Re: New member with VE table Q's

["nacelp" <nacelp@bright.net>]

Hi Joe

> Hey guys, I'm new to this list and modifying ECM tables.  My name is Joe
> and I have a '92 Camaro with various mods.  It's been running well until
> recently when I put on AFR 190 heads and a 212/218 CC cam, then the off
> idle drivability became poor.  I have a Diacom I use to capture the car's
> sensor readings and try to figure things out.

Good so far.

> The MAP readings at idle went from 25-30 kpa before the swap to 50-60 kpa
> after it.  The stock fuel map appears to give the engine too much fuel at
> idle now and the BLM drops to 108.

That's about what mine is/was.

When the car starts moving, the MAP and
> integrator values increase but the BLM stays at 108, the O2 readings get
> very low, and the car hesitates.  The computer finally figures it out and
> increases the BLM to mid 120's and it drives better.  What I'm interest in
> doing is modifying the VE table for low RPMs to lean out the mixture.  I
> believe this would stop the BLM from dropping to 108 at idle and then
> produce better acceleration off idle.

Yep, ya want to get to 128s, and work from there.

> The diy-efi list archives seem to be down so I can't search them to see if
> this issue has been covered.  First of all, have others seen the MAP
> readings go up considerably at idle after a head/cam swap or is there
> something else causing this?

Sounds about normal.

> I've read my stock prom and a hypertech prom and I'm using winbin to
modify
> them.  The 7730v3.ecu file I'm using lists the VE tables at 0x6EE (low
rpm)
> and 0x79A (high rpm).  The data from my chips map into this range nicely,
> but I want to verify that this is the correct known location for these
> tables.

If 0008 is 8D, then go to the ecmguys site, and look at the hacs (the 730
one)

 One concern I have with the ecm file is that it lists 1600 RPM in
> both low and high tables.  Is this correct and if so, why?  Another
concern
> is that I've seen another '730 ecu file that has VE tables in the same
> location, but laid out differently (basically RPM/kpa swapped).  Is the
> 7730v3 table layout correct?
> I believe that lowering the numbers in the VE tables tells the ecm the
> engine is less efficient and will reduce the amount of fuel given to the
> engine.  I'm really only interested in the low rpm table at this
> point.  How sensitive is the ECM to changes in the VE table?

Depends on what ya mean.  All changes make a difference.  Might not be
noticeable to you, and at times seem like there is little to no change, but
just make more changes.  I general us 10% as a roughing out measure.  If
your close use less, it's a matter of feel for alot of this stuff.

  If I lower
> the values for RPMs below 800 with MAP readings below 70 kpa, should I
> lower them by 1 point, 2 points, 5 points?  I know 1 point at a time would
> be safest, but if someone already knows that the tables don't produce a
> large difference then maybe I can tune them in quicker with larger steps
> and fewer prom burning cycles.

5 then 3, then 1s.  Again, depends on what diacom shows, and how it feels.
Might try reading tuning.doc at the FTP.
Les Grumpy

> Any help with this would be appreciated.
>
> Joe
> 92 Z28
> http://home.cfl.rr.com/shuhy/chevy.htm
>
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