Any efi gurus out there?

[David_S]

I am converting my old Nissan P40 engine (MQ) to fuel injection using a throttle body (central point injection) off an EA Falcon.

I have now reached the stage of fiddling around with air filter and throttle combinations and realise it would be a lot easier to fit these if I raised the tbi unit some 25 mm or so with a spacer. This will increase the distance between the injectors and the inlet valves. I have read that increasing this distance increases torque, reducing it increases power. Is that right?

At present I have the injectors roughly level with the top of the inlet ports. (I have welded the EA inlet manifold plate to the Nissan manifold). This was as low as I could reasonably place them in order to leave room for a transition between the tbi and the original air filter. Since then I have found a GQ air filter which I can modify and have also done a 50mm body lift so space above the tbi is not at such a premium any longer. Raising the tbi unit 25mm will also increase the clearance between the fuel hoses and the exhaust manifold which are a little close (though I have installed a heat shield to protect the hoses).

My questions
1) Is that torque/power relationship to the length of manifold true?
2) Will an extra 25 mm make any significant difference?

Thanks, David

[Gribble]

It doesn't increase your tourque, it really just shifts the point at which you will make maxium torque. Shorter will move this point upwards in the RPM band, longer will move it down.

The reason this phenomenon exists is because when your inlet valve shuts you still have alot of inertia in the air that backs up behind the valve.

Think about a whole shitload of post christmas shoppers running into Myer and then security instantly shutting the front door on them. The people at the back of the crowd are still running forward so the crowd compresses up, when they can no longer keep moving forward the crowd then starts to uncompress and move backwards. The same thing is happening with the air entering your cylender.

This sends a smallish wave through the inlet manifold and back out the throttle body. When it exits the throttle body it now creates a vaccum around the inlet of the tb and another wave travels back down towards the inlet valve.

So you now have a shitload of shoppers charging at the front door. If security time it right and open up the doors just as the wave gets to the front you will have a more compressed crowd of shoppers getting through the door, which means more shoppers. In terms of the engine this means more air which you match with more fuel which makes a bigger bang.

Now, because these waves always travel at the speed of sound the time it takes for the wave to travel from the inlet valve, out the tb and back to the valve remains constant. A longer runner in your inlet manifold means the wave takes more time to travel back and forth, meaning a longer runner is going to maximise the lower end torque of the RPM band. A shorter runner will mean the wave doesnt need to travel as far so the oscillations are much quicker, meaning its better suited to higher RPMs.

Hope that makes sense, and after all that to answer your second question.....

...no, you wont notice a difference at all.

[juls]

Im assuming you have the CFI TB on a traditional carby type inlet manifold where the runners arent even lengths?

I cant see that any amount you space it will make much difference at all.

On equal length runners (such as factory efi manifolds) it will make a difference but you are talking 30-50cm runners. Even 2.5cm here will not make much difference.

However if it makes mounting the aircleaner then why not!




Good luck with the ford CFI TB. I was running this TB on my mazda 1600 engine and seemed to work well. I would have preferred mulitpoint injection but it is certainly an easy way to get EFI.

What air filter are you using?

Hers is a few pics of my setup:
http://gallery.teamshitbox.com/gallery/ ... temId=4466

http://gallery.teamshitbox.com/gallery/ ... temId=4470

[David_S]

Thanks Gribble and Juls for your prompt and informative replies. Your photos Juls look familiar and I see you had a problem routing the throttle cable over the rocker box too. Did you remove the Ford idle control solenoid - I don't see it in the pics. I have kept mine in place even though I have not figured a way to control it off my ecu (Megasquirt). Instead I have wired it up as a hand throttle but suspect it might be a bit too rapid acting.

Yes I am using the stock inlet manifold with 30-35cm runners. Central point is easier to install than multipoint and anyway I am not sure that I could install multipoint on this manifold as the outer two runners both feed two cylinders. i.e there are only 4 runners feeding 6 cylinders. Maybe you could install 2 injectors on the outer runners? But I have enough problems as it is without going down that track! I have renamed my project "Fool injection".

