The facts about 20V VVT

[EFN]

The other day I installed one simple light connected to the VVT trigger pulse from the ECU. It was quite exciting because after that i get to see how VVT works.

VVT will always switch on whenever the engine is cranked up. And will shut off once the ECU sensed some load on the Throttle Position Sensor, Oil Pressure and Vacuum(?). Yes, initially I tought VVT was RPM activated similair to VTEC or MIVEC, no it's totally the opposite.

Upon hard acceleration, VVT will shut off completely to return the Cam angle (retard) to accomodate High Revving. This is very consistent as whenever I plunged the pedal, VVT will immediately shut off. But it will turn back on instantly when pedal is released. And on cruising (Closed Loop ECU mode) it will always be on regardless of the RPM.

So my conclusion is that VVT is purely designed for optimised fuel delivery while maintaining substantial performance - specially on Closed Loop operation where the ECU will fully revert to Engine Sensors (specially O2 sensor). While in Open Loop Mode (70% or above on Throttle opening) where the ECU tries to match the best setup for performance, VVT will be completely ignored.

VVT - MCSB solutions for uncles hahahahaha

PS: Oh yes, just in case you ask, the other RED light is connected to radiator fan, just to tell me when the fan is turned on. The yellow indicator is for VVT

 

[yolk]

i think you pasang your vvt light salah already laaa .. hahahahaha .. this one you ask zul .. he also got this problem before .. where got vvt on as soon as engine on one :blink:

 

[4agze]

when full throttle VVT talak on? <_<
when high rev also talak on? <_<

aiya, then VVT is not 100% usefull in 20v throttle engine la.. :D

i thought VVT engaged on high rev, or some claimed based on TPS... :unsure:

and also, no VVT save fuel a bit... ps: without putting aftermarket cam pulley la. this is what i am experiencing now. also, mid-range a bit em... good .. but high-rev no good la...

 

[TRD16v]

Question: Then how about VVT-i and VVTL-i? does dis 2 uses similar engagement from the engine? wonder.... :unsure: :huh:


Sorry hah dun tembak me k? heehehehe.. juz wanna know :)






Regards,
Mike

 

[Blacktop20V]

My VVT light is the other way round. When start or the accelerator is not press, the VVT light is not on.
According to my VVT light setting/wat I know is that, VVT is to advance your inlet cam when you accelerate/throttle at a certain degree.
e.g. VVT will not work/on during engine cold and running at minimum throttle. VVT will work/on when warm-up and when you give a certain degree of throttle.

*dun tembak if wrong cos just sharing thoughts.

Cheers :lol: :rolleyes: :D

 

[wllim5]

Mike,
VVT-i mean it can variable in a controllable degree of advance or retard.
Regards

 

[4agze]

I don't know about VVT-i and this one have to ask sifoo master QiW laa... but here's how the VVTL-i works...

1. The variable timing is achieved by shifting the phasing of the intake camshaft. Intake and exhaust camshafts highlighted on the diagram are driven by a timing chain. The intake camshaft phasing is controlled by a hydraulic actuator.

2. When the intake valve is fully open, the exhaust valve is nearly fully shut and this giving the engine good low-speed torque characteristics at low revs (2k-3k revs).

3. Above 6k revs, the high valve timing 'overlap' so enough fuel mix can enter and exhaust gas can leave the cylinder and where the VVTL-is are 'lifted'.

4. The VVTL-i changes cam on high revs. It is the unique rocker arm switch that enables the change of cam profile. This changes increses the amount of lift of both intake and exhaust valves at high engine speeds.

5. At engine speeds above 6k revs and when the water temperature has reached 60deg, hydraulic oil pressure pushes against a tappet, engaging the rocker arm pad, thus activating the high-speed cam.

6. The "i" or intelligent in VVTL-i provided by Toyota advanced ECU engine management, that takes speed, acceleration and engine load into account when adjusting valve timing and valve lift.

7. The pistons are coated with iron and tin for better friction reduction and with lightweight and high-strength connecting rods thus giving lower fuel consumption.

8. The engine block is also made of a lightweight high performance alloy. The cylinder walls are toughened by MMC (Metal Matrix Composite) to ensure wear resistance and achieve a liner-less construction.

 

[4agze]

Pic shows different valve position at different engine speed..

 

[4agze]

Pic shows how the cam lift works... pic 1

before engaging advance lift...

