you got fitted? and did you try standard manifold back on it to see what way the power curve was?
 


colmbarr1988

New Member
Joined
Oct 31, 2010
Messages
95
Do you have a oil pressure gauge? Do you see an issue at VTEC engagement on your gauge or data log? If you do, you may have an oil pump issue or a clog in the system. Gauges to the rescue.

no i dont have a gauge dude.....

i had the oil pressure tested while it was on the dyno and at 6krpm(were vtec is set)
the oil pressure shot up to 65/75 psi
the graph on screen didnt budge
it rat flat till 7.5 rpm
pressure didn fall off or nuttin stayed up
and at 7.5 rpm the graph lifted off
 


Darragh

Over 9000!
Joined
Oct 16, 2008
Messages
2,988
no i dont have a gauge dude.....

i had the oil pressure tested while it was on the dyno and at 6krpm(were vtec is set)
the oil pressure shot up to 65/75 psi
the graph on screen didnt budge
it rat flat till 7.5 rpm
pressure didn fall off or nuttin stayed up
and at 7.5 rpm the graph lifted off

Oil pressure at the pump/block should drop when the vtec engages ?
 


tama666

VIP Member
VIP Member
Joined
Jul 24, 2009
Messages
6,294
no i dont have a gauge dude.....

i had the oil pressure tested while it was on the dyno and at 6krpm(were vtec is set)
the oil pressure shot up to 65/75 psi
the graph on screen didnt budge
it rat flat till 7.5 rpm
pressure didn fall off or nuttin stayed up
and at 7.5 rpm the graph lifted off

:nice:

Well that does not seem to be the issue then...
Note: I am at 81PSI at 7.5K, B18C5 OEM oil pump, but its NEW.
You are not that far out from a new pump, so this may not be your issue, good that you checked tho!
 


tama666

VIP Member
VIP Member
Joined
Jul 24, 2009
Messages
6,294
...have you reset the ecu?
Have you tried a programmable ECU just to see if it clears up?
 


harvey j

PSN: DIRTY-JDM-B20
Joined
Mar 15, 2011
Messages
704
hello mate this is a very strange one.

have you tried your earthing leads?

my friends car just came out of the tuners and whilst on the dyno when hitting boost and vtec his power went up and down on the graph, it would gain and then loose power and so on.

the tuner noticed the earth lead going to the cylinder head was attatched to his rocker cover which was a carbon fiber cover.

the tuner suggested that it couldnt earth properly cos the carbon cover and the fact it had a rubber gasket on it.

he explained to us that the voltage was trying to escape through the earth lead but couldnt and was travelling up the intake manifold and was earthing out on the TPS Sensor, which was tricking the ecu into thinking it was on partial throttle even though the throttle body was wide open!

he repositioned the earth lead to the head and connected it under the power steering bracket a good earth!! and this solved the problem

im not saying it could be this but if the voltage is shorting some thing out it could mess with any of the sensors.

Hope this can help you out and get your car running how it should, all the best and keep us updated
 

Last edited:

Rory

New Member
Joined
Mar 21, 2010
Messages
48
Have you tried putting the standard cams back in to rule out them huge cams..?
 


colmbarr1988

New Member
Joined
Oct 31, 2010
Messages
95
The leak down test would have indicated if the compression rings weren't sealing and you would definitely have oil usage if that was the case. What ex. manifold have you got fitted? and did you try standard manifold back on it to see what way the power curve was?

But it wud not have the pressure while been cranked as it wud at 6k wud it?
Yes I done tat at first and it lost power
 


EK9turbo

its a rush!
Joined
Jan 17, 2008
Messages
2,174
More information is needed...

get a datalog of fuel pressure and afr. ideally on the graphs.
 


Top