Results 1 to 12 of 12

Thread: New wide band shows lean cruise in closed loop, 24x LT1

  1. #1
    Tuner
    Join Date
    Aug 2014
    Location
    Bend, OR
    Posts
    94

    New wide band shows lean cruise in closed loop, 24x LT1

    I'm sure I've said this before and I'll say it again. Bucking while cruising around town has been my arch nemesis since day one with this engine. I recently added a new weapon to my arsenal in the fight for all that is good and just: Ballenger Motorsports AFR500. It is literally a re-stickered NGK Powerdex AFX, and is the official continuation of that wide band. I bought the NTK calibration grade sensor to go along with it so there is no question about the wide band's accuracy.

    It looks like the sensor has provided a clue towards a contributor for the bucking: lean cruise. I always suspected the car might have been running lean and the wide band confirmed it, showing an afr of 15:1 +/-0.2 for the cells I cruise around town in. 95% of the other cells that matter are 14.7 +/-0.2. Does anyone have any ideas for how I can fatten up the cells I cruise in? Mods are in the sig.

    Base idle airflow was set with Russ K's config file. I tuned MAF and VE to death over the course of the last 9 months. Today I logged with the wide band then did Paste Special>Multiply by % for both MAF and VE tables. That didn't make any difference in my MAF and VE AFR error histograms afterwards. I changed MAP, LTFT, and RPM zone boundaries. My injector data isn't exact but it's close. I adjusted EOIT so that during cruise all fuel is injected AFTER the cam's overlap event so nothing gets sucked out the exhaust. Target AFR is set to 14.42254 since my local gas stations have up to 10% ethanol. Made some minor adjustments to the closed loop proportional and integrator tables for the mid length headers. Finally, I'm using a stock LT1 spark table.

    I'll post my current tune and my latest log. This log was done during some WOT tuning after multiplying the VE and MAF tables by the AFR Error histogram.
    Attached Files Attached Files
    Last edited by AdsoYo; 07-11-2015 at 05:49 AM.
    1994 Trans Am: LS3 Crate Swap - Cam Motion 216/226-116+3 - 0411 PCM with Lingenfelter 58x > 24x Converter - 4L60E to RPM T56 - Strange 12 Bolt - UMI Suspension - TSP 1 7/8" Headers - GMMG Exhaust

  2. #2
    Senior Tuner mowton's Avatar
    Join Date
    Mar 2007
    Location
    Florida
    Posts
    3,773
    Make sure your VE is tuned in these area's. Try setting tune to open loop. My last LT1 24X upgrade I had a lot of problems in the idle and low rpm area's with the WB and Narrowbands not agreeing...I mean by a lot. When I tuned all in open loop with the WB, going to closed loop created a lean condition, which of course the PCM tried to correct via + trims. I eventually delivered the car in open loop because it ran so much better. Didn't get a chance to figure it out. Have another on on the schedule next week so will look at it.

    As far as fattening, log the MAF HZ and MAF airflow as well as Dynamic airflow. Make sure both MAF and Dynamic are very close. The Dynamic airflow will be the final calculated airflow by the PCM including any filtering or VE biasing based on operating in the blended mode. Find the HZ cell(s) in question and increase them accordingly. If it gies leaner, then you still have "short circuiting" issues and need to actually lean it out or more inj timing tweaks.

    Ed M
    2004 Vette Coupe, LS2, MN6, Vararam, ARH/CATs, Ti's, 4:10, Trickflow 215, 30# SVO, Vette Doctors Cam, Fast 90/90, DD McLeod, DTE Brace, Hurst shifter, Bilsteins etc. 480/430

    ERM Performance Tuning -- Interactive Learning ..from tuning software training to custom tunes
    HP Tuners Dealer- VCM Suite (free 2hr training session with purchase), credits and new Version 2.0 turtorial available
    http://www.ermperformancetuning.com
    http://www.facebook.com/ERMPerformanceTuning

    [email protected]

