Does a speed density tune need a COS?

[zapp168]

I have swapped a LQ9 into a 70 GTO using the 0411 computer. To retain the RAM AIR hood I opted to use a 4 barrel throttle body setup. I was initially going to fabricate a mount for a MAF and put it in the air cleaner, but i have simply started the car with a nearly stock tune and with few changes it runs and drives really well. Should I switch to a COS or what is the best was to run SD with the tune as is? Or I guess would it be worth it to fab up that MAF?

Thanks

[LastCall]

I have swapped a LQ9 into a 70 GTO using the 0411 computer. To retain the RAM AIR hood I opted to use a 4 barrel throttle body setup. I was initially going to fabricate a mount for a MAF and put it in the air cleaner, but i have simply started the car with a nearly stock tune and with few changes it runs and drives really well. Should I switch to a COS or what is the best was to run SD with the tune as is? Or I guess would it be worth it to fab up that MAF?

Thanks

I don't think a MAF would work to well in the air cleaner. It may easier to go to SD. And to use low and high octane spark tables with adaptive spark, you will need to run a COS. Running the tune as is would make it run on the low octane table all the time.

[joecar]

MAF plumbing needs to be straight before/after the MAF.

+1 what LastCall said...

summarizing:
- MAF-less, the GM OS's run from LO spark table.
- MAF-less, the COS's run adaptive HO/LO spark

[zapp168]

MAF plumbing needs to be straight before/after the MAF.

+1 what LastCall said...

summarizing:
- MAF-less, the GM OS's run from LO spark table.
- MAF-less, the COS's run adaptive HO/LO spark

So the COS would still allow the HI/LO spark tables to function VS. copying and pasting the HI table to the low table. And for my own knowledge the large opening on the one side of the MAF into the air cleaner housing would make it inaccurate? I honestly was not crazy about making it work anyway....LOL.

I believe it was CO3? Correct?

Thanks for the replies!

[joecar]

Yes, COS allows adaptive spark to continue functioning when a MAF DTC is present (which is needed for failing the MAF for running SD).

MAF sensor needs straight and uniform air flow... i.e. nearby bends in the ducting cause the air flow to bunch up on the outside of the bends.

Yes COS3.

What GM OS id do you have...?

[zapp168]

Yes, COS allows adaptive spark to continue functioning when a MAF DTC is present (which is needed for failing the MAF for running SD).

MAF sensor needs straight and uniform air flow... i.e. nearby bends in the ducting cause the air flow to bunch up on the outside of the bends.

Yes COS3.

What GM OS id do you have...?

That was actually going to be my next question. I am currently running 12202088, in the past no matter what I always changed to 12212156 figuring it was a later system thus better. Is it worth while to change to 12212156 then go to the COS?

[joecar]

That was actually going to be my next question. I am currently running 12202088, in the past no matter what I always changed to 12212156 figuring it was a later system thus better. Is it worth while to change to 12212156 then go to the COS?Yes and no, depending on your plans...

12212156 is a year later (I'm told GM fixed some things compared to 12202088)...

but it also has COS5 available (if you ever need alpha-N), 4L80E variants (trans segment), and Express Van variants (fuel system segment).

[zapp168]

Yes and no, depending on your plans...

12212156 is a year later (I'm told GM fixed some things compared to 12202088)...

but it also has COS5 available (if you ever need alpha-N), 4L80E variants (trans segment), and Express Van variants (fuel system segment).


Ya.....Might as well!

Thanks for your help!

[joecar]

Copy your 12202088 tables to 12212156 (take your time, go thru each table), and then full flash in 12212156 and make sure it runs at least as good as 12202088 did.

If it does not, go back thru the tables to see what's different.



Shortcut: F-car 12212156 runs exactly the same as F-car 12202088 without any edits.

[zapp168]

Copy your 12202088 tables to 12212156 (take your time, go thru each table), and then full flash in 12212156 and make sure it runs at least as good as 12202088 did.

If it does not, go back thru the tables to see what's different.



Shortcut: F-car 12212156 runs exactly the same as F-car 12202088 without any edits.


It was the stock 2001 tune with the security turned off...... So I can't imagine the stock 2002 12212156 tune with the security turned off (maybe just check the IFR) shouldn't run the same if not better.
Thanks

[Supercharged111]

Do you have an automatic trans? Electronically controlled? Reason I ask is because pre-411 swap I ran a VE tuned blackbox. I don't recall if I ran the 411 MAFless but I don't see why I would have. I do recall that being MAFless caused the trans line pressures to max out. I'm not sure if a COS would fix this or not. With the Transgo in the 4L60 I ended up cracking the case where the servo sits. It wasn't until well after the 4L80 swap that I plugged it back in. I think I plugged it back in right after the 411 swap because it was shifting so harshly no matter what settings I changed. I went so far as to double the factory torque reduction on upshifts and it did nothing. So I plugged it in and forgot about it. The next day on my way home from work the truck was shifting much more smoothly so I went into the tune and altered shift times to my liking and the truck took to it. I'm glad I plugged it back in, sure would have sucked to frag another trans.

[LastCall]

That can happen running speed density. There is a note in the AutoVe tutorial. I've pasted it below, you may want to check it out.

Vehicles equipped with automatic transmissions should go to table {E0104} Transmission DTC Fault Pressure Modifiers and set P0101, P0102, and P0103 to NO to prevent the PCM from increasing shift pressures.

[joecar]

Yes, set those to No...

and make sure the VE table does NOT under-report airmass.

[zapp168]

Did not check those tables, but the car is running and shifting perfect, I actually lowered the voltage on the force motor to firm up the shift a little.

[rich24v]

MAF plumbing needs to be straight before/after the MAF.

+1 what LastCall said...

summarizing:
- MAF-less, the GM OS's run from LO spark table.
- MAF-less, the COS's run adaptive HO/LO spark

Does this also apply to MAF-less E38 ?

[joecar]

Does this also apply to MAF-less E38 ?
MAF-less E38 runs from LO table (i.e. in presence of MAF DTC).

~Moderator~

[zapp168]

Did not check those tables, but the car is running and shifting perfect, I actually lowered the voltage on the force motor to firm up the shift a little.


They were already set to "no"