Darkshot

iTrader: (4)

I'm running open loop decel, and when I take my foot off the pedal my AFR goes into the low 11s and even 10s and holds steady. Commanded is in the high 13s. Why don't these match up, and how can I get them to?

RBob

iTrader: (1)

Just need to lower the VE in that area. Check the data log for the MAP & RPM during decel, then go to the VE table and lower those areas. Also, it is common to get a rich slug just as you lift off the gas. This is from the extra fuel being pulled off the intake walls. So ignore the first second or so that the throttle closes.

RBob.

dimented24x7

iTrader: (2)

Like said above, its very common to have the AFRs go extremly rich on the first few seconds of decel with aftermarket manifolds and such. When its cold out, mine will go right to the rich burn limit and stumble when I let off the gas, despite lots of decel enlean to counter it. This can last for a few seconds.

If you have a stock manifold, then its likely be too much VE. Those wont hang onto much fuel.

Darkshot

iTrader: (4)

Its more than a few seconds. As long as I'm in open loop, its rich lke that.

dimented24x7

iTrader: (2)

Whats the VE look like there? Typically, its going to be pretty low in those areas as the throttle is shut and there is only a small volume of air going through the motor.

Darkshot

iTrader: (4)

Raising the VE in those areas helped bring the AFR back up, I got it to about 13.4 on average around those areas that were once in the 10s and 11s. When I do WB VE learns however, it keeps wanting to bring the VE back up in those areas and push my AFR back down. If I'm doing a learn session, and the WB shows 13.4, why would the VE learn be adding fuel? Higher VE = more fuel...... right?

RBob

iTrader: (1)

A WB Learn compares the WB reported AFR to the ECM's commanded AFR. Check to see what AFR is being commanded, it will be from the 'Open Loop - AFR vs CTS & VAC' table.

Check the data log to see what the EBL is seeing for the WB AFR when in decel.

RBob.

Darkshot

iTrader: (4)

How is a WB learn supposed to work with regards to Closed loop and BLMs/INTs? I did a lot of VE learns from BLM and now I'm using a wideband to go over those. My goal here is smooth closed loop operation and I cant visualize how this is supposed to work. I'm just trying to formulate a game plan for WB tuning and I dont know where to start.

I assume the reason for running open loop for WB learn is so the WB02 sensor can see the results of running the true VE tables straight up without the BLM interfering. So in Open Loop I am tuning my VE tables to produce the commanded AFR for Open Loop. When I can cruise around with the desired AFR in open loop, can I then re-enable Closed Loop operation? Then what happens when the BLM kicks in and starts making corrections for the theoretically "perfect" VE tables I have produced with a WB?

Some general guidance would be appreciated.

RBob

iTrader: (1)

Once the WB VE Learns have completed and the WOT AFR has been adjusted, go back to some BLM VE Learning sessions. Once they dial the VE back to the BLM settings you are done.

The reason for this is that the BLM doesn't target stoich (typically 14.7:1). It targets the O2 sensor window. This is defined by the voltage tables (Mean R/L, Lean, & Rich O2 vs MAP). These are in the 'INT - ' tables.

RBob.

Darkshot

iTrader: (4)

Thanks.

I recently tried re-enabling closed loop to see what would happen. I unchecked "open loop cruise" and "open loop idle" and drove for a bit. The engine never went into closed loop, and I got a lean spike on a out-of-gear throttle lift that goes up to 20:1. Here is a datalog, what does this look like?

RBob

iTrader: (1)

Without looking at the BIN values, the most likely cause of not going into closed loop is the O2 sensor value. There is a window that the O2 sensor needs to be outside of this window in either the greater then, or less then direction. Once it does this the ECM believes the O2 sensor is alive. Which will allow it to go into closed loop.

The stock values are 200 mV lower and 800 mV upper, which the O2 sensor never exceeds.

For the lean drop, this is a combination of decel enleanment (DE) and IAC Throttle Follower (TF). The TF is being delayed before the IAC starts to close, then closes at a particular rate. The intent is to burn off HC in a smoother manner. Less of a spike.

The DE is the opposite of AE.

RBob.

Darkshot

iTrader: (4)

Is that lean spike going to reek havok on my engine? I put my DE Enleanment Factor at zero and no change. Messed around with the TF Decay Delay and TF Filter and no change. Given the nature of a TBI setup it doesn't make sense to me that it could go THAT lean (25:1 on the WB at times?). I can even hear it, the engine / exhaust tone changes dramatically for a split second that coincides with the lean spike.

RBob

iTrader: (1)

Under no load going lean won't hurt anything. More important is that as the driver you can feel it when it goes lean. The PW gets small at .778 msec. It may be that the injectors stop flowing fuel at that PW.

Set your DE & TF values back to the prior values. Then add some offset to this table: 'INJ - Injector Correction offset'

Try adding 50 usec to every entry (in TP can highlight all of the rows then use to toolbox to add in an offset). The injector offset values are dependent upon the actual injector and the fuel pressure. The larger injectors take longer to open along with adding fuel pressure causes a longer opening time.

A side affect of increasing the injector offset is that some areas to get a little richer. The smaller the PW at that area the more affect it will have. Areas of higher load/PW will be barely affected.

RBob.