Beginner Questions

[linville88]

Sorry if these questions have been answered somewhere already or if it should just be common knowledge. I can't seem to find the exact answers I'm looking for no matter what different searches I do. I've been reading over many threads on tuning and VE tables and tutorials.
I plan to do a 383 TPI engine build this year sometime and will be using 1227730 ecm with $8D bin. First time tuning and don't want to mess things up. Of course I plan to start small and learn as I go and right now I'm just tinkering with TunerPro and trying to grasp the concept of everything so I'll be ready to tune when the time comes.


-In the bin there is an upper VE and a lower VE table. Assumingly this is off idle tuning and idle tuning.
I understand the idea of driving around datalogging and filling history tables and adjusting upper VE through a spreadsheet provided by these forums. But how do you tune for the lower VE table? Is it the same idea as driving around except for lower rpms? Is it when idling in the driveway or coming to a stop?

-Should the engine be in Closed Loop or Open Loop when datalogging and tuning for VE?

-Do OL and CL BOTH run off the VE tables? I get a little confused about the o2 sensor or possibly tables being used only when in either CL or OL.

-Do I need a wideband o2 for any reason?

[dave w]

Using Closed Loop data for tuning both upper and lower VE tables is a good plan.

A wideband is a good tuning tool, not 100% necessary. The wideband provides good Open Loop information, Choke, Warm up, Acceleration Enrichment, and Power Enrichment.

dave w

[linville88]

So how is fuel calculated or tuned in open loop, say just after startup and on warm up?
Is this just calculated between Displacement/Injector flow/MAP/TPS? Or does it use the VE tables?
How do the Open loop % change afr vs temp/map tables work or affect the rest? I don't understand the values in those tables.

A little more info:
I'll be using a Speed Density 90-92 F-body 1227730 with $8D bin.
Planning to build a 383 with FIRST TPI Intake, Brodix 1021007 Heads, Comp Cams 08-305-8 Cam, and will have around 10.3:1 static compression.

Thanks

[1project2many]

The $8D VE tables are indexed by MAP and RPM but are not throttle position dependent. Regardless of throttle position the lower table is used to 1600 rpm and the upper table is used above 1600 rpm.

When the engine is running, fuel is calculated to deliver 14.7:1 AFR using VE, MAP, and CTS. Injector on-time is calculated using injector size and calculated fuel. There are small tables to tweak the fuel calculation and the injector on-time as well as separate tables used during acceleration enrichment. Open loop, cold start, and PE % change tables are used to richen desired AFR from 14.7. Closed loop is also a tweak to the original VE calculation based on O2 sensor signal input.

Tuning with the engine in closed loop allows one to adjust the VE based on NBO2 feedback. We use the BLM and INT to scale VE so the O2 tweak is as close to zero as possible. This is good for warm, moderate driving conditions but does nothing for adjusting the open loop and transient conditions. Cold start, acceleration enrichment, power enrichment, and deceleration enleanment are part of the driving experience and if these are not tuned well enough the vehicle is no fun to drive. A heated wideband can provide feedback in a wider range of operating conditions. Logging WB readings allows one to drive the vehicle under conditions where the engine is misbehaving then evaluate the best path to correct the issues.

At one time people were running into problems using $8D on high HP engines when the calculated fuel delivery time was too high. There is a fix that can be implemented in code. I believe that limitation is less a problem today as larger injectors with faster reponse times may reduce the need for large on-time values. Links to the problem and the fix are here .

[linville88]

I highly appreciate you guys taking the time to explain some things. Your information definitely helps.
Once I understand the basics and get going I should be fine. But I'm sure there is still years of learning to be done as well.

[linville88]

So in the BLM Tuning Tutorial it says to disable the following:

1. EGR
2. PE.
3. Air pump.
4. DFCO
5. Hiway Lean Cruise if applicable.

What about AE? Does AE affect it and should it be disabled? If so, how?