Idle woes .....

seight · Post by **seight** » Sun Jun 16, 2013 7:52 pm

Getting somewhere now with the mapping on my MS. But idle speed is a steady 1100-1200 !!! Even when up to temp.

Turns out I have a problem with my nice neat throttle body/IACV setup. I have an ACT carbon plenum with a hotwire IACV and a throttle off a GEMS engine.

My car only idles because the IACV is open - turns out the throttle doesn't have any kind of built in air bypass (like the hotwire versions) to set a base idle speed and the throttle stop has been made 'unadjustable' at the factory by bunging up the other end of the screw hole so I can't use that.

Could the IACV be stuck? Is it meant to control idle speed in all situations?

MS is set to 'IAC Stepper Moving Only'.

Any ideas.

Mike

stevieturbo · Post by **stevieturbo** » Sun Jun 16, 2013 7:57 pm

There should be parameters that determine when idle control is off and on.

Usually RPM and TPS based.

Once you know these conditions have been met, simply increase or reduce the valve duty on the computer. If it responds, then the valve is doing what it should.

But a base idle speed is always a combination of a few things.

Actual throttle opening, idle valve, ignition timing and fuel. Not 100% sure how MS works, but in general.

Set idle valve duty to around 5-10%, ignition timing to around 5deg, and then adjust throttle position to achieve your desired hot idle speed or a fraction below it., whilst keeping an eye on fueling at the same time and keeping it within sensible ranges.

Once that is done, you can sort out the idle valve settings for cold start and normal idle etc.

seight · Post by **seight** » Sun Jun 16, 2013 10:10 pm

Ok, that all kind of makes sense. Just need ot work out how it translates to TunerStudio ! lol
There is an 'Idle Valve Test' option but not worked out how to use it yet.
Always wondered how the ecu knows where the valve is - particularly if I stick a new one in.
Mike

stevieturbo · Post by **stevieturbo** » Sun Jun 16, 2013 10:18 pm

seight wrote:Ok, that all kind of makes sense. Just need ot work out how it translates to TunerStudio ! lol
There is an 'Idle Valve Test' option but not worked out how to use it yet.
Always wondered how the ecu knows where the valve is - particularly if I stick a new one in.
Mike

It's wherever you tell it to be lol

OEM ecu's will often reset a stepper motor type valve on key on, or key off engine shut down.

Havent a clue what MS might do though.

Other types of valves dont need reset in such a manner.

DaveEFI · Post by **DaveEFI** » Sun Jun 16, 2013 10:19 pm

seight wrote:Ok, that all kind of makes sense. Just need ot work out how it translates to TunerStudio ! lol
There is an 'Idle Valve Test' option but not worked out how to use it yet.
Always wondered how the ecu knows where the valve is - particularly if I stick a new one in.
Mike

I'm at the moment building a new MS which will make use of the hotwire stepper motor so can answer that part - I think. At power up, it closes the valve fully onto the seat, then 'steps' it open by the amount determined in software.
Can't help with your main question - haven't yet had a play with the software side. At the moment my SD1 MegaSquirt still uses the original Bosch EAV for fast idle.

SuperV8 · Post by **SuperV8** » Mon Jun 17, 2013 8:33 am

There is an Idle valve test section in Tuner Studio. Take the valve out and check if it actually moves in and out?

Don't try and turn the plunger with pliers to check it's not stuck as you will brake it! don't ask how I know! You should be able to push it in by hand when it's not powered up.

The plunger may pop out when powered up and not fitted in the housing so just be ready to catch the plunger and spring. they push in easily if they do pop out.

When you key on the ignition the valve goes through a reset process, it will close a number of steps, so the ecu knows where the valve is, then will re-open a set amount of steps to help the engine start.

Quite a few setting to adjust for the idle valve:
http://msextra.com/doc/ms2extra/MS2-Ext ... tm#stepper

I set mine to always moving as I found the valve occasionally moved when my supercharger made boost.

