Opening VTEC....

[D-IV]

From my point of view, the reason why the temp is there is because of valve lash.

Remember when setting the cams? Why do we need to wait for the head to be cold? so the measurements aren't affected by the heat.

Similar to when the engine is in use, cold means that the cam lobes and the cam followers aren't really taking up the slack of the valve lash?

What happens when valve lash is too loose?

What happens when valve lash is too tight?

That, people, is a good question to ask your mech.

Refrain from answering....... refrain from answering

 

[crower75]

abe crower, u still up north kah? when wanna bring ur EG to test test with penang adik adik,...?

Penang all very laju nowdays.......all pakai Roket ehehe...EG in KL oredi, retired. Nowdays ViVa miahahahah

 

[arrowhead]

omg. when shiro speaks, i go into this state of blurness, then i have to drink a cup of water, wash my face with water, and read his post one more time... but still i dont get it.. LOL

 

[sazleej]

VTEC temp, I'm not sure stock, but I think it's about 50-ish, so DIV is close.. for hondata, I set mine to 65, because I know I won't rev the car when it's cold.

From my point of view, the reason why the temp is there is because of valve lash.

Remember when setting the cams? Why do we need to wait for the head to be cold? so the measurements aren't affected by the heat.

Similar to when the engine is in use, cold means that the cam lobes and the cam followers aren't really taking up the slack of the valve lash?

What happens when valve lash is too loose?

What happens when valve lash is too tight?

That, people, is a good question to ask your mech.

sifooo... buler 11 ambo kelik kelater.. pindah dari sabah! eheheheheee mujo ado master.. duduk beloh mano??

 

[hattech-v]

different afr setting will produce different sound...
other than it, cam overlap, cam type n bla bla...
oit klower, long time no see...
ur viva running what engine?

 

[shiroitenshi]

sifooo... buler 11 ambo kelik kelater.. pindah dari sabah! eheheheheee mujo ado master.. duduk beloh mano??

dok "red soil".. tapi kadang kadang dok 'new town' ha ha.

What car you driving?

 

[fobs]

different afr setting will produce different sound...
other than it, cam overlap, cam type n bla bla...
oit klower, long time no see...
ur viva running what engine?

running dohc dvvt,... hehehe!!! also got the prangggggggg sound eh???

 

[J101]

what tuning was it? u running on standalone or piggyback? just wondering

it used to be at 5.5k, but suhaimi from avantech did some minor tuning to it, now it opens back at 5.8k... however my question was regarding the soft vtec sound on initial attempts... :hmmmm:

 

[hattech-v]

j101, its a chip with p30 oem map....
not a tuned chip one...

 

[D-IV]

different afr setting will produce different sound...
other than it, cam overlap, cam type n bla bla...
oit klower, long time no see...
ur viva running what engine?

How can different AFR produce different sound? Thats news to me... please elaborate...

 

[hattech-v]

try to make ur afr fr 12.5 until 14 at vtec point... listen to the sound...
lean will make the vtec sound scream nicely and rich will make the sound like sebu... haha

 

[shiroitenshi]

Hmm.. I think I've tried that.. but I achieved that by running 13's AFR and increasing ignition.. but I've experienced extreme knocking when advanced too much, and coupled with the vtec scream... I reduced it to something a little more manageable. But I could never make it sound like a sohc vtec. that's why arrowhead's comment about the sound is strange to me.

My friend that tested the car with 13AFR and 30+timing mentioned the vtec sound like the sound of a 'grinder'..

Settings are fine, but he wouldn't keep it floored.. scared it blows.. lol.

 

[D-IV]

I've never noticed that when i was tuning. When i was doing my wire tuck project, i ran the car without the intake pipe on. hit vtec at 11.5 AFR sounds basically the same to me when i hit it at 13.8 AFR during the nights... Whats the technical reason behind the sound anyway? If its baseline run with stock original intake vs. after tuned with aluminium pipe intake ... ofcourse the sound will be diffferent. I'm not so convinced yet so go technical if its explainable...

 

[arrowhead]

omg too technical... but good info.

 

[shiroitenshi]

I've never noticed that when i was tuning. When i was doing my wire tuck project, i ran the car without the intake pipe on. hit vtec at 11.5 AFR sounds basically the same to me when i hit it at 13.8 AFR during the nights... Whats the technical reason behind the sound anyway? If its baseline run with stock original intake vs. after tuned with aluminium pipe intake ... ofcourse the sound will be diffferent. I'm not so convinced yet so go technical if its explainable...

