ignition timing

[SteveW]

I have just put a 1.9 dg in to my bus that had a 2.1 dj in. So it is running injection and gas. The replacement engine did not come with a dizzy so I have taken the one out of the 2.1 by undoing the clamp fixing rather than the clamp. This was good enough to start the engine but i feel the timing is out as I am now get a bit of a backfire both on gas and petrol.

What I need to know is what should the timing be for the 1.9 and how do I go about setting it with the 2.1 setup?

[toomanytoys]

I think you will have a few other problems... best thing is to time it up to the 10 deg the DJ should be run at, will be fine on LPG, but might want to use superplus when you have to put some juice in... either mark up the DG pulley, or it the DJ pulley back on
I think you will notice the lack of performance...

the DJ injection will just think its running on part throttle as it wont be pulling as much air.. when you run on petrol...

[HarryMann]

There was a recent thread on this I think, maybe the other way around (1.9>2.1) - suggesting you should endeavour to get the correct distributor for the 1.9 as it will almost certainly have a different advance curve.
The well known club spares traders will be able to supply I should think.

[SteveW]

I think that they are probably close enough and the engine is running a treat on LPG and a quick check on 98 ron seems Ok too. I have done a table showing the values but do not know how to post it here but looks a bit like this.


Timing DG 5°±1° BTDC@900±50 DJ 10°±1° BTDC@800
Advance check 0°-2°@1500 0°-2°@1050
Advance check 10°-14°@2400 2°-6°@1300
Advance check 24°-28°@4200 12°-16°@2400
Vac advance 12°-16° 12°-16°
[/code]

[SteveW]

toomanytoys
Where in central France are you? I have friends and family in 87 Haute Viene

[HarryMann]

Steve,

I've plotted those advance curves, presuming the figures are correct, and extrapolated the best DG matching DJ dizzie static setting curve (yellow) at both ends (dotted line)



Because the 2.1 breathes a lot more lower down, the curves are quite different below 2000 rpm, and its seems more attention is paid to the accuracy of the DJ timing low down, with no specs far up the rev-range... would be intersting to have an advance cut-off point, as centrifugal devices all usually limit at a set advance e.g. 30 ~40 degrees, giving a straight horiz. line at whatever figure that is. Should think the DJ might limit earlier.

Anyway, 2 degrees at 800 rpm (static setting if cent device against its stop at 800), seems to be the best compromise to match up as best you can with the DG's required curve. Perhaps expect some light tinkling, if not heavy pinking, around town on plonk petrol, at anything over 2 degrees..

Wicked!

[SteveW]

Ah that is great Thanks. I have the timing set at 5 degrees btdc as I am running on LPG which I am led to belive is like running extra octane. This seems fine but I will try the 2 degrees and see what happens. when the 2.2 goes in I will then go back to 10 degrees standard 2.1 timing.

I think that I need to buy another van so I can messabout with Megasquirt and some sort of edis ignition with the 12 x 12 maps Oh and a turbo would be fun.

[HarryMann]

Aha! Plans then...

Or back to 5 BTDC as Simon says for de 95 plonk

Incredible how far up the standard 2.1 curve is c.f. the 1.9, that's a lot of difference in breathing at low rpm, or poorer combustion.

Where did thjose figyures come from, for the Wiki, as its not unusual for slighlty diff ones from diff sources.

The highest one is 4200 rpm for the DG and 2400 for the DJ... couldn't be a typo there? Only asking

[SteveW]

From here
http://194.242.159.246/brickyard/info/e ... engine.htm
But I also have the same figures on my copy of E--- eeeer I meen I have heard that these figures are on the official VAG software