Hard Question: Plotting Advance Curve

[jono1986]

Hey, i bought a programmable ignition system from Jarcar some time ago for my Ke35. i finished building the electronics and got stumped over plotting the original igntion timing values. I have read the manual and it pretty much says to use the timing marks on the crank pulley, also another method is to use a secondary coil pack and an ellaborate setup. So i guess if someone knows the advance curve for a 3k motor or an easy way to plot the original curve it would be very helpful.

[altezzaclub]

I would assume one person looks at the crank pulley with a timing light while the other person reads the rev counter with their foot on the throttle.

 

I clean the crank pulley and mark the cuts/pointer with white Tippex, and add a few extra if needed using a protractor.

 

If you put the timing light on the coil you will get a flash from each cyl, and will read 1 & 4 (2 and 3 will be on the other side of the pulley) which will give you twice as many flashes and be easier to see.

 

Just read off the degrees of advance every 500 rpm until you get no increaase, when you will be at full advance.

 

Post up a How-to about the kit, I'd be quite interested to try it.

[philbey]

Johno, that's basically it. I wouldn't even get too hung up on plotting the initial curve; Just set it at 10 degrees at idle, progressively ramp up to 25 Degrees at ~3500 and then hold. You then go about tuning it by driving, advance til pinging, back off.

 

The problem is with the timing light method, you'll only get the mechanical advance curve, and no vacuum advance curve. If you read the silicon chip article on that kit, they basically said to start driving up hills and keep advancing the load curve until it begins to ping, then back it off.

 

Also, you can set up a knock sensor with that unit I reckon. Otherwise, I'd use the knock sensor kit to at least tune the curve.

 

There is also an Autospeed article on the kit, and they talk about making a simple little headphone device that amplifies knock so you can hear it when tuning. That would be handy.

 

Jono, if you could post your experience with the kit, that would be great. I was looking at chasing down that path ages ago, but nobody here, or on the greater internet even had much to say about them. I'd love to give it a shot one day, it would be wicked for tuning for Ethanol mixes and all sorts of wacky stuff!

Edited October 15, 2009 by philbey

[jono1986]

Thankyou for the replies, i'll try that progressive progamming with the mechanical. do you think i would be able to use the same method for the vacuum advance, the toyota manual says the maximum advance is 10 deg's at 10.63 in Hg which is about 0.36 Bar, so if i get an initial idle pressure it should be uniform in that as pressure goes up so does the advance???

Oh and i just remembered something my leading hand told me, he said that the mechanical advance is down in two stages. As in it increases quick to start then pans out (or the other way round)....

 

 

I was thinking of not putting the system on, but since in this past week i've upgraded to manual and a weber might as well try this aswell.

Edited October 17, 2009 by jono1986

[Taz_Rx]

I reckon your max mechanical advance will have to be more around the 35-40* range than 25*.

 

I know my max advance is set at 28* BUT THATS ON BOOST!!!! When tuning we wound it up to 32* and it didn't knock, just made less power. Obviously for you being NA you'll need more.

[rob83ke70]

fairly sure you wouldn't want to go over 36 degrees total. if you have a cam or increased compression you might want more initial and have it get to the total a bit faster.

 

Robert.

[philbey]

Some mechanical advances have different weights and spring rates. Not quite a 2 stage thing, they just have a parabolic curve not a linear one. I reckon from looking at corollas they are a fairly basic setup though.

 

There's something else that I know I'm forgetting here, but it escapes me.... I had an article on it somwhere....

[beerhead]

Have a bit of a google for Megajolt programmable ignition. A while back I read some good articles on setting up a base timing map on them, and there was also many base maps you could use from other vehicles to get an idea whats going on. Though the best way to get the most power would be a quick dyno run.

[camerondownunder88]

This might help....

 

Taken from the Toyota factory engine building manual for K motors.

 

It is surprising what Toyota have printed in some of there manuals here and there.

 

Cheers

Cameron

[jono1986]

Hey guys, thanks again for your replies. i was going to write a whole lot more but have an eventful day with the head (of the motor :) ) So instead i uploaded a picture of the control system and the hand controller. Oh and is using a weber going to change anything with the vacuum advance??

[philbey]

You will need to lock the dizzy mechanical and also do away with the vac advance. Run a MAP sensor instead of the vac advance. The jaycar kit has a MAP or TPS input.

 

Mind you, if you just want to get it running, lock the mech advance and use the stock vac advance in the meantime while you get a MAP setup working.

 

MAP will be easy, you just need a basic pressure transducer with a 0-5v signal I'm pretty sure, and they're not expensive.

 

To me there's not a lot of point to running the vac advance with a programmable ignition when you have the option for MAP, other than as an interim solution.

Edited October 20, 2009 by philbey

[Taz_Rx]

You've only got to remove the vacuum line to stop vacuum advance.

"locking a dizzy" means stopping the mechanical advance.

[philbey]

yeh but you need to lock the mechanical advance as well otherwise there's not much point running a fully programmable ignition!

 

Edit - Just re read my previous post and it could have been a little clearer... :)

Edited October 20, 2009 by philbey

[Taz_Rx]

Thought that was the case, just clarifying. :)

 

Thats just how the ignition side of an aftermarket ECU works:

Static incoming pulse from dizzy (locked) as a reference for "box" (ecu or jaycar kit)>timing manipulation in "box" (dependant on load [TPS] and transient [MAP] sensors)>ignitor*>coil.

 

*I reckon it would be a MUST to use an ignitor with one of these jaycar kits just like an ECU as well. Because they fire the coil by grounding it you need to use an ignitor otherwise the discharge from the coil will fry your ECU or jaycar kit if it goes through it.

Ignitors are really simple, they're just a fast switching, earthing relay. Yell out if you want me to explain more.

[philbey]

Yeh that's it. I reckon the jaycar kit recommends setting to a particular timing point as well?

 

My plan is to run a jaycar programmable ignition coupled with an MSD or Crane CDI.