On/Off idle valve 101

[RGA-1200]

Next question thrown out to the Autronic oracles. Idle valve.

I now have a good "cold" start in the current temperatures by manually cranking my throttle bodies open to 1-2%, it will even start and idle from "cold" (20C-ish CHT) with zero throttle, but it is struggling a little and I prefer to have an idle around 13-1400 for the initial period.

Today I found a solenoid (on/off) valve for free, and tee'd a line into my MAP line to bleed air in past the throttle butterflies. Valve is 1/8" BSP port MAC 35A series (maybe too small?).

A word about my setup; engine is three cylinder 1200cc, 3x throttle bodies are GSXR 42mm, these throttle bodies have 3mm vacuum ports after the butterfly, all three are tee-d together and run a 4mm vacuum line about 1m to the ECU MAP sensor.
Today I have inserted a 4mm tee about 3" from the manifold 'rail', and run a 4mm vacuum hose about 600mm to the location of the solenoid valve. At present the hose is left off the valve, open to air so flow rate through the valve is not affecting things.

I enabled the output, looked at the idle valve settings and scratched my head, started the bike. Just made it run rougher, not faster. I have been through the manual, but it mostly seems to refer to stepper type valves and I'm not seeing a lot of correlation between that info and what I would think I need to put in. I would think I just need a GPC table that does a 0 to 100 switch at a certain coolant temp (open below say 50C or so), and the various parameters dialed in so it fuels it accordingly.

I have a LM-1 (gasp!), but it is currently removed to save electrical load. I will reinstall it again for setting this up. I know it may not be as good as an Autronic product, but it gives me an idea. When I did the dyno work to map fuel I used their Autronic analyser.

My first thought is, perhaps my air bleed is hopelessly inadequate flow for a fast idle system? I figured that as it started and idled just ok without any extra air, that a little bit extra would maybe be enough. We're only talking about 3/4 of a 1.6lt 4-banger. What sort of size valve/hose would people expect to require?

Other thing of course is that the setup of my idle valve enrichment in the software is obviously completely wrong. I have looked through the manual without much success. I am a fairly competent fiddler once I have a basic idea of what's required, some ideas on mechanical setup and basic software settings for a non-stepper idle valve would be a great help.

Maybe the other option would be just a throttle kicker solenoid, which is effectively how they did it with the orignal GSXR install, although in a very clever way. Would be mechanically a bit harder to set up though.

Sorry for the long post!

Many thanks in advance
Steve

[Chris]

The MAP line is sacrosanct. Seriously, look it up in the dictionary.On engines with no IAC, try to get the best hot/cold compromise using idle ignition timing. Open the throttle a bit when hot reset tps and reduce idle advance.

Chris

[MRMRacing]

First I looked in you older post and noticed you had a SM4 :) ( need the info to know what to answer.)

You can test the valve with 12 volt just to See if it help starting.

I would set up a GPC for this, since I do not know the current on your valve (you can probably run it from the stepper O/P and just ground the valve) I will use PWM 1 or 2. Enable GPC 1 to pwm 1, select 20 hz or preferred frequency. Go to GPC 1, menu GPC setup 1, set gpc set point to a user table (so you can control it if revving to high).Set feed back to pwm/on/off.

In menu inhibit you can choose when you do not want the valve to operate.

Select X axis to coolant temp & Y to what you prefer. Set up like this.....here I have used TPS as Y so it will close the valve at a certain tps angle.

In this example the valve is open 100% under 10 degrees, slowly close to 30 % at 49 degrees and at 50 closed. You set this up to suit your engine.

[Wroom]

As for controlling idle with a small solenoid - You should set the PWM at a very high frequency to get a more "analog" response in the valve.
Try 150 Hz at least.

A way to get a more even air flow from the small valve, is to have an "accumulator" volume between the valve and the vaccum ports. Could be something like a fuel filter.

And maybe you should instead make it an on/off cold start idle air valve, by adding an adjustable nozzle before the solenoid. So that you regulate the amount of air it will provide with the adjustable nozzle, and that the solenoid will simply switch extra idle air on/off based on input like engine temperature, post start timeout. And maybe also an rpm inhibit for stall rpm?

Also, if map is TPS based or TPS+MAP based, dont forget to add IAC extra fuel, or it will lean out on idle and be a "stall pig" to ride.

The tip from buzzard to open up the throttles a bit, and setting the correct idle by lowering the general idle ignition and set up an ignition ramp, (or idle ignition correction factor), is also very useful.

[Ian]

Buzzard has the answer totally correct for the problem although he may not have explained it clearly. What you have done is put an air leak between the engine and the MAP sensor. So when your valve is open the MAP sensor is not seeing the real pressure under the throttles so the fuel control will go wrong. You have to find another way to introduce air into the engine other than the MAP sensor hose.

[MRMRacing]

Today I found a solenoid (on/off) valve for free, and tee'd a line into my MAP line to bleed air in past the throttle butterflies.

Grate that at least someone is reading the hole text before answering...

