VTEC cutting out then back in
01-17-2017, 05:51 PM
#1
VTEC cutting out then back in
I recently installed SOS stage 1 supercharger and I'm having trouble with vtec cutting in and out. I decided to make another thread to focus more in this issue.
I installed a vtec indicator and it blinks at 5200rpm then goes solid. The car can be felt hiccupping a bit during this time. Any ideas on what can I do to troubleshoot this? So far, I have checked for continuity to vtec solenoid from ecu and its good. Also put 12v to vtec solenoid and it can be heard clicking.
I installed a vtec indicator and it blinks at 5200rpm then goes solid. The car can be felt hiccupping a bit during this time. Any ideas on what can I do to troubleshoot this? So far, I have checked for continuity to vtec solenoid from ecu and its good. Also put 12v to vtec solenoid and it can be heard clicking.
01-17-2017, 06:38 PM
#2
I forget, have you checked the vtec unit screen to make sure its not clogged up for some reason. There is another one in the sandwich adapter/bracket for the blower under it, so make sure both are free and clear, not damaged.
My other suggestion was to unplug the fvm box to test that stock vtec is working, but never mind, since the MAP clamp is also part of that unit and will cause ignition break up if not intact. The old kits had the MAP clamp wired in separate. On a related note, Im wondering if it might not be a fault with the MAP clamp feature in the fvm box, rather then vtec. Just a thought, and all I got for now off the top of my head.
Make sure your plugs are gapped right. Remind us what plugs your using and what are they gapped to? Failure to gap right, or using the wrong plug could cause /hiccup/break up symptoms as well.
My other suggestion was to unplug the fvm box to test that stock vtec is working, but never mind, since the MAP clamp is also part of that unit and will cause ignition break up if not intact. The old kits had the MAP clamp wired in separate. On a related note, Im wondering if it might not be a fault with the MAP clamp feature in the fvm box, rather then vtec. Just a thought, and all I got for now off the top of my head.
Make sure your plugs are gapped right. Remind us what plugs your using and what are they gapped to? Failure to gap right, or using the wrong plug could cause /hiccup/break up symptoms as well.
01-17-2017, 07:11 PM
#3
I forget, have you checked the vtec unit screen to make sure its not clogged up for some reason. There is another one in the sandwich adapter/bracket for the blower under it, so make sure both are free and clear, not damaged.
My other suggestion was to unplug the fvm box to test that stock vtec is working, but never mind, since the MAP clamp is also part of that unit and will cause ignition break up if not intact. The old kits had the MAP clamp wired in separate. On a related note, Im wondering if it might not be a fault with the MAP clamp feature in the fvm box, rather then vtec. Just a thought, and all I got for now off the top of my head.
Make sure your plugs are gapped right. Remind us what plugs your using and what are they gapped to? Failure to gap right, or using the wrong plug could cause /hiccup/break up symptoms as well.
My other suggestion was to unplug the fvm box to test that stock vtec is working, but never mind, since the MAP clamp is also part of that unit and will cause ignition break up if not intact. The old kits had the MAP clamp wired in separate. On a related note, Im wondering if it might not be a fault with the MAP clamp feature in the fvm box, rather then vtec. Just a thought, and all I got for now off the top of my head.
Make sure your plugs are gapped right. Remind us what plugs your using and what are they gapped to? Failure to gap right, or using the wrong plug could cause /hiccup/break up symptoms as well.
Can I take off supercharger belt, lower rrfpr a bit, and run my stock ecu to see if vtec is engaging correctly without the fvm? SOS said this vtec hiccup is not normal.
I'm running BKR7EIX11 I just bought last month gapped at. .036".
01-20-2017, 10:06 AM
#4
Is it safe to run a supercharger with belt disconnected? I'm going to take it to operating temp and hit vtec without fvm to see if the indicator flashes. This will tell me if the hiccup in vtec is caused by the fvm module.
Then I'll I connect the fvm and try it with no belt connected to see if the hiccup is boost related.
Also will lower fuel pressure in both tests (I'm running pretty high pressure right now at 76 psi at atmospheric) to rule out the fuel pressure causing hiccup.
Then I'll I connect the fvm and try it with no belt connected to see if the hiccup is boost related.
Also will lower fuel pressure in both tests (I'm running pretty high pressure right now at 76 psi at atmospheric) to rule out the fuel pressure causing hiccup.
01-20-2017, 11:10 AM
#5
VTEC requires WOT as well as rpm. Not sure where/how WOT is determined, especially on a supercharged car. Some sort of blue smoke and mirrors in the ECU I imagine. If your rpm is right around the VTEC set point I'd think it would go in and out depending on minor throttle settings.
