Ignition Curve Mapping Question

[Philip]

Hi all,

Ive now got my ECU to control the Ignition map, but Im a bit stumped as to how to tune it. Its a Rover 3.5 EFI, the old dist was set for 8 degrees static and had a mechanical advance capable of a further 28 degrees, so total was 36. The dist. is locked up now and Ive set the map up for 8 degrees at tickover till around 1300 rpm, then it ramps up to reach 36 by 3500 rpm. Works fine here but going to try getting it at max a bit earlier and see if that improves accel. But my problem is doing the vacuum side of it. Ive set the map to slowly ramp a further 10 degrees advance at max vacuum whilst decellerating. It seems to work but this is all a bit of guess work on my part, anyone have any idea how much the vacuum advance mechanisms actually alter things or how to tune the map better than my guess work?
Phil

[kev]

I've got a map for a Vitesse that uses 16 load sites set on throttle position against every 500rpm, this takes into account advance due to vacuum. While you may not be able to use the map it should give you some idea where to set the advance curve as a start position. I don't know what you use for engine load sensing but if this of help let me know and I'll email you the map with the programme to view it.

I didn't know the megasquirt could control ignition, when did it become available?

regards
Kev

[Philip]

Hi,
its being constantly developed, think spark was available for a while but needed another ECU, now its controlled on the original ECU. Im rewritting the code to control my water injection depending on manifold air temp, revs and boost. Beauty of it is it costs next to nothing to make and the software is free, as the spark bit was only a code change and a slight rewire I thought id do it but I dont really know what im aiming for. The ECU can use either throttle position or manifold pressure which is what im using. I would appreciate a look at your table, the Megasquirt uses an adjustable 8x8 table revs/manifold pressure,

Phil

[kev]

Double click on m3d.exe after unzipping. Then file - open - and point to the V8 sartup map. This is the base map I used to begin the mapping process on my car which was very close to what I ended up with. Unfortunately I can't retrieve the map out of my ECU as my car is currently in pieces.

When the map is loaded go to ignition to view the numbers in tabular form, then click on graph to view a 3D map, don't forget this is total ignition advance. Beware that the load sites are skewed toward the bottom end, i.e. there are more sites at low throttle openings where the relative change is greater than there are at wider throttles. I don't know how much difference this will make to the actual curve, my guess would be very little to the shape of the curve.

I looked at the DIY wide band O2 sensor from WBO2 site but decided my electronic skills weren't up to building it , so I guess I'll have to buy one, so I'm very impressed that you were able to build the Megasquirt.

My next door neighbour owns a company, Europarts motorsport, which specialises in performance tuning the Renault 5GT turbo. He has had bad experiences with water injection in that the injector becomes blocked with "crud" from the water, stops cooling the charge, leading to detonation destroying the engine. Maybe you can find some way of monitoring the water injection to stop it happening in your car.

Good luck and let me know if you want anything else
regards
Kev

[Philip]

Thanks Kev,

looked at your map and the lower throttle positions are very similar to how ive guessed mine, but mine is with respect to manifold pressure. Ive been out in it again today and got the curve to reach max advance of 37 degrees by 3000 rpm and what a difference, really pulls from 2000-2500 now as the curve rises. Didnt think this mod was going to make a lot of difference to be honest but as it didnt cost me anything i thought id give it a go.
Ive got a spare WB pcb if you want it, it is very easy to build, youll have to source the components, ive got a few you can also have. Most expensive bit is the sensor, £130ish. If you want it let me have your address and i'll post it to you, dont want anything for it, but please have a go at it if i send it to you, its worth having a go and you will surprise yourself. As long as youve got a soldering iron and a meter youll be OK. I can always give you some advise if you get stuck. As for water injection, i dont think im going to need it but im going to fit it just as a precaution, so if it does fail it wont do any damage, hopefully. May end up with a flow rate sensor in it if i get bored and need something else to do,
Phil:tu

[Barry Davolls]

Philip,
What max advance are you running under full & near full throttle
positions?

Baldric

[Philip]

Hi Baldric,
running 36 degrees, tried 38 and 37 but made no difference to power that i could tell any how. Heres my map,

revs 500 1300 2100 3000 3500 4400 5000 5800
kpa
25 8 18 30 45 45 45 45 45
35 8 10 30 45 45 45 45 45
45 8 10 30 40 43 43 43 43
58 8 10 25 36 40 40 40 40
80 8 12 22 36 36 36 36 36
100 8 12 22 36 36 36 36 36
125 8 12 22 35 34 33 33 31
150 8 12 22 30 31 31 31 30

100 kpa is atmospheric pressure so obviously above 100 kpa is a guess as blower not running yet,
Phil

[Barry Davolls]

Phil,
I know we run different engines but I am a little surprised at the amount of advance you are running.
My unit runs appx 28 degree full-on (with & without charger)with max advance appx. 36d in mid range areas.

Baldric

[Philip]

Hi,

I just used the figures from my initial advance of 8 degrees and added the mechanical advance that was in the distributor. That had 14 written on it which apparently means 28 degrees advance. So total being 36. Hope ive got this right? I have read on the net that total for a V8 is around 36 - 40 degrees and Ive also read that tvr's use a total of around 36 on all rover derived engines.
Please let me know if ive got this totally wrong,
Phil

[Barry Davolls]

Phil,
Seen several TVR units & a host of other 5ltr+ breathed on motors on the engine Dyno of perhaps the most respected RV8 tuner around.
None of them (including mine) ran more than 29d total advance (full-on throttle/load).
Ignition timing is not my thing (yet). I have tried upto 32d on my unit. The motor did not like it & I ran slower.
I can see various data for standard RV8`s showing between 30 & 34d.
I think you should seek more knowledgeable advice on this subject but for my money, 36D as a starting point is too high.

Baldric