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Clive59

Mad idea? Electronic ignition with vacuum mapping etc...

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Hi all, Just having thoughts on improving my 'soon to be acquired' Elite, and I have been wondering if a little modernising might be worthwhile with the ignition. One of the first things I will do is put an electronic ignition with Hall Effect sensor, so getting rid of the points issue. Then I thought, the vacuum advance is probably going to be worn, and the advance curve will probably far from optimal, so what if I put a pressure sensor on the inlet, add a crank angle sensor somehow, and design a controller which can be mapped to adjust advance with vacuum, engine speed, oh and I guess temperature to make cold starting easier. Does such a thing already exist? I guess it is just a part of an engine management system, but I don't want to play with injection, at least not yet, as experimenting with that can be dangerous for the engine!

Just wondered if anybody has played with this sort of thing, and of so how did it go. As I have summer holiday period coming up (yep, on bottom side of the planet), I might get a chance to at least investigate it. Any thoughts, suggestions, etc gratefully accepted.

 

cheers, Clive

 

hmmm, maybe add a knock sensor and automatically advance ignition to optimal point? Better stop there for now.

 

 

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Why not just fit an ignition only engine management system, and get rid of the distributor and old-style coil all together?

 

This is the ignition only version of the ECU I have on my Esprit: http://www.sbdev.co.uk/Engine_Management_Systems/ECU_Details/MBE9A4i/MBE9A4i.htm

 

Lot of work to set up though...

 

Scott

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Thanks for that Scott, looks interesting. Pretty much what I was thinking off, I just hadn't seen them before. Pretty expensive though, so I still think I might have a go at rolling my own. Any other features anybody?

 

cheers, Clive

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Megajolt is the ignition side of Megasquirt. There is lots of information on the net about megasquirt/megajolt and it has been successfully fitted to a Lotus 907 before (in a jensen healey). NB the ignition only version is available (megajolt) if you don't need something to control efi.

 

Another one to research is 123ignition, which has a mappable version called 123tune. I believe it is available for pretty much any distributor. I've been looking at this for my Rover V8.

 

I have a feeling MSD will produce something similar which will be available locally in NSW,

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Thanks guys, Megajolt looks much more reasonably priced from what I can see, and the others look interesting too Dunc.

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Another vote for megajolt from me! I had it on a kit car I built. It never failed me and improved the starting and general running. I'm fitting its bigger brother megasquirt to my Eclat, fingers crossed it will be as reliable.

Steve

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I had LotusBits fit a DTA S40 electronic ignition to my Excel SE. I only had ignition, and not fuel injection, which of course is also possible.

The results are great! Much better to drive at low revs, plus starting.

After looking at MegaJolt, and many others, I went with DTA since this is what LotusBits knew and had installed on many Excels (possibly Elite/Eclat/Esprit also). They had the necessary crank sensor wheel, crank sensor mounting bracket etc.

We went for throttle position sensor, rather than vacuum, and this solution seems to work fine for me.

The actually fitting of the electronics, position of sensors, wiring harness etc is often a source of problems. If you know what you're doing and have experience you'll be fine. If not you may encounter some teething problems and possibly reliability issues down the road.

I took the conservative route and used a tried and tested solution, rather than debug my own installation, and have been very happy with the result.

Highly recommended.

FYI - electronic ignition with carbs works fine. I've no plan to go the next step and fit fuel injection (at the moment!)

Edited by TonyPoll

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If I run out if things to do I still might have a go at making one, then again, not sure when that will be, especially if I do eventually get to own an Elite(in a few weeks hopefully). Thanks for all your input.

Clive

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This is a general observation. 

I fitted electronic ignition to the wonderful 1750 engine in my Alfa GTV and would NEVER go back to points and other messy bits. This does not entitle me to discuss mapping of course but I'd like to know what progress you make Clive.

 

BTW I'm having sensor issues on the inlet side - it seems that the engine management system is not entirely happy with what's going on between the BMW M44 and the Eaton M62 supercharger (or the gubbins thet we've lashed it altogether with!)

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Sounds like a great excuse to go to mapped ignition Rex!

As you know I am gathering the bits and the inclination to fit an Eaton M90 gen 3 blower to the rover V8 thats in the eclat.

Some general observations that I have picked up on supercharging are as follows:

Cam overlap is important. A normally asperated engine will have an amount of overlap between the fueling valve and the exhaust valve on the draw stroke, where they are both slightly open at the same time. This helps power on a normally aspirated engine, but when you have forced induction, you end up blowing fuel and air mixture out the exhaust, giving terrible economy and flames from the exhaust. On a twin cam, you'd adjust this with verniers, on mine, I have to change to a cam with a different grind.

Ignition timing objectives are different from the normally aspirated engine. The intention is to start on retard, then bring the advance in at low revs, then retard it backwards to prevent detonation as the revs and boost pressure rises.

On an engine that was normally aspirated that is now blown, moving to mapped ignition will help it run properly. Megasquirt would be a really worthwhile item on your efi car in my limited humble opinion.

go for it. It's December. Ask santa for megasquirt!

Edited by Dunc

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This is quite an interesting overview. It only raises more questions for me. Looks like the only way to really get it right is to put car on a dyno and do a lot of data logging over the whole rev range and load range. There are obviously 'rules of thumb' that give reasonable results, and the law of diminishing returns on practical and theoretical outcomes. Sort of like do I make an 'n' order polynomial equation to fit the ideal, where a few straight line 'best fit' approximations do 95% of the job.

 

http://autospeed.com/cms/title_Getting-the-Ignition-Timing-Right/A_109132/article.html

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I had mine mapped after fitting the ECU. Some of the settings were quite unexpected. The operator advanced/retared the ignition at each throttle opening to give a 'reasonable' driving experience. I was not looking  for the untimate power, but the best day-to-day driving experience. I'm very satisfied with the result.