  3. #3
    Tuner
    Join Date
    Aug 2014
    Location
    Bend, OR
    Posts
    94
    My narrowbands seem to coincide very well with the wideband. I haven't tuned OL with the wideband yet, that's on the list of things to do. Didn't know that about dynamic airflow, thanks!
    Last edited by AdsoYo; 07-11-2015 at 06:01 AM.
    1994 Trans Am: LS3 Crate Swap - Cam Motion 216/226-116+3 - 0411 PCM with Lingenfelter 58x > 24x Converter - 4L60E to RPM T56 - Strange 12 Bolt - UMI Suspension - TSP 1 7/8" Headers - GMMG Exhaust

  4. #4
    Advanced Tuner
    Join Date
    Nov 2013
    Posts
    208
    Looked at your logs. Two areas jumped out at me:

    1. Your ign timing is VERY low when its super lean, like 2-3 deg. Any idea why?

    2. I'm looking at your inj timing, and for starters your Normal table shouldn't be small like that at colder temps. It should be at least the same value as the higher temps.

    Also would you add the inj pw for B1 and B2 and shoot us another log? That way we can look at the inj timing, PW, and RPM and figure out if a bunch of the fuel is going out the exh at ~2,000 RPM. After plugging your inj timing into the spreadsheet I posted on the inj timing thread, it looks like you'll be close.
    Also remember that the 0.050" lift events are not the same as "fully closed" for intake or exh valves...

    Attached is an image using your inj timing and inj pw that I logged (~4 ms). Same inj you have, bigger cam, smaller displacement. So it isn't apples to apples, but it does show where your issue may be coming from.

    Cruise SOIT with 0.050" cam events
    7-13-2015 1-04-25 PM.jpg

    Cruise SOIT with 0.006" cam events
    7-13-2015 1-16-34 PM.jpg

    Notice how the SOIT (pink line) drifts down toward the EVC link (orange). So at some combination of RPM and inj pw you'll be loosing unburnt fuel out the exh. Especially when you look at the 0.006" cam events.

    HTH,
    Jason
    Last edited by JasonS5555; 07-13-2015 at 03:28 PM.
    1996 Camaro SS M6 - 24X conversion - stock bottom end - heads - shorty headers - 58mm TB
    Ultradyne 230/238 .565/.565 112+4 - 30 LB red top SVO injectors - LOTS of suspension...

    2002 GMC 2500 HD Duramax M6 - Just starting the tune on a stock motor now that I have a good clutch on order...

  5. #5
    Senior Tuner mowton's Avatar
    Join Date
    Mar 2007
    Location
    Florida
    Posts
    3,773
    1. Your ign timing is VERY low when its super lean, like 2-3 deg. Any idea why?
    Thats decel........ Theres no TPS% pid but the map drops to 20!!!!! need to tune it off if TPS is still active.
    Ed M
    Last edited by mowton; 07-13-2015 at 07:05 PM.
    2004 Vette Coupe, LS2, MN6, Vararam, ARH/CATs, Ti's, 4:10, Trickflow 215, 30# SVO, Vette Doctors Cam, Fast 90/90, DD McLeod, DTE Brace, Hurst shifter, Bilsteins etc. 480/430

    ERM Performance Tuning -- Interactive Learning ..from tuning software training to custom tunes
    HP Tuners Dealer- VCM Suite (free 2hr training session with purchase), credits and new Version 2.0 turtorial available
    http://www.ermperformancetuning.com
    http://www.facebook.com/ERMPerformanceTuning

    [email protected]

  6. #6
    Tuner
    Join Date
    Aug 2014
    Location
    Bend, OR
    Posts
    94
    Quote Originally Posted by JasonS5555 View Post
    Looked at your logs. Two areas jumped out at me:

    1. Your ign timing is VERY low when its super lean, like 2-3 deg. Any idea why?

    2. I'm looking at your inj timing, and for starters your Normal table shouldn't be small like that at colder temps. It should be at least the same value as the higher temps.

    Also would you add the inj pw for B1 and B2 and shoot us another log? That way we can look at the inj timing, PW, and RPM and figure out if a bunch of the fuel is going out the exh at ~2,000 RPM. After plugging your inj timing into the spreadsheet I posted on the inj timing thread, it looks like you'll be close.
    Also remember that the 0.050" lift events are not the same as "fully closed" for intake or exh valves...

