EFI Megasquirt users idle control valve question, mostly.

[mjheathcote]

I'm sorting out the last few challengers on my EFI project to get it finished, only been 10 years since I started!

Cold start, is an idle control valve or IAC really necessary?
As I'm using motorbike Suzuki GSXR 600 K1 throttle bodies, I don't have an easy facility to add one.
I do have little vacuum ports on each of the 8 throttle bodies, but they are really small (maybe half a mm diameter each) and I don't think would introduce sufficient air. Don't really want to be adding 8 additional air inlet connections to each inlet runner.
What I do have however is the facility for a manual 'choke' that was used on the bike. All this does is manually open the butterflies slightly to introduce more air and increase the idle speed. So not a 'choke' in the true sense, just a little extra throttle.
I assume Megasquirt automatically enriches the fuel/ignition advance on coolant temperature anyway, so this manual method to increase idle speed at the same time might work, or maybe isn't necessary anyway?

Few other curious questions really:

MAP or throttle position?
I'll be using throttle position, apparently this is the way to go with multiple throttle bodies, and I already have two available to use on each bank, but only need the signal from one.

Fuel pressure regulator.
Some use the vacuum signal to vary the fuel pressure, some don't, keeping the fuel pressure fixed at the same pressure no matter what the inlet manifold vacuum level?

I've spent most of the weekend looking, playing, and looking again on how I am to control all 8 throttle bodies in perfect synchronisation.
With me spacing out the bodies wider than when fitted to the bike, I'd lost some of the original synchronisation along each bank of 4, however I've now sorted that one out with careful modification, fabrication, and extension to original interconnecting levers.
The challenge is now applying the single throttle cable from the pedal, to moving both banks together. I think I have found the answer, but don't like the price!

https://www.efihardware.com/products/2246/Bell-Crank-with-Adjustable-Cable-Pulley-and-Return-Spring-Tensioner

I can't believe there isn't anyone in the northern hemisphere that sells the same thing!
Jenvey do one, at the same price, but not a patch technically on this Aussie one!

[KOY 23]

Hi Mike.
I have an IAC and should connect it but it idles fine with adjustment screw on Rover plenum. MS has loads of options for warm up and after start enrichment. MAP sensor and fuel regulator are sensesed from full vacuum in plenum. Didn't the Jag V12 have a bellcrank throttle assembly?

[GDPR]

Certainly did, and sounds perfect judging by Mikes description

[alan_thomas]

That settles it! I have only been working on (mostly off) my EFI project for a mere 8 1/2 years but I can't let Mike beat me to it
- I'm off into the garage now!
Alan

[kev100]

That settles it! I have only been working on (mostly off) my EFI project for a mere 8 1/2 years but I can't let Mike beat me to it
- I'm off into the garage now!
Alan

I didnt even start mine yet (still in the researching phase) but will start it in the new year .. wonder if I will finish before you and Mike ... the challenge is on ..

Actually, just bought me one of these so technically I have started I suppose ..

ahe045.jpg

[bullstarz]

Most of the control valves work via PWM. Its worth having as it smooths out the revs at idle. Or you could go for a full fly be wire system which could operate both sets of carbs, or just use a the mechanical and electrics out of a throttle body
( http://www.ebay.co.uk/itm/FIAT-PUNTO...8AAOSwmLlYBqCm)

There a few good bit on here:

http://www.v8forum.co.uk/forum/viewtopic.php?t=5937&sid=113d6830dacefc199a56be9dafcea846

[jakesmig]

Hi Mike,

I run an Emerald ECU on my lump' however most of these work on roughly the same principle. The Emerald came with basic maps therefore the engine would start and run with just refining to be done to start with.

In the Emerald case, the Ignition and fueling is tuned in once the engine is hot so that the optimum running mixes are fixed at that time. Once the tuning is carried out then adjustments are made in sub programs which control the additional fueling, cold starting, idle air valve etc. It takes a lot of tinkering about to tune in the cold starting and running because you only have short intervals during warm ups to intervene in the ratios, and generally each stage will interpolate with the one above / below.

The idling process with the Emerald unit starts off with the butterflies being set to allow the engine to idle with the IACV valve operating to even out the idle and also to open up to allow cold start rise in revs. I would have thought that the small diameter vacum ports you have would be adequate to allow for that, it is surprising how small a movement in the butterfly will affect revving. To be honest, you may find that you can live without additional air once you start using the system, using small throttle movement to initially increase the air volume.

Pressure regulator. As far as I know, all injection systems adopt a constant pressure in the fuel rail during normal running and use the vacum to release the pressure in the rail during the over run, thereby cease fueling during the over run.

The controling sensors on my system are, Crankshaft sensor, throttle position, engine temperature and air intake temperature. An additional, but not essentials on, is a Lambda Sensor.

