GM TBI info needed

[Stowe, Ted-SEA]

Shannen, thanks a lot for the info, it has been very helpful.

interesting about the non-closed loop. Do you think that this is a good
choice for something like a 77 mgb 1800 cc, manual trans? I am neutral about
it, it is one thing less I have to do & worry about. then again it sounds
like a nice idea.

I wonder about the parameters stored in the ECU, for a 2.0 sunbird, I am not
sure how well that relates to a 1800 BMC engine. or does that matter ? I
would of thought that with a closed loop system, that would of worked itself
out.

I think the ECU may of had some sort of power steering input too, I suppose
that would of raised the idle when the ps pump was running or under load ?
or something like that.

I think I have 2 main problems left. what to do about the VSS input, the
books I have recently found show that the pulses came from a wheel in the
speedo cluster, which were amplified & cleaned up by a little module on the
speedo cable, this module did not, (at least in 85 ) generate the pulses
itself, or so I am led to believe. someone here mentioned that 2000 pulses
per mile/hr was the standard in that era ? 

also the EFI stuff, I was wondering if I could actually use the gm EFI spark
module with my current distributor, which now has an aftermarket hall effect
sensor. the schematics lead me to believe that all of the action occurred in
the module, and the rest of the distributor just fed it pulses, I need to
check to see how many pulses, might be more than just 4 per revolution.

oh problem 3 is the TSS ? switch which I think was from the transmission
solenoid via the brake pedal (+12). some books tell me that a solenoid got
engaged in 3rd gear, which I guess was the top gear of the auto trans. so
did the ECU actually engage 3rd gear with this ? it brought the line low, I
know that, so I am wondering what exactly the solenoid was for ? kicking it
into 3rd ? at the appropriate speed & conditions ? I suppose I could ignore
that line. or just simulate the load in case it checks for current draw.

thanks for your help. this has been interesting to research.

Ted.

-----Original Message-----
From: Shannen Durphey [mailto:shannen at mcn.net]
Sent: Saturday, September 19, 1998 7:36 AM
To: diy_efi at efi332.eng.ohio-state.edu
Subject: Re: GM TBI info needed


Stowe, Ted-SEA wrote:
> 
> Hi.
> 
> I have an ecm/throttle body from a 1985 Canadian sunbird.
> I am trying to figure out a little more detail on the cpu
> and what the ecm requires
> 
> the Serv. No. is 1226867        DJU
> 861611 M51197560
> 
> the eprom has on it "DJU 4085"
> 
That's the Broadcast code, the calibration if you will.  This is from a
1985 J body (cavalier, sunbird) 2.0l tbi, non closed loop (no O2),
without air conditioning, 3spd thm125 automatic, 3.18:1 final drive
ratio.

> the throttle body has the following numbers
> 17085082
> 0385HSK2S
> 
> I do not know the VIN code of the engine, nor anything else about the car.
> 
> I am trying to figure out if it had an O2 Sensor and what/where the speed
> sensor was.
> 
> also as I ponder over the chilton's book , looking at generic examples
from
> '85
> 
> I see that there was an input from the brake pedal through the torque
> converter solenoid, C2 pin 19 ,I presume that was just an input 0 volts =
> brake pedal pressed ?
> 
> I suppose I can ignore the air conditioning inputs/outputs ? (C1 7,9,21)

 I'd say yes.  The prom will.

> what would the gear selector switch do ? (C2 pin 6) looks like it was
> grounded in some selector position, or positions ? 
Signals the ecm to bump idle speed slightly when engaging a drive gear,
preventing stalling.
> 
> & finally, the 4 lines to the hei distributor, C1 10,2,3,19 ? were these
> inputs or outputs ??
>
 Yes to both.  One is reference to ECM, one is 5v bypass output, one is
timing signal from ecm, one is a ground shared with ecm. Don't remember
wire colors offhand.
Shannen
> thanks, this looks like it's going to be fun.
> 
> I am going to attempt to put this on a 77 mgb.
> 
> Ted Stowe
>