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By tx_haggis
#47572
I have a MX-5 PNP (NA6) & am looking to add VVT control for a 2001 Miata engine. IIUC, the VVT sends 12V to the ECU, which then pulls it to ground - very much like an injector or PWM idle motor.

Is this a suitable circuit to put in the proto area to run that VVT?

Diagram Deleted - it was WRONG.
Last edited by tx_haggis on Sat Jan 30, 2021 12:56 pm, edited 2 times in total.
User avatar
By PSIG
#47626
tx_haggis wrote:
Thu Jan 14, 2021 1:24 pm
I have a MX-5 PNP (NA6) & am looking to add VVT control for a 2001 Miata engine. …
The NA6 board has four utility outputs; Idle, Boost, Fan and Tach. Available unused outputs may be reassigned for another purpose, such as VVT.
By tx_haggis
#47634
PSIG wrote:
Sun Jan 17, 2021 8:04 am
tx_haggis wrote:
Thu Jan 14, 2021 1:24 pm
I have a MX-5 PNP (NA6) & am looking to add VVT control for a 2001 Miata engine. …
The NA6 board has four utility outputs; Idle, Boost, Fan and Tach. Available unused outputs may be reassigned for another purpose, such as VVT.
Thanks - I plan on using all 4 of those for their intended purpose.
User avatar
By Chris Wolfson
#47698
Think twice about the radiator fan controlled by Speeduino.
In most cases, a conventional sensor/switch, at the output of the radiator, is better than using " in engine water temperature" for fan control. It will always be a little late, while the radiator based sensor switches when actually needed.

So using the external fan control, which most engines already have, free´s up an ECU output and keeps all switching related noise away from it while giving better water temperature control.

I know, not very popular idea, but works just fine.
By theonewithin
#47713
This last post makes no sense at all...

You can change the on/off point to anything you like within Speeduino so can have much better control vs an 1 step switch.

No idea how this could be considered "late" especially if the sensor is in the same position?
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By Chris Wolfson
#47716
My post may not make sense to you...

I have done quite a few things on cars in my live and one thing I repeatedly tried was the nice idea to move the fan switch from the radiator to the engine. Or, more important, not to have to install a switch in a radiator that had none.
Tried it a few times, in any case this gave fluctuating water temperature, much more than with the radiator switch. The radiator switch controls the temperature of the water that runs to the engine. Too hot,it instandly turns on and a few seconds later the temperature drops as far as the fan can do.. If you use the engine water temperature sensor, its position is in most cases optimized for the ECU or a gauge, which should not react too fast. Controlled from this position the engine has to get too hot before the fan kicks in.

Understand the difference? A cools the water before it enters the engine, B reacts when the engine gets too hot.

I do not say that this will ruin an engine or even cause trouble, but it makes people nervous when the engine temperature in slow traffic cycles from 90-105°c instead of 90-95°C.
VW, for example, intentionally makes their dash instruments insensitive from 80-105°C, so the needle does not show noticeable movement in that region.

If you do not want to believe me, maybe think a second about why car manufacturers go the expensive way of positioning the fan switch in the radiator, causing trouble on installation and extra wires, instead of the cheap way of screwing it into one of the already existing plugs most heads have in the casting? See, no nonsense young Jedi...

A well working water thermostat combined with a radiator thermal switch works best so far. Maybe try it out before calling something nonsense.
By theonewithin
#47721
Well 1 big issue with reading radiator coolant temp is that it's NOT reading the temperature of the water leaving the engine.

SO there is NO way to know that the engine is overheating...

Also all of the engine management needs engine temp not radiator temp.

Also the coolant leaving the radiator may have been cooled but there will obviously be a delay before the engine actually cools. If it cools. To bad if there is a problem and the temp switch doesn't see hot coolant even though the engine is overheating!

Your idea is totally old school and has not been in use for modern EFI for a long long time...

What next? Move back to carbs because they "respond better" as they are all mechanical?

EDIT:

I won't be responding to any of your posts directly from here on out.

I will correct bad info though.
By moonie223
#47734
If you put your engine coolant temperature sensor at the outlet of the radiator and legitimately think that's correct or even remotely necessary you need to set down the wrenches and retire.

It also shows a complete lack of understanding of the function of the thermostat and mixing manifold. All getting cooler water in the radiator is going to do is decrease the cycling frequency of the thermostat. Big whoop.

I have seen mini add a thermoswitch to control the fans after the ECU is switched off. I highly doubt it is used to control the fans at any other time.

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