Assuming each butterfly has its own idle setting screw, my suggestion would be to get the engine running and up to operating temperature then disconnect each butterfly from the linkage and use a carb balancer to tune in each port to your required idle rev. Once you've got that reconnect the linkage and you're near enough there.

[flying farmer]

Your biggest problem is not having the necessary ports to connect any idle valve.
I use the old Bosch extra air valve for my cars as was fitted to the Rover V8s. Works fine for initial warm up as the ECU is mapped to allow for the extra air flow not seen by the closed throttle.
I have found the only problem is on restarting after a few minutes as the extra air valve cools rapidly due to it being fitted to the top hose rather than the inlet manifold.
When restarting the valve is partly open letting in extra air but the coolant temperature sensor still sees a hot engine so the mixture goes very weak for a minute or so until it warms up again.
I seem to remember my step daughters Vauxhall had a stepper motor that worked the throttle linkage for idle control, but I don't know if it could be made to work on an 8 throttle set up. Maybe the original motorbike choke cable option could be made to work well, the ecu would see the throttle opening and respond with extra fuel regardless of the engine temp.
I am using throttle position on all three of my Megasquirt units. This is reckoned to be the best option for long duration cams with poor idle vacuum as this confuses MAP based systems, and all my cars have long duration cams.
The guy who set up my cars on the rolling road reckons it is easier to set up (He is actually an agent for Emerald and doesn't do much megasquirt).

His reasoning is that the throttle load sites are fixed, you apply a fixed amount of throttle and can then map fuel and ignition from that fixed point.

When using Manifold Absolute Pressure sites vary according to whether rpm is increasing or decreasing and generally needs to be averaged over 3 runs.

I suppose a lot of the reason I have stuck with throttle position is that having done the first one like that, it is far easier to do the next one the same way.

My first attempts at auto tune all went very wrong, probably due to my ignition system being extremely marginal to begin with. Any misfire due to ignition problems saw an increase in exhaust oxygen which the auto tune interpreted as a weak mixture, it would then richen the mixture until the engine stopped!
I found it simpler to do it all manually.

I think the main reason for the vacuum driven fuel pressure regulator is mostly due to injector pulse width at light throttle settings.

The reduced fuel pressure at idle means the injector can operate over a longer period. For instance, most of my idle settings are around the 35-40 level. This means that if I want to weaken the mixture slightly, I can drop the idle fuel to say 39 from 40 and it has removed 1/40th of the fuel or about 2.5%

If the fuel pressure stayed high due to no vacuum regulation then the injector pulse width might have to be dropped down to maybe 20, so a cut of 1 from 20 to 19 would be a 5% cut, ie double the amount.
IIRC I read something by Dave Walker in PPC magazine about fitting pressure regulators to one throttle per cylinder set ups. He reckoned a damper was needed to take care of the pulses for both the fuel regulator and map sensors. It took the form of a traditional Stag type fuel filter inserted into the vacuum line.
Neil

[mjheathcote]

Didn't the Jag V12 have a bellcrank throttle assembly?

Yes, but trying to find one...

That settles it! I have only been working on (mostly off) my EFI project for a mere 8 1/2 years but I can't let Mike beat me to it
- I'm off into the garage now!
Alan

There a few good bit on here:

http://www.v8forum.co.uk/forum/viewtopic.php?t=5937&sid=113d6830dacefc199a56be9dafcea846

There is, a few posts by me too, confirming how long this project as been on the go!

Hi Mike,

I run an Emerald ECU on my lump' however most of these work on roughly the same principle. The Emerald came with basic maps therefore the engine would start and run with just refining to be done to start with.

In the Emerald case, the Ignition and fueling is tuned in once the engine is hot so that the optimum running mixes are fixed at that time. Once the tuning is carried out then adjustments are made in sub programs which control the additional fueling, cold starting, idle air valve etc. It takes a lot of tinkering about to tune in the cold starting and running because you only have short intervals during warm ups to intervene in the ratios, and generally each stage will interpolate with the one above / below.

The idling process with the Emerald unit starts off with the butterflies being set to allow the engine to idle with the IACV valve operating to even out the idle and also to open up to allow cold start rise in revs. I would have thought that the small diameter vacum ports you have would be adequate to allow for that, it is surprising how small a movement in the butterfly will affect revving. To be honest, you may find that you can live without additional air once you start using the system, using small throttle movement to initially increase the air volume.

Pressure regulator. As far as I know, all injection systems adopt a constant pressure in the fuel rail during normal running and use the vacum to release the pressure in the rail during the over run, thereby cease fueling during the over run.

The controling sensors on my system are, Crankshaft sensor, throttle position, engine temperature and air intake temperature. An additional, but not essentials on, is a Lambda Sensor.

Assuming each butterfly has its own idle setting screw, my suggestion would be to get the engine running and up to operating temperature then disconnect each butterfly from the linkage and use a carb balancer to tune in each port to your required idle rev. Once you've got that reconnect the linkage and you're near enough there.