    Attached is an image using your inj timing and inj pw that I logged (~4 ms). Same inj you have, bigger cam, smaller displacement. So it isn't apples to apples, but it does show where your issue may be coming from.

    Cruise SOIT with 0.050" cam events
    7-13-2015 1-04-25 PM.jpg

    Cruise SOIT with 0.006" cam events
    7-13-2015 1-16-34 PM.jpg

    Notice how the SOIT (pink line) drifts down toward the EVC link (orange). So at some combination of RPM and inj pw you'll be loosing unburnt fuel out the exh. Especially when you look at the 0.006" cam events.

    HTH,
    Jason
    Jason, good to hear from you again.

    1. My log wasn't the best, some important PID's are missing. When timing gets low like that it's DFCO.
    2. Why's that? I kind of like the idea of the fuel sitting on the valve while the engine is cold.

    I would be happy to post up another log. Any other parameters that could be helpful? I haven't messed with EOIT since purchasing the wideband and upgrading to hptuners pro. I'm gonna have to get back into it. I'm going to head back to the EOIT thread and grab your outstanding spreadsheets again.
    1994 Trans Am: LS3 Crate Swap - Cam Motion 216/226-116+3 - 0411 PCM with Lingenfelter 58x > 24x Converter - 4L60E to RPM T56 - Strange 12 Bolt - UMI Suspension - TSP 1 7/8" Headers - GMMG Exhaust

  7. #7
    Advanced Tuner
    Join Date
    Nov 2013
    Posts
    208
    1. I didn't realize that until Ed pointed it out. Makes sense, and it looks from the log like that's the only time its going crazy lean. Did I miss another place where it was lean and not in defco?

    2. Because your cam has overlap and the stock cam doesn't. So with the stock cam, the fuel has more time to vaporize on the back of the cool intake valve. With overlap, more of the fuel just exits through the exh valve since its still open when the intake valve opens. The same reasons you move EOIT for warm ECT still apply.

    3. I guess, TPS, and both banks of inj PW should be sufficient to help us figure out the best EOIT compromise.

    Jason
    1996 Camaro SS M6 - 24X conversion - stock bottom end - heads - shorty headers - 58mm TB
    Ultradyne 230/238 .565/.565 112+4 - 30 LB red top SVO injectors - LOTS of suspension...

    2002 GMC 2500 HD Duramax M6 - Just starting the tune on a stock motor now that I have a good clutch on order...

  8. #8
    My 2009 CTS-V is doing the exact same thing. Open loop VE and MAF are near perfect but as soon as I put it in closed loop it's lean. I'm getting to the conclusion that because the placement of the NBO2 is so much different than the stock manifolds the Closed Loop proportional airflow, O2 error, and Integrator Delay all need to be adjusted to suit but I've yet to find a method to do this accurately.

    Plus I have ID850's in for injectors which are about twice as large as the stock injector.

    I'm currently relegated to trial and error.

    I've seen a VERY SLIGHT improvement in response by halving my proportional airflow and increasing my Integrator delay by 1.5 times. I'm going to try doubling my Integrator delay soon.

    My rationale, if the Proportional airflow influences the amount of fuel injected to move off stoich and I doubled my injector size perhaps half makes sense. The NBO2 location is more than double the distance from the original location in the exhaust stream so double the integrator delay. I'm just fumbling in the dark now.

  9. #9
    Tuner
    Join Date
    Aug 2014
    Location
    Bend, OR
    Posts
    94
    Here's a log with injector pulse width. I reset the fuel trims for this log. For the first few minutes, the bucking is very slight but the car feels pretty smooth. Then when the trims start adjusting, the bucking gets worse. Haven't changed the tune. Also, I ran open loop with some changes to MAF curve and fueling that had me cruising at 14.3-14.5. The bucking did not go away but it did improve slightly. Also throughout all this, and I may have mentioned it before, there is popping in the exhaust. There's the purr of the engine, then in the background there is what sounds like bubbles. I haven't ridden in any other LT1's or LS1's so I have nothing to compare to except non performance oriented vehicles, but maybe that noise is a clue? I'm going to attempt to get a sound clip of it.

