Bench racing ecms Even if ya hate 101 please read

[Bruce Plecan]

-----Original Message-----
From: garfield at pilgrimhouse.com
Subject: Re: Bench racing ecms Even if ya hate 101 please read

>>A rpm signal generator, but have to work out an interface to module
>>     is a transformer necessary?.  Ya think just a 1.2v DC pulse would
>>    fire the module?.  Use a monstable 555 for the 1.2v, and then
>>    an adjustable astable for rpm?
>
>In the off chance I could help, I'm puzzled; yes, 1.2V pulse is fine to
>trigger a GM module, but your last question has me puzzled. I presume
>you're tryna mimic a dizzy/crank sensor feeding the ECU & module, so
>WHERE's the 1.2VDC pulse coming from? Presumably from your "rpm
>generator"? Yes? Then no I don't think you'll need anything more than
>that for the module, but the ECM's another story. Usually, the mag
>pickup goes to the module, and an ECM compatible IGN signal is derived
>from the module to signal the ECM. This I presume was the way things
>"began" at the "electronic IGN big bang", cuz they wanted the IGN system
>to be able to live on, in spite of the death of the ECM. Later, that was
>just a fond farewell, but anyway, normally the mag dizzy/crank sensor
>for the IGN goes to the module, and THEN back to the ECM.

I understand what you've said, and despite my language are on the
same page.
>
>IF you're gonna get into the ECM's that expect both crank AND cam
>signals, then we'll have to reconnoiter again (not hard, just more), but
>for your present safari, yes, the falling edge of a 1.2VDC pulse will
>fire a GM module, and the GM module can then be used to produce the REF
>waveform back to the ECM (assuming still we're in GM-land).

Ya still working on gm

 The GM ECM's
>appear to expect to take over IGN timing at about 300-600rpm (depending
>on #ofCyls), and take this REF signal as input for them to drive out to
>the module, their adv-timing corrected result to the signal EST on the
>IGN module, after raising BYPASS, so IF youNeye are still on the same
>page, this should all work fine.
>
>>Was going to use pots for MAP/TPS/Coolant/IAT.
>
>This is fine for Coolant/IAT, but for MAP & TPS, to really prove you're
>really able to handle transients (I know, this come's later; just
>offering some "future thot"), you could/should have a mechanical arm
>connected to a real TPS, and a vacuum pump connected to a real MAP.

Well how about a aquarium pump (diapharm type), and a variable
bleed orifice?..  This connected to the MAP....  Sound better, and then
OK a real TPS.
I
>have "extras" of both, just lemme know. I ALSO got an extra for this
>"hand-held vacuum pump" if you should want one later. Only thing, I GOT
>the extra by getting a better pump that models both vacuum AND
>boost/pressure, from them MituVac guys. They're ALL really pretty cheap,
>y'all, but get their latest one that provides BOOST and VAC simulation.
>But, Dr. Pelican, if you wanna play with NA eXperiments at first, lemme
>know and I'll get you the pump, gratis cum grano salis.
>
>BUT, yes, for static testing, pots will do just fino.

The following is a short summary of planned items;
Initial stuff is comparing how the various ecms think.  ie 32/128/256
prom series of ecm and how they handle temp corrections.  Then
MAF to MAP comparisions for a similiar series of engine conditions.
How much actual difference there is.  Then figuring out what AFR
in a MAF ecm compare to VE of MAP.  Then being able to have two
similiar systems to run in back to back tests.  Then be able to verify
switch/table locations without having to run a car.

>
>>12v lawn tractor battery, and circuit breakers.
>
>Well, when the battery charger and the weight becomes a pain, you oughta
>consider a surplus PC computer power supply which has both +- 12V and
>+-5V, and for most of what you wanna do, would supply plenty of current
>without the obnoxious presence of a lead-acid battery and charger.
>Again, I got some big extra's if you wanna avail yerself of same. My
>pleasure.

Well my thinking was to eliminate any voltage corrections from the
list of variables, so the 14.2 was a "must have",  or is this an error.
Seems like the PW corrections were a slim issue, but with the TBI
ecm firing the injectors twice as often didn't want that to cloud the issue,
or have a few variables accumulate to be an issue.
>
>P.S. As lame as I may be concerning ECM/ECU/computerized engine
>management things, I think this "bench ECM racing thang" is a really
>cool idea! If it's perfected, it could lead to diy_efi guys building up
>their stuff on the bench and fairly completely being able to test it
>before putting it on the DUT ('device under test', in my trade; the REAL
>engine). THAT can't hep but be a good thang, Dr. Pelican!, not to
>mention the fact that it's a cool idear.
>
>Gar
>
This will go one of two ways,

Cheers
BPelican     If this don't answer my questions I'll have to surgically
                    remove my Cone Shaped Hat