help me find a relay to suit please

steptoe · Post by **steptoe** » Mon Jan 12, 2009 9:40 am

Ooh, mid blue on dark blue background, grrrr

OK looking for some advice, knowledge, help here in selecting a suitable relay.

*Using the TPS as a switch for a relay.The TPS will not be ECU connected
TPS usually switches ECU 5 Volts
*Ultimately I need to switch 12 Volts to open close a normally 12V powered EGR vacuum solenoid - hence need for a relay
*Thinking 12V may be too much across the TPS for good service life (I could be wrong) and plan to use a USB power supply to get 12V down to 5V to put across TPS to put across the coil side of a relay to switch the 12V
*wondering if 5V will activate a 6V relay coil

If so, will ned a coil that switches 12V using 5 - 6V across its coil. Looking at Jaycar catalogue of 2007 I am getting some idea

Anyone of you electronics boffins able to asist or comment please?

thanks, Jonno

fredsub · Post by **fredsub** » Mon Jan 12, 2009 9:54 am

The idle switch part of the TPS is mechanical, it should be able to handle 12V low current, ie to energize a relay, standard 30AMP relay uses about 250mA @12V
Your not having a ECU connected to this so nothing else to worry about.
Although I must note if your only using that to switch the EGR, it won't be good at cold engine. Use the thermal EGR switch found on a carby ea82.

I expect a 6V relay will energize with 5V (normally).
The hold-in voltage/current can be much less after it is initially energized.
In car environment, given over vibrations I would think using the specified voltage is best.

Don't worry about the 5V, your not connecting to the variable resistor part of the TPS, are you?

To minimize any possible arcing the switch has when releasing the relay, put a diode across the relay coil.
The arrow of the diode needs to point at +Pos Volts.
Any 1 amp diode will do 1N401 for example.

steptoe · Post by **steptoe** » Mon Jan 12, 2009 10:44 am

thanks fredsub,

just don't wanna burn it out for future reuse as ECU input

so that would be a diode protected relay then would it?

About $12 instead of $6. Good suggestion. We use them on LPG conversions on ECU side stuff. Get invoiced for diode protected and get a basic relay !! time and time again !!

Cold engine is not a worry at present on LPG and not giving any bad symptoms at all with EGR concerned. Need to hook back up to petrol to see if it all still works after 9 months on gas, as the EGR was inactive at that time while chasing a miss, will be chasing that miss in next fortnight yahoo when i expect to be able to do an engine swap and pull down current engine to replace valve springs

steptoe · Post by **steptoe** » Tue Jan 13, 2009 7:41 am

fredsub wrote:The arrow of the diode needs to point at +Pos Volts.

So what did I do ? I bought a diode protected relay with the arrow pointing the other way.! I could just reverse the connections 85.86 but being a bit of a stickler for 85 always being the earth , I'll get it swapped. I had tthe option of either,looked at the diagrams - and picked the wrong one. The other direction was not stocked so gonna try using the soft blue plastic enclosed diodes found under the dash of a few of my wrecks in the past. Took a whle for it to dawn on me what they were !

steptoe · Post by **steptoe** » Tue Jan 13, 2009 9:58 pm

I think the penny just dropped...the diode goes across the contacts rather than the circuit go through the diode as part of the circuit ?? So when I make up my wiring, wire in my blue subie under dash blue diode soft plastic housed connecting the pointy end to the power side 86 and the other end to the earth side 85. And this is what stops any spike if it was to occur ? found a good website called the12volt.com that sort of explains things and has some good relay diagrams for doing some neat tricks, one using just one relay to reverse a polarity when I have used two to do same thing

discopotato03 · Post by **discopotato03** » Tue Jan 13, 2009 10:42 pm

I must be missing something here , it sounds like you're using an MPFI TB and TPS ?
If that's the case then aside from the throttle being closed (TPS idle contacts open) whats going to break the circuit and close it when the throttle is at more than the "cruise" position .
I suppose you could use a 3 plug TPS and wire in another relay to open the circuit with its second set of (wider open throttle) contact points .

