hello, I have a lq4 with 821 heads and ms4 cam
when I wot fast (from 0% tps to 100%) the car stumbles I noticed that the timing dips down to 5-7 degrees timing, if I can get some pointers on this and car is having a hard time idling in cold weather until the fuel trims kick in. dee2.hpldee with 80.hpt
2000 ss-stock w/ls6 intake 3.42 a4
1985 El Camino ss 327
2002 z28 built 347 ls1 A3
Do you have a wideband on this?
You need to remember that you put this into speed density, so it's only running off the low octane timing table. Those really low values in the timing table where it's 800-1400rpm and .44-.68 cylinder airmass is pretty much where the computer is grabbing those low timing values from. Raise the timing and smooth it out so it won't nose dive when you get on the throttle.
There is also a bunch of negative timing that can be pulled on cold starts. Look at the ECT spark correction table, it can pulll up to 8 degrees out. If you are trying to set the idle timing to a specific value or area (like 18-22 degrees), this table is going to skew those numbers downward. Zero out that portion of the table to stop it.
The in park to in gear idle timing has a pretty large jump in timing, keep those closer together and maybe it will help you out.
It may even need a touch added to the base running airflow, it's something you need to data log and play with.
Work on the VE more with a wideband, if the airflow model is smooth it will make idle and it's transition into the throttle way smoother.
Try to clean up your logs too, there are too many channels and on my computer it's slowing many of the channels down. Remove some of the duplicate channels or channels that report zero useful data. Like the APP sensor, baro pressure, all your MAF channels that aren't being used, evap channel, fuel tank pressure, oil life, oil pressure and things like that.
Last edited by 5FDP; 03-29-2020 at 12:39 AM.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
A smoother VE table, will certainly help smooth cylinder air mass from jumping around in the spark tables and help fueling. I would probably redo the dynamic boundaries to fall between cells rather than on top of them and maybe space them away from the middle of parts of the map you most fall into. You aren't seeing where spark is on a graph properly because you are only getting about 3 updates on the cylinder airmass PID every 10 seconds. Best thing you could do for your self is make an optimal channels list, Prioritizing the ones you want to use in the axis values and fill values of the graph, so you can really see what's going on. Not sure why its polling so slow, your other channels seem ok.
The best I could do with this log is convert your dynamic MAF to cylinder air using RPM and a user Math, the table below is what it showed for spark.
If removing channels doesnt improve your cylinder air mass channel:
Math is ((dynMAF in KG per min *1000)/RPM))/4 intakes per revolution, this was giving me about 20ms polling speed, the same as RPM and spark. For comparison, my zeitronix MAP sensor and wideband read about 10 times faster, much more like what the ecu sees compared to the OBDii. External sensors will get you better results, when and where you can use them. When looking at logs you have to factor in that what you are looking at is not an exact picture, so dips/peaks in your VE table may not show up, but the ECU certainly didn't miss it.
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Last edited by murfie; 03-29-2020 at 05:37 AM.
burst knock off
remove PE delay and up the enrichment rate to between 1.5 and 1.9
something is wrong with airflow model.... what injectors? you should see a bit more than 0.36 load at WOT in the spark table.
work on making a decent VE table.
stumble is usually lean spot or missfire. pop out intake is lean pop out exhaust is spark related misfire as rule of thumb.
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