It's actually the timing, div. if you advance enough, the peak pressure is achieved just as the exhaust valve opens fully. That's causes higher exhaust speed which goes out the exhaust giving you the sound. But with higher timings, comes higher risk of knocking. How fast would the fuel burn (the burn rate) given the conditions dictate how much timing is optimal. That's why some people would say increasing fuelling would give you the 'louder' sound, while some would say the 'timing'

You can actually run lean settings to get power on NA, but it's not really without risk.

Why I say this is because you can observe from the original mapping of factory ecus, that the peak rpm has higher AFR recommended mixtures is because a speed density system only estimates the amount air coming in, based on MAP and IAT, the ECU calculate the density of the air coming in (the TPS is there for another reason). The inherent inaccuracies in this type of system means we have to 'allow' some safeguards in the tune.

In fact, if you notice, when we floor the accelerator, there's usually a quick lean spot (how lean is based on the part throttle tune), even though we can see on the ECU mapping that it's already reading the high load portion of the ECU. I'd have to wait a few moments for the AFR to stabilize, and tune from there. Adjusting some other cells also affect the adjacent cells, so it's up to the tuner to figure out which cells are involved, in order to get a good tune out. Sure, you might not get that ultimate power tune, but when reliability is involved, it pays to play it safe.

That's why tuning is a matter of being able to get reliable AFRs out, and estimating the timing needed to get the most out of the engine without incurring too much risk.

But it seems to me that your AFR would swing so wildly from the day to the nights.

Usually it's 12+ for me in the day, 13+ at night. About one point difference only.
from 11.5AFR to 13.8 AFR, you must have really hot/humid days and really cold/dry nights. NICE!

If anyone wants to read about AFR and don't want to pay for the SAE research papers, this is something I dug up from google.. I also have the book, lol.
http://books.google.com.my/books?id=RYsglAO9f8gC&pg=PA133&lpg=PA133&dq=humidity+air+fuel+ratio&source=web&ots=bT7Kz_hO9y&sig=9JC4QiDF0ToZnvk4GgGgW0R0nvA&hl=en&sa=X&oi=book_result&resnum=2&ct=result

Page 134 is a gem (make sure your engine is healthy and tunable) LOL. Doesn't apply to Malaysian s though.. I saw cars being tuned in less than healthy conditions.

But some of his info is outdated or a little inaccurate due to the fact that somethings have changed from during his time, which include engines that can exceed of 8,000 rpm by A LOT 'unworkable' rod stroke ratios (in his time) which influences the leverage, hence the peak pressure point is no longer the claimed '15 degrees' ATDC. and also the fact that EMS have more cells and faster processors now.

Not to say that he is wrong.. he is right in his time, but with new engines and new technologies, some rules have changed. But most basic stuff is there, and they're all supported by SAE white papers (if anyone have ever bothered to check)

 

[D-IV]

It's actually the timing, div. if you advance enough, the peak pressure is achieved just as the exhaust valve opens fully. That's causes higher exhaust speed which goes out the exhaust giving you the sound. But with higher timings, comes higher risk of knocking. How fast would the fuel burn (the burn rate) given the conditions dictate how much timing is optimal. That's why some people would say increasing fuelling would give you the 'louder' sound, while some would say the 'timing'

Thanks. It does sound logical that increased cylinder pressure would affect the exhaust note but that is also dictated by the exhaust system. Though i've tried it last night but just played around with the fuel pressure and opening up back my intake hose so the throttle body is exposed during the run.

I've tested it within 30 mins:
AFR - 12.5 - 14.3 = same exhaust note (well atleast no noticeable changes).

 

[hattech-v]

ur vtec not on perhaps...

 

[D-IV]

I would if its not ON~ Can't sleep until it can turn on

Seriously... it is on... trust me and its loud as hell if your original intake pipe is not assembled to cover the TB but mine is :slug:

 

[arrowhead]

ur vtec not on perhaps...

that would be me lol

 

[sb3]

Check your solenoid as well, its spring operated. Sometimes sludges get in there and can cause it to be stuck too. Take out the VTEC solenoid and clean it out. Hardly the problem though, my first impression would be like Shiro's, might be the oil pressure sensor acting up..

Once the water temp passes 60, VTEC will open. I'm not so sure whether there is such thing as partial opening of VTEC.

Nope dont think VTEC can be partially open, its either the big cam lobe is operating or otherwise (small cam operating).