Help with fine tuning 402
12-19-2007, 12:36 PM
#1
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Help with fine tuning 402 Alright - been in Hong Kong for 6 weeks and have a couple of days to play with my tune prior to Christmas - hopefully you guys can help shed some light for me.
Few questions:
1) How clean can you get the VE? I have put over 200 miles on the car in OLSD, making adjustments after getting nice, full AFR Error histograms, cell counts set to 50. Low RPM cruising is killing me as I try to get it consistent. Same weather, same amount of data collected, I can't get the histogram to keep everything under 5%. For the most part it is, but I still get the occasional cells with 8-9% error.
Am I at the point that I need to quit fudging with it?
2) Calibrating the MAF - On the last 3 or 4 drives I plugged the MAF back in and started logging it's values in order to get the corrections on the appropriate histogram. I started out with the table from a 6.0L truck and have made a couple of adjustments, but it has been fairly accurate (3% or less) across the board.
How accurate do I strive to be here? If I am at the point where I need to quit adjusting the VE, should I be reenabling closed loop and start watching my fuel trims?
3) Returning to idle - This is really confusing me at this point. Working with Russ's input and then slowly moving things around I have gotten it to return to idle smoothly 95% of the time. The other 5% I can't figure out - 2% of the time the idle just falls off and dies, the other 2-3% of the time it hangs up about 300rpms above idle. There are a few times where it falls to idle nicely, but only for a split second and it jumps up 100rpms, then settles back down (Can see this in the log almost every time I come to a stop). If the car does end up dying, the idle hangs 3-400rpms above idle 100% of the time until I reload a tune. (Any time it hangs up high, it does so until I come to a complete stop for a few seconds, then it falls to idle speed).
I'm at a loss here, and can understand why I keep reading that idle is one of the hardest things to get locked in. I notice that the advance locks in solid when coming down to idle (locked exactly where the idle spark advance tables command it to be). Are there any modifiers to that table? It may be that I n
Specs:
2002 SS with a new 402 LS2
11.5:1 compression ratio
244/250...114 LSA cam
AFR 225 62cc heads
Kook's headers
FAST 90/90 Intake/TB
SLP 85mm MAF
42lb Racetronix injectors (48.83lb/hr @ 58psi)
255lph fuel pump
Manual transmission
Latest tune and latest log are below. You can see towards the end of the log when it dies coming down to idle...
Thanks in advance for any advice.
Few questions:
1) How clean can you get the VE? I have put over 200 miles on the car in OLSD, making adjustments after getting nice, full AFR Error histograms, cell counts set to 50. Low RPM cruising is killing me as I try to get it consistent. Same weather, same amount of data collected, I can't get the histogram to keep everything under 5%. For the most part it is, but I still get the occasional cells with 8-9% error.
Am I at the point that I need to quit fudging with it?
2) Calibrating the MAF - On the last 3 or 4 drives I plugged the MAF back in and started logging it's values in order to get the corrections on the appropriate histogram. I started out with the table from a 6.0L truck and have made a couple of adjustments, but it has been fairly accurate (3% or less) across the board.
How accurate do I strive to be here? If I am at the point where I need to quit adjusting the VE, should I be reenabling closed loop and start watching my fuel trims?
3) Returning to idle - This is really confusing me at this point. Working with Russ's input and then slowly moving things around I have gotten it to return to idle smoothly 95% of the time. The other 5% I can't figure out - 2% of the time the idle just falls off and dies, the other 2-3% of the time it hangs up about 300rpms above idle. There are a few times where it falls to idle nicely, but only for a split second and it jumps up 100rpms, then settles back down (Can see this in the log almost every time I come to a stop). If the car does end up dying, the idle hangs 3-400rpms above idle 100% of the time until I reload a tune. (Any time it hangs up high, it does so until I come to a complete stop for a few seconds, then it falls to idle speed).
I'm at a loss here, and can understand why I keep reading that idle is one of the hardest things to get locked in. I notice that the advance locks in solid when coming down to idle (locked exactly where the idle spark advance tables command it to be). Are there any modifiers to that table? It may be that I n
Specs:
2002 SS with a new 402 LS2
11.5:1 compression ratio
244/250...114 LSA cam
AFR 225 62cc heads
Kook's headers
FAST 90/90 Intake/TB
SLP 85mm MAF
42lb Racetronix injectors (48.83lb/hr @ 58psi)
255lph fuel pump
Manual transmission
Latest tune and latest log are below. You can see towards the end of the log when it dies coming down to idle...
Thanks in advance for any advice.
12-20-2007, 08:28 AM
#3
If your VE is as close as you say, leave it. Same with the MAF if its +/- 3%. Reenable STFT and see where you're at. You can histogram them also and see what that looks like. As for the idle, I'll look at your log later when I have some time. Sorry no input on that right now.
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