Standalone ECU guys - what're you doing for hot/cold idle?

[spuggy]

Motec, twin-plugged, 3.2 manifold/throttle body.

Right now hot idle is pretty stable @ 1050 (with SC cams, it always felt happier idling there, even with CIS).

Issue is that cold idle is lumpy, erratic and kind of low (750-800 or so, you can see it rise on the tach as it warms). Warmup comp table for fuel seems to be in the ballpark; it doesn't bog or splutter on tip-in, so can easily raise RPM on the pedal, pull away etc.

There's a pit in ignition map for idle to sit in: 6 degrees; warmup comp will typically trim in another 6-8 degrees, depending on how cold it is/RPM range. Without adding more timing, cold idle was lower still by 100-200 RPM (way too clanky...). Adding yet more advance doesn't raise the speed much/any, but does increase how erratic it is.

I'd ideally prefer cold idle @ 1400 RPM or so. I don't usually let it idle before driving away - but be nice if it Just Worked...

An obvious approach looks like adding the factory ICV to let more idle air in when cold, which is about where I'm at.

Before I do that, anyone got any better ideas/approaches? Anything stand out as obviously wrong/weird with this picture?

[quattrorunner]

sub

[David]

I'm about to get way more familiar with my Motec system than I have in 10 years and I'll see what my settings are in the next few days. It's been too long for me to remember but I do have it idling around 1200 until it warms up and settles to about 1000.

[scottrx7tt]

I use a 3 wire ICV from a 964. It works pretty well. I am just running microsquirt, so that is really all it will run without modifications.

[993Speedster]

Ironically enough, my VEMS standalone was controlling my idle air control valve just fine but I've deleted/unplugged my IACV and configured that output for a boost control solenoid because I didn't feel like running extra wires and I don't have A/C or power steering loads anymore.

The key to getting a stable idle without an IACV is more base airflow (throttle stop adjustment) and less timing when hot. If your ECU has a "timing based idle control" tab and settings, this will help big time. If not, you'll have to get real creative with the load cells and RPM. Crack the throttle open just enough to keep it idling stable cold and use timing control to bring it back down as engine temp goes up.

This is all assuming you don't have any large loads on the engine like A/C, power steering, etc. With A/C running, cold, and trying to steer in a parking lot for example, you'll guaranteed need an IACV unless you run E-throttle.

[IROC 912]

My infinity 6 controls the factory idle control valve on the 3.2 manifold and cold / hot idle and warm up from cold start is just like a modern car. Pretty happy with this setup.

Sandeep

[jpnovak]

unless you add more air you will not raise idle speed. You need some type of idle valve or hand throttle to keep it running above your lower threshold. Most systems will drive the stock ICV or you can add your own. Motec can handle it. Just find the wire, build the circuit and connect it up. Or have someone who know's the system handle it for you.

[kevinbodman930]

Which Motec are you using?

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[smurfbus]

I run hand throttle with no other idle gadgets. Works pretty nice and is stupid simple.

[kevinbodman930]

That's a great idea.I forget are you running Efi or Cis?

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[smurfbus]

I had hand throttle when CIS and same now with MS3pro

[Porsche 935]

I use no ICV but add a few degrees timing during warm up. Always a bit lower rpm when cold but still smooth and responsive so really doesn't matter.

[spuggy]

Originally Posted by jpnovak

unless you add more air you will not raise idle speed. You need some type of idle valve or hand throttle to keep it running above your lower threshold. Most systems will drive the stock ICV or you can add your own. Motec can handle it. Just find the wire, build the circuit and connect it up. Or have someone who know's the system handle it for you.

Yeh, timing alone won't cut it - don't get the range.

If I had the ICV, I'd just put it back. But I never got one with the manifold, so need to source everything. Factory stuff is not cheap; $50 for the two hoses, $7 a clamp - and the ICV itself has been discontinued by Bosch since 2013.

Seriously considering just buying a Bimmer ICV that looks the same and is still in production - as new they're about 1/3 the cost of NOS 501 valves. I'm a little loathe to buy a $40 ICV, as I don't want to waste any time only to discover it was bad out of the box.

Hand throttle, LOL - I used to lust after one when I had CIS with a dodgy warmup, but never followed through because I liked the dual heat levers on the '77, and the two things never overlapped AFAIK...

[xbmwguy]

I got my icv from a 5 series bmw in a boneyard. 10.00 working for 5 years

[smurfbus]

I use the hand throttle also for cruise control even though its considered unsafe (accident and engine run off). I have stripped everything out of my enginebay years ago so no heat or AC either. We dont have over 30C here and I dont drive when its under 15C usually.

[Tippy]

I'm confused. If you have a 3.2 intake, where is the ICV that came with it?

I'd use that. If it's missing, Volvo uses the exact same valve for a fraction of the Porsche one. Stupid Porsche tax....

I have my idle valve open all the way during startup for a big "VROOM" when it lights off and holds usually around 14-1500 RPM when cold and tapers down to around 900 idle.

[David]

It's amazing how much I've forgotten about my own car since I haven't had to work on the fuel injection in almost 10 years! I do have an idle air control valve which explains why I can have a higher warm up idle speed.

[spuggy]

Originally Posted by Tippy

I'm confused. If you have a 3.2 intake, where is the ICV that came with it?

The throttle body was rotated (and Kokeln modified to match) prior to my ownership. No ICV came with it.

Originally Posted by Tippy

I'd use that. If it's missing, Volvo uses the exact same valve for a fraction of the Porsche one. Stupid Porsche tax....

Bosch discontinued that valve (0 280 140 501) in 2013. So even Volvo replacements are not cheap; everything new offered for sale is NOS - at 3x, 4x the price of a valve still being made. Found them listed (usually specifically as Porsche items) for $600, $700. LOL. Yeh, right.

If you're sourcing everything from scratch, the impulse is to find a Bosch one that's still made for ~$150 or so. Even the frickin' hoses (which may not even work for me) are $50.

Originally Posted by Tippy

I have my idle valve open all the way during startup for a big "VROOM" when it lights off and holds usually around 14-1500 RPM when cold and tapers down to around 900 idle.

Ya, something almost exactly like that seems ideal.

[spuggy]

Originally Posted by David

I do have an idle air control valve which explains why I can have a higher warm up idle speed.

Interesting - that doesn't look like a Bosch, any idea what it is?

I like the idea of factory parts, but they may not even fit in my application...

[David]

Originally Posted by spuggy

Interesting - that doesn't look like a Bosch, any idea what it is?

I like the idea of factory parts, but they may not even fit in my application...

I don't remember where I got it. It looks like a simple billet aluminum housing with inlet/outlet bungs that a GM IAC valve stepper motor bolts to.