6 replies to this topic

[darkcat]

Afternoon all! 
I am currently tuning my injected turbo mini and it it running "Sort of ok" My next step is to tune the ignition table, as I have been running a base map so far but am looking for some advice on idle and pulling-away advance. 

Remember that this is a 2D map based on RPM and Load (which is based on MAP/Vacuum)

So at idle, the engine is pulling a high vacuum, as it would be on a normal distributor with the idle advance connected. (Bottom-left of the table)
Where-abouts should I be idling advance-wise? 
I have it set to 16 Deg BTDC, but seem to remember it should be more like 20-24 at this point on a normal distributor car with vacuum attached...

I'm having an issue also where as I pull off (slowly) despite trying throwing a load of fuel at it, it tends to bog down, so I'm thinking maybe this is timing? This is at part throttle, 1500-2000 rpm. 

Any advice from Megasquirt/Megajolt users much appreciated 

Let's forget boost (>100kpa) at this point!!! One step at a time...

I'll upload a screenshot of the current map when I get home.

Edited by darkcat, 15 May 2018 - 03:34 PM.

[Turbo Phil]

I presume you've dropped the compression somewhat ? The lower the compression the more advance you'll need to make it pull until boost when you'll start to retard it.

 

Phil.

 

[darkcat]

Hi Phil - Waves :-D

Yes it's (calculated at) 8.25:1


 

[Spider]

I have it set to 16 Deg BTDC, but seem to remember it should be more like 20-24 at this point on a normal distributor car with vacuum attached...
 

 

Although there is high manifold vacuum at Idle, this does't or shouldn't be ported off for any vacuum advance at idle. Most carbs have a vac advance port on them for this purpose and is more or less level with the edge of the butterfly so at idle and for a bit there after there is very little or no vacuum on that port.

 

I know the HIF44 has this port further down stream and so does pull some vacuum on it at idle, but it was intended to be fitted up with other controls in that circuit.

[mini13]

16 degrees sounds about right at idle,  

 

a common method of tuning idle advance is to edge it up until it idles fastest, and then back it off a couple of degrees, then in in the RPM bins below (500rpm) put the fastest setting in, ( or better still if you can set it up for fastest rpm at 500 iff it'll idle that low)  that way if the rpm drops it'll advance slightly and try to bring the rpm back up.

[darkcat]

Thanks guys - This is where I'm at right now, I've lifted the idle area to 18 deg and must say its made a world of difference to idle stability and gentle take-off. 
I may well push it a bit further and see what happens. Obviously I dont want it too advanced in start.


(The -4's are for overrun pops'n'bangs, just because )

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Edited by darkcat, 16 May 2018 - 09:53 AM.

[mini13]

looks the right sort of shape, you probably find cruise can be advanced more, but thats for further down the line, whtas you idle KPA? 50-60?

 

not sure how jolt handles cranking, but meggasquirt has an idel craking setting so below X rpm the advance will be somthing less so it wonkt kick back, i think my setting was 5 degrees below 400rpm.