1989 FJ1200, looking for the ignition advance MAP

[great white]

I'm in the process of changing over to a TCIP-4 ignitor box (programmable with multiple inputs, outputs, options, etc). But the manufacturer doesn't have the ignition MAP for the FJ series.

I'll need to build my own advance curve map. That's not a big problem (easy as click and drag in the TCIP-4 software), except I don't have a very detailed IGN MAP to start with.

What I have is the IGN advance maps that come in the factory manuals. As anyone who has seen them knows, they're pretty......"sparse".

Anyone have a more detailed chart for ign advance?

My 89 only has the Base curve, without any information on the advance curve when under the MAP sensor data input (yep, my 89 has the map sensor input). I can build the advance map, but I need at least a basic starting point.....

[great white]

 I've got the base map from the manual, but it's not very descriptive of how the curve is affected by the MAP sensor:



Not beyond my abilities to flesh it out, it's just going to be a lot of detailed, trail and error work to build the curve for the load data inputs.....

[great white]

 At least the manual for the fj1100 models gives a decent idea of map sensor effect on the curve:



I'll probably try and use the 1100 info to build a 1200 curve if I can't find any further info on the 1200 map curve. At least it's a starting point....

[great white]

I must not be thinking right or something because that 1100 ign advance curve isn't making sense to me. at low pressure (WOT) the advance is lower. At high pressure (throttle closed) the advance is much higher. That seems to be the opposite of how it should be.

Higher RPM (ie: WOT) should require more advance, not less.

then there's the fact that the chart shows 10 degrees base advance under throttle closed, but 5 degrees at throttle open. Base timing is base timing and I'm not quite sure why they want 10 degrees at idle without throttle. or how you would get WOT at 1000 rpm to make your 5 degrees base.

Or am I just having a thick moment here.....which actually wouldn't be too surprising. It's be a while since I've messed with timing curves.

[great white]

yep, a quick re-read of some of my reference material showed I've forgotten more than I thought about ignition timing vs load vs rpm. In a nutshell, low vaccuum means a weaker mixture which requires more timing while high rpm packs denser charge into the cylinder which requires less timing.

How quickly info fades from the gray matter when you're not using it all the time.......

[great white]

 Crap. seems my degree wheel has also grown legs. Can't find my TDC stop tool either.

Oh well, 30 bucks got me a new degree wheel and I'll take this opportunity to build a new TDC stop. I've always wanted to build a "better" stop tool, so I'll turn out a 14mm threaded adapter (spark plug hole thread size) and use a dial gauge to read the piston movement. It's not a new concept, you can buy them ready made:



But I've got the parts to build one here already and it's a relatively simple afternoon project on the lathe.

I could just make a hard stop and call it a day, but the dial gauge will also let me accurately measure dwell at tdc.

[Pat Conlon]

The 2 ignition advance curves you see are due to the vacuum advance.
The lower curve is the normal timing ...low vacuum
The upper curve is the advanced curve which happens under high vacuum.
Remember where we read the vacuum from....behind the throttle plates...IOW the vacuum port is between the throttle plate and the engine......high vacuum happens when the throttle plates are closed. Low vacuum when they are open...again, remember where the vacuum signal is coming from...
So....what you are looking at is an emissions control feature. The advance ignition timing flash's off any unburned hydrocarbons in the cylinder...when the throttle plates close (deceleration)
Ever wonder why your plugs are white? It's this advance

Not all FJ's have this emissions control feature. I've been informed that the AU bikes don't have any vacuum advance.
More reading on this subject: https://fjowners.com/index.php?topic=11690.0

If you want to build an ignition curve, use the lower curve...to start...but also remember many of us also use 5* advance rotors on our ignitions with no ill  effects (with properly jetted carbs) it really wakes things up...these rotors advance the entire curve 5* across the board.
My point being you could probably take the lower curve and add 5* on top of it....and be just fine (with properly jetted carbs)

Cheers

Pat

[great white]

this is a bit interesting:



Ignition advance curve from the Dyna 2000 DDK7-1 (from the documentation for the fj1200).

I have to read and think about it more though. It shows base timing as 5 degrees, but states static set at 35 BTDC. Seems to my old brain that means 40 degrees BTDC at idle.....that can't be right. I must have it all turned around in my head....

[FJ1200W]

From my files from the PO