need a reminder to read later good stuff here
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need a reminder to read later good stuff here
I have been having massive lean tip in issues with my speed density open loop ls1 383 stroker. I have a large cam with lots of overlap, AFR 230cc heads and a FAST 102 manifold and throttle body. Below 3000rpm anywhere from 55kpa - 100kpa I would get huge lean spikes by rolling into the throttle. This was with a near perfect tuned steady state VE table. For reference I Multiplied the 100Kpa row of the Impact Factor table by 2 and interpolated back to the 60Kpa row at all coolant temps. My Lean tip in is more or less gone and throttle response is up. Some more fine tuning would nail it down some more but great results with little effort so far. I definitely recommend playing with this table if after Steady State VE tuning you still have transient problems.
Does this look like a transient issue. This is a 24x lt1 so the transient tables have to be different. But I get a strong lean in when I get into the throttle below 3k. It's got heads and 234/244 cam. It also seems to only happen on warm up. I believe it still happens when warmed up just not as noticeable.
Also this is a speed density open loop tune. I don't think it was as noticeable when running in closed loop bc the oxygen sensors seemed to correct it
great information gentlemen thank you
Any updates on this topic?
Whoa. Been tackling a new issue with transient fueling after swapping intakes on the same motor this write up was, well, written up for.
Completely forgot I wrote this, and was googling and found it haha!
I'm new to tuning, but have dove into the deep end while knowing only how to dogpaddle. I've read through this thread and copied the Maths into my Maths folder. Could someone add some detail on how to set up the graph for this to properly work?
On my '52 Cadillac with 6.0/4L70 TSP Stage II Low lift, LS6 intake and injectors I've got my MAF and VE dialed in, but occasionally get hit up to tune other GenIII swapped vehicles. This method would save some time.
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I know this is an old post, however I have just spent some hours dialing in my transient fuel on my L31 Marine intake on my 383 using a P59 with a 12592618 OS.
Here is what I have found. HP Tuners does not have all the tables that need to be used to correct the transient fueling defined. The reason the results people seeing are somewhat unpredictable, is because they only have what appears to be a few multiplier table defined. There are like 10 transient fuel tables all together.
We are missing several tables on most P59 operating systems including Impact and Evaporation tables for both Closed Throttle and WOT, as well as the Throttle Stomp compensation table. There is also a decay table for the Throttle Stomp missing. I also looked at the same stuff in my P01 0411 and it is missing most of the same stuff as well on the HP Tuners Transient fuel tab. The throttle stomp table has a large effect on sudden throttle increases similar to accelerator pump in a carb. The decay table changes how long the added burst of fuel is. I have tuned on both and my tip in no longer goes lean like it was. Still working on a slightly rich tip-out but it have also greatly reduced that. The throttle stomp table functions similarly to the Impact table but is for large TPS transients. Together they function similarly to MAP and TPS AE as well as DE on the older OBD1 stuff. The throttle stomp table gets more transient fuel flowing more quickly than the normal Impact table that has a delay until the MAP changes.
If HP Tuners would add the correct tables tuning the transients would actually become possible.
I have also done some more work on my Proportional and Integral 02 sensor settings in closed loop. The engine runs smooth as silk in closed loop now going down the road even with Doug Thorley Tri-Y long tubes and double the factory injector size.
Hmm.. I missed that last post I guess. Could explain why I'm having trouble. Wonder if the wild '411 tuners have anything to add?
Jim