Procedure for turning off MAF and forcing open loop for SD?

[AllCammedUp]

Would someone mind to post the parameters that need to be changed and what values they need to be changed to in the TUN file in order to turn off the MAF and force open loop in order to do speed-density tuning?

I've been looking at the {B4205} - Closed Loop Temp Enable - table, and thought about making that table something like 255, but I didn't know if that's the proper way to go about it. Not sure on the MAF - didn't want to guess even more than I am for the open loop 'switch'.

Thanks!

[wait4me]

well, turn the ses light off for code p0102 and turn it to non emmissions, but dont turn it off all the way, then copy over your high octain table to the low octain table. Set your maf fail rate to 0. or just dissconnect your maf sensor after dissabling the 102 code... then to dissable the closed loop enable, {B3801} Long Term Fuel Trim Correction turn to off.

[SinisterSS]

Disable power enrichment to more easily track your commanded A:F to PLX actual.

Whitney, are you using a wide-band?

[AllCammedUp]

Cool Jesse and Rick - this helps out a lot!!

Yes, I've got a PLX-300 permanently mounted in the car, so I can see and log my AFR at all times.

How does disabling PE help track commanded AFR? Isn't tracking commanded AFR via a PID sufficient? Also, with PE disabled, I take it I should NOT attempt to get the car into PE, correct?

Please bear with me, I'm learning this as I go.

Thanks to both of you guys - I really do appreciate it!

[SinisterSS]

With PE mode on, it will dump extra fuel in during acceleration. This extra momentary fuel "polutes" your A:F values in the PLX map.

Another alternative is to leave PE on and set your PE A:F the same as your commanded A:F.

With PE off or set to the same as commanded, you can run hard and not screw up your map. It is good to get the PLX readings in the high MAP values (normal PE areas) to validate your VE table.

[AllCammedUp]

With PE mode on, it will dump extra fuel in during acceleration. This extra momentary fuel "polutes" your A:F values in the PLX map.

Another alternative is to leave PE on and set your PE A:F the same as your commanded A:F.

With PE off or set to the same as commanded, you can run hard and not screw up your map. It is good to get the PLX readings in the high MAP values (normal PE areas) to validate your VE table.

Oh, OK. I see what you're saying in regards to 'polluting' the map - that does make sense.

That, however, leads me to the next question(s):

What is the best way to turn off PE?
What is the best way to set the commanded AFR under varying conditions?

I understand that I'd change the PE AFR via the PE/RPM table, but I'm not sure where I match those values up to the commanded AFR other than what the scan tool shows me via the commanded AFR PID.

[SinisterSS]

There are many ways to do it.

Engine Calibration -> Fuel -> Mixture -> Parameters

Maximum Enrichment = 13.0:1
Delay before Entering PE Mode = 410 seconds
PE MAP Threshold = 105 kPa

Engine Calibration -> Fuel -> Mixture

PE Modifier Based on RPM - set all to 13.0
PE Modifier Based on Coolant Temp = 0
PE Modifier Baed on Intake Temp = 0

To pick your commanded A:F, set all the cells to 13.0 in

Engine Calibration -> Fuel -> Mixture -> EQ Ratio When in Open Loop

Once you've tweaked your VE table and commanded is fairly close to your actual and you are no longer scared of a lean melt down, you could change your PE and commanded A:Fs from 13.0 to 14.7 or any other value you wish.

[SinisterSS]

Disclaimer: I may have missed something - it's late and I'm tired. :?

When logging the commanded AFR map, you'll know quickly if you missed something in PE that is screwing up your ratios.

[AllCammedUp]

OK Rick, I see. Thanks much for the insight. I wanted to make sure I knew which parameters to change and to what so that I didn't go messing around and tear up something I've got so many $$ invested in. I feel safer just knowing what to change (and what to change back ) in order to accomplish the goal.

[Blacky]

Ross and I were discussing this the other day:

If you are happy to drive around with a flat AFR of say, 13:1 then try using bidirectional controls to command the AFR to 13:1 which effectively turns of all PCM fuel control. (You can use whatever AFR you like).

I don't think it is necessary to set the Open loop bidi control or the Fuel learn bidi control because you are forcing 13:1 ALL the time. The PCM will use the VE table to try and figure out the correct pulse width to achieve 13:1 and whatever error you see in the BEN PID will be the amount your VE table is "out".

As soon as you switch off the ignition, bidi conrols are terminated and it is "back to normal". But you'll still have your map for auto updating your VE.

I have not tried it, I do not know if that will work, but I thought I might throw it the thread for discussion.

Regards
Paul