I think I may have <ahem> "stumbled" () across something that may help people with the dreaded throttle tip-in stumble on these types of manifolds. Forgive me if this is already common knowledge....

I started taking notice of the fact that very small changes in TPS produced large MAP deltas (at low throttle positions). This is particularly apparent around idle speeds (when the tip-in stumble is generally the worst). So I went to the AE table entitled "Accel Enrich Delta MAP Factor Multiplier vs TPS". For small TPS values, 0% & 12.5% in the table, I richened up the multiplier by 15% at 0%TPS and 10% at 12.5%TPS. My thinking was that at idle, the absolute throttle position is zero and at just barely off idle (where the stumble generally occurs) the it's somewhere between zero and 12%. So I figured could target just the off idle transition by increasing the overall AE vs delta MAP for just these two throttle positions. Now, unless I'm mistaken, the TPS% in this table is NOT a delta TPS, but rather it's the absolute TPS. For example, 0% is closed throttle and 12.5% is 12.5% throttle (NOT a 12.5% change in throttle position).

Any rate, test driving it produced a noticeable results in that the throttle feels particularly more crisp coming off idle. It was pretty damn good before using the $DA3 AE tables, but this little mod almost makes it perfect. I'm still going to play around with it a little more to see if there's any more improvement to be had, but I like the results I'm seeing so far. My '06 Pontiac Vibe commuter car has a VERY crisp off idle transition so I'm kind of using that as my goal. I'm almost there... Though I'm not sure if I'll get there until I completely solve my rough idle issue (I just hope I don't have to start from scratch on the tuning when and if I do).

 

Great stuff.

Please keep any future "Miniram/LT1" intake tuning tips you develop within this single post and later I'll try collecting this (and other Miniram/LT1) tuning tips together and add it to the "Tuning Guide" in the sticky section.

I believe it is posts like this that people are often looking for, but have difficulty finding.

 

If you are talking about the $8D code then this is true. I played around with it quite a bit last year getting the transition from N/A to boost right. It also plays a big role at low throttle settings. One thing to keep in mind is that MAP AE is sync and TPS AE is async. I tried removing as much async as possible. LT1 intake here.

 

I'll try to remember that.
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You know, I still don't get the sync vs async thing...

And yes... $8D.

 

Well, I tried some different values (higher and lower) for this particular AE table "Accel Enrich Delta MAP Factor Multiplier vs TPS" and didn't see anymore improvement. It would appear I discovered the optimum setting on the first try- richened up the multiplier by 15% at 0%TPS and 10% at 12.5%TPS! Not that I'm complaining...

 

Hi

this thread is pure gold!

i tried ever to solve the low throttle stumble when taking off really slowly..

58mm TB here, single plane...when i step on the gas very light, AFR went up to 16, car stumbling, good feelable through the M/T

i uppended the first value to 1.09, second to 1.05, all other to 1

also, set the AE delta TPS scale factor to .200 (previous .125)

now, no more stumble, just a nice dip down to AFR 13, getting rolling is very smooth now

thank you for your research!

 

Wow, old thread resurrected!

But cool, glad it worked out for you. I've learned A LOT while tuning on this Miniram both from trial and error as well as from knowledgeable people on this board.