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Nudgedidit

Wiring for distributer ignition

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Hi all, I'm running a 3s-ge in a Fraser Clubman.

The original ignition system failed and I decided take the opportunity to upgrade to an Atom. I only need it for ignition functions at the moment as fuel requirements are taken care of by a pair of Webers. Also I will be able to add functions at a later date.

From the info I have been able to gather, I have drawn what I believe to be the correct wiring diagram, see attached image, if some one with any knowledge of the correct way to connect it all up could comment, that would be great.

 

 

 

 

image.thumb.jpeg.536ec40d141df998cbb7615995d32c6c.jpeg

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All looks good to me.  The pin you labelled as IGT on the Atom would actually be "ignition 1".  "G-" on the distributor should go to the "Shield/Gnd" pin on the Atom (rather than chassis ground).

You may want to think about adding a temp sensor so you can control Fan etc but above would be the bare minimum needed to run ignition only.

 

 

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Would also be nice if you had a way to measure load (MAP or TPS, although I am not sure how feasible either is with Webers as I've never looked into it - must be options) for ignition mapping.

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Hi there Adamw

Thanks for taking the time to have a look at the diagram. I'll change the drawings to reflect the changes and install accordingly 

just a couple of other questions. The other ground cables on the ECU, do they have to go to the engine or would a good ground elsewhere be ok?

The other thing I was a bit concerned about was the primary coil resistance, it's 3 ohms, I know this will effect the current flow and thus the output of the coil, but will it have a detrimental effect on the ECU or igniter?

i do intend to use as many of the ECU functions as I can, but this will require a bit of a rewrite so it will have to wait until winter.

cheers

Dan

Hi there CamB

The idea sounds intriguing, and I did a little research, it can be done ( a MAP sensor that is ) how successful it is I don't know but I will look into it.

The throttle position may be a better, read simpler, way to do it. Either way it will have to wait till winter. I'll let you know how it goes.

cheers

Dan

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7 hours ago, Nudgedidit said:

The other ground cables on the ECU, do they have to go to the engine or would a good ground elsewhere be ok?

The should be run as 2 separate wires direct to the engine block (connect to the same bolt).

 

7 hours ago, Nudgedidit said:

The other thing I was a bit concerned about was the primary coil resistance, it's 3 ohms,

No that will be good, the J121 is good for about 7 or 8 amps from memory.

 

8 hours ago, Nudgedidit said:

The idea sounds intriguing, and I did a little research, it can be done ( a MAP sensor that is ) how successful it is I don't know but I will look into it.

The throttle position may be a better, read simpler, way to do it. Either way it will have to wait till winter. I'll let you know how it goes.

For ITB's you will be better using TP.  You can get bolt on TP kits for DCOE's from Webcon and Burton etc.  If its a road car you can get a big improvement in drivability with 3D ignition, if its a race car that spends most of its life >70% throttle then less so.

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Hi AdamW

Thanks for the information, I've now wired it up as you say, checked it all at least 10 times, flicked the switch and was rewarded by a glowing blue light. Entered my ECU pass word and it all looks good. I'll start the configuration tomorrow.

i actually managed to find the web con site today and it does look promising. A simple kit and  voilà 3D mapping, a winter project I think.

thanks

 

 

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Hi there Adamw

Again, thanks for your help.

I have made the wiring alterations as you suggested and configured the ECU as best as I am able at this stage of learning

The engine started first time and now runs smoothish, however when I tried to set the timing to 10 deg btdc i found that it was running at about 30+. Trying to change this resulted in no 1 & no 4 cylinder no longer firing, as indicated by the timing light. I adjusted the trigger levels down and it now seems to be firing ok but i am still reading about 30 deg btdc with the timing light.

I have attached  the PCIR file, could you take a look at it please. I am only using the atom for ignition at present.

Cheers

nudge1.pclr

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Your map still shows a trigger offset of zero so it appears you havent set the base timing.

You need to set base timing in the triggers>calibrate>set base timing screen.

With engine idling, and timing light on, adjust the "offset" number up or down until your timing light/timing marks show the same value as whatever you have in the "lock timing to" box.  Note you have to hit the enter key when you adjust the offset (it should turn blue if done right).

