camaro1185

First, my car is completely stock except for some minor things. TB bypass, cut airbox with stock filters. The car runs GREAT.

I'm running a 89 350TPI bin with 6e. It has the EGR tuned out due to it not working. It has a lot of new parts. MSD blaster coil, Napa wires, cap and rotor. STOCK 23 YO dist, Micro-tech maf (computer chip kind), IAC, 22lb bosch 3 injectors, fpr ETC....


This past weekend I figured I'd try and get the best possible tune from my car before I have to really start tuning when I do some modifications.

I went out and did a quick drive and datalogged (stayed in Open loop the whole time) it with some idling, easy accelerating and some WOT runs. It was on mostly flat land and no highway runs.

I got home and the first "weird" thing I noticed is that throughout my datalog I had 128INT throughout the whole thing and 118BLM at idle(7.xx G/s to 8.xx G/s), the second I cracked the throttle it went to 130BLM and didn't change back to 118 unless my foot was off the gas. So it stayed slightly lean at cruising and at WOT.

I went home and tried to lean out the 118BLM by SUBTRACTING 8.xx% from the MAF tables that between 7-8G/s. I went out and did another datalog and NOTING CHANGED. I still have 118 at idle and 130 at cruising or WOT. What is going on? Something is weird?

helo

INTs are not updated in open loop; BLMs are updated based on INT changes. The BLMs you see are stored from the last closed loop run. BLMs are still used for PW calculation even in open loop.

Since you forced open loop (WHY?), the ECU didn't update the BLM even though you changed the fuel table.

118/130 does not mean it's running rich/lean, the BLM cells are just a representation of what the ECU is doing to the injector PW calculations to maintain stoich. 120-132 "ain't bad." The BLMs will always wander because of humidity, air temp, fuel composition, etc.

You want VE to be accurate so that open loop AFR and PE AFR calculations will be accurate
Edit: yeah n/m, I haven't worked with $6E yet. VE applies to $0d or $42 (among others)

camaro1185

I thought I read that you are suppose to tune in open loop? Is this not correct?

Can you please explane your last statement "You want VE to be accurate so that open loop AFR and PE AFR calculations will be accurate."

What do you mean. Bare with me, im a tuning noob.

RBob

iTrader: (1)

3rd gen MAF set ups don't have VE tables, so don't worry about them.

To use the BLM values need to use closed loop for tuning. This will allow the INT & BLM to adjust the fuel for the targeted O2 voltages (basically the AFR).

The reason the BLM didn't change is from being in open loop. The cell values you saw are from the last time the ECM was in closed loop.

If you were tuning in open loop, with a WB set up, the BLM values need to be reset back to 128. This can be done by setting the key-on BLM limit values to 128.

RBob.

camaro1185

So let me see if i get this. I need to tune in closed loop for part throttle tuning. Once that is good, I lock that out by setting the temp really high and tune in open loop with a wideband (assuming this is AE and PE tuning)

Again, noob here. I have read all the stickies, but need some clarification.

RBob

iTrader: (1)

Yes, for the most part that is correct. The other side is getting the SA correct. As it is changed the apparent AFR will also change. Proper SA for power and driveability.

Then final adjust the AFR to a safe area.

RBob.

camaro1185

Thanks, i havent even thought about the sa yet, i gotta master tuning the fuel first. It sounds like a really long process to get it perfect, but im sure it will be worth it.