A master cold water temp sensor operating something to disable EGR would be good .

This is all sounding quite complicated , the factory EFI control units had a variety of engine sensors to tell them what was going on and only opened the EGR valve to control combustion temperature - NOX goes up with elevated combustion temperatures ie lean light load (cruise) conditions .

Cheers A .

fredsub · Post by **fredsub** » Wed Jan 14, 2009 7:26 am

steptoe...yes, you got it, its the contacts of the TPS I was concerned about,as they would be make/break often. So the arc occurs when the relay it is energizing is switched off.

I think that a TVV (Thermal Vacuum Valve) could solve all these problems simply and without electrical trickery.

Its activated by vacuum - on cruise
The thermal part means it will only pass vacuum once the unit is warmed up, so it needs to be located close to engine.
The vacuum passes to EGR, hence opening it, allowing exhaust gases back into combustion hence to cool combustion and reduce NOX.

I was looking into doing this on my ea82t, hmm just relooked at these emission diagrams, confusing aren't they? I recall experimenting with it, unsuccessfully tho, but didn't try hard anyway. No rego inspection ever checked if hoses are missing anyway, theres so many, anyone who can only allow a limited amount of time to check things wouldn't see it.

steptoe · Post by **steptoe** » Wed Jan 14, 2009 10:09 am

I shall elaborate....

My 87 L series sedan flapper style afm 3 plug ecu ea82T GLTA GL Turbo Auto Oz delivered
is according to the factory manuals supposed to have ecu control over the EGR.

1. ECU is not supposed to allow EGR to open until a certain temp has been met (about 45 deg C) I have found with testing that this EGR operates when stone cold. I do not mind as the LPG does not give any hint of drivability when cold. MPFI use ECU and vacuum solenoid, carby uses a thermal vacuum sensor switch and same electric solenoid. To eliminate whats not needed I am not and have no intention to include the thermal vac switch. ECU does not have any control over EGR regardless of engine temp.

2. ECU is supposed to shut off the EGR at speeds above 45 kph, no ifs or buts. Asuming speed sensor is there to tell ECU car is moving say 4kph according to manuals test procedure. I guess it is same speed sensor giving more pulses at 45 to say shut off EGR . I have found with testing that my EGR opens at all speeds.

3. I have found that as expected , boost pressure I think is keeping it closed need to test that, ECU could be switching with boost signal. Other than this possibility it loooks that the only ECU control on my EGR is at idle or foot off acc pedal assuming it is idle switch circuit.

4. The only times I have foun EGR works as in opens is between light vac of about 1 in Hg to about 10 in Hg. Above 10 is foot off acc pedal, below is boost pressure.

so it is working as such when it should on light throttle to reduce Nox as Adrian says

I want to fit EA82T to my Brumby with no ECU, no ECU hook up or control or the associated wiring. It will be dedicated LPG as Brumby is now and as motor is now in GLTA. BrumbertyMatt did this with his EJ in his Brumby with a points dizzy and LPG and he supercharged it too!

And yes I want to retain EA82T throttle body and its TPS but use TPS only as an earth switching for a relay to control the EGR solenoid vacuum switch to replicate how the EGR is working currently as described above. If necessary will also shove boost pressure switch off green dash light to switch off vac at boost

I have referred to soft blue plastic diode cases - these I have found under dash wiring of MY and L series, are a lightish blue in colour about 40mm long 8mm thick 14 mm wide and have two male spade terminals at one end. I have found these to be diodes. May be tied up with A/C fans switching and more.

The other relays I have mentioned are diode protected relays with an internal diode across? the 85 86 terminals and are available in the bosch catalogue anyway of either direction between 85 86

Have also noticed resistor protected relays in same catalogue - some may understand _ I do not

As Fredsub has suggested, just use the TVV to avoid electrickery (Catweasel?) but that little dude will not stop EGR opening on throttle off or idle position. It needs to be shut at throttle off for decel or engine braking like when backing off down a hill with 20in Hg !!