I'm not tied to going Megasquirt, and Emerald is still a possibility.
There is a small cam available that cracks open the butterflies that gives the same effect as the vacuum ports, but it is a manual cable operation. Don't think I'll bother at first. Thinking of adding a Kenlowe hot start (or similar), so the engine is already warm, and see how it goes...
It was I am sure Dave Walker from Emerald who does not bother with the vacuum connection to the fuel pressure regulator, could be wrong though...
I have all the same sensors incl. wide band.
Each throttle body has an adjuster, however they are interlinked, so if you adjust one, they effect the next in-line, which you can accommodate for. That actually thinking about it could cause me a headache interlinking across the banks in the middle. I need to think about this some more...

[mjheathcote]

Maybe the original motorbike choke cable option could be made to work well, the ecu would see the throttle opening and respond with extra fuel regardless of the engine temp.

Yes this is how Suzuki do it. Doing a search, some riders also use it as sort of cruise control!

I am using throttle position on all three of my Megasquirt units. This is reckoned to be the best option for long duration cams with poor idle vacuum as this confuses MAP based systems, and all my cars have long duration cams.
The guy who set up my cars on the rolling road reckons it is easier to set up (He is actually an agent for Emerald and doesn't do much megasquirt).

His reasoning is that the throttle load sites are fixed, you apply a fixed amount of throttle and can then map fuel and ignition from that fixed point.

Agree, also having individual bodies is not good for a reliable MAP signal apparently.

IIRC I read something by Dave Walker in PPC magazine about fitting pressure regulators to one throttle per cylinder set ups. He reckoned a damper was needed to take care of the pulses for both the fuel regulator and map sensors. It took the form of a traditional Stag type fuel filter inserted into the vacuum line.
Neil

Okay, all 8 signals into a little cylinder. I also recall now, but had forgotten!

[mjheathcote]

I didnt even start mine yet (still in the researching phase) but will start it in the new year .. wonder if I will finish before you and Mike ... the challenge is on ..

Actually, just bought me one of these so technically I have started I suppose ..

[ATTACH=CONFIG]39231[/ATTACH]

Just don't underestimate the amount of work required!
I couldn't have made it harder for myself to be honest the way I decided to go with individual bodies per pot, hopefully it will work in the end!!

[kev100]

Just don't underestimate the amount of work required!
I couldn't have made it harder for myself to be honest the way I decided to go with individual bodies per pot, hopefully it will work in the end!!

I am pretty sure it wont be easy .. but I love a challenge .. the harder the better .. a better sense of satisfaction at the end .. of course, there could also be a greater sense of disappointment too, but all that means is try harder next time ..

Yes individual bodies does seem a harder route .. but whatever the outcome .. it looks great, and am sure after setting up will work as expected, and hopefully better , its going to be great to watch our systems develop over the next year (or several years)

[Stagdad]

Regarding the need for 2 shafts needing turning off of one throttle cable, along the same lines as the Jag linkage suggested by John, is the stag standard linkage not doing exactly that. I've just had a look at it (in the book as I don't have one any more) and I'm sure I could adapt it to work for what I need which is one cable in and 2 cables out to go to separate throttle bodies. Just a thought.

[mjheathcote]

Each part of the system is a challenge!
The initial intake manifold was a big one of course, fabrication and machining from scratch.
Spacing out the throttle bodies to each intake runner was not too bad an exercise, plenty of machining though.
Then a custom fuel rail was required, and a method of supporting it to keep the injectors in position.
Timing wheel on front pulley took some time, took Alan's idea there but mounted the sensor differently to keep the timing quadrant.
No room for the distributor, and going wasted spark not required, more machining to make a dummy from an old distributor just to drive the oil pump.
Fuel system in boot, went down the swirl pot route, more bespoke fabrication.
That is where I am, linkages, and ECU.
Also need to sort out an air box. Bought an old bonnet years back in case I feel 8 trumpets straight out the top is the way forward!!

[mjheathcote]

Regarding the need for 2 shafts needing turning off of one throttle cable, along the same lines as the Jag linkage suggested by John, is the stag standard linkage not doing exactly that. I've just had a look at it (in the book as I don't have one any more) and I'm sure I could adapt it to work for what I need which is one cable in and 2 cables out to go to separate throttle bodies. Just a thought.

Already thought about that one, and actually took the linkage off my original Stromberg carbs to have a play this last weekend.
It also has the advantage of being able to drive the kickdown cable as well.
I haven't ruled it out, but it's a little too big to use alone in between the throttle bodies, so one thought was using one of the linkages to the bellcrank. Then I thought you can buy the bellcrank already to accept a throttle cable, neater solution...but still need to link up the kickdown cable somewhere.
One cable in, two out. That has been done before with bike throttle bodies on Rover V8's. Problem is getting synchronization with two separate cables, and cable stretch. It is a better solution if using rods.