my idle control for megasquirt!

[Toby_Unna]

I've had standalone management on my e30 for a year or so now, and have thus far had to choose between easy starting and smooth cold idling, or a sensible idle speed once the engine's warm. in its current state it would start easily and idle at around 900-1k when cold, but would then creep up to almost 1500 once thoroughly warmed up. which isn't very good on fuel

so after playing around with it i've bodged a solution together. I tried normal idle valves off various cars but none would close enough to get a sufficiently slow idle speed. the separate throttles on my engine have their own bypasses to balance them against each other so the engine needs no extra air from the main idle screw once warm. so then I started playing with these...



they're fuel vapour control valves (or something like that!) from E36s. normally open but shut completely when shown 12 volts. unfortunately they don't flow very much air, so i've ended up using three - one to close or open the main idle air inlet, and two more to allow air into the engine separately when cold. they all open and close together from a switch on the dash, though i think the megasquirt could probably operate them if i knew more about it



looks like a right bodge at the moment, but seems to work really well. cold starting is still in the 1000rpm region, and once fully warm with the valves shut it's still 1000rpm which is good enough for me.

the valve on the right in the first pic is a bit better - it's larger and flows much more air. unfortunately it came off a merc C class and the breaker only had one of those in when i went.

also been fiddling with the rest of the inlet, it's had a crappy (tiny) air filter on since the turbo was fitted because it seemed like that was all that would fit; however Andy335touring let me try his old cone filter, which just fitted once I'd removed the front panel for better access!

old vs new (does the one on the left really look like a 300bhp plus filter







complete inlet up to the turbo compressor...



while the front panel was off i took the opportunity to remount the fan nearer the rad, which will hopefully mean faster cooling once it comes on - it used to blow loads of air around the rad instead of through it!

unfortunately i can't find out if the new inlet has made any difference yet because i'm putting a different water reservoir on to make it easier to bleed, and there's no coolant in it at the moment

[blingsta]

looking good Toby... how the hell did you manage with a 1500rpm warm idle.. .. i would have pulled my hair out!, but glad you found means of sorting it..

[Jhonno]

wouldnt like to drive that in the rain with the air filter so low to the ground?!

[Toby_Unna]

trust me there's bigger problems in the rain than the engine sucking a bit of water in Dan

'traction' for one thing

tbh the position in terms of height is no lower than the other filter was, it isn't likely to be a problem unless i try to drive it through a flood or something daft

[Andy335Touring]

Glad it fit OK mate, i hope it get's you a few more BHP's

[jkarran]

Has anyone tried the standard M20 or M30 idle control valve with their turbo conversions? Will it open and or stay shut against boost?

[Ant]

M20/30 three wire ICV is no good for S-alones(any ! , the two wire unit from an M40/42/43/44 works well though and you can set target rpm cold-hot and PWM between the two, leaking boost is not an issue as the ICV would have to pickup from the charged pipework. although I have seen a few bupbbles around the crimped joint in the castings.

ICV is nice, but not 100% required, you can bump idle speed by two other methods and achieve the same result.

[Turbo-Brown]

It's funny, neither my car nor my mates have IACVs (and run the same ECU as it happens) but mine idles reeeeeally low when it's cold whereas his does just under 1000rpm whatever the temperature.

Very odd!

[Andy335Touring]

It's funny, neither my car nor my mates have IACVs (and run the same ECU as it happens) but mine idles reeeeeally low when it's cold whereas his does just under 1000rpm whatever the temperature.

Very odd!

Sounds the same as mine, just needs some more time on the correction maps i guess ?

[Turbo-Brown]

Just gonna go for an IACV o the next setup I think

[jkarran]

Cheers Ant, curiosity got the better of me in the end so I pulled my idle valve out of the M20 for a look. I'd been wondering about using one (or similar) as a bypass for my blower (hence the 'leaking boost' question). Looking at it I'm sure I could make it work (drive-signal wise) but the flow would be too small through all those restrictions. It was just a backup idea as I was getting sick of machining up my original design. Useful to know the M40/2 ones are two wire though if my plan goes to hell

Toby, I'm sure there's some configurable outputs in MS that could drive that very simply, from memory you can set outputs to respond to temp, rpm, tps etc etc. However, the fan control would seem the most obvious if you're not already using it, just set the fan on-temp to ~45deg and the hysteresis to ~5deg so the valves don't chatter.
jk

[Ant]

Toby can use the FIDle output in on/off config to control the PCV solenoids, that leaves the fan contol for other goodies

jk, for the bypass you could use an EGR valve( french car donor ) and use a PWM output to control the vlve to float bypass in/out.

2 wire connection and would flow well as its 44mm diameter on the shitroen I borrowed one from.

[Gunni]

M20/30 three wire ICV is no good for S-alones(any ! , the two wire unit from an M40/42/43/44 works well though and you can set target rpm cold-hot and PWM between the two, leaking boost is not an issue as the ICV would have to pickup from the charged pipework. although I have seen a few bupbbles around the crimped joint in the castings.

ICV is nice, but not 100% required, you can bump idle speed by two other methods and achieve the same result.

I don´t agree,
Just installed a standalone on a M20b25 used the stock icv and it´s
rock steady and smooth,

[Ant]

not saying it wont work dude, but the ICV does put a lot of current back to the ECU and could fry the driver FETs , power flyback on the circuit is possibly the answer there though but TBH, the 2 wire M40 type unit is better in control and construction.

a lot smaler too and doesn't pump heat into the intake.

O/T you get my mail Gunni ?

[Gunni]

if you just sent it then no, but I got the one the other day you sent,
where you waiting a reply and I didn´t?