what sensors needed for proper spark?
 

I'll be going megasquirt here pretty soon in my S4/S5 hybrid TII thingy,(megasquirt for fuel/ stock ecu for spark)so I want to pull out any wiring I can that won't mess with the stock ECU's ability to adjust spark correctly. so, what can I get rid of/need to leave? obviously, I will need the CAS and the knock sensor, and I think I read the intake air temp sensor needs to stay as well, but I'm sure there's quite a bit more... can you guys help me?(esp. those that have done this same thing before).

I don't think this is a common question, since I've never seen it asked before here... but if there's somewhere else I should look, please point me in the right direction.

Disclaimer: I don't actually know anything...


What i've come up with is this.
CAS, MAP sensor, Air & Coolant temp sensor, TPS. Basically all the sensors except the AFM.
However it does say in the FSM that the ignition timing is somehow changed by the AFM.

So... who knows.
I ran without it for a long time and it worked ok i guess.

okay. um.. does it need all the coolant temp sensors, or just the one in the side of the block?(there's also the ones in the water pump and in the radiator... etc...)

anyone have any more info on this AFM thing? that's what I'd like to rid of more than anything else. hehehe.

also, anyone know if somehow i could use the stock TPS for both megasquirt AND the stock ecu? or will I have to hood up another one...?

thanks so far!

The water thermosensor (behind wp housing) is the one you will need since it is the only one that interacts with the ECU.

okay, cool.

Well I should say you still want to have all the coolant sensors connected and working. The one on the radiator (coolant level sensor) will sound off if low on coolant and the coolant temp senso (on the block) will show the temp on your gauge cluster. It's just that the ECU only cares about the waterthermosensor for the car to run properly in concerns to the water sensors.

right, I wasn't planning on removing the level sensor... I was thinking about the one on the lower left side of the radiator (it has2 wires going to it) ?

and I'm running plenty of aftermarket gauges, so I'm not too worried about the stock temp gauge...if it even still works. hehehe. thanks though.

Not sure which other sensor on the rad you are talking about... probably an s4 only thing.

Where do you have your aftermarket water temp gauge installed? If anything you should put it in the stock location on the block since it is the hottest point in the entire water system.

yeah, probly just a S4 thing... I guess I'll just try without it and see how it works... lol.

and yeah, the aftermarket sensor will hopefully be going into the stock gauge's sensor location. if not, then somewhere in the water pump. thanks.

anyone know about the AFM though?

bump.

anyone know more precisely exactly which sensors control spark? is the above info correct? what about the AFM?

from looking at wiring diagrams, looks like I will need:

-water temp
-air intake temp
-knock
-TPS
-CAS

not sure about pressure sensor and AFM

and what is the ATP sensor?

thanks

You need the pressure sensor dude. Especially if its for a TII, but even for a N/A they're important.

No idea what you mean by ATP, but if you mean the IntakeAirTemp sensor then that is used by the ECU aswell, not nessesary, but i believe it is used.

oh, sorry. yeah, I know I need the pressure sensor, I don't know why I wrote that.

the ATP sens is in my wiring diagrams, I don't know what it is either, thats why I'm asking.

it has 4 wires going to it, grn-yel, Brn-wht, blk-wht, and brn-blk. and on the diagram it is a box...

okay, I think ATP is the atmospheric pressure sensor. do I need that?

bump.

noone has any info on this?

bump. please!!! I've almost got my wiring harness done. I just need to find out about the AFM, and ATP (atmospheric pressure sensor).

also, is there anyway to use the S5 TPS with the S4 ECU. I want to use the S5 one for megasquirt, and it'd be a lot easier if I could just use the S5 for both rather than trying to fit both of them on the TB... or whatever.

The atmospheric pressure sensor is inside the car. It looks similar to a boost/pressure sensor. It's above and to the right of the passengers feet, on a series four. Look in the FSM and I'm sure you'll find that it will default to a given value if disconnected. I THINK in a series five it's built in the ECU. I don't KNOW that for sure and ain't a gonna look it up.

cool. now I know where it is. I think I changed it in my TII swap... and since its under the dash, I might as well leave it... its not like I'll even be able to see it. hehe.

okay, now just the AFM, and the other question about the TPS, and I should be set.

How elevated is Boulder? Anything like Denver? If so, you'll probably need the inputs from the ATP for proper fuel scheduling. Guys like me that live just a hair (in cosmic terms) above sea level wouldn't need to worry too much about a "bad" ATP, because I do believe the ECU fail safe is sea level...

Just in case you changed your mind and want to remove it :)

yeah, boulder is a just little higher than denver. it wouldn't matter if it was only for fuel scheduling, since megasquirt will be taking care of that. I just don't want it to fuck with the ignition.

AFM anyone? any insight on it? I can figure out the TPS thing on my own. just need AFM help!!!!

BUMP!!!!!!!!

PLEASE!!!!!!! do I need the AFM to make and adjust spark properly?

yes

..What makes you say that?
Just a blind guess or have you actually read the timing off the crank without an AFM attached?

See the FSM says the AFM has an input into it, BUT I ran my car without it and the timing was good. Had alot of 'other' problems that i thought was related but turned out not to be.

For "proper" timing you need the AFM. Its the main load sensor for the
ECU (IAT and ATP also play a part in this but not so much). Without
the AFM attached, at best you're timing would only vary with RPM and
not load.

-Henrik

The AFM is the main load sensor for fuel, not ignition.
The main 'load' sensor for the ignition is the map sensor.

Wrong - On what basis are you making this claim?
The MAP is only used for trims, fuel cuts and a couple of
other minor functions.

-Henrik