drag race corolla update caution long

[GSMnow]

In a message dated 98-05-08 03:52:20 EDT, duanered at pacbell.net writes:

<<     1) throttle position sensor ? how can I tell (what test can I perform)
 if its compatible with the buck computer Toyota is a 4 connector type and
 does not look like I can modify the buick piece and it goes the other
 way?(using the Toyota throttle body its bigger) >>

This should be easy. the GM computer just needs a smooth 0 to 5 volt signal as
the throttle opens. The later Toyotas had this and an idle switch, that is the
extra pin. With an ohm meter, you should be able to find the switch pin, don't
use it, then find the pair with the least resistance at idle, one of these and
the last pin should be the least resistance at wide open throttle. The GM ECU
will have a ground and 5 volt output to feed the sensors. The 5 volts and
ground go across the leads that stay at a constant resistance (should be about
5,000 ohms) and the signal is the wiper. If the voltage is high and comes down
as you open the throttle, the reverse the 5 vplt and ground leads. At idle you
need to have about .6 volts. A GM service manual will have the exact spec. At
full throttle, it should not exceed about 4.5 volts or the ECU may think the
ground wire went open and set an error code.

<<     2) cam position?  still don't know where/how the sensor gets its
trigger
 from. is there a spinning magnet (Frederic did you take those pictures?) >>

What year and engine is the ECU from?? What Harness are you using?? The 86 87
Buick Grand National used a Short stub in place of the distributor that had
the cam position sensor in it. I think it also supplied the crank signal. The
3800 motor cars use just a crank sensor, but it is a dual ring setup with a 30
pulse disk, and 3 different wicth pulses to sync the ignition. Let me know the
computer you are using and I can get full diagrams and timing disk specs. You
can make the right signals with a hall effect sensor, magnet, and a sheet
steel disk. The edges of the slots must be accurate though, so you should cut
it on a milling machine with a rotary table. The timing disk can be done in a
hollowed out distributor so it is easy to work on and put in the motor later.
This also makes fine tuning the timing easy. I run anElectromotive TEC II and
I had to drill the mounting holes for the trigger disk in perfect timing. I
did it on an engine stand. It was tempting to do it in a distributor setup,
but the timing chain in the 22R is rather sloppy, and I wanted the beter
precision on the crank. 

<<     3) ecu power?  does it run off 12v,ideas on when it shoud power up, how
 should I regulated, does it need to be and fuse size  >>

The standard GM ECU power setup has a full time power lead for the internal
learn and error code memory, this comes off of the hazard light or dome light
circuits and draws well under an amp. Thene there is an ignition power supply
that is hot whenever the key is on. Make sure it is not interuppted when the
starter is engaged. I used the old coil feed in my Celica. This will be about
a 15 amp circuit for powering the injection and ignition. The fuel pump and
cooling fans will be operated by relays that get their own power feeds. I
think you will also need an oil pressure switch to keep the fuel pump running.


Is there a big reason that you don't want to use a programmable aftermarket
ECU?? I think it would save you alot of time and trouble. My friend has
programmed many DFI systems for Grand Nationals, and they perform much better
then the GM ECU, even with special chips in them. The GN air flow meter has
poor reliability and a bit of restriction that you can eliminate. Being able
to tweak the tunig at will has to be a big plus with your motor setup as well.

If you must use a GM ecu, try to get one from a Syclone/Typhoon or Trans Am
Turbo 3800. They were all speed density, but they will need to be re-mapped.

Gary M.