Tuning 1227747 VE tables in open loop with a wideband gauge

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11-20-2013
mmigacz

Tuning 1227747 VE tables in open loop with a wideband gauge

I’ve seen a lot threads about tuning VE tables with BLM data. However, If I have access to a wideband to read AFR, what is the best procedure for tuning VE tables in open loop? This is what I plan on doing, let me know if this makes sense.

-Warm the engine up to operating temperature
-Set Closed Loop - CTS to Enable to the highest value to keep the ECM in open loop
-Set all values in the Open Loop - AFR vs Temp table to 12.5
-Set all values in the Choke - Cold AFR vs. VAC kPa table to 0
-Set all values in PE – AFR table to 12.5
-Vary the rpm and load and record AFR data from the wideband
-Adjust VE tables until the wideband readings are 12.5 throughout the range of RPM’s and loads.

My assumption is the VE tables are dialed in now, right?]
If I’m right I can bring all the values back to their original AFR’s or tweak them if needed.

Note: the only reason I picked 12.5 is it’s a safe AFR. After the VE tables are dialed in I would move the AFR’s closer to 14 when cruising or idling.
11-20-2013
EagleMark

I had to edit your post do to Font color, there's a choice of forum colors here, dark and light. So I use light and could not see White fonts. You can use all font formatting if you want. But leave font color default and there will be no issues with people who use differant forum schemes.

You've got the right idea. But choke really does not need to be messed with so it will still start and run. All data and adjustments are made warmed up anyway.

Need to calibrate the WB as well for Stoich value of fuel since it is converted from Lambda. Actually the better/easier/accurate way is just use Lambda.
http://www.gearhead-efi.com/Fuel-Inj...g-using-Lambda
11-20-2013
mmigacz

Quote:

Originally Posted by EagleMark

I had to edit your post do to Font color, there's a choice of forum colors here, dark and light. So I use light and could not see White fonts. You can use all font formatting if you want. But leave font color default and there will be no issues with people who use differant forum schemes.

You've got the right idea. But choke really does not need to be messed with so it will still start and run. All data and adjustments are made warmed up anyway.

Need to calibrate the WB as well for Stoich value of fuel since it is converted from Lambda. Actually the better/easier/accurate way is just use Lambda.
http://www.gearhead-efi.com/Fuel-Inj...g-using-Lambda

So the only AFR tables (fully warmed up engine) I should be looking at is in open loop is (Open Loop - AFR vs Temp) and (PE - AFR), right? The part that confused me is the notes from the (Open Loop - AFR vs Temp) table. It says:

This table details corrections to the A/F ratio, based on engine temperature. It includes startup enrichment (choke).
Also Choke - Cold AFR vs. VAC kPa effects commanded AFR while in Open Loop.
The current commanded AFR is used in the BPW calculation. This is true of both open and closed loop operation. While in open loop the ECM generates the commanded AFR from two tables: AFR vs manifold vacuum and AFR vs coolant temperature. While in closed loop the ECM uses the stoich AFR term.

Which table is AFR vs manifold vacuum? I was assuming it was the Cold AFR vs. VAC kPa table.

Also, I should toggle my wideband to Lambda and target .85 (12.5/14.7), right?

Note: I'm running 0% ethanol gas in this engine.
11-20-2013
EagleMark

I know that's what it says. But I've never tested to be sure? It does not add up if say warmed up and 13.0 AFR in "Open Loop - AFR vs Temp" then add like 3.00 for 40 VAC kpa for "Choke - Cold AFR vs. VAC kPa (Added to AFR vs. Temp)" then your cruising at 16.0 AFR? Poof, running OL is instant lean cruise? If it were subtracted you'd be PIG rich which is more on the safe side...

Now at 0 Vac kpa od 0.00 would be WOT so staying at 13.0 is OK, but not optimal.

That VAC kpa is kind of strange as it's 80 column is 100 MAP and 0 is 20 MAP. I've changed them on some other Parameters to be more user friendly to MAP, but truly not accurate as per dissasembly and the way the ECM calibrates it. Works good for end user.

So while your doing this test it and let us know if it is truly used in OL warmed up as stated and added to Open Loop AFR, or just something with choke! We will add comments to XDF.

Yup 85 Lambda for 12.5 AFR with Stoich of fuel at 14.7.

The PIA of doing WB tuning in 7747 is no way to get WB data into same data log and TP history tables. So need to use the WB software and spreadsheets etc... this is why I usually just do the BLM data in $42 and save the WB for the WOT runs to do PE.
11-21-2013
mmigacz

Quote:

Originally Posted by EagleMark

I know that's what it says. But I've never tested to be sure? It does not add up if say warmed up and 13.0 AFR in "Open Loop - AFR vs Temp" then add like 3.00 for 40 VAC kpa for "Choke - Cold AFR vs. VAC kPa (Added to AFR vs. Temp)" then your cruising at 16.0 AFR? Poof, running OL is instant lean cruise? If it were subtracted you'd be PIG rich which is more on the safe side...

Now at 0 Vac kpa od 0.00 would be WOT so staying at 13.0 is OK, but not optimal.

That VAC kpa is kind of strange as it's 80 column is 100 MAP and 0 is 20 MAP. I've changed them on some other Parameters to be more user friendly to MAP, but truly not accurate as per dissasembly and the way the ECM calibrates it. Works good for end user.

So while your doing this test it and let us know if it is truly used in OL warmed up as stated and added to Open Loop AFR, or just something with choke! We will add comments to XDF.

Yup 85 Lambda for 12.5 AFR with Stoich of fuel at 14.7.

The PIA of doing WB tuning in 7747 is no way to get WB data into same data log and TP history tables. So need to use the WB software and spreadsheets etc... this is why I usually just do the BLM data in $42 and save the WB for the WOT runs to do PE.

When I trial this, I will definitely post some feedback. Thanks.
04-18-2014
mmigacz

I was tuning in open loop today. I set all the values in Open Loop - AFR vs Temp. to 12.5 AFR. Next, I set all the values in the Cold AFR vs. VAC kPa to zero. The engine was fully warmed up. I was watching the Wideband gauge and it was reading 12.5 after adjusting the VE tables (at about 1800 RPM, in nuetral). With my emulator I changed all the values in the Cold AFR vs. VAC kPa to 2 AFR. The wideband reading jumped from 12.5 to 14.5.