[Chris]

On the subject of Map lines they should go to the manifold,ecu and fpr if you wish and absolutely nowhere else. Do not tee off your MAP line for boost gauge, boost controller, idle valve or other pressure device.

Extra system volume will cause delays in manifold pressure changes as seen by the ecu. This will cause significant fueling issues.

SM4 users should seriously consider direct manifold mount/near manifold mount MAP sensors for improved transient response.

Chris

[Wroom]

Funny i didn't spot that he used the same connection for both MAP and IAC. That will most certainly never work, as stated above.

Please note that i would never suggest adding an accumulator between the MAP sensor and the vaccum ports.


Concerning the placement of the MAP connection on a plenum:

Placing it near the throttle body will introduce measurement error because of the air speed passing the port in combination with the airflow expanding into the plenum. When the port is near the throttle "from the factory", then the throttle body is designed to cancel out theese errors.

Placing it in one of the extreme ends of the plenum will make the measurement uncertain due to both pressure drop in the plenum, and also due to wave reflection.

Placing the MAP port in one of the runners will give the highest pressure variation due to both wave reflection in the runner, and also because of the opening and closing of the valve/valves. But if the MAP is connected in parallell to all runners, close to the cylinder head, then one will get a very honest reading of the pressure.

Best general advice is to connect the MAP port about 2/3:rds of the plenum length from the throttle body, on the plenum wall that is some 90 degrees from the runners. (At the side of the funnels. Not in front of, and not behind them). This will give the most stable pressure reference in most plenums.

[RGA-1200]

Thank you all for the fast and concise responses!

OK n00b error, don't mess with the MAP line. So basically I need to add a completely separate set of 3 ports into my inlet manifolds, tee them together and run that to the idle air valve. That might get a bit tricky as space is limited, my manifolds are 25mm long if that, and most of that is obscured by cylinder head fins. Will see what I can do. Maybe a throttle kicker will end up the more suitable method.

I have some upcoming events and don't want the bike off the road for the moment, so for the moment I will implement buzzard's tips on achieving a better hot/cold compromise based on idle advance.

Regarding running the small valve on PWM, I didn't even think of that, the opportunities the SM4 allows are amazing. I was just thinking of a simple on/off fast idle valve for the first few minutes of running.

MRM, sorry I didn't state SM4, totally overlooked it.

This has brought up an excellent discussion about MAP placement and so on. On my install with ITB's with not much more than 150mm from throttle body inlet to valve head I was seeing an almost immediate drop on the MAP line as soon as the throttle was cracked. I had the mapping initially set to Baro/MAP (fuel by throttle% / ignition by MAP) as that sounded like the best match according to the manual (ITB's and fairly big cams).

When getting dynoed for initial setup, my dealer said you need EXTRA volume in the MAP line (he said newer skylines with ITB's have about a 1" rail to give the system some volume) and as such changed ignition axis to throttle % as well, but it is still set to Baro/MAP. I thought it perhaps should have been changed to Baro/TPS for the overall setup. The engine runs really well now, and it would also be more dyno $$$ to go back to square 1 and re-map in Baro/TPS mode, but I wonder whether that would be the better setup for a motor like this and use the SM4 MAP as a baro update?

Cheers
Steve

[Wroom]

As bikes normally has ignition set by only rpm's, and rarely on RPM+TPS, you should be able to get success with fuel controlled by RPM+Baro/TPS and ignition controlled by RPM+TPS.
(As long as it is naturally aspirated with no greater intake induction gains in the intake due to high speeds).
Then you have the MAP-lines free for use as idle air channel.

But you will get best driveability by setting fuel control to be RPM+MAP/TPS and ignition control on RPM+MAP. This will utilize more of what the Autronic has to offer in transient handling.

And driveability for a bike is what it's all about. "Power without control is nothing".

[RGA-1200]

As bikes normally has ignition set by only rpm's, and rarely on RPM+TPS, you should be able to get success with fuel controlled by RPM+Baro/TPS and ignition controlled by RPM+TPS.
(As long as it is naturally aspirated with no greater intake induction gains in the intake due to high speeds).
Then you have the MAP-lines free for use as idle air channel.

But you will get best driveability by setting fuel control to be RPM+MAP/TPS and ignition control on RPM+MAP. This will utilize more of what the Autronic has to offer in transient handling.

And driveability for a bike is what it's all about. "Power without control is nothing".

Thans Wroom,

I am very happy with how the bike runs at the moment, so I think I should leave it well enough alone. Response from closed throttle is very good, quite progressive and not at all snatchy like a lot of fuel injected bikes were in the early times of injection on bikes (90's). My engine is pretty old-tech, and has a heavy crank which helps.

For the idle, I had another look at the throttle bodies and there is an undrilled port blank next to the port for the MAP line. So I will drill those through, and make some brass tubes to create two separate vacuum ports. The original will go to the MAP alone, the others will tee together and go to an idle valve. So once I've done that I might be here again asking about settings.

I want to ride the bike over the next few weeks so this will wait until April now.

Cheers
Steve