theory on the power drop after 5k

[Crashes]

I think its this...read

Meanwhile, variable valve timing delivers more torque and more power than a conventional engine.

To achieve the aggressive targets on improving torque, horsepower and smoothness, Mazda engineers focused on several other areas, as well. First was developing a new intake manifold. Using an array of powerful computer aided engineering (CAE) tools to compare various designs and options, engineers developed a sophisticated new friction-welded nylon intake manifold with equal length runners that incorporate new devices called swirl control valves. Mazda engineers fitted these specially designed control valves into each of the intake runners, close to the cylinder head flange.

These valves or "tumble flaps" in the variable induction system are controlled by a solenoid actuator and are closed during light-load operations, such as idling at traffic lights, shifting actions and deceleration, to maximize combustion efficiency, fuel economy and emissions performance.

The valves are fully open during higher load conditions, roughly 5,000 rpm, to maximize volumetric efficiency and power output.

The intake manifold is constructed of part-recycled material. Its design improved engine sound quality by emphasizing the even-order engine harmonics - a key to the equal length design.








perhaps mazda didnt remove it, thinking it gained us more power when its really bottle necking it..perhaps someone can buy an intake and remove it? I may try it, if nobody trys...

 

[chriscecc914]

great info. The car would probably run horrible without these "flaps" unless you get a retune. Id like to see what comes of this.

 

[Silo]

There is no need for theories if you have logged the TPS on a full throttle run...

You will clearly see that it is the odd (ECU controlled) throttle behaviour that is causing the massive drop!

 

[Killer]

Yep..ECU does it.

 

[dadasracecar]

This is the VTCS or Variable Tumble Control System flaps. The are used to speed up the intake air at cold start so that he combustion is hotter and lights up the catalytic converter more quickly. You can do lots of searching on this in the N/A 6 forums. It's purely a cold start emissions reduction mechanism. Probeturbo (drives a Speed6) and I removed the VTCS flaps from his intake. The result was that his car pulled well past the 5500 rpm cutoff (pre recall) that we all have and a little bit of rough idle when cold. Once it warms up there is no difference. Basically these flaps are a restriction in the intake. Removal should only improve performance.

 

[Silo]

Dada, removing the VTCS intake butterflies shouldn't make any big difference on the 5k+ cut off as they should be open at this time and the ECU will still be closing the throttle.

PS: Didn't you received my PM regarding the Standback map?

 

[chriscecc914]

Dada, removing the VTCS intake butterflies shouldn't make any big difference on the 5k+ cut off as they should be open at this time and the ECU will still be closing the throttle.

PS: Didn't you received my PM regarding the Standback map?

in the first post it reads that the flaps stay fully open until 5000rpm. It doesnt state what they do after that but im guessing they start to close

 

[jbspeed6]

This is the VTCS or Variable Tumble Control System flaps. The are used to speed up the intake air at cold start so that he combustion is hotter and lights up the catalytic converter more quickly. You can do lots of searching on this in the N/A 6 forums. It's purely a cold start emissions reduction mechanism. Probeturbo (drives a Speed6) and I removed the VTCS flaps from his intake. The result was that his car pulled well past the 5500 rpm cutoff (pre recall) that we all have and a little bit of rough idle when cold. Once it warms up there is no difference. Basically these flaps are a restriction in the intake. Removal should only improve performance.

What was the *un*-install time on this?

 

[LBV]

Dada, removing the VTCS intake butterflies shouldn't make any big difference on the 5k+ cut off as they should be open at this time and the ECU will still be closing the throttle.
QUOTE]

Well, actually it will because you don't have them there at all. In other words, removing the assembly completely is better than leaving them in and open.

 

[probeturbo]

wow i just stumbled on this!! ok i have had the Flaps out of my car for about a month or so now. i do have a slight hesitation on COLD mornings for about 5 minutes and it clears up. But on warm mornings it is fine. As for low end torque I have not noticed ANY LOSE. I have been a little silent with this as i have been wanting to wait til i went to the dyno to see if there is an improvement. What i can say is before i could feel my car fall flat on its face like others have at about 5700 or so. Well i have not felt the car fall like that until 6100 or so now. I wnat to prove this on a dyno though first.

Other proof that it must be working is i have raced my friend from a 40mph roll with his 13.7 sec altima and he USED to instantly pull me and just keep going. Now i am able to stick with him til about 130 from a 40mph roll before he starts pulling away. I don't and haven't had any downsides to this mod at all. I am at the point of recommending it. I know the probe gt with the VRIS is sorta the same set up and i have seen 7hp gain with them taken out of their intake. I think what was going on with the upper end was both the throttle and the butterflies are closing at that point.

also NO IDLE PROBLEMS AT ALL!!!

 

[jcgemt2003]

wow i just stumbled on this!! ok i have had the Flaps out of my car for about a month or so now. i do have a slight hesitation on COLD mornings for about 5 minutes and it clears up. But on warm mornings it is fine. As for low end torque I have not noticed ANY LOSE. I have been a little silent with this as i have been wanting to wait til i went to the dyno to see if there is an improvement. What i can say is before i could feel my car fall flat on its face like others have at about 5700 or so. Well i have not felt the car fall like that until 6100 or so now. I wnat to prove this on a dyno though first.

Other proof that it must be working is i have raced my friend from a 40mph roll with his 13.7 sec altima and he USED to instantly pull me and just keep going. Now i am able to stick with him til about 130 from a 40mph roll before he starts pulling away. I don't and haven't had any downsides to this mod at all. I am at the point of recommending it. I know the probe gt with the VRIS is sorta the same set up and i have seen 7hp gain with them taken out of their intake. I think what was going on with the upper end was both the throttle and the butterflies are closing at that point.

also NO IDLE PROBLEMS AT ALL!!!