 

hFEpB0t.png

Also, attached below is your map that I have tweaked a couple of things.  I removed manifold pressure reference from the ignition table to just make it 2D and put a more suitable advance curve in there.  Also a few other small changes such as dwell table.

Load this in before you do base timing.

 

nudge2.pclr

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Hi AdamW

Ok that seemed to work, now its firing at 10 Deg BTDC by the timing light. I did notice that as the revs increased, the advance only went to about 15\20 deg is that right? or do I have some thing else wrong?

Also do you know of someone up here in Whangarei that can do tuning link and weber as i think the carbs may be causing the uneven running?

Cheers

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6 minutes ago, Nudgedidit said:

I did notice that as the revs increased, the advance only went to about 15\20 deg

Was that using the map that I attached above?  Below is the ignition table I put in so you should see a peak of about 28deg.

J2bfEMT.png

 

I cant think of anyone up whangarei way for tuning sorry.

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H there AdamW

Hmmmm seems not all computers are created equally (especially mine), I had to down load the file on my mac, put it on a stick and load the windoz machine from the stick. There was some sort of file error occuring when I loaded it from windoz, I'll look into it so its not a problem in the future.

So with the correct file installed to the ECU and the trigger offset set to -23 deg it ran like a dream, I cant thank you enough for your help and guidance in setting this up, cheers mate!!

Cheers

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Hi 

I  know it's taken a while, but I have got a TPS for the weber carbs and am in the process of setting them up.

You will have to make allowances for my lack of understanding !!!

From the research I have done, and please correct me if I'm wrong, the function of the TPS as fitted to my particular setup is pretty much the same as that of an old vacuum advance system, that is, that whenever the throttle is in the closed position there is maximum vacuum and therefore maximum vacuum advance, around 13 to 15 degrees plus the static, in this case 10 degrees, plus the programmed (or centrifugal weights) advance. So at idle the advance would be 10 + 15 = 25° and a closed throttle at max revs would be 10 + 15 + 17 = 42° (27° is the max advance I have)
42 seems a bit excessive as I don't have a knock sensor, or does this not matter as there would be minimal fuel entering the cylinders?

As soon as the the throttle is opened the manifold vacuum dies away and we are back to the static plus programmed advance.

I have set up the voltages from the TPS to the ECU but not set up any ignition maps.

Also it is my intention to have the idle speed controlled by the ECU, would this be a case for using a 4d table

Bearing all this in mind, does anyone have any maps, insights, helpful comments?

Cheers 

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Its a lot more direct than that.

the TPS readings are fed into the ECU via the voltage output from the TPS. ie 0.5 v = 0% throttle, 4.5v = 100% throttle. This way the ECU knows exactly how much you have pressed the throttle. Kind of like vacuum advance but think of it like the computer reading the engine parameter that is causing vacuum, rather than the vacuum directly.

Once the ECU knows the tps%, you can use this as a vertical axis on your ignition table, so at 100% throttle you might be running 10deg more advance than at 0% throttle. you can tune this in any increments you like. The horizontal axis is already set to engine RPM as per the table Adam posted above (and it seems like you are using in your current map). In this sense the horizontal axis functions similar to RPM based weights would in an old dizzy.

The last point is that the values in that ignition table are exactly what the ECU is using to fire spark. no multiplers, advance, base timing, or anything like that (at least not yet, thats a whole other story about overlay tables within the ecu). The point is, what the ECU decides as the correct ign angle is, is exactly the angle it will fire at.  If you put that screenshot from Adam above as your 100%TPS row, when you are at 4500RPM and at 100% TPS, it will fire at 28*.

The bit that I think you are getting confused with here is the base timing from when you did trigger 1 calibration. This is not added back in anywhere, and it just a way for you to tell the ECU what degrees the marks are on your crank. That whole trigger calibration process is all so the ECU in the back end knows where 0 angle actually is.

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Hi cj

thanks for the info there, I think I understand what you are saying.