Air filters are a bit of a problem with the oval intake on the TB. I tried the EA Falcon one but it's far too big. I think I will cut the bottom out of a filter box I salvaged off a TD42 Patrol and weld the hole from the Falcon in. This box is a nice oblong shape which should fit neatly alongside the engine, not over it. Only problem is it points the wrong way, but that should not be too difficult to remedy.

Once (if? when?) I get it running I will post some pics,

Thanks, Guys

Cheers, David

[juls]

Excellent, another MS project.. good to see. The 808 was my 2nd MS'ed car and a few mates have done/are doing MS installs. On road tuning is where its at!


What you have said is correct regarding the multipoint. A friend was running mulitpoint on a stock L20 manifold and had issues at idle however it seemed to run fine otherwise.

My filter is a generic aftermarket one and I cut the oval shaped hole with a jigsaw. If I were doing it again I would space it up a bit so it clears the FPR. I just cut a hole for the FPR and put gaffa tape over it to seal it.. not ideal but works

Modifying an existing filter box like you mentioned sounds like the go. You can potentially water proof it too, which would be difficult on my car.


I didnt use the idle control solenoid. One of the things i was going to do but didnt "have" to do because it would still drive, just sometimes didnt like idling when cold....

I think I actually modified the throttle cable lever/catch bit so it pulled from the other side. I cant remember why i didnt use the factory EA throttle cable.. It might have been another thing I'd do differently next time

[fool_injected]

What you have said is correct regarding the multipoint. A friend was running mulitpoint on a stock L20 manifold and had issues at idle however it seemed to run fine otherwise.

Multi-piont v- Throttle body argument is realy a sequential -v- batch fire agrument
With sequental fire each injector is fired seperatly but with batch fire they fire simutainously (even with mpefi)
At not many RPM above idle sequental fire is a load of crap as the time taken to fire each injector with relation to the mechanical efficiency of the injector means the injecter is never realy open or closed at any given time
Does that make sense? There is a good explaination somewhere in the MS forum


The spacer also do something to the inlet temp by moving the TB further from the heat source. This is why they are often made of bakelite or similar. Falcons have a space about 10mm, you could just stack these

[fool_injected]

I have renamed my project "Fool injection".

Thanks, Guys

Cheers, David

I am calling copyright, interlectual property, blah blah on that title
It is/was my username first

Funny, the username was actualy given to me by a guy at work when I was doing a MS set up (single TB on a 308 One Tonner)

This guy also ended up starting a set up before he left
Using two Falcon TB ontop of a 351 in his XY ute
We machined up a custom shaft which run between both throttlebodies and paralleled all the injectors
Then we got two holley 2 barrel to 4 barrel adaptors flipped them upside down and drilled the two barrel side out to accept the TBs
Should catch up see how this setup went

PS The throttle bodies look unreal after a little bit of polishing
But DON'T split it in half though as the gaskets are impossible to get, think I got the last set in Australia from a Perth Dealer after much searching

Don't know if much about electronics but here goes
The Idle Control Solinoid is operated by PWM
0% is fully open and 100% is off. Use about 200Hz as the frequency
Think of it as a servo rather than a solinoid

http://www.msefi.com/viewtopic.php?t=24 ... omoco+idle
By hooking yours up as a hand throttle (good idea) you are running at 0% duty cycle, flat out

MS are set up to run with GM gear and I think there ICS is the on off type (like an idle up solinoids for AC on old carby cars)
There is a firmware download somewhere on the MS Forum to control PWM ICSs

Got a spare ICS kicking about
Might hook it up to the 1600 MPEFI I am putting the Zuk ATM as a hand throttle using a picaxe to supply the PWN via a dashmounted pot

[juls]

Multi-piont v- Throttle body argument is realy a sequential -v- batch fire agrument
With sequental fire each injector is fired seperatly but with batch fire they fire simutainously (even with mpefi)

I disagree about the"sequential -v- batch fire " comment . Its not as simple as that. Especially in the EA tb case.

If you look at a EA tb it sprays the fuel directly onto the butterfly. Runner lengths are also shorter and uneven lenths. This effects efficiency of the engine. The EA tb is bascially a carb but I think its design is probably not even as efficient as a carb especially at low throttle openings because of the way fuel is sprayed onto the butterfly, you can actually see it pooling there at idle... :S

Some TBI throttle bodies may be better design however in general mulitpoint has to be more efficient, be it sequential or bank fire.

juls wrote:


What you have said is correct regarding the multipoint. A friend was running mulitpoint on a stock L20 manifold and had issues at idle however it seemed to run fine otherwise.