Just what stops same on the carby model I don't know, praps an idle solenoid contact in carby??

discopotato03 · Post by **discopotato03** » Wed Jan 14, 2009 3:30 pm

I don't think you're going to need anything to switch "vac" off under boost because the manifold pressure will be (should be) positive anyway so won't pull on the EGR valve diaphragm anyway .

I've just been looking at the 85/86 Subaru WSM Fuel Injection System chapter and it has this to say about the early 3 plug systems "TPS" .

(1) Aust non turbo , (2) Aust Turbo , (3) Other .

Idle contacts closed from 0 - 2 Degrees Throttle Rotation (DTR - ?!)

Part throttle range (both contacts open) (1) 2-22 (2) 2-47 (3) 2-32 degrees

What this tells you is that there is a 20 45 or 30 degree range where both contacts are open and the ECU is relying on the air flow metre to regulate fueling from mass air flow (corrected by temp sensor in AFM assembly) .

After the 22 or 47 or 32 (20 or 45 or 30 range plus the 0-2) the second set or wide open TPS switch closes to signal the ECU of high load conditions .

Because of the "part throttle range" variation between NA Turbo and Other models you can have some say over what signals your EGR solenoid valves "control system" based on part throttle running .

All this sounds like a complex system of relays fighting for control of one poor solenoid valve .
Sorry to be negative but if it worked theres no way to know how well it can control combustion temperature burning LPG , the system was designed to work with electronically controlled ULP fueling given its burning properties .

I really can't see how to build on the cheap an effective LPG turbo system , its low octane nature means retarded timing to prevent detonation so it won't be any power house or give good consumption under load .

Ultimate consumption engines on the cheap have high compression ratios and use water or water methanol injection to supress detonation with the cheapest lowest octane fuels .
High CRs are what it takes to make good part throttle torque and the water is used to cool combustion temperatures at wider open throttle where the dynamic or effective CR is higher .

Later I'll get into measured or "static" and dynamic "effective" CR and how it affects detonation .

All this would work far better with a carbed EJ if you can do it .

A .

steptoe · Post by **steptoe** » Wed Jan 14, 2009 9:43 pm

Yeah, have sort of discussed the first part of your post in another recent post.

I am going to need to replicate the ECU control of the EGR to hopefully satisfy an engineer. Only going for one relay, one side of TPS, and one solenoid and will leave boost to just stop at EGR.

You trying to gee me up on LPG stating it is low octane ? Have seen LPG stated as 109 RON. The timing retardation only needs to occur higher up in the revs and takes more advance at low revs so knock sensor not likely to be working as much with LPG. Not wanting it for a drag strip beast or even boy racer just a 2500 - 3500 rpm mover. The requirements for conversion to LPG is that EGR is retained so you'd 'hope' that those that be had engineers with them when making this requirement.

discopotato03 · Post by **discopotato03** » Wed Jan 14, 2009 11:23 pm

I never ever hear people in the performance industry speak favorably about burning LPG - and let me tell if they could find a way of getting a 109 octane fuel as cheaply and easily as LPG it would be front page news .

People talk about E85 being the new "high octane" wonder fuel and its supposed to have a relative octane rating of around 110 .

High octane fuels are all about being able to run higher compression ratios NA and higher than the usual 8-9:1 CR on forced induced engines .

Most engines inc turbo'd ones can usefully use more advance than the octane of readily available fuels will allow without detonation . Best mean torque ignition timing is about being able to light the fire and have the optimum cylinder pressure rise with the pistons in the 10 - 15 degrees past top dead center on the power strokes .
This is the point where detonation occurs and doesn't have to be at very high engine revs .

I don't know if you get a chance to drive late high compression ratio vehicles with sophisticated engine management systems but they make noticably more torque starting from low revs burning high octane ULP than they do burning low octane ULP . The difference is that the knock sensors detect detonation long before the human ear can and pull the timing back until it stops detonating . With retarded timing the burning efficiency falls as does the cylinder pressure so you get less torque .

Admittedly a reasonably high mileage EA82T won't be getting its static 7.7:1 CR so you get away with a bit more timing because is compression pressure is lower .

I'm not sure which page of the hymn book your engineer is reading from but I guess if all you have to do is please him use whatever method achieves that .

