How to fix lean tip in-off idle-stumble like no carb accel pump?

When I hit the gas from an idle, I get a lean flat spot, like having no carb accel pump. Its friggin annoying, it goes it to 20:1, stumbles then its fine, its worse cold but still there warm. Which parameters do I need to tweak?

Sounds like you have the T-SMEC misfire bug - you just don't get a misfire with it, just lean transient.

Why don't you try this:

Find the table called LMAPTC. This is the lookup table for the time-constant that's used to calculate the average MAP that is used in the transient fuel calcs. Technically, this is not a MAP-based table, so it doesn't get scaled for MAP. But, obvioulsy, the number of bits ber PSI changes when you change the MAP sensor. So, this table should get some tweaking.

In the T-SMEC thread, I asked a couple of guys to try this, and it didn't really do much for them IIRC. But, maybe there were other things going on at the same time.

I would start by scaling this table down by 66% on the Y-axis in D-Cal and see if it's any better. I think the table is a constant return. You could also try to add a couple of points, and simply reduce the time constant at the lower temps and see if that helps. But, I'd start simple and see if you can make it better or worse with that table...

EDIT: I also think that table should come into play when you put in a bigger throttle body (which I think you have). This is because as you increase the size of the throttle chamber, the MAP reading will change faster than with a smaller T/C. So, the time constant for the averaging function should be shortened with a bigger T/C. The question is - how much? I really don't have a feel for that...

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Originally Posted by ShelGame

EDIT: I also think that table should come into play when you put in a bigger throttle body (which I think you have). This is because as you increase the size of the throttle chamber, the MAP reading will change faster than with a smaller T/C. So, the time constant for the averaging function should be shortened with a bigger T/C. The question is - how much? I really don't have a feel for that...

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This is exactly what I was thinking, the 58mm flows too much air and I get the stumble.

It could be a misfire but to me, feels like a lean shift. I'll try what you suggested and see what happens.

Ok, its called the "time constant" and I can't adjust it, the tbl file we have doesn't have it activated so to speak. I am using a current TSMEC cal.

Hmm, it should be. What version are you using? v15?

ON a side note, I scaled this table in all of my 'modified' cals. When I realized it wasn't a MAP based table (and that Geoff didn't scale it for Ladybug), I changed it in T-SMEC to unscaled. None of my modifed cals have the lean stumble/misfire thing...

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Originally Posted by ShelGame

Hmm, it should be. What version are you using? v15?

ON a side note, I scaled this table in all of my 'modified' cals. When I realized it wasn't a MAP based table (and that Geoff didn't scale it for Ladybug), I changed it in T-SMEC to unscaled. None of my modifed cals have the lean stumble/misfire thing...

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Its your latest one, I made this one a few weeks ago, its not there, its just childish scribble. :(

So your saying that could be the fix?

I need another tbl file with that in there to adjust it.

Hmm, maybe you swapped over a table file from a different cal? If you get lines all over the place for that table, then that's what happened. It should be a single-point table, I think.

It could be the fix. Like I said, we tried it in the T-SMEC thread, and it didn't fix it. But, there likely were other things going on then, too. I think this table should be scaled with MAP. I'm just not 100% sure it needs to be scale the SAME as MAP. It might need to be a different facto than the MAP scaling. But, I think the same factor as MAP is as good a guess as any...

Ok, can you send me another tbl file.

Send me (or just post) your bin/tbl file, I'll try to find the right address for the LMAPTC table...

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Originally Posted by ShelGame

Send me (or just post) your bin/tbl file, I'll try to find the right address for the LMAPTC table...

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Ok, I'll have to do that tonight, its at home on my thumb drive.

I'll post it here.

I get the same thing when turning right if I have less than half a tank of gas. I know the cause of it is different for me, but it is quite annoying. Also very odd since it only happens when turning right, never when turning left.

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Originally Posted by SebringLX

I get the same thing when turning right if I have less than half a tank of gas. I know the cause of it is different for me, but it is quite annoying. Also very odd since it only happens when turning right, never when turning left.

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So then, you know the solution, don't turn right, :drum:

I'm up for another half hour, if you post those files, I can fix your .tbl and repost it for you...

Ok, I can't attach it here even though its saved to my computer?

Do I have to rezip it?

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Originally Posted by turbovanman

Ok, I can't attach it here even though its saved to my computer?

Do I have to rezip it?

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Yep, zip them up...

Ok, lets try this-

I need the .bin, too. That's just the .tbl file. Send me the files that have the f'd up lines for the LMAPTC table...

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Originally Posted by ShelGame

I need the .bin, too. That's just the .tbl file. Send me the files that have the f'd up lines for the LMAPTC table...

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You want ALL of them? I figure that's at least 6-10.

I just need the .bin and .tbl that you load up that has the messed up LMAPTC. I don't need the T-SMEC build files (the .asm's)...

Ok here's the bin file, I have more but I'll just give you the main one I am using.

Removed, bad fin file.