[Gmecm] $6B, $8B, $A8 for 1228707 or 1228708 to control Cadillac Northstar

[William Lucke]

Thanks for the info!
What code mask were you using?
What's the max RPM for the VE table?

The peak/hold drivers can still drive HiZ injectors, right?



William


> I've done quite a bit with the 1228708, not so much with the 7730 but this
> is what I remember.
>
> The 707 and 708 were both designed to interface with an ignition "module"
> it could be a  distributer, or the ignition module/coil pack setup.
> The crank signals go to the ignition module and are interpreted and sent
> to the ECM.
>
> The quad 4 code RPM limits are well suited for the Northstar, but the
> 707/708 hardware injector drivers in these ECM's have 2 outputs for peak
> and hold, great for a 4 cylinder car, not so great for the V8, it also has
> slightly different A/D addressing.
>
>
> One thing that might work would be to use the Quad4 code in the 7730, and
> change the A/D addressing for the 7730 hardware.
>
>
>
>
> -----Original Message-----
>>From: William Lucke <william.lucke at highspeedlink.net>
>>Sent: Nov 16, 2010 11:12 AM
>>To: gmecm at diy-efi.org
>>Subject: [Gmecm] $6B, $8B,	$A8 for 1228707 or 1228708 to control Cadillac
>> Northstar
>>
>>This question also applies to:
>>$5C for 1227749
>>$CE for 16156450
>>$E8 for 16173278
>>
>>I've worked with a guy (who may be subscribed to this list) to adapt $A1
>>in a 7730 (originally '91 3.1 DIS) to run a '93-'99 Cadillac Northstar
>>with 8 cylinder DIS.
>>
>>There are a number of ways in which the $A1 is not appropriate to this
>> task:
>>-VE tables go to ~4500 RPM while the Northstar revs to 6700
>>-Primitive BLM layout only has "idle" and "off-idle" BLM cells
>>-RPM/25 datastream location can only report 6375 RPM
>>-Others I'm probably forgetting right now.
>>
>>To overcome the last, he implemented an RPM/35 variable and dropped it
>>into the datastream in the location occupied by EGR position. This allows
>>RPM reporting up to 8925.
>>
>>The Quad 4 was GM's roughest and tumbliest engine of the late '80's and
>>early '90's, being roughly equivalent in state of tune to the 195 HP 2.3
>>litre S14 used in BMW's E30 M3 from '87 to '91ish.
>>The code masks and ECM's listed above and in the subject line were used
>>with Q4's, according to Tunercat.
>>
>>What's the ending RPM for the VE tables in these masks?
>>What's the BLM structure? (IE, 16 cell like $8D or 2 cell like $A1 or
>>somewhere in between?)
>>
>>What sort of extra I/O do the 8707 and 8708 have?
>>How does the triggering of the Q4 ECM work? Does it read the crank sensor
>>signal directly, or is there an ignition module which reads the crank
>>sensor and outputs a 0-5V signal as with the V6 engines?
>>I @$$ume the 8707 only has a single ignition output and the ignition
>>module takes care of ignition distribution.
>>
>>Starting with a code mask that has VE tables that already go to a pretty
>>high RPM would help out a lot with tuning a Northstar, as would a 16 (or
>>more) cell BLM structure.
>>
>>Thanks!
>>
>>
>>
>>
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>
>