Cheers A .

discopotato03 · Post by **discopotato03** » Thu Jan 15, 2009 4:48 am

I did a bit of a refresh search on octane ratings and can see where you got the numerically high number for LPG .
BTW LPG is a mix of Propane and Butane and neither is really sparkling when you look into the why fors .

Do a search on RON (research octane number) MON (motor octane number) and AKI (anti knock index) .

The figures I looked at showed LPG's AKI as I think 105 and neat ethanol as 129 .

It's interesting to note that the Australian "headline" std is Research Octane Number where in the US and a few other places its an average of the Research Octane Number and the Motor Octane Number .

Cheers A .

fredsub · Post by **fredsub** » Thu Jan 15, 2009 8:33 am

:)Disco doesn't need sleep:rolleyes:, 12:45AM..5:48, hehe - been thinking this all nite?
It was a warm warm night, didn't sleep too well either, only the 2nd one this season, not enough to get used to it;)

steptoe wrote:Yeah, have sort of discussed the first part of your post in another recent post.

I am going to need to replicate the ECU control of the EGR to hopefully satisfy an engineer....

Has me thinking could be a market for a simple micro controller using TPS input (so configurable TPS range using the variable resistor) and temperature input (hi-temp thermistor) and speed input (tacho pulse?).
I know if you don't get it right, the EGR can cause the engine to run horribly if its open at the wrong times........

discopotato03 · Post by **discopotato03** » Thu Jan 15, 2009 10:23 am

Yes it was a warm night but doing an overtime backshift and having access to the net helps .

LOL , A .

steptoe · Post by **steptoe** » Thu Jan 15, 2009 4:30 pm

it is a bad time to be near work - whatever way !

I had a report produced for the Federal Government on LPG as a fuel into the future by someone whose name I will never recall. Chucked it recently but it made reference the the 109 RON. Sooo.. you'd expect it to be correct ??

Yeah, I hear you on CR raised with LPG. I run an old Ford that when it ran on smelly old super petrol a race tune workshop who was to curve the dizzy for me invoiced me for their labour. a used or dirty HT lead and wrote in angry caps across it staitng the compression is too high for road use.

The wonderous individual mistook the sixpots timimg marks for V8 when he set the timing. I took it home and undid his tune , reset to what I had before, fiddled with advance springs ,and since then my cars have never been in another workshop or worked on by anyone else except for exhaust work in 24 years!
On gas this baby with too high compression (230psi) and tall diff runs really well with over 300,000km on it. Limiting the max mech advance and adding more initial turned it more towards slingshot end of scale

an interesting website from here in Australia is http://www.performancelpg.com it has a small following and does not get looked in very often but there has been some interesting work going on by some with turbo gas. Whack a dot au on the end and it links to a WA guy developing a sequential LPG vapour ECU for cars not built with efi or sequential - land of early subies !

A call to Parnell may get a comment re EJs and LPG having some troubles with valve longevity due to the intake tract causing LPG vapour already mixed to stratify at the head, erk!! so staying EA82T

Propane 100% is good for BBQ's, it'll make your meat sizzle. Get sneaky and cheapo and run your barbie on car gas (mix of propane and butane of which proportions we are not given or guaranteed) and you will struggle to cook with hardly a sizzle. There are some outlets that many drivers have noticed better economy and power when LPG purchased at these sites, figure they have the correct mix ratio. The last BBQ bottle I had filled cooked with the low sizzle. I figured someone got $neaky, so I went out and bought a George Foreman grill. I believe the US has a guaranteed rated LPG for road use

Back to subie, which is why i have a good EA82 to screw turbo heads on for its raised CR to try.

discopotato03 · Post by **discopotato03** » Thu Jan 15, 2009 6:59 pm

Yes I was there - must be back in the early middle 80's - altering advance curves in Mini distributors to make Cooper S engines with works camshafts run on 10.5 static CR and leaded super fuel .

A real S distributor has no vaccum advance mechanism so I was altering springs and bob weights to get more innitial but less total advance .