Anyway, i think you have misunderstood what my point was regarding the stock carb manifold being converted to multi point. This issue is that you have two cylinders on the same runner which seems to make metering fuel difficult at low engine speed.

[David_S]

I am calling copyright, interlectual property, blah blah on that title
It is/was my username first

Surely there's room for more than one fool in this injection conversion game!

The spacer also do something to the inlet temp by moving the TB further from the heat source. This is why they are often made of bakelite or similar. Falcons have a space about 10mm, you could just stack these.

The Falcon spacers are only 6mm so I would need a lot. I will just use 19 or 25mm alloy flat with Falcon spacers top and bottom.

Don't know if much about electronics but here goes
The Idle Control Solinoid is operated by PWM
0% is fully open and 100% is off. Use about 200Hz as the frequency
Think of it as a servo rather than a solinoid

I don't think the Falcon cfi idle control is operated by PWM. The link you gave looks a lot more like the bypass-air type fitted to the mfi Falcon. Mine according to the Falcon efi tech notes (I have these on a 5MB pdf file if anyone wants a copy) is

D.C. motor idle speed control is used with the EFI(CFI) system. The D.C. motor controls extension and retraction of a linear actuator. The actuator acts as a variable throttle stop to control the engine idle speed. The D.C. motor is controlled using what is called a " H " driver circuit. This circuit can flow current through the motor in either direction - when current flows through the motor in one direction the actuator retracts, and when current flows through the motor in the other direction the actuator extends. The current flow reversal is achieved by having two output lines to the motor, DCM + and DCM Forthe motor actuator to extend DCM+ sources current and DCM- sinks and for it to retract the opposite is true i.e. DCM + sinks current while DCM- sources it. These are the only EEC-IV outputs which do not only sink current but can either sink or source current.

Presumably I could slow down the motor using PWM but that would be another project! At the moment I have just wired up the motor to a DPDT switch in the cockpit. This may be all I need as I only want it for winching - a steady 1500rpm though it might also come in useful for cold morning starts. The unit incorporates an idle tracking switch which is just an on/off switch in the nose of the actuator - open when the nose contacts the throttle, closed when no contact. I have wired this to an LED in the instrument panel which lights up when the hand throttle is engaged.

A final question. Anyone know how the Falcon throttle cable is attached to the throttle pin? There is a fitting on the end of the cable which fits over a ball on the throttle plate. Is it just retained by the spring on the cable or is there something more positive? Just seems a bit dodgy as it is so I have fabricated a screw-on retaining lug.

Thanks all, David

[juls]

Pretty sure it presses and clicks on, sort of like a RC car suspension strut.

[fool_injected]

There is a little clip which holds it in place
I will see if I can find one in the garage and take a photo of it for you

[David_S]

Pretty sure it presses and clicks on, sort of like a RC car suspension strut.

Must be a plastic insert or something missing on mine as it is just a loose fit and pops off if you wiggle it.

Another question. Is there any preferred location for the offtake for the manifold vacuum line? At present mine is as shown in

http://sparkandfuel.com/colorvalve/gall ... m=62&pos=0

the blue pipe under the TB. If I raise the TB by 25mm with a spacer is it desirable to raise the offtake too? It is currently located just above where the airflow divides left and right.

Thanks again for the help. I am working on my own (apart from my two boys) on this project and none of us have any previous experience with efi so all assistance is welcome. The usual comment I get round here is "Why don't you just do an engine swap?" Apart from the cost they miss the whole point of the challenge of designing, installing and tuning a diy efi system from scratch.

Cheers, David

[fool_injected]

Couldn't find the cable so I took a pic of clevis pin from an air ram
The clip looks like the round bit on the end


The ICS I was refer to is the four wire one pictured below, know the link was for a diferent type but it explains the control a little
I am working from my vague memory as I have not done this stuff in like five years. Thought they were PWM controlled??