 

[4agze]

this is after engaging the advance lift and high engine speed i.e. above 6k revs

 

[AE80TypeD]

nice to have sifu material instead of NATO kok tok all the time.. good job! after this u still say YCSB i cut ur balls and throw down gohtong jaya :lol:

 

[koolspyda]

whhaaa and it mean the 2ZZGE engine (minus the transmission) will sell for RM3K? :huh:

 

[4agze]

muahahaha... Khairul, my car now talak jalan VVT or anything advance so my car much more slow bai MCMMSB lor... :lol:

err... maybe engine kosong only cost RM3k, if halfcut RM7k and above, but still cheaper than B16B :D

 

[GT20v]

its a wrong place...u shud tap at the sensor.then you can see the true operation.

 

[GT20v]

Originally posted by Blacktop20V@Jan 4 2005, 09:21
My VVT light is the other way round. When start or the accelerator is not press, the VVT light is not on.
According to my VVT light setting/wat I know is that, VVT is to advance your inlet cam when you accelerate/throttle at a certain degree.
e.g. VVT will not work/on during engine cold and running at minimum throttle. VVT will work/on when warm-up and when you give a certain degree of throttle.

*dun tembak if wrong cos just sharing thoughts.

Cheers :lol: :rolleyes: :D

you are so correct sir,

this mean VVT engage by TPS and abit of water temp sensor and rpm

 

[AE80TypeD]

i was initially wondering abt fueling issues after disabling/ignoring the VVT function. would there be "wasted" fuel from the ECU map for some of the low and mid range rpm? would the ECU compensate and still give the correct (not over) amount of fuel to the now VVT-less engine operation? i assume that the fueling would still be adequate due to the ECU's nature of deriving correct mixture requirements from various sensors, but would there be some "confusion" or unnecessary compensation for the VVT (which is gone by the way) built into the ECU?

i do know that the 20v can operate like any normal NA engine given a suitable (aftermarket hehehe) management system and proper disabling of the VVT mechanism & systems, among other things... all im wondering abt now is in the case of Stock ECU minus VVT plus adj cam pulley, would there be a discrepancy in the fueling?

note that im not scoping my enquiry in the aspect of power output and delivery; its more towards "would there be wasted fuel leftover or signal control issues by ECU from removing the VVT?" :blink: not trying to argure here, honestly and simply dont know blur case :lol:

altho im hungry for more power, im not ready to sacrifice the lesser but wider distribution of power over the RPM range provided by the VVT... so far it has served me well enough for my gratitude :lol: (excuse for not having the money to go TRIAL actually :lol:) coz if my understanding is correct.. once u off them VVTs, u'll have to choose a narrower spot to have max power/pull... undoubtedly the max gained is worth it, BUT having to live with reduced power at all other ranges (usually low end)

some ppl may think its still good enuff for streetability; im just confused whether keeping the stock ECU with VVTless operation is the most optimum option (when not thinking abt cost lah). im not with or against TRIAL's offer with this post. i may even try it one day... thats what my spare SVT pulleys are for muahahahahahahah :lol:

 

[4agze]

errr... if VVT works with at correcto water temperature, TPS and also engine speed, i think if you're running with VVTless, i think the ECU can recalculate your map fuel to suit your engine running with VVTless? <_<

 

[yolk]

Actually my engine is running leaner without VVT pulleys and also running higher/more stable oil pressure ... so go figure ... hahahahahahahah ... :P

From previous dyno run done the AFR with or without VVT almost 99% the same .. so i would assume that VVT or VVTless the ECU does not compensate on fueling or igntion ... MY ASSUMPTION LAAAAAAAA ... dun tembak me ... :P :lol: as VVT is purely mechanical mechanism in the 20v ...

As for the pulley well ermmmm only way for you to know the difference is to sit in one that has already done it B) :lol: you'll be suprised .. that's all I can say ... hahahahaha ... ideally you can set the adj cam pulley to your most desired powerband yes it will be narrower but since it's going to be the most used rpm it will be better what instead of having a wider spread but not optimum power at the desired rpm .... hmmm what i talking ahhh ... also the adj cam pulley that william did is BRAND NEW MACHINED pulley .. no need old pulley all to modify etc etc B)

 

[AE80TypeD]

cool... :)

 

[AE80TypeD]

oi dat day TT all oso too syiok borak here and there forgot to ask for my fuel pipe+meter oi oi! :lol:

how to mod to EFN regulator like this!?? :lol: