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Join Date: Jul 2003
Location: Glorious Pac NW
Posts: 4,184
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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?
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'77 S with '78 930 power and a few other things. |
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Brando
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Turbo powa! 1977 911s. it's cool |
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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.
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2014 Cayman S (track rat w/GT4 suspension) 1979 930 (475 rwhp at 0.95 bar) |
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Registered
Join Date: Feb 2009
Location: Knoxville, TN
Posts: 1,347
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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.
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Registered User
Join Date: Jul 2012
Posts: 106
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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.
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"Frankenstein" - 964 C4 chassis/driveline - 993 widebody/Speedster look - VEMS standalone - twin plug high compression 3.6L N/A engine - 945cc cc/min injectors - Bosch 044 pump - GT45 @ 1bar/14psi - non intercooled/wingless - E85 fuel - turbo inlet water meth inj. - 3.5" exhaust - GT3RS clutch + LWFW Last edited by 993Speedster; 09-16-2019 at 03:18 PM.. |
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912-6 Turbo
Join Date: Jun 2014
Location: Toronto, Canada
Posts: 99
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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
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1966 912 Turbo - Carrera 3.2L - GT3076R - Bosch 044 - Intercooled - 55lb injectors - 0.5 Bar - Tial F46 - Magnesium 915 7:31 - BBS E26 15x9, 15x10 - Link G4X Fury |
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I would rather be driving
Join Date: Apr 2000
Location: Austin, TX
Posts: 9,108
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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.
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Jamie - I can explain it to you. But I can not understand it for you. 71 911T SWT - Sun and Fun Mobile 72 911T project car. "Minne" - A tangy version of tangerine #projectminne classicautowerks.com - EFI conversion parts and suspension setups. IG Classicautowerks |
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Join Date: Feb 2016
Posts: 360
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Which Motec are you using?
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Turbofrog
Join Date: Aug 2009
Location: Europe
Posts: 1,677
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I run hand throttle with no other idle gadgets. Works pretty nice and is stupid simple.
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************************************************** ******************************* 10/78 930: HX40Super, MS3pro+IDX1050+044+E85, ITB, 12 Denso COPs, TrueSplit-BB/2*38WGs, Weight<1100kg |
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Join Date: Feb 2016
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That's a great idea.I forget are you running Efi or Cis?
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Turbofrog
Join Date: Aug 2009
Location: Europe
Posts: 1,677
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I had hand throttle when CIS and same now with MS3pro
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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.
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3.3 ltr, stock compression, efi, twin turbo - no intercooler. |
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Join Date: Jul 2003
Location: Glorious Pac NW
Posts: 4,184
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Quote:
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...
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'77 S with '78 930 power and a few other things. |
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I got my icv from a 5 series bmw in a boneyard. 10.00 working for 5 years
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88 930 3.4 ,Twin plugged billet Xtreme cylinder heads and denso COPs, Dougherty custom GT 2 evo cams,pauter rods,Garrett Gt40,ms3x Efi ,1100cc injectors,extrude honed 3.2 intake,TK billet fullbay I/C,MODE headers,KEP stage 2, E-85, 706 rwhp |
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Turbofrog
Join Date: Aug 2009
Location: Europe
Posts: 1,677
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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.
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************************************************** ******************************* 10/78 930: HX40Super, MS3pro+IDX1050+044+E85, ITB, 12 Denso COPs, TrueSplit-BB/2*38WGs, Weight<1100kg Last edited by smurfbus; 09-17-2019 at 08:32 PM.. |
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Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
Posts: 9,138
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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.
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Cory - turbo'd '87 C3.2 Guards/Blk, 3.4, 7.5:1 CR, 993SS cams, Borg-Warner S366 turbo @ 1.2-1.5 bar, Treadstone full bay IC, 70mm TB, TiAL F46 WG, HKS 1 1/2" BOV, twin 044 pumps, MicroSquirt AMP'd w/GM smart coilpack, Bilstein coilovers, Tramont replica Speedlines (285's rr, 225's frt), Big Reds frt, 993 rr., tower brace, MOMO wheel |
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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.
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2014 Cayman S (track rat w/GT4 suspension) 1979 930 (475 rwhp at 0.95 bar) |
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Quote:
Quote:
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. Ya, something almost exactly like that seems ideal.
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'77 S with '78 930 power and a few other things. |
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Quote:
I like the idea of factory parts, but they may not even fit in my application...
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'77 S with '78 930 power and a few other things. |
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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.
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2014 Cayman S (track rat w/GT4 suspension) 1979 930 (475 rwhp at 0.95 bar) |
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