Please for the love of God go and dyno!!!!!!!You will be credited for solving the the 2nd Biggest problem we have with power on this car.(1st fuel)....I will personally start a THREAD NAMED YOU ARE A GOD were every board member with a speed3 or 6 will thank you....No joke....that is only if it works.

(attn)

 

[probeturbo]

I will!! But i have a question. i did a test tonight on the way home and wanted to see if it wasn't just me. I punched it at about 4000 in 3rd and i took it all the way to 6500. Now one it fell at about 6000-6100 but my boost all the way to 6500 stayed at about 11-12psi. What is your boost at about that rpm if you do that test. I am not talking to just you jcgemt2003 but anyone? Just curious as i have heard that about 6500 most are at 7psi???

My previous hp was 217 hp and 246 torque done about 1 month ago on a dynojet. So when i get a chance to get up there then i will dyno again on the same dyno.

Also am i the only one that has this mod? That can test this? I know whoosh has emailed me a few time about this as he was supposed to be doing it.

 

[Silo]

+1 on the dyno!

I am not aware (nor is it written somewhere) that the VTCS is closing after 5k rpm. Why would Mazda do this anyways? Of course removing the VTCS all together will free up some space in the intake runners and probably smoothen the air flow as well which should translate into more overall power and better accelleration - but there is still the question why they should be closing at 5k.

Can the VTCS be monitored through OBD? I haven't looked into this yet.

 

[jcgemt2003]

I gotta tell you that I dont have the stock turbo anymore so my boost doesnt nose dive quite as much but if you look at some of my dynos the power drop is still the same.

 

[Afroman]

Sort of off topic, but here are some thoughts from my previous car.

These flaps sound incredibly similar to what is refered to as "secondary intake runners" on my old cougar. For each cylinder there were two ports for air to come in. At low RPM up to about 3000 RPM one of the two ports would be closed by a butterfly valve.

Once 3000 RPMS was reached the secondary intake runner valve would open and allow for more air to get to the the engine. Thiis increased performance. If by chance they butterfly valves were malfuncitoning and stayed closed, it was like hitting a brick wall at 3000 RPMS. The ECU would dump extra fuel compensating for the airflow that technically wasnt there.


Several people tried to remove these flaps and had so-so gains. For the most part, idle was crappy especially. The engine was getting way more air that it normally would. So it would be running pretty lean. This was especially true on cold starts.


The power band was much more stable without a huge jump typically associated with the opening of the secondaries.

Overall, it was a not very porpular. Many people felt that you needed to properly tune the engine if these were ever to be removed.


This instance sounds like a wierd reverse case. According to the article the flaps OPEN at 5000 RPMS and people are LOSING power. Something does not add up. Why would additional air flow into your engine result in less power? I can see if the air flow wasnt monitored and you were running way to lean. But inthis case the ECU knows about the additional air and should be supplying the appropriate fuel.

 

[MrTea]

though not ont eh speed, i removed the flaps about 2.5 years ago now. the benefits are all top end, and though subtle, are felt. it's like knife edging and/optimizing yoru TB so it blocks as little airflow as possible. even when open those flaps disrupt a lot of air.

i tried to have someone get me the info from the speed, but it never came to. but on the reg. 2.3, the flaps are ONLY in use (some degree of closure) when temps are under like 130* and rpm/load us under like 2700 and 27* throttle i think. so it only really effects cold start....that's it, in any sort of negative way.

given all the info/logs we've seen on the TB closure....i don't think this is gonna help much. sure the added flow might hold power a tad longer, but the TB "should be" restricting air BEFORE those flaps. there have also been logs that show the speed's ecu changes things from time to time....closing TB at 5500 on this dyno run, 5700 on this run...it's not super consistant. so i wouldn't put too much into "i had power past 6k TODAY" as tomorrow it might not?

though the mod is free (relatively) it can be a b****! some people leave the rod in there as well, which still disrupts flow, as it's hard to seal the manifold....and then there's the "hows the dealer gonna look at this" factor. i think my friend and i were the first to do this on the 6i (plenty on the protege's) and the pro's vs. con's really haven't pushed me to recommend it to anyone yet.

...again, reg 6i not speed6. though i'm boosting now, i don't have a before and after dyno for the manifold.

 

[Silo]

Nope, you got it wrong...

VTCS closed at cold start - otherwise always open!

This is why *I* don't see how they should be causing a power drop as long as they operate properly (i.e. stay open).

 

[Afroman]

correct as long as they are open when the should be, I dont see how any power loss could come of it.

If by chance thye malfunctioned and slammed shut then I could see the car running extremely rich.

 

[probeturbo]

well i don't have any problems with my removal. No power lose, no CEL's, hesitation other than if i start the car on a cold morning and i don't let ti warm up then i get a hesitation til it warms up then it is all good.

I have a question, does anyone know if the butterflies are closing as well as the throttle at 5800? Maybe this is why i might be feeling the car pull just a tad bit longer. Also how do the butterflies know what degree it is on cold starts to stay open if it vacuum operated? I know the opening of the flaps at 3000 is done through vaccuum.

 

[MrTea]

again, i only have the tech highlights from the 2.3 and not the speed. but it IS controlled via vacuum, but control is by the ecu and a solenoid that sits on the manifold. there are 2, one is VTCS and the other is VLIM. again, this is a light load operation thing, for me it's easy, but for you it's obvious that you CAN'T activate something off of vacuum if you are in boost. so there is not way it could be activated while you are on the throttle.

no matter what the ecu does, it can't apply the flaps at 5800. unless someone gets the highlights and it is connected to the brake system for vacuum.