Quick initial timing question

[Force Fed Mopar]

When you are setting the distributor, is it set at 12* on every car, regardless of what cal or what mods you have made to the AdvanceFromRpm table?

[turbovanman²]

Yes, IIRC, Rob say's that basically puts the computer at 0 and works from there, kinda like its TDC.

[Force Fed Mopar]

Thought it made the computer fire at 12* and that's why we set it to 12?

[turbovanman²]

Thought it made the computer fire at 12* and that's why we set it to 12?

Its something to do with the sync of the HEP/dizzy and TDC.

[ShelGame]

Thought it made the computer fire at 12* and that's why we set it to 12?

Exactly. Unplugging the CTS sets the timing to 12* by default. You set the timing there just as a sync point. They chose 12 deg because, the engine idles like poo at 0deg...

[turbovanman²]

Exactly. Unplugging the CTS sets the timing to 12* by default. You set the timing there just as a sync point. They chose 12 deg because, the engine idles like poo at 0deg...

There we go, :nod:

[Force Fed Mopar]

Exactly. Unplugging the CTS sets the timing to 12* by default. You set the timing there just as a sync point. They chose 12 deg because, the engine idles like poo at 0deg...

Okay, so that is true regardless of what changes we make to the cal? Basically that 12* is hard-coded into somewhere we can't access/screw-up?

[ShelGame]

Okay, so that is true regardless of what changes we make to the cal? Basically that 12* is hard-coded into somewhere we can't access/screw-up?

No, you could change that value if you wanted to. But, you won't screw it up by adjusting the normal WOT, PT, or RPM timing...

[Force Fed Mopar]

No, you could change that value if you wanted to. But, you won't screw it up by adjusting the normal WOT, PT, or RPM timing...

Okay, that's what I wanted to know.

[Force Fed Mopar]

No, you could change that value if you wanted to. But, you won't screw it up by adjusting the normal WOT, PT, or RPM timing...

What is the name of the table that sets this? Is it "ConstantSparkAdvanceWhenSettingBasicTiming"? If so, it is set at 6* in the B151 template. Which would advance the entire spark map by 6 degrees if you set the initial timing to 12*, correct? Might be why I (an others) having issues tuning the 2.5 :) Haven't checked any other cals yet for this.

[ShelGame]

Yeah, I don't understand why it's 6deg either (though 0x0c = 12dec; but the value is /2 = 6deg actual). Every single SMEC and SBEC (2.2 or 2.5, auto or manual) cal has this value set to 0x0c. It's only used when idling and the coolant temp sensor error code is set, which is when the CTS is unplugged.

[Force Fed Mopar]

Okay, so whatever that table is set to, it doubles it?

[turbovanman²]

What issues are you having Rob M?

[Force Fed Mopar]

What issues are you having Rob M?

Not really any at the moment, just trying to dial in the new timing tables for this 2.5 with the stock turbo. Others are having issues with cold idle, and if I read things correctly, timing has a lot to do with holding idle rpm. Also the timing that people run in boost seems to vary a good bit.

[turbovanman²]

Not really any at the moment, just trying to dial in the new timing tables for this 2.5 with the stock turbo. Others are having issues with cold idle, and if I read things correctly, timing has a lot to do with holding idle rpm. Also the timing that people run in boost seems to vary a good bit.

Gotcha. I know my setup likes alot of timing, its very sluggish if I run stock tables.

[Force Fed Mopar]

Gotcha. I know my setup likes alot of timing, its very sluggish if I run stock tables.

Same here, I just want to make sure that what I'm putting in doesn't end up 6 degrees more in practice :)

[turbovanman²]

Same here, I just want to make sure that what I'm putting in doesn't end up 6 degrees more in practice :)

But if it doesn't knock, and your tuning anyway, what does it matter, ;)

[Force Fed Mopar]

But if it doesn't knock, and your tuning anyway, what does it matter, ;)

Doesn't really I guess, I'm just particular about that stuff. Has to be just so or I'm not happy :p

[ShelGame]

Okay, so whatever that table is set to, it doubles it?

I don't see the code doubling it anywhere. I dunno what else to tell you about it. I would say that maybe it's in cam degrees (cycle degrees) instead of crank degrees, but then that wouldn't make sense for our regular timing.

---------- Post added at 08:35 AM ---------- Previous post was at 08:34 AM ----------


Not really any at the moment, just trying to dial in the new timing tables for this 2.5 with the stock turbo. Others are having issues with cold idle, and if I read things correctly, timing has a lot to do with holding idle rpm. Also the timing that people run in boost seems to vary a good bit.

I'm not sure it varies that much. The WOT and PT tables might be different, but if you look at the total timing, it's probably clipped at the bottom end to the same value.

[Force Fed Mopar]

That's fine, it just seemed odd that it is set to 6 degrees. As long as I know it is 12 degrees in actual practice I don't really care. More or less just curious as to how it works. It obviously has to be doubled somehow since it does fire at 12 degrees.

[wowzer]

perhaps its just a display issue. note that the y axis min/max is set to 0/128. should it really be 0/255? the raw value is dec 12.

[John B]

I'm pretty sure the sticker under the hood of my '91 says 14 degrees :confused:?

[John B]

I'm pretty sure the sticker under the hood of my '91 says 14 degrees :confused:?

OK, I was pretty sure but I was completely wrong. Wiping away the smudge and using my flashlight I can see it's 12 degrees.