-- Chuck
-- Chuck
01-21-2017, 06:15 AM
#6
Join Date: Nov 2007
Location: Illnoise. WAY downtown, jerky.
Posts: 8,357
Received 1,377 Likes
on
1,029 Posts
VTEC doesn't require WOT. It requires like 12% throttle, IIRC. If the car has piggyback or aftermarket ECU tuning, the electronic portion could have ONLY RPM as a parameter...or whatever parameters are set by the tuner/tuning media.
His screen is probably clogged. Or there's an issue with some signal that the ECU and/or tuning media needs for VTEC.
His screen is probably clogged. Or there's an issue with some signal that the ECU and/or tuning media needs for VTEC.
01-21-2017, 04:18 PM
#7
Ok so I did those tests I mentioned earlier.
With no boost and running stock ecu, there is no vtec stutter. Engages perfectly at 6200 rpm.
With no boost and fvm module from SOS, there still isn't vtec stutter and vtec engages at 6200 rpm.
So this tells me that the Fvm does not lower vtec unless it senses boost. Because vtec is usually at 5200rpm with my. Belt connected. And when it lowers to 5200, there is the slight stutter.
Now I'm wondering if this hiccup is normal with the fvm module but it's so slight that people usually don't notice it.
With no boost and running stock ecu, there is no vtec stutter. Engages perfectly at 6200 rpm.
With no boost and fvm module from SOS, there still isn't vtec stutter and vtec engages at 6200 rpm.
So this tells me that the Fvm does not lower vtec unless it senses boost. Because vtec is usually at 5200rpm with my. Belt connected. And when it lowers to 5200, there is the slight stutter.
Now I'm wondering if this hiccup is normal with the fvm module but it's so slight that people usually don't notice it.
Last edited by jdmz; 01-22-2017 at 02:13 PM.
Trending Topics
01-22-2017, 06:50 AM
#8
Your problem... It's not mechanical, it's electronic. 100% ... The indicator light is picking up off the VTEC solenoid circuit...? If the circuit closes then randomly opens again, something is wrong with the control.
Your troubleshooting is excellent. Seems you've isolated the FVM as the problem, but only under boost.
Given that it works fine with no boost, I'd speculate there's a problem with one of the associated inputs, or thresholds set in the FVM. I don't know how the module works though, so it's a problem for SOS to sort out.
...
Do you have any provisions for datalogging? This is all speculation, but... I'd expect a small drop in MAP on a supercharged car, when VTEC engages... If you had belt slip and boost was already a bit low, and VTEC kicked MAP just below the boost threshold... Dunno.
Your troubleshooting is excellent. Seems you've isolated the FVM as the problem, but only under boost.
Given that it works fine with no boost, I'd speculate there's a problem with one of the associated inputs, or thresholds set in the FVM. I don't know how the module works though, so it's a problem for SOS to sort out.
...
Do you have any provisions for datalogging? This is all speculation, but... I'd expect a small drop in MAP on a supercharged car, when VTEC engages... If you had belt slip and boost was already a bit low, and VTEC kicked MAP just below the boost threshold... Dunno.
01-22-2017, 08:33 AM
#9
VTEC doesn't require WOT. It requires like 12% throttle
-- Chuck
01-22-2017, 05:51 PM
#10
Your problem... It's not mechanical, it's electronic. 100% ... The indicator light is picking up off the VTEC solenoid circuit...? If the circuit closes then randomly opens again, something is wrong with the control.
Your troubleshooting is excellent. Seems you've isolated the FVM as the problem, but only under boost.
Given that it works fine with no boost, I'd speculate there's a problem with one of the associated inputs, or thresholds set in the FVM. I don't know how the module works though, so it's a problem for SOS to sort out.
...
Do you have any provisions for datalogging? This is all speculation, but... I'd expect a small drop in MAP on a supercharged car, when VTEC engages... If you had belt slip and boost was already a bit low, and VTEC kicked MAP just below the boost threshold... Dunno.
Your troubleshooting is excellent. Seems you've isolated the FVM as the problem, but only under boost.
Given that it works fine with no boost, I'd speculate there's a problem with one of the associated inputs, or thresholds set in the FVM. I don't know how the module works though, so it's a problem for SOS to sort out.
...
Do you have any provisions for datalogging? This is all speculation, but... I'd expect a small drop in MAP on a supercharged car, when VTEC engages... If you had belt slip and boost was already a bit low, and VTEC kicked MAP just below the boost threshold... Dunno.
Nope no data logging. When I get that capability I will ditch the fvm.