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I have a 03 Type S, Kproed and supercharged.

long story short, dynoing the car and all of a sudden, no VTEC. Swaped out ECU, swap engine harness, swap VTEC and VTC solenoid, swaped out VTEC Oil pressure switch, swap out multiplexer and still no go.

VTC voltage under load is around 6V, not quite 12V to activate it. Does anybody
know why? did I miss anything?
 

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Maybe something dumb, But have you checked your Oil level. I dont know if this is true or not but I hear if your low on oil Vtec will not work also. This did come from a mechanic that worked at a performance shop.
 

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yes, there is plenty of oil. even a fresh oil change, checked the VTEC and VTC filter, all good. Had a mechanic verify that the VTEC mechanism working properly too.
 

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Any CEL's

Any TPS or MAP issues?
 

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Discussion Starter #6
Any CEL's

Any TPS or MAP issues?
Nope. engine check light didn't come on and Kpro says everything is good. TPS is reading fine and Map is reading fine and registering boost.

are you sure your just not feeling vtec engage?
for sure. The problem happens while the car was on the dyno. First 6 runs was making good power and then on the seventh run, we had to shut it down around 5K and horsepower was down significantly. Thats how it all started. weird anomaly was that on the seventh run, it killed connection to the ECU and fried the Knock sensor. There was no knock in previous 6 runs and AF ratio was rich to the point of loosing power then back off 2%.

I later got a new knock sensor, put it in and it was happy, still no VTEC.

What I like to know is for the guys that are doing K20A2 swap, there are 3 connector that plugs into the ECU, the 2 connector on the right is main engine sensor, ignition, and injector wire harness. The connector on the left, closest to the driver is part of the internal main wiring. Do you splice most of the wire from this connector to the sensors?
Does most of those wire go to the multiplexor or just that yellow wire? I know Part of that connector connects with the main engine wire harness with that flat long connector which is part of the engine wire harness.
Does it go out to the fuse box under the hood?

the manual doesn't say much about where that connector go.
 

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check if your oil pan is dented real bad.. that could cause loss of oil pressure which would definately cause vtec to not engage.
 

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check if your oil pan is dented real bad.. that could cause loss of oil pressure which would definately cause vtec to not engage.
yes, I have checked the oil pan and no dent.

Been Going over the Helms manual and comparing data to a friends 03RSX which is the same as mine.

It seems the voltage output from the ECU is correct which lead me to believe ECU, wiring, and Sensors are fine.

Right now, everything is pointing to mechanical, I know there is oil cause VTEC oil pressure switch is kicking in. Its either the pins aren't firing or there is a block in the oil gallery to the rocker arm. I will have to perform some test in the next few days.
 

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1.could be low on oil 2.vetec solenoid clog up 3.check for disconected vectec wire on solenoid and computer 4.make sure tps plug is conected 5.check for any cut or broken wires 6.typically if the tps is not functioning correctly when you are data logging the sensor needs to be replaced. the k series tps is widely known to be a very fragile piece so handle with care!
 

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also check and see if your gauge is working properly. Mine was not working...and i went on my kpro and changed vtec's minimal speed to 0 instead of 6mph and BOOM it worked....worth a try....:up:
 

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Why dont you find out what your oil pressure is?
The oil pressure is 35+PSI at idle and shoot up to 60+ PSI when engine is rev.
After 3000RPM its 85+ PSI


did you check the strainer on teh front of the head.
I did and it is clean.

1.could be low on oil 2.vetec solenoid clog up 3.check for disconected vectec wire on solenoid and computer 4.make sure tps plug is conected 5.check for any cut or broken wires 6.typically if the tps is not functioning correctly when you are data logging the sensor needs to be replaced. the k series tps is widely known to be a very fragile piece so handle with care!
Oil level is full, I even did an oil change when the problem began, switch out complete Vtec solenoid with casing holding the Vtec Oil pressure switch, even the Oil pressure switch is swapped. A known good Engine wiring harness was completely swapped in, I gone over the wiring and voltage on the solenoid and everything was fine.

=egkswap;550053]also check and see if your gauge is working properly. Mine was not working...and i went on my kpro and changed vtec's minimal speed to 0 instead of 6mph and BOOM it worked....worth a try....
I will try this as I haven't tried it yet.

Thanks for all your help as multiple people thinking is better than one. I have been fighting this for the past 3 months.:)
 

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d0000d wtf I have the same issue, no cels, changed everything etc, except mine just cuts out...... GL man I think its electrical
 

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UPDATE!!! UPDATE!!!! UPDATE!!!!

It seems like a map sensor problem all along. Kpro tells me that the map sensor is working fine but when going into boost, it bog down, piss and miss here and there. This doesn't happen all the time but its so bad that it feels like VTEC won't kick in. So VTEC was checked out and it was fine, sensors was swapped out and even engine wire harness was swapped.

After map sensor switch, the car missfires in the mid range but ran ok in the top RPM. A new set of spark plugs was installed and now no miss and just fuel tuning as this map sensor(stock) was reading differently from previous map sensor.

So K20Spooner, swap out your map sensor, Kpro reads the map fine but it was definately defective probably from a power spike that ruin it.
 
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