    *edit* just realized I forgot to log TPS. When cruising on flat ground it's always at 7-8%, sorry about that.
    Attached Files Attached Files
    Last edited by AdsoYo; 07-25-2015 at 04:11 AM.
    1994 Trans Am: LS3 Crate Swap - Cam Motion 216/226-116+3 - 0411 PCM with Lingenfelter 58x > 24x Converter - 4L60E to RPM T56 - Strange 12 Bolt - UMI Suspension - TSP 1 7/8" Headers - GMMG Exhaust

  10. #10
    Tuner
    Join Date
    Aug 2014
    Location
    Bend, OR
    Posts
    94
    Installed brand new stock LS1 injectors to rule out the SVO's 100%. Set flow rate vs kpa accordingly, started the car in open loop and it was so lean it wouldn't idle. Loaded up my closed loop tune with 24# flow rate vs kpa and it idled but it was still way lean, the check engine light was flashing, no DTC's. It was at 15.8 on the wideband and when closed loop kicked in, the trims maxed out and it was still 15.8. The injector pulse widths are split horribly. Fuel pressure was good at 43.5 psi. Dropped flow rate vs kpa to 22 lb/hr and still no better. Tried cylinder balance test in hpt and it ran the test but gave me a bunch of N/A's, no idea why. I'll try again tomorrow but I suspect one or some of these never used injectors are bad.
    Attached Files Attached Files
    1994 Trans Am: LS3 Crate Swap - Cam Motion 216/226-116+3 - 0411 PCM with Lingenfelter 58x > 24x Converter - 4L60E to RPM T56 - Strange 12 Bolt - UMI Suspension - TSP 1 7/8" Headers - GMMG Exhaust

  11. #11
    Advanced Tuner
    Join Date
    Nov 2013
    Posts
    208
    Back to the injector timing discussion. I entered your cam info, cruise inj PW and with the boundary and normal where you have them (6.73 and 6.77) you're dumping fuel out the open exh during cruise (the cause of the small backfires). Look at when SOIT is on the graph below compared to the EVC events (both 0.050 and 0.006).

    8-5-2015 2-19-30 PM.jpg

    If you move the values up to (7.60 and 6.49) the SOIT doesn't start before the exh valve closes until ~2800 instead of ~1900. As seen here:

    8-5-2015 2-25-33 PM.jpg

    So you should see better fuel economy and smoother operation. The down side is that you will also start to have WOT issues with the fuel going in before the IVC on the previous cycle. Since I didn't have your inj PW for WOT, I used mine. But you can see the issue here:

    8-5-2015 2-31-00 PM.jpg

    I have attached my version of the inj timing ws with your cam events so you can play with the inj timing once you enter some WOT inj PW. Then you can come to your own compromise.

    JRS SOIT EOIT Worksheet ADSYO.xls

    Let me know if you have any questions.

    Jason
    1996 Camaro SS M6 - 24X conversion - stock bottom end - heads - shorty headers - 58mm TB
    Ultradyne 230/238 .565/.565 112+4 - 30 LB red top SVO injectors - LOTS of suspension...

    2002 GMC 2500 HD Duramax M6 - Just starting the tune on a stock motor now that I have a good clutch on order...

  12. #12
    Advanced Tuner
    Join Date
    Sep 2017
    Posts
    736
    Quote Originally Posted by JasonS5555 View Post
    So you should see better fuel economy and smoother operation. The down side is that you will also start to have WOT issues with the fuel going in before the IVC on the previous cycle. Since I didn't have your inj PW for WOT, I used mine. But you can see the issue here:

    8-5-2015 2-31-00 PM.jpg
    n
    This is a very old post but if anyone knows, what issues is Jason referring to when injection starts in the previous cycle?
    1997 30th SS. Torqhead 24x, TFS heads, 223/235 cam, 4l80e, S60 D1SC 14psi