VTEC engagement and Turbo
Originally Posted by riceburnrex
The 02+ Si's VTEC system is NOTHING like the D17's or any other D series for that matter. Nothing is comparable. It does not work the same at all.
and it IS similar to the d17a2's vtec in a sense that it is 2 lobe, built for fuel efficiency and engages at about the same rpm (~2200)
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Originally Posted by riceburnrex
This guy is exactly correct. I'm looking at the Honda Factory Service/Repair/Diagnostics manual for my 01 right now, and under "Troubleshooting: VTEC will not engage" it says to hook up voltmeters to all the sensors caorndorff just said, and it says that if one of those conditions is not met, then VTEC will not engage. All of the above conditions must be met, including the RPMs. I've also used an oil pressure gauge on my car, and it does not hit 65psi until 3700 rpms or so, so the RPM's must be at least that to engage VTEC.
You guys talking about the B series... you do know that most of those motors also have secondary intake runners, right? Those butterflies do not have to have anything but RPM and throttle % to engage, and the RPM point is lower than VTEC engagement. That's what you're hearing with the whistling sound.
You guys talking about the B series... you do know that most of those motors also have secondary intake runners, right? Those butterflies do not have to have anything but RPM and throttle % to engage, and the RPM point is lower than VTEC engagement. That's what you're hearing with the whistling sound.
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Originally Posted by 4drcivic2k1
Properly configured, the VTEC transition point will not be evident, even in a B series. The only exception is in large cams that have a significant difference in lobe size. Most hondas have different VTEC activation points as the motor configuration is different.
Mr. Honda Parts Guy, I recommend you learn how to correctly express your feelings towards guns using proper english, because all it does is make you look like an idiot.
Ok, a "ting" is not a word. "Thing," on the other hand, is. And if you work at a honda dealership, why do you mistype VTEC? It's not v-tec.
Mr. Honda Parts Guy, I recommend you learn how to correctly express your feelings towards guns using proper english, because all it does is make you look like an idiot.
Ok, a "ting" is not a word. "Thing," on the other hand, is. And if you work at a honda dealership, why do you mistype VTEC? It's not v-tec.
So if you're a Honda tech why don't you go take a diognostic drive in a 2001+ EX, print the sheet out and show us when vtec actually kicks in. That'd finish this discussion off pretty quick.
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Rep Power: 0 I’m not a Honda tech, Guns mix up my words, I work in a Honda parts department and I have some friends that are Honda techs. But if this isn’t good for everyone I will bring more evidence to the table.
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It's funny that you guys don't believe a tuning device connected to the ecu that shows when the signal is sent to switch cams. Oh well. I guess everyone has their own opinion about it.
Originally Posted by caorndorff
1 Your MAP (Manifold Absolute Pressure) sensor must read 0hg (aka 0 inches of vacuum). When it reads this it will send a 3volt signal to the ECU.
2. Your throttle has to be open 100% because your TPS sensor has to send a 4.5-volt signal to the ECU.
3. Your coolant temp has to be at running temp.
4. Vehicle speed has to be above 20mph.
5. You have to have 65-80 oil psi.
6. The engine must be running at a minimum of 4500 RPM
When all of this happens your ECU sends a 12-volt signal to your v-tec solenoid that activates your 4 lock Motion assembly’s (or if you have DOHC 8 LMA’s because SOHC has vtec on the intake only)
First off you cannot hit v-tec at 2500 RPM because your engine is making only about 35 of oil psi.
Second you have to have 100% Throttle because 50% throttle only sends 3 volts.
2. Your throttle has to be open 100% because your TPS sensor has to send a 4.5-volt signal to the ECU.
3. Your coolant temp has to be at running temp.
4. Vehicle speed has to be above 20mph.
5. You have to have 65-80 oil psi.
6. The engine must be running at a minimum of 4500 RPM
When all of this happens your ECU sends a 12-volt signal to your v-tec solenoid that activates your 4 lock Motion assembly’s (or if you have DOHC 8 LMA’s because SOHC has vtec on the intake only)
First off you cannot hit v-tec at 2500 RPM because your engine is making only about 35 of oil psi.
Second you have to have 100% Throttle because 50% throttle only sends 3 volts.
2. I don't believe this to be completely correct ... if you launch at 6000 rpms and feather the clutch on say .. a gsr, vtec crosses over when you are not at full throttle.
4. I don't believe engine speed matters. If a car had a new transmission swapped into it with very short gearing, then I'm sure things would change.
for 2's argument, I guess could be waved off if this 100% throttle thing refers to ONLY d17's and maybe k20a3's.
still doesn't explain why the vtec light lights up ~2200-3000
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Different motors hit VTEC at different rpm (but never under 5000) each motor has a set rpm in the ecu when VTEC hits example b16a hits at 5500 and not before and not after. and it will not change at all unless you use an ECU hack (like VAFC which stands for VTEC and Air Fuel Controller). what an VAFC does is lies to the ECU and sends a 12 volt signal to the solenoid at the rpm you set on the VAFC. All you guys who think VTEC engages at 2000 on a stock motor. go get on honda-tech.com and post somthing about it they will prove you wrong in 2 seconds. the best honda techs in the world are on that site.
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Alright, I just used my scantool/datalogger on an 02 EX and here are the results...
VTEC solenoid kicks in only with wide open throttle
Oil Pressure was at 65psi
RPM's were at 5100.
Repeated this test 5 times, results were the same. This was with a portable Honda scan tool.