Tom.

seight · Post by **seight** » Mon Jun 17, 2013 7:29 pm

OK, took valve out and powered up ignition - not a sausage from the valve. I cleaned it all up before fitting but maybe it's FUBAR anyway. So I've ordered a new one off fleabay. Either that or my wiring isn't right. Will see how it goes.
Mike

DaveEFI · Post by **DaveEFI** » Mon Jun 17, 2013 10:34 pm

seight wrote:OK, took valve out and powered up ignition - not a sausage from the valve. I cleaned it all up before fitting but maybe it's FUBAR anyway. So I've ordered a new one off fleabay. Either that or my wiring isn't right. Will see how it goes.
Mike

if it's the normal 4 wire type, there should be two coils which are easily checked with a DVM. It's not unusual for MS to do nothing with the stepper at switch on if you have a wrong connection or software setting.

seight · Post by **seight** » Thu Jun 20, 2013 8:44 am

New IACV arrived - this one actually moves !! Just need to calibrate it properly but even out of the box the idle is lower

Did have a hot start issue though but that's another subject.

Mike

SuperV8 · Post by **SuperV8** » Thu Jun 20, 2013 10:07 am

They don't need calibrating. Each time the ignition is cycled the plunger will move in/close a set number of steps (defined by you) this needs to be more than the max number of steps so that even if the valve is fully open it will close back to the defined point, then it will open a set (by you) number of steps to help with starting.

Tom.

seight · Post by **seight** » Thu Jun 20, 2013 11:52 am

Sorry, yes that's what I meant - I think.
But I was reading http://www.megamanual.com/ms2/IAC.htm which implies you have to do various checks.

The screen shots on http://msextra.com/doc/ms2extra/MS2-Ext ... tm#stepper contain a couple of extra settings (like cranking position and acceleration) from TunerStudio so I'll check my setup in MegaTune. The two apps are sometimes a bit difficult to reconcile with each other. I thought the cranking setting would be taken from the coolant based crank steps table.

I have theory on my hot start problem though - the idle steps grid (IAC Step Bins) in my tune is set to 160 for > 71 degrees coolant temp which I think is the max movement for the valve so when starting hot the valve is probably shut - in my setup the valve is the only way to get air in at idle. It's a possibility and something I'll check as I don't know how that is used with the cranking settings for the valve.

Mike

DaveEFI · Post by **DaveEFI** » Thu Jun 20, 2013 12:48 pm

You *really* don't want to use MegaTune - it's not supported any more. And won't work properly with the latest Extra Code anyway.

Seight-V8 · Post by **Seight-V8** » Thu Jun 20, 2013 7:07 pm

I have a act plenum on my westfield with a custom modified throttle housing from the GEMS engine made to meet the plenum.

Works fine for me with the stepper set at 22 steps at 77degc (warm idle)
and about 180 steps at -40degc.

Rover GEMS info says 180-200steps is home position depending on which type of stepper you have.

Mine idles about 900 warm & 1200 cold, but I do have a Piper285 cam.

As mine has the stepper in the throttle housing not the plenum, and does have a air bypass in the top of the throttle.

I modded the plenum myself and think it was the best option.

I run VEMS not MS, but you could maybe use spark cut for idle control, although don't ask me the theory for this.

scott

SuperV8 · Post by **SuperV8** » Fri Jun 21, 2013 11:20 am

I presume you are using 'extra' firmware for your MSII
I would only stick to one manual - The extra manual
http://www.msextra.com/doc/ms2extra/MS2 ... n.htm#idle

And also as above, I would just use tuner studio. You don't have to use the paid version (although even just the VE analyze live feature is worth paying for the full version)

Tom

seight · Post by **seight** » Fri Jun 21, 2013 3:39 pm

Yep, it's one of Phil's. BTW I was wrong, it's a THOR throttle I'm using:

http://www.roverviews.co.uk/ekmps/shops ... -755-p.jpg

I've been watching a few of Phil's videos - very useful. I now know I can just test the valve steps by feeling if it buzzes !

Mike