turabo87

Hi guys,

Just finished my top end upgrade this weekend and been retuning on the street since Monday. I'm starting by redoing my speed density tables (VE Primary and Secondary) in open loop. I'm reaching very high levels of difficulty and frustration tuning the AFR of idle, driveability and tip in areas below 2000 RPM. I'm basically still very lean (16-19AFR) despites efforts of heavily refueling those areas, especially in tip in below 2k RPM I can see even 19-20AFR. It's so lean on tip in that I get engine hesitation until it clears up into another area of the table. I even did two tests to do a blanket fueling addition of 30% and then 40% across the entire affected area and ran worse, still supposedly lean and tons of hesitation.

I personally think it's actually lean and AFR gauge is reading correctly, because the AFR is actually much closer to stoich in cold starts as engine coolant warms up, since my charge bias tables favor a richer mixture as engine is still cold. However I'm not seeing an AFR correction by adding more fuel thru VE tables on those areas. I'm stuck and frustrated and need some pointers. I'll post my current tune and datalogs later.

PS: Areas over 2k RPM have not been an issue to do AFR corrections. Also, I tuned successfully drivability with SD with the previous stock 853 heads and LS1 TB right before I put the mods, so it's not my first rodeo on SD.

My setup:
PRC 227 (milled to 57cc chamber for 11.5:1 comp) CNC ported heads
LS2 Silverblade (used) with a mild port job
FAST92 intake
Trickflow Cam .585/.585/228/230/112LSA
Stock LS1 bottom end
Long Tube 1-3/4 headers and catless X
93 Fuel

aaronc7

I know you've posted before...but can you post your current tune and a log of some sort to show the lean tip in? Mainly the tune. What injectors are you running?

turabo87

Attached is my last SD tune (called SD 2.4) and a log file, and subsequently the MAF tune I did and a log file. After my last post I did another final attempt on fixing the SD tune and gave up after chasing my tale for hours. I tried even running STFT to see if the narrowband O2s would tell me anything; it didn't make a difference. After giving up, I gave the MAF a try. I was able to tune it with MAF within 3 flashes in less than 1 hour of tuning. Incredible. All my problems went away. I have no hesitation, no significant lean spots, great throttle response, basically perfect driveability now with MAF. So the problem was not the LS2 TB at all, it was something in the SD tune that I was never able to figure out.

tblu92

I never recommend an SD Tune unless you OUTGROW your MAF table looking at your mods I think you are OK using your MAF set up --SD can be troublesome for the same reasons and issues you are having---
When data logging at WOT see where it lands on the MAF table as long as it does not go over the final HZ value you should be fine
PS Are you using the STOCK injectors ???
Another way to richen like below 2000 is via the IFR table--The IFR table is scaled by MANIFOLD VACUUM PSI--- So data log that up to 2000 RPM's and see where it lands--The SUBTRACT a % from that reading down to IDLE
If you were like in the 16-19's AFR I would start by subtracting 10% (subtracting the IFR value below the actual installed injector value richens it Adding a % leans it down

TurboLX

Did you "fix" your VE tables by doing steady state measurements on a load bearing dyno or by logging while driving around? The transients you get while driving will mess up the data you need for the VE tables, which should come from ONLY steady state measurements. Once those are set, you should have a reasonable number for intake volume and throttle area/%. With all that set correctly, you can proceed with correcting any remaining lean isuues on tip-in with transient fuel control calibration in in the impact/evap model.

turabo87

I'm using resized 42# injectors @58PSI, from Injector Connection. Injector data had been appropriately resized since I first put them in over a year ago and never were an issue, but what you're saying makes sense and maybe now the IFR table would need retweaking. All I know is that when I was in SD OL with the new heads, wouldn't matter how much I would richen the VE table (I could've richened it by something ridiculous like 60% more fuel on the VE) and the injector PW wouldn't increase much in idle and low RPM tip in areas.

I'm running with the MAF now and driveability/AFR is near perfect everywhere now.

CinciZ06

I am COMPLETELY a newb at learning HP Tuners, and am buying Greg's courses to get my shizzy together on this. But anyway, while dealing with my own idle issues I have done a ton of reading on HPTuners Forum and one thing that jumps out to me immediately about your tune is you still have your ETC Scaler (Engine/Idle/Airflow) at the stock value, but the LS2 throttle body should have a .0192? There were a number of threads where people experienced driveability issues with a jacked up ECT Scaler value and the LS2 throttle body. Maybe someone that actually knows what they are talking about could chime in and tell me to have a seat. haha.

turabo87

Hmm interesting you mention the ETC Scalar. I'm a relative beginner too so I'd have to let someone else with experience such as Greg chime in, but I don't think ECT scalar has much to do with the leanness issue on SD. Although now that you mention ECT Scalar, I might revise the values. Luckily I haven't had any serious driveability issues with the LS2 TB. I've had some minor gripes, which now thinking about it might be because I haven't redialed the ECT scalar. For example, I can feel that the throttle response vs actual throttle input is slightly behind/slightly less sharp. My MAF transfer calibration now is SPOT ON though. My biggest driveability issue right now that is still unsolved is occasional stalling when RPMs drop during a clutch in (not finding idle quick enough when RPMs drop and it just plummets past idle below 500RPMS and just stalls). I THINK this might in part due to ECT Scalar, but I have yet to mess with Throttle Cracker to alleviate this and avoid stalling on clutch in.

PS: My startup and idle is perfect, even with ECT Scalar on stock settings. Only issue is what I said of engine stalling sometimes when clutching in from higher RPMs. It just doesn't "catch" idle quick enough and stalls.

turabo87

Well I updated the ECT scalar to 0.0192 and engine did not agree with this at all. Wouldn’t idle and stall very easily so back to my stock scalar. I’ll have to do adjustments elsewhere else bc it throws off completely my idle control.

CinciZ06

Well damn. Im very curious what the solution is, just for my own education.

turabo87

After some HP Tuner forum diving, I was able to get the idle just right with just a tad (3%) added to the base running airflow, and with the stock ECT scalar. Drives beautifully and for me the throttle feels great so I’ll leave it like that, even though I know it’s not the kosher way.

TurboLX

The throttle body area scalar should match the actual dimensions of the throttle body. There are a number of other things that must be balanced to get idle right (min airflow, spark vs MBT, AFR control as a result of injector data, VE and MAF...) I avoid "ported" throttle bodies like the plague since they also tend to ruin the carefully engineered progressive opening rate that the TAC module is expecting. But that's another different can of worms.

Set the data to match your physical parts (injectors, TB) and solve for VE and MAF in steady state before chasing other made up problems. The idle airflow trim will attempt to fix it over time if you feed it accurate data. Then you just have to make the learned value the first guess to make it happy right away.

CinciZ06

Ugh. It's like drinking from a fire hose. Glad there are smarter dudes than me on here like yourself. I am still learning the theory portion of this noise before what your saying makes total sense to me, but I need to find time to finish digesting Greg's book.