Hey guys, L98 with 870 ECU, miniram, cam, headers, 58mm tb, and a whole bunch of other smaller mods.

I've been fooling around with the tune and before, throttle response was awful in open loop but decent in closed loop. I modified the tune a little bit and was able to increase the throttle response in both of them, but now the car runs better in open loop than in closed loop when it comes to throttle response. Closed loop throttle response just doesn't feel, well, as responsive.

Is there anything in the tune that I can modify to correct the problem? And is there anything in the tune that I can modify that will increase responsiveness all together? Thanks!

 

I have noticed the same thing with my set up. I also noticed that my fuel economy is much better in open loop as well. I am currently tuning in OL and working on getting my injector compensation in better alignment. I think much of it has to do with more fuel modifiers in CL. It probably will just take time and patients to make the minor changes. The reason why your engine probably ran terrible in open loop at first was because it was getting to much fuel and now that you have done a little tuning, you have better control over the fueling. Do you have a Wide Band O2? If not, I would recommend getting one. They make tuning much easier, but keep your stock Narrow Band for steady state, CL operation. Also, what do your VE tables look like? are they smooth and blended (they way they should be), do they look like the Grand Canyon, or do they look like the Rocky Mountains? Your VE tables have a dramatic effect on almost every aspect, if not all, of the fueling requirements.

 

Sorry, I don't know how to modify anything with the VE tables. I can't find anything in the tables that has VE in it.

I had someone else do my initial tune and then I was tweaking it here and there. It's also the 870 ECU. Thanks!

 

I run my car in open loop at all times. I didn't' even attempt to tune in closed loop. Good gas mileage left the equation long time ago. I tune with a WB gauge, and data logging......it has made the learning experience much easier and enjoyable.

Man is it fun to drive!

 

VE is your Volumetric Efficiency tables. What software are you using?

 

I'm using Tuner Pro RT with the $1F definition file.

 

I'm not familiar with with $1F, but you don't have anything in the "tables" that cover your VE? There has to be something. Are you able to do and "self-learns" where you set it up to "learn" as you drive, and then you save the data? If so do you know where that data gets stored to? Try searching for a table that looks kind of like and inverse of your Spark Timing tables. It should be a 3D graph (the table its self will be a 2D with RPM v. kPA and the data in the data fields is your "VE") with RPM and 0-100 kPA for the x and y planes and then for the z plane it will have your "VE".

 

I found a table called "Coolant Compensation Spark Vs. Load". Here is a picture of both the table and 3d graph.

 

Try your mass air flow tables. Can you take a screen shot of those?

 

Sure. They are displayed in order, just like reading a book.

 

I am not 100% on this, but I think those might be your version of a VE table. If I remember correctly, mass air works by reading the amount of current it takes to maintain a certain wire temperature within the sensor it's self. So I'm guessing that is what the "counts" are for and the gms/sec is the air flow rate. A higher air flow either means that you are turning more RPMs or the load has increased and since the mass air is used to measure load, I'm then deducing that this is your engine load reference tables. Now I saw a table for maximum air/RPM and I'm guessing that applies here as well because that would give an RPM reference table for the mass air tables. I'm guessing the tables get multiplied together to come up with a value which the computer then uses to determine how much fuel needs to be injected based on the amount of air that is being ingested. I hope someone's else's chimes in to either correct me or not and also to help you on how to modify these tables if these really are the correct tables to be modifying for your engines airflow.

 

Speed Density = VE tables

Mass Air Flow uses well mass air tables. Check out stickies above....

you may be able to convert to SD. Not sure any advantage unless you surpass the capacity of the MA sensor.

You may be a candidate...

 

If you want to goto the 1227165 send me a pm, I hate the 870 but it works. Adjusting fueling you will be working with the maf tables for each rpm range. there is a lot of good tuning information in the stickies. Btw your to lean