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Can you expand on your comment re "Some of the settings were quite unexpected"? thanks

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Here's the map in my ECU for my Excel SE. A standard engine in good condition with standard cams.

As you can see at small throttle openings and, say, 3000 rpm the advance is over 50 degrees, which is much larger than I'd expected. But there again, I don't know what I was expecting!

Apologies for the poor layout of the table. You can import it into a spreadsheet for easier reading.

I've also given you the settings for other variables (temperature, air-con on/off etc).

 

Basic ignition map
Throttle % 0 2 4 7 11 16 22 29 37 46 56 67 79 92
RPM
500 12.0 4.3 2.5 -0.2 -0.2 1.3 1.8 3.2 4.0 5.3 5.3 6.2 5.7 6.1
750 12.6 14.9 13.7 9.3 5.3 6.1 6.5 7.3 8.5 9.6 10.8 10.8 11.6 12.7
1000 13.9 26.5 22.5 18.4 13.8 12.2 12.2 12.6 13.8 16.5 18.5 17.7 18.1 18.5
1250 12.8 36.0 31.8 26.4 22.1 18.3 15.4 16.9 17.9 20.0 21.6 23.1 24.7 26.2
1750 24.1 43.2 40.2 35.2 32.4 30.2 26.9 24.0 24.8 28.2 31.6 32.6 33.5 34.5
2000 31.6 48.5 44.6 40.4 37.1 33.6 31.2 29.0 27.8 29.1 31.6 32.8 34.5 34.7
2250 40.1 51.6 50.1 44.0 40.2 39.1 36.8 32.3 28.8 30.4 32.1 33.7 34.1 34.4
2500 41.8 51.6 50.1 44.3 39.8 39.5 37.0 29.7 29.4 30.8 32.3 33.6 33.9 33.7
3000 43.6 51.7 50.2 44.5 40.3 39.9 37.2 30.3 30.0 31.2 32.5 33.5 33.8 35.1
3500 43.0 51.7 50.2 44.8 40.9 40.2 37.4 31.0 30.6 31.6 32.6 33.4 33.6 34.0
4000 43.6 51.7 50.2 45.0 41.4 40.6 37.5 31.2 31.2 32.0 32.8 33.3 33.4 32.8
4500 43.8 51.8 50.3 45.3 42.0 41.0 37.7 32.3 31.8 32.4 33.0 33.2 33.3 32.8
5000 43.6 51.8 50.3 45.5 42.5 41.4 37.9 33.0 32.4 32.8 33.2 33.1 33.1 32.9
5500 44.4 51.8 50.8 45.8 43.1 41.7 38.1 33.7 33.0 33.2 33.3 33.0 32.9 32.9
6000 44.4 51.9 50.4 46.0 43.6 42.1 38.3 34.3 33.6 33.6 33.5 32.9 32.8 32.9
6500 45.0 51.9 50.4 46.3 44.2 42.5 38.5 35.0 34.2 34.0 33.7 32.8 32.6 32.9
7000 44.7 51.7 50.4 46.5 44.7 42.9 38.6 35.7 34.8 34.4 33.9 32.7 32.4 33.0


Water temperature compensation
Degrees c Ignition Advance compensation
-20 100
-10 100
0 60
10 60
15 50
20 40
25 30
30 20
35 20
40 20
45 20
50 10
55 0
60 0
70 0
80 0
90 0
100 0
110 0
120 -20

General engine settings
Ultimate RPM limit 7200
Normal RPM limit 7000
Defaults on sensor failure
Water 90 degrees c
Throttle 75%
Coil on time 3000 micro-seconds

Fan switching temperature 80 degrees c

Air con uplift 10 degrees

Idle Target speed
temp deg c RPM
0 1000
20 1000
30 1000
50 1000
80 950
 

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If you fit megasquirt with a narrow or broadband sensor in the exhaust it can map itself as you drive using megatune (its a free bit of software available to download from various sources). Therefore no need for expensive dyno tuning time.

Its a clever piece of kit that does more than most of the premium systems at a fraction of the cost.

Steve

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One of my best freinds is a mapper for Saab's (faero on the SAAB forums). He maps them from the passenger seat using a laptop as the driver boots it up and down the road. I think the inputs are from a wide band lamda measuring the Air/fuel ratio, the engines knock sensor and the MAF/vacuum.

 

400+bhp in a Saab 9000 isn't to be sniffed at. His car goes like an missle...almost the ultimate Q car (the power is from more than just a re-map though)

 

last time I spoke to him he was thinking of using that power in a xv220.

 

Anyway - off topic, but it shows what can be done without spending a fortune on rolling road sessions.

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He maps them from the passenger seat using a laptop as the driver boots it up and down the road.

 

400+bhp in a Saab 9000 isn't to be sniffed at.

 

I've heard of this being done with a highly-tuned Jap car (over twice the bhp of that Saab) with catastrophic results. :cry:  Be careful out there.

Edited by StrokerBoy

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That's useful info Tony, thanks. The water temp compensation seems a bit odd? Is that degrees advance at the relevant temp? Never knew it was that much!

 

I know my Subaru has a fuzzy logic system apparently which tunes the mapping depending on driving style, but that is pretty standard with a closed loop system I guess, so the Megasquirt with the the O2 sensor is close, but the next step would be a knock sensor as well, and the controller can just do continuous learning.

 

I think i will happy if I get more drivability, cold starting and hopefully better overall performance.

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The water temp compensation seems a bit odd? Is that degrees advance at the relevant temp?

I believe that's correct, but I've never driven my Excel at -20 c, so can't sure :-)

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