My call for me but I only see limitations with LPG fueled automotive engines .
They create all sorts of different packaging issues compared to ULP and it doesn't matter what you do with gas carburettor/converters , like petrol carbies they will never be as accutately controlled as an electronically regulated system .

IMO LPG is not about performance it's about being a cheaper fuel so the focus is on cheap not most effective .
My approach is finding the most effective means and exploring ways to make it affordable .

I deliberatly bough a car with factory EFI/turbo etc because its reasonably easy to coax a little more urge from what the factory supplies - and they did most of the hard work developing the thing .
I'd rather take advantage of the best EA82 MPFI bits Subaru had to offer and apply a bit of later thinking to make it work a bit better than they had it .
They didn't have the benefit of hindsight , we do .

Anyhow if LPG floats your boat go for it , I wish you every success .

steptoe · Post by **steptoe** » Fri Jan 16, 2009 9:03 pm

speaking of boats, my gas guru runs his boat on... you guessed it!!! The number of times Ive got a peek into his shop - I keep seeing performance set-ups, including turbo. Think one of them was liquid injection and turbo.

Adrian, you didnt hex me did you? Got a umm... backfire today, that sort of scared me. Do not think it would have happened if I had replaced the possible weak valve spring causing the lifter pump up at about 4000 in second - overtaking, then.....the noise mat on the underside of the bonnet softened the blow as the alloy turbo pipe went ^^^^ skyward, so no dent. The ECU should also disengage the EGR above 45 - wondering if this new connection is related? EGR been inactive 'til last weeks.

Floats a mates boat too...so much so that I do not think I will let "McGuyver" drive me anywhere again in his Maloo whether it be on efi petrol or vapour injection - IT HAMMERS !! (which might be the reason why he is yet to fine tune it onboard with the laptop - no one will travel with him !! )

discopotato03 · Post by **discopotato03** » Sat Jan 17, 2009 5:54 pm

A friend of mine worked at Irvines for a while and that fella was drag racing an I cant remember what with a blown methanol burning Keith Black in it .
Judging from the pics on the walls you'd believe a bullet can have a keel , in fact once at speed it looked like you could throw away the hull and defy gravity .

From what people tell me somewhere between Methanol and Toluene lies very high detonation thresholds - in most things . Toluene was the rocket fuel used in the dying days of turbocharged F1 engines , part of what was required to crank out 1300-1400 Hp from 1500cc (90 CID) engines (at 4 Bar or 60 psi manifold pressure) and that's no typo ...

I don't want to ignite our fire but where LPG has changed is the ratio of Propane to Butane , Propane is the good gear but it must be more expensive than Butane because LPG these days has a higher ratio of Butane to Propane than in past times .
You can thank the Taxi and Fork industry for this because they placed cheap as their top priority , as far as they're concerned lower octane is fine .

One other my been a mechanic (technician really) forever friend mentioned was that LPG tends to burn at a higher tempersature than ULP and he knows EA82 EFI heads already have a problem with thermal cracks through their exhaust ports and into their water jackets .

LOL , don't ya hate it when people sow those little seeds of doubt ?

I'm just the messenger , cheers A .

steptoe · Post by **steptoe** » Sun Jan 18, 2009 10:01 am

Gees, we have gorn a bit off thread eh?

Radio tech I know sent me off to look closer at my Jaycar cattle dog. A frequency switch kit KC5378 . Is intended that this little kit if constructed in a succesful end result will use tacho or pulse input -say from my cruise control pickup or its own. Can use this to shut down EGR above 45 kph as it is supposed to be at the ECU. And now understand how my relay needs to be wired up and why.

Yeah, LPG burns hotter and damages some makes heads. I supose a way to attempt to counter this is colder range spark plugs, colder thermostat and cold air intake. Also 'thinking' of something Gannon dredged up - cooled EGR air. Pipe the EGR gas through say A/C condensor or the underdash unitt mounted up front with a wet spraybar ??

phillatdarwin · Post by **phillatdarwin** » Thu Jun 18, 2009 5:17 pm

get a nail and wrap some wire around it till u get 5 volt and all fixed but put after the relay .