I'm going to trust the results of that over the display of an aftermarket device designed to change the VTEC engagement point.
VTEC solenoid kicks in only with wide open throttle
Oil Pressure was at 65psi
RPM's were at 5100.
Repeated this test 5 times, results were the same. This was with a portable Honda scan tool.
I'm going to trust the results of that over the display of an aftermarket device designed to change the VTEC engagement point.
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Rep Power: 812 It seems so hard to believe about wot activation. But I'm gonna believe it because of what you posted--thanks for clearing it up. So is there any problem with never having the vtec work? I think I floored my car a total of 3 times since I've owned it. I guess I don't even know what it feels like then.
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Rep Power: 0 On our cars, it's not really that easy to feel. If you have an open intake you might be able to hear it, but it's not a punch like the B series and the H series were. Since ours only has VTEC on the intake side, it's not nearly as much of a power gain when it kicks in.
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i dont know about all this oil pressure and speed poop, i know thats how vtec engages on a b-block. i have the little vtec light right, a friggen light bulb in parallel with the vtec solenoid. it comes on every day, no doubt about it at ~2500 rpm at wot with engine at normal operating temp and speed > 0 mph. partial throttle depends on rpm etc, but its always below 4000. i dunno guys, this is a pretty intense argument, i just know what i see every day when i hit ~2500 rpm at wot. take it for what you will. -- Jeremy
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Rep Power: 339 well wtf? why would they make vtec-e engage so high? are they trying to make the car run rich?
you have to take into account the 2 lobes on the intake side of the camshaft, both lobes are the same size, so one of them is always on, the other is only on at certain times..
now the only way to prove this is...
1. get a clear valve cover
2. film it on a dyno, engine, revs and so fourth
3. slow down the camera enough to see when when it engages
now if anyone would like to try those.. go right ahead...
you have to take into account the 2 lobes on the intake side of the camshaft, both lobes are the same size, so one of them is always on, the other is only on at certain times..
now the only way to prove this is...
1. get a clear valve cover
2. film it on a dyno, engine, revs and so fourth
3. slow down the camera enough to see when when it engages
now if anyone would like to try those.. go right ahead...
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part #012 SWITCH ASSY., VALVE TIMING OILPRESSURE
so i assume oil pressure and valve position is involved in the system
see for your self! http://www.hondaautomotiveparts.com/...R+HEAD+%282%29
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Rep Power: 0 VTEC works the same on a d series (intake only)as it does on a on a b series. and the reason your light turns on is probly because one of the 5 peramiters needed to engage VTEC was activated and that sent a few signal volts to the solenoid, it only takes about 3 volts to light up the L.E.D and 12 volts to engage the solenoid and thats why the L.E.D is lighting up. and if you dont belive me belive riceburnrex he used a scantool/datalogger cant argue with facts. There are 3 lobes on the intake (per cylider) 2 of which are the same size the third (in the middle) is the VTEC lobe which is bigger. while VTEC is engaged the other 2 lobes dont touch their respective rocker assemblies. both rocker arms are locked to the Mid rocker arm by a electronicly controlled hydralic system (part of VTEC). then both valves are opened by the VTEC lobe.
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Rep Power: 0 All this sounds strange to me. But it does explain why the car looses power when you change the vtec engagement point. The VAFC2 only sends a sinal to engage VTEC but it does not change the 5 othewr things you guy are talking about.
I for one loved my D17 when I had it. But Even with a Cam and highly modified I never felt a VTEC kick,
I for one loved my D17 when I had it. But Even with a Cam and highly modified I never felt a VTEC kick,
Originally Posted by ludes-r-cooler
VTEC works the same on a d series (intake only)as it does on a on a b series. and the reason your light turns on is probly because one of the 5 peramiters needed to engage VTEC was activated and that sent a few signal volts to the solenoid, it only takes about 3 volts to light up the L.E.D and 12 volts to engage the solenoid and thats why the L.E.D is lighting up. and if you dont belive me belive riceburnrex he used a scantool/datalogger cant argue with facts. There are 3 lobes on the intake (per cylider) 2 of which are the same size the third (in the middle) is the VTEC lobe which is bigger. while VTEC is engaged the other 2 lobes dont touch their respective rocker assemblies. both rocker arms are locked to the Mid rocker arm by a electronicly controlled hydralic system (part of VTEC). then both valves are opened by the VTEC lobe.
maybe the vtec signal changed with our cars, who knows. but on my friend's 99 ex, his vtec light lights up at 5500 rpms, and you can definitely hear it with his mods. older d series vtec was 3 lobe vtec, not like ours.
so basically are you meaning to say that the light doesn't mean anything? so my friend's vtec actually kicks in at 6500 or so?
... I believe what I can see ... and I don't see concrete proof (ie. cam switching over, etc).my theory: vtec does not kick till about 4-4.5k (there is a very faint tone change) ... perhaps the reason vtec lights up is because of the 4 other valves are opening up (ie. d17a2, like the k20a3, is a 12 valve engine until 2200 rpms) ... which I guess it wired through the vtec solenoid
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Rep Power: 812 I do hear the noise change after 4k rpms. I just can't buy the part that the throttle has to be 100%. I just got my vafc tuned and they set the engagement at 2800rpms. I changed it back to stock just in case of damage, but I didn't notice a difference. Then went around flooring the pedal and making sure the throttle reading was 100%. Still can't tell the difference.