I'll have a go at setting it up this evening and post the table for you to have a look at

cheers

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Yep that looks roughly correct.  Not sure on the exact values and you could smooth the 60-70 transition over a few cells vertically but the idea is right. Just one thing to note, you probably see very little air flow/torque/any other change between say 70% and 100% TPS, but you may see a lot between 0% and 10%. Typically for a street driven car you would use numbers like 0,1,2,3,5,7,10,15,20,30,40,50,70,100 as your Y axis. The ECU will interpolate between any numbers you use, but because your engine output changes a lot more per TPS degree at the low end, you may need more granularity there than up top.

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Hi there Adam, cj.

Well,  that is a little different from the table generated by the ECU!

 I'll try to get both of the maps loaded and tested over the weekend and let you know the results.

nice to know i may be running the same ignition map as a 911 lol

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Hi there guys.

i managed to load and try out both of those maps over the weekend, the difference between them is quite a lot!

the one that Adam supplied has a noticeably better mid to top end performance but the low end is quite poor with a lot of popping and spluttering under load up to about 2500 rpm, easing off on the throttle helped a bit. Also a bit of blow back through the carbs at high revs and the throttle shut. May be good on track days though!

the other map seems much more tractable at low speed, but the mid to top end is definitely no where near as good.

i think the carb set up is about right, but as there is no one within 150km that has a clue how to set them up I guess I'll just have to make do. I have balanced them with the snail type manometer and the plug chop looks ok.

i tried to do a blend of both maps by using the mid to high part of Adams map and the low end of the other one but as I'm a noob and don't want to damage anything I thought I best get some feedback from you guys first.

Cheers

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Because you are tuning ignition timing you ideally want to be listening for knock at the same time. Best done on a dyno if available. To a point, more timing will produce more power, but in some cases the engine will be knocking while making this power so you may have to back off a little bit. If you put in too much timing you can also start to lose power as well as you will be making the fuel ignite before its optimium angle in the compression stroke. The below assumes that your engine is not generating knock. Do not just put big numbers in and hope to make more power.

The generated map has a couple points that you want to think about when creating your own timing map. 

1) the 0 row between 500 & 1500rpm is where you will idle. Higher numbers here will give you more torque just off idle, and if you leave the throttle screw alone, increasing these numbers will increase your idle rpm. Adam's map has your idle ign angle at 5* which on a lot of engines is quite low. Compared to your generated map at 12-13* (assuming 1k ish rpm). Depending on you engine and cams this value could be anywhere from 5 to about 20. pick what makes your engine happy and gives you reasonable response from idle if its a street car. Having a relatively smooth transition from idle to 2% TPS will make it less jumpy when taking off too. (smooth meaning <5* change between rows)

2) the high load, low rpm values are quite low. This is where you will often hear knock on an engine. Its less damaging here than at high RPM but still isnt great so generally you will see single digit and sometimes even slightly negative numbers in the <2500rpm full throttle cells. 

With these 2 artefacts in mind, you could probably take pretty much everything below 3k from your initial table, and use it to replace the left half of Adam's table. just copy the columns that match the rpm's, ignore the middle/missing column for now. Then select the left+right+"wrong" column in the middle and select interpolate horizontal. It will average out the numbers and fill that in for you.

From there look to manually smooth out any sudden changes where the 2 "sides" meet.

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4 hours ago, CamB said:

@Adamw - do you know if that is a table from a twin plug or single plug 911?

Hi Cam,  That was a single plug engine that had been converted to COP.  And I think I have labelled it wrong, Im sure that car was actually only a 3.0 now I think about it.  Does yours have ITB's?  I have a map from a 3.2 with single throttle body that I tuned also.

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28 minutes ago, Adamw said:

Hi Cam,  That was a single plug engine that had been converted to COP.  And I think I have labelled it wrong, Im sure that car was actually only a 3.0 now I think about it.  Does yours have ITB's?  I have a map from a 3.2 with single throttle body that I tuned also.

Thanks Adam. Mine is twin plug and ITB and I was interested as that one you posted is only slightly higher than I would have expected for twin plug (max 28* under load) but slightly more conservative than I would have expected for single plug. I've just been collecting data points. Either way I will get mine tuned properly - I've been told that MBT is pretty clear on a twin plug 911 and occurs at quite low advance.

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