devilfish

Im doing a bin as my "base" bin. Just to get me started. I wounder if you could give me some feedback on this SA? First I here is my setup: 1991 vette 6spd LT1 intake Trick Flow 23 alu heads 62cc heads LT4 hotcamkit Longtube headers No EGR I used the stock vette bin with some mods. I lowerd the cruise timing from 46 (stock) to 44 due to not having EGR. I also took away a dip in the SA from the stock bin at 3600rpm@70-75Kpa, I guess GM made it there cause thats where the old TPI made most torque right?, and I made it more "smooth". I also changed the low (20Kpa) from 46 (stock) to 38 to help deaccel. On the 95 and 100Kpa I added all the PE spark advance i got and zeroed out that tabel. My closed TPS SA is 29 at idle.

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Grumpy

I've not seen any real reason to run over 40d. I'll give a 1-2 MPG for longer engine life.

If you must, you must. Smooth is for you, not the engine.

OK

That's what I do.

The idle timing seems a tad high, and the 600-800 jump might cause some idle speed wandering.

devilfish

thanks! Thats just the kind of feedback I whanted.

Yes I thought the crusing timing whas VERY high in the stock chip ( 46 degrees ), I guess GM did that for mpg .
Please correct me if im wrong, but does more timing tend to give better throttel response?
So I should I keep it around 36-37 in those areas, and then go from there, increase it only if the engine seems to like it?

thanks for the input.

gta324

Depending on your idle speed you may look into the area where it goes from Closed TPS to Main spark table and make it a smooth transition.

I've found that 0 out the "Idle spark Advance/retard vs rpm error" is helpful when it comes to tune the idle, you could return to theese tables when you are done (with closed TPS SA and VE and O2 swing points) to see it helps to stablize the idle......

/N.

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jackballs529

I have yet to tune spark tables. Can anyone tell me how and why the spark table have different timing in the cells that flow left to right? I understand that a RPM needs a certain timing but why do the table change in all the cells left to right. I hope I'm making myself clear.

Dave_Jones

The difference is in MAP value, which you can think of as representing engine load.

Consider the difference between pulling up a steep hill, or coasting down it. You could be at 2000 RPM in either case, but the load on the engine would be dramatically different. So, the amount of fuel & air in the cylinder is different, and requires a different amount of time to burn, which is why you have a difference in SA.

On a MAF car, it'd be LV8 (a calculated load variable) instead of MAP, but it's the same concept.

jackballs529

So the 20,30,40, etc. columns are a Load variable?

Dave_Jones

In the example above, it's Manifold Absolute Pressure, in KPa...which you can consider as reflecting engine load.

Atmospheric pressure is very close to 100 KPa at sea level. So, MAP=100, means full atmospheric pressure in the manifold, which means WOT. (for a N/A car, anyway ) Think of that as being max load.

A stockish car might idle at around 20-30 KPa, so you can think of that as being minimum load.

Make sense?

jackballs529

So I guess on my MAF car, more timing for less load?

devilfish

Anyone else got some ides besides grumpy. I trying to learn a good way to work with the SA

devilfish

'

grumpy, you dont se any other abnormal with the tabel, its pretty much a stock vette bin.

cheers.