I'm a novice tuner tuning my single turbo 2010 Camaro SS L99
The car runs great idle, part throttle and WOT. The only issue I have and it maybe normal is the car goes pig rich on decel (WB 11.5-12.0) then jumps back up to 14.7ish.
This mainly happens while driving in town. any insight on this would be great!
here are my mods:
Turbonetics kit
DW 65lbs injectors (905cc @58psi)
livernois dual pump
Meth injection
Cat delete
3" exhaust
3 bar map
More than likely DFCO is not working. If you have installed an aftermarket cam which you probably did. The settings to enter DFCO are not being satisfied now.
I'm running a stock cam, valve covers have never been removed..Originally Posted by openwheel25
If DFCO is active and getting triggered, then it should go way lean. If not, then its using the MAF/VE filtered airmass reading to control your fueling there. I have been SD tuning without the MAF and noticed on decel that the amount of fuel it wants at various decel rpm's can swing around a fair bit. What you get during decel is a very low MAP reading at any rpm level. My MAP read's something around 15-20 kpa weather I'm at 5000 rpm or 1000 rpm on the decel.
If you want to fix this, you should force open loop and fail the MAF. Do some decels and record your AFR error. Go in and adjust the first 2 MAP rows in your VE table based on the error your getting. You may need to do it a couple of times because some of the error may be greater than your wideband is capable of reading. Then at least you have your VE dialed in. You would then need to turn the MAF on and stay in open loop. And then adjust your MAF table similarly. But the MAF might be all over the place on this one.
I really don't think its a big deal to worry about in your tune though. Going a bit rich on decel is probably completely ok. We know that GM deems going lean on decel is okay because they have DFCO as part of every tune out there.
2010 Camaro LS3
Kenne Bell 2.8 Supercharger
BTR stage 3 PDS Torque Cam
Frankenstein M311 heads
9:1 forged rotating assembly
Speed Engineering Headers
ID1000 Injectors
Twin return fuel fuel pump
PLX Wideband
HP Tuners
The DFCO is active but only appears to function at 1500 RPM and above. My Tune is MAF only no SD
But your VE table is getting referenced. Even when running MAF only, the VE table can be referenced during transients and other conditions (complex model from GM). I am no expert on this...but it may be that during decels it is also referenced. Which may be why you are seeing this.
2010 Camaro LS3
Kenne Bell 2.8 Supercharger
BTR stage 3 PDS Torque Cam
Frankenstein M311 heads
9:1 forged rotating assembly
Speed Engineering Headers
ID1000 Injectors
Twin return fuel fuel pump
PLX Wideband
HP Tuners
CC nailed it. Even in MAF only mode the ECM uses the VVE to determine airflow during transients both positive and negative. Also it appears your coastdown spark is VERY negative. You may not be allowing enough time for the charge to finish burning. I have not tuned turbo LSs but I would not think this was a good thing.
Being new to tuning, can you explain what coastdown spark is and what is does
For some reason at low rpm and light throttle you are no longer triggering DFCO. The fix is to rise the requirements that DFCO looks for. Rising the minimum cylinder air or the minimum throttle position. You will want to make the changes slowly so you don't have DFCO cutting fuel and stalling the car.
Very likely but I have a hard time stating that conclusively without him logging "DFCO active"For some reason at low rpm and light throttle you are no longer triggering DFCO. The fix is to rise the requirements that DFCO looks for. Rising the minimum cylinder air or the minimum throttle position.
If you look at 11:03:05 it looks like the typical DFCO pattern for the spark (Ramp down hold then ramp up). He is already at his minimum injector pulsewidth during this period (even though the O2s are showing rich) and eventually his O2s start reading lean. Then the spark transitions to the ramp up and out. This is why I think it is a combination of things. Is it DFCO probably but hard to tell. Also the coastdown numbers look out of whack.
If you look at 11:02:44 you see what looks like a DFCO entry then this lazy arc in the timing down to about 9 degrees and then you don't see the normal transition out of DFCO. Is the car not in DFCO there? Maybe not be if not then when did the timing swing down so much initially. Also this thing really doesn't start to lose RPMs until the throttle completely closes (18.4 vice 19.6). This has me thinking that someone tried to band aid bad VE data using the coastdown spark (max idle is set to 1100 and target idle is set to 525 - that is a lot of room for the idle control algorithms to do weird things ). But maybe not. Again I think it is a combination of things so it is hard to tell...
SCV_guy,
IMO - You need more data in the logs to tackle this. The new scanner is fast so I don't think you should be limited to only the current number of parameters to keep good resolution. I am not an E38 guy so I don't have a channel config that you would want but my suspicion is that you want DFCO active, Throttle control source, Idle base advance, and Idle adapt advance to start. There are probably example channel configs on the site to get you started.
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