I know on the speed3s that as long as the solenoid was left connected the computer was none the wiser. Im assuming it would be the same here?

 

I've read that the stock NB2 ECU has some trouble idling properly on cold start with the butterflies missing. Not that it's really relevant to this thread, because duh, don't use the stock ECU.

--Ian

 

A revision to my previous statement:

Having looked more closely at the vacuum hose routing, I believe that so long as you leave both the solenoid and the VTCS sensor connected, that the ECU will be happy. There is a sensor which verifies operation of the VTCS system, however it's merely looking to see that vacuum is or is not present at the actuator, not that the actuator moved in response to the change in vacuum.

The sensor is labeled "VTCS VACUUM SWITCH" below:

 

<p></p><p>&nbsp;</p><p>I respectfully disagree with your disagreement of his post. The control scheme of the stock ECU cannot make a seemless transition between the VTCS engagment without ETC and a torque modeled ECU.&nbsp;</p>

 

The ms3 cold start is rough too haha, spits and sputters for about 20-30 seconds before it sorts itself out.

 

maybe if it's tuned like crap

 

That's just tuning. Base map will get it to run but every car needs to be fine tuned. I'm impatient so it usually takes me a few weeks. Commute with lap top in car one day a week for cold start, droop. Run errands on weekend to tweak hot start and A/C idle up etc.

I had Deviate running really well, better than OEM and that's with cams, Rotrex and no idle air bleed (Skunk2 TB). Took maybe 12 tuning sessions over the course of a few months to get to that though.

 

Tune your car, please

 

It seems to do a rather good job of it. Again, in my '04, the transition out of VTCS actuation at part-throttle is barely noticeable.

I feel that people should refrain from offering opinions in this thread with regard to the "feel" of the VTCS system unless they have actually owned a VTCS car or spent considerable time driving one.

 

VTCS came out in 2001. By 2004, that part of the tune may have been refined?

Pure conjecture as usual. Just wanted to be the first to break the "rules."

 

We dont have the ability to tune the ignition or VVT timing at idle / low load. We can populate the tables all day, but the computer does whatever it wants, Cobb doesnt have access to all the logic it seems.
Also, I'm not trying to "pull rank" on anyone here, but i've tuned no less than about 20 speeds, 5 of which were over 500 whp, and the stock turbo record car has my tune on it i know my way around a computer - just here to learn my way around a miata.

Edit: For the sake of disclosure, the record setting car did have all the means to make big power, and we were running it HARD on a built motor with a healthy dose of pre-turbo methanol, so i'll only claim partial credit for that. Point still stands though.

 

I'm a bit confused. You stated MS3 in your OP but referenced COBB here. There are quite a few settings to play with on my UI. What tuning software are hardware are you claiming doesn't idle well?

Hornetball,

Hadn't thought of that. 01-03 is EPA Tier 1. 04+ were Tier 2. Quite possibly some changes made to improve driveability. Overall, I get the impression that the NB2 calibration, originally advertised as 155bhp, was a last minute patch job done with very little budget. Mazda lost a bunch of money on the 01's having to buy a bunch back or dole out big refunds because of erroneous power claims. The impressive thing is that they stuck to their (marketing and branding) guns and kept producing the car for 4 more years virtually unchanged.

 

You just have to pull the vac line (and plug the manifold side) under the throttle body or nearby. EZ.

 

<p></p><p>&nbsp;</p><p>I'm guessing mazdaspeed3 instead of megasquirt3?</p>

 

You're talking about mazdaspeed 3 or something? Why? I mean c'mon, man. I hate to crap on your rank, but some of us have tuned multiple times the amount you just mentioned, many of which were well over the 500whp number you mentioned, if we're talking about tuning other platforms.


Our miata's have no problem cold starting with MS3 unless the tune is bad. Let's stay on topic here.

agreed. I've owned 3 vtcs cars over the past few years, both bp4w and bp6d.

IIRC the "feel" of transition actually varies depending on the solenoid (newer/older solenoids actuate with different speed, this is even more evident with the MSM "bog" solenoid in addition to the vtcs solenoid)

*edit: Emilio just mentioned a similar thing in regards to the ecu calibration end of it too. I'd tend to agree.

My 04 MSM did this vtcs transition WAY smoother than my 01 vvt

 

This. He was speaking of pulling the VTCS out of the manifold on a Mazdaspeed 3 and leaving the solenoid connected. Doesn't throw a cell but makes a racket on startup. We don't have the tuning tools to fix this currently.

I removed the butterflies and rod from my NB2 engine and only sealed up the outer hole that would cause a vacuum leak. Subbing for results.

 

Mazdaspeed3, thats my fault.

This, again, sorry about the confusion.

My tuning abilities were brought into question, i felt it warranted to defend myself. I understand now i created a lot of confusion with "ms3," however, my initial response was in regards to the butterflies and was in fact on topic.

^^ Good to see another MSfer here, thanks for adding some more clarification.

 

I've got a de-butterflied VTCS manifold (jb welded all the holes) that I'll give away for science. anyone want it?

 

You thought that anecdotal data from an engine which is literally nothing at all like a BP-Z3 engine (aside from having the same number of cylinders) was somehow relevant to a thread about modifications to the BP-Z3 engine?

 

<p>We have 2 nearly identical builds at the shop:</p><p>(1) My car.&nbsp; 2001 chassis, BP6D VVT motor, VTCS manifold</p><p>(2) Kevin's car.&nbsp; 1990 chassis, BP6D VVT motor, VICS manifold</p><p>Both cars have RB headers, 2.5&quot; exhaust, and MS3-Pro ECUs.&nbsp; Both cars have good compression and leakdown.&nbsp; My car has a virgin VTCS manifold.&nbsp; Kevin's car has a ported VICS manifold with the flaps removed, and has light port matching on the head (CSP rules).&nbsp; Kevin's car makes 12whp peak more than mine on pump 93.&nbsp; The shape of the curve is the same between my car and his until about 6500, where my power falls off and his keeps climibing.&nbsp; I've played with exhaust and traded intake tubes to no meaningful change.&nbsp; The seat of pants difference is large, and frankly this has bothered me to no end, and of course he reminds me of it frequently.<br /><br />Not sure if I have a spare VICS manifold (I might), but I do have a Euro flat top.&nbsp; I'll try to get some back to back with a before/after manifold swap.&nbsp; I need 8 or 10 extra hp like I need air and water.&nbsp;</p><p>&nbsp;</p>