If you make your own adaptor/spacer be sure to still use the insulator


PS I was only joking about the Fool_Injected bit, at the end of the day were all a little foolish for delving into the 'unknown'

[David_S]

Thanks Fool-Injection. Very helpful. That clip is definitely missing but I have fabricated another which should do the trick.

See http://xs411.xs.to/xs411/07016/Throttle_connection.JPG

Your idle control solenoid is identical to mine. Would you like me to PM you a schematic of how I have wired it up as a hand throttle? Will almost certainly need a mod to give more precise control but I have not been able to test it as the truck is still in bits!

And, yes, I will put an inslator beneath the spacer and probably above too to seal the join properly. Any idea what these insulators are made from in case I have to fabricate one? There is not much "give" in them.

Cheers, David

[juls]

Another question. Is there any preferred location for the offtake for the manifold vacuum line? At present mine is as shown in

http://sparkandfuel.com/colorvalve/gall ... m=62&pos=0

the blue pipe under the TB. If I raise the TB by 25mm with a spacer is it desirable to raise the offtake too? It is currently located just above where the airflow divides left and right.

I had issues with my map signal wavering by like 10kpa which must have been due to the intake pulses. I used one of those clear plastic fuel filters as a reservoir to smooth the signal and it now varies 1-2kpa.

The further you get it away from the runners the better it will be, but i suspect you will have similar issues to me requiring a little reservoir of some time.

The insulators are made of some kind of plastic which is really brittle, and they have a plastic gaskety material on either side. You must be able to buy these new. I grabbed a few from the wrecker where i got my TB

[-Scott-]

I would guess a four wire idle control device is a stepper motor - direction and speed controlled by sending appropriately timed pulses to different wires. I thought MS could control an idle stepper?

[fool_injected]

MS can do what ever you want it to
It 's default set up is to work with GM gear if you want to run the ford ICS you need to download the source code
Check the MS forum the code is in there somewhere

I havent hooked a hand throttle up yet, your idea just got me thinking of building a stand alone unit
Send me that Manual you got and I will work a circuit out
Little tricky though as you need to cancel it if there is an input from the throttle or brake (as in cruise control)
Brakes easy but throttle is more complicated

The insulators look like they made from bakelite

[David_S]

I would guess a four wire idle control device is a stepper motor - direction and speed controlled by sending appropriately timed pulses to different wires. I thought MS could control an idle stepper?

The four wires are DC+ve, DC-ve, Earth (sensor ref) and ITS (Idle tracking switch) The ITS is just an on/off switch located in the nose of the actuator to indicate when it is in contact with the throttle.

I am sure MS could be programmed to control the actuator, but hell's bells, the last thing I want to be doing at the moment is fiddling with the code. I will probably have enough problems just getting it to run reasonably fuel only before experimenting with the "spark" side getting MS to control dwell and timing advance using my Pertronix ignitor as a "trigger".

So initially I will just use the Ford idle control as a manual hand throttle (and probably as a manual cold start aid too!) So, yes, I will be interested in your circuit, fool-injected.

David

[bru21]

without reading all of the above,

the length will have insignificant effect on what is essentially a truck engine with a central injection point. the only place where length ofthe inlet matters is for economy, and pulse "supercharging" to gain greater chamber filing at a specific rpm.

fo all the info yiou need see your local library as they have the $440 ford manuals - a simple photocopy away.

tb injection is far better than a carb as it works on hills and cuts fuel on deceleration thus saving fuel. the single body principal in my head is far better than multi unless an o2 sensor is fitted to each exhaust as an overall engine balance can be reached easier. I nearly shat myself when i saw my BA on the computer at 1st first service the pots were so different!

look under the bibles as I have done this mod before

best of luck

bru

[David_S]

tb injection is far better than a carb as it works on hills

which is precisely why I started on this project - after a day winching up a long, steep, deeply-rutted hill in the rain with the engine dying every time I lifted my foot to climb out the window as the ruts were too deep to open the door, using precious battery power to restart, and covering onlookers in a cloud of environmentally unfriendly black smoke as the engine went progressively from a 6 cylinder to 5 to 4 to 2 as the plugs fouled! Also the reason why I am fitting a hand throttle!

But thanks Bru and all for your encouragement.

David