Joe Perez

iTrader: (8)

I'm a retard.

We're talking about a parallel build here, so of course VVT is a non-issue. Forget everything I said about that. It was late and I was tired.

evank, my bias towards using the NB sensors is two-fold.

First, they are already there as 18psi says.
Second, a belt-driven CAS sensor is always going to have a degree of slop in it owing to the flexation of the belt. A crank-driven sensor will be inherently more precise.

Obviously the CAS works well or we wouldn't have 8 years worth of Miatas driving around on it. But if you already have a crank trigger, why not use it?

paul

iTrader: (21)

Remind me again. Can MSI handle the stock crank trigger or only MSII?

Matt Cramer

Just MSII.

esp140

What he used to do it (ms1/2, stock CAS, etc), and more specifically how he did it.

post compy!

sooo the let the stock ecu run VVT and not have the MS worry about it? can it do that?

Joe Perez

iTrader: (8)

Of course. After all, that's the whole point of doing a parallel install vs. a standalone install in the first place; to put the MS in charge of the important stuff (fuel and spark) and let the stock ECU handle all the rest- idle, AC, the alternator, and of course VICS/VTCS/VVT.

esp140

ight that makes perfect sense. sooo its really not near as complicated or complex as i was making it to be. soo build and run an ms2 and im good to go? nothing else needed in that mix?

paul

iTrader: (21)

Before you jump in with an MS2 have the 2-3 NBs with them on here gotten all the **** fixed?

arga

It's working for me but I haven't put many miles on it since I changed the input circuits. Pat went w/ a 36-1 wheel, I'm pretty sure Abe's was working until he had other unrelated problems. Last I heard the two guys in Europe were both working. I know they were both using MS2 but I don't know the details.

Joe Perez

iTrader: (8)

Abe seems to have "other unrelated problems" with his valvetrain, pistons and rods rather more frequently than most.

But yeah, his setup was working like a charm. I rode in his car a couple of times prior to the most recent blowup, and it was quite nice.

patsmx5

iTrader: (16)

Well, mine's working pretty good. It's 99% perfect. Driveability is better than stock. But could still be slightly improved through tuning and fine tuning the acceleration enrichments.

Only advice I can give is:

Use high ohm injectors. Don't use low ohm. Just don't. Do not.

If you are a genious, I would suggest designing a new 36-1 trigger wheel that would replace the factory 4-oddly-spaced trigger wheel. Then let the stock crank sensor read it. But that's never been done to my knowledge, but should be possible. And would be the "best" overall setup for a 99+.

esp140

i am by no means a genius, so im sorry umma have to leave that to someone else.

im relying on the fact that i can read an follow directions well, and learned to solder at an early age.

so since im initally running it natuarlly aspirated, alls i need to buy is the MS2 itself, build it and hook it up and tune it? i know i need a boomslang right? so i dont have to splice any factory wires.

y8s

iTrader: (8)

parallel anything with an 01 is fine, and YES you can fool the ECU into no error codes by using a PWM output converted to varying voltage sent to the AFM input signal to the ECU. creating that map is relatively simple if you approximate airflow as increasing with MAP and RPM. I may still have the duty cycles I used in the Tec3.

also, DONT DONT DONT USE THE FACTORY ECU FOR VTCS (01+ cars)!!
it stays closed at a relatively high RPM during cold start that chokes a boosted engine. it needs an off-on type signal set to <2000 rpm and <60C coolant temp. Or just leave it disconnected. You may have cold start idle issues though.

Joe Perez

iTrader: (8)

For that matter, don't use VTCS at all. Rip the damn thing out of the manifold and plug the holes with JB weld. (Yes, I'm serious about the JB weld this time.)

y8s

iTrader: (8)

sure why not, assuming you can idle the car cold for 5 minutes somehow.

OT: the MR2/3SGTE guys have a thick plate independent of the mani that houses butterflies similar to the VTCS. They often remove and plug. A quick google search turned up a phenolic plate that replaces the whole assembly.

Joe Perez

iTrader: (8)

Huh?

An '01+ manifold with the VTCS removed is functionally pretty much identical to a 1.8 NA manifold. Those little plates are just there to stir up the air a bit- they're not chokes. Whether or not the engine idles properly when cold is entirely a function of fuel delivery and the operation of the IAC valve. VTCS is simply the latest in a long line of tiny, incremental improvements to emissions performance during cold start and warmup.

Such a system is also found on newer Subarus. They call it TGV (tumble generator valves) and the system closely resembles a pair of short Weber IDA/IDF carbs. The removal of these valves is such a common mod that several companies sell a pre-modified set of manifold risers. Here's a picture showing the stock system, and the modifed riser with the valves removed:



Long story short: Assuming the capacity to tune the fuel map accordingly, removing the VTCS valves is not going to negatively impact the ability of the car to be driven when cold.

patsmx5

iTrader: (16)

My 99' doesn't have VTCS, or any other air tumbling device. For that matter, I don't have a working IAC valve either. Still idles pretty damn good at 700 RPMs from a 28*F start. Only complaint is it will hunt just a bit for ~30 seconds sometimes. This could be curred by idling up a bit or adjusting my timing table.

To the OP, just read in the MS forum. The more you read, the more you'll know. And the more you learn, the more confident you'll get.

y8s

iTrader: (8)

Joe: the extra tumble basically reduces the need for super rich cold starts. if it's just for emissions, then it's a no brainer. if it's part of a mitigation of a compromise in intake design, it may be harder. when I left my VTCS disconnected, the car wouldn't stay running from cold (<50F) start. no other map changes--which is probably why it wouldn't.

Joe Perez

iTrader: (8)

Well, the '99s didn't have VTCS to begin with- they had VICS, which is a whole different animal. The VICS valves aren't in series with the airflow through the manifold, they just open a sort of resonance chamber. VICS is a performance enhancing device- it's been dyno proven that disabling the system causes a decrease in torque across a certain portion of the RPM band. In '01, VICS went away and was replaced with VVT & VTCS. Of these, the former is a performance enhancer and the latter is a cold emissions reducer and a potential performance decreaser, as even when fully open, the plates and shaft are still inline with the airflow through the manifold and into the head. It's a bit like having two throttle bodies in series.

This is why in my previous post I compared a VTCS-less '01 manifold to an NA manifold, rather than a '99-'00 manifold.

Well, I can't explain your issue in disconnecting VTCS, unless you left it in such a configuration that the plates were still present but uncontrolled.

Which engine management system are you running? I ask because I'd imagine that a little work with warmup enrichment ought to solve the problem. Given that VTCS's purpose is essentially to allow stiochiometric operation when cold, it stands to reason that after removing it, one would have to richen up a tad like the rest of us when cold.