Part Throttle: VE vs. MAF vs. IFR Tuning
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Originally Posted by Another_User
Oh, and lids are the devil. Or maybe just the fact that we don't have a way to caibrate our MAFs. If those buttheads that made the lids would flow the friggin things and give us a MAF table it would help. Heaven forbid they spend a few bucks at SLP.
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Stock longblock
Stock Heads
TR224/112 Cam.
918 springs
Ti Retainers
Grot. headers
QTP/Mufflex Y-pipe.
Mufflex 4" with Borla XR-1 Muffler.
Stock throttle Body/Stock MAF.
LS1 Motorsports Lid.
T56.
I think those are all the applicable mods. As you can see, pretty basic setup.
#22
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Originally Posted by XJGPN
Actually, that's a good point... anyone have a MAF table for that SLP lid that was available as an option on SS's?
#23
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Don't forget that cams with narrower LSAs alter the airflow measured by the MAF due to overlap/reversion. Also, some fuel and O2, via the open intake valve during overlap, is exhausted - throwing the AFR somewhat lean at idle. FWIW.
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Originally Posted by XJGPN
Went out again, this time I tried the Closed loop SD tune. My car just plain will not even start without the MAF. Starts and idles really nicely with the MAF, but if I pull the maf, car seems to start okay, but then stumbles and dies. If I give it any gas it dies immediately. Are my VE tables just that far off, or is it something else I am missing?
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I tried to put the MAF in different angles, hoping to find out the best one with my Vortech setup.
It's all the same. No matter wich angle, the MAF table has to be adjusted.
What I see is that as soon you touch the intake the cells corresponding to low RPM and low MAP are more negative that usual (richer).
That's why I reduced the lower frequencies by 7%. The higher the frequency the lower the correction. After 4625 Hz I left the stock values.
It's all the same. No matter wich angle, the MAF table has to be adjusted.
What I see is that as soon you touch the intake the cells corresponding to low RPM and low MAP are more negative that usual (richer).
That's why I reduced the lower frequencies by 7%. The higher the frequency the lower the correction. After 4625 Hz I left the stock values.
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Originally Posted by CamTom12
How did it work out?
Getting HP Tuners as soon as the check clears...
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Getting HP Tuners as soon as the check clears...
PS- You won't regret getting the software. It really is as great as everyone says.
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Originally Posted by JimMueller
So when one finishes with the SD tuning phase and if one decides to re-enable the MAF, how do we determine which RPM's to scale and by how much?
Here is my update. I didn't disable DFCO, so occasionally I would get a false lean reading (as in ~~19.99:1). These anomalies were driving me nuts, and I thought it was something with the connection between the LM-1 and the computer. Once I realized that these symptoms could be caused by DFCO I disabled it. I did it by turning DFCO Enable Normal and DFCO Enable Clutch Transition to 250. Did an extremely long log and didn't get the anomalies any more. Hopefully this step will get added to the SD tuning directions soon. Regardless, the values didn't throw off my numbers too much... So hopefully won't add too much more time on getting this VE table tuned in. My biggest thing now is just smoothing it... I read the suggestions for hand smoothing the graph... but I can still see it being a tough battle between making it look pretty and getting the data in a given cell to hit my target. If I figure out a good method, I'll pass it on. Right now I'm thinking I'm just going to take the VE table I have, keep hitting the polynomial smoothing to get an idea of where the numbers would fall totally smoothed out, then compare those values to my current values and the resultant AF ratio and see if I can find a middle ground.
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I saw a video once of an Aussie car starting and the guy (I guess 'Bloke' is appropriate here, hahaha
) saying something like "sounds nice for a cam they say couldn't idle. That's what you call Speed Density tuning," or something like that
Why don't more people here tune in SD? Are there any major drawbacks other than emissions testing?
Sorry if I'm off topic...
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Why don't more people here tune in SD? Are there any major drawbacks other than emissions testing?
Sorry if I'm off topic...
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Originally Posted by CamTom12
Why don't more people here tune in SD? Are there any major drawbacks other than emissions testing?
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Originally Posted by Nic00Z28M6
Very easily. Use a wideband and write down the values you need to change in your VE table, repeat. HP tuners just makes it quicker.
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Originally Posted by XJGPN
How would you have logged a histogram to know exactly which cell in the VE table to modify without being able to log your MAP sensor, RPM and AF with the same device? I'm not saying it couldn't be done, just that it would be so much more time consuming than it is using the histogram and enhanced interface with HP tuners.
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Originally Posted by JimMueller
So when one finishes with the SD tuning phase and if one decides to re-enable the MAF, how do we determine which RPM's to scale and by how much?
You scale the entire table. This step isn't about tuning individual cells, that's what the SD part of the process is for. This step is about scaling the MAF so that you are operating in the VE range.
So here's what happens -- you set your SD VE values, and plug back in the MAF. From then on your LTFTs and STFTs are going to be lean (mine went from 0 to -3 throughout the histo to 10 to 13) so you scale the MAF upwards to move the entire table back down.
One more thing -- after I scaled my MAF globally, to get the majority of the table back to 0 to -3, I have some sections (lower rpm and lower airflow) at -5. I haven't gotten back to the tune since then, but am not too worried about it.
I am also looking into the 4k+ rpm range which is 0 to 1 for me in lower airflow cells (this is the MAF only range). Not quite sure what to think about that yet. I am maxing the MAF at boost without question, but these ranges aren't under boost...