The 1227749 was used in two turbocharged configurations: The 1987
1991 Pontiac 2.0 and the 1991 - 1994 GMC 4.3. This ecm can still
be found in wrecking yards and on Ebay as the 2.0 turbo came in Grand
Am and Sunbird cars as well as some 2.3 powered Pontiacs and
Olds'. It was originally used with a distributor and
a 2 BAR MAP sensor good to about 14 lbs of boost. Support for
tuning this ecm has been around for almost 20 years and there's even
custom code and special software and hardware tools available.
make the 7749 worth considering for any turbocharged project.
Installing the 7749 in the Toyota will require *significant* reworking
of the stock harness. If you're on a tight budget but you have
time, and you have experience reading wiring diagrams, this might be
the approach for you.
The 7749 only requires a handful of
sensors to work. The ecm programming eliminates the cold start
injector and controls all the functions previously handled by
thermostatic vacuum switches. This provides a few opportunities
to clean up the engine bay. In LH photo, the Manifold Air
sensor is installed in the hole previously occupied by the cold start
injector. The hole must be tapped to 1/2" pipe and a bushing
reduces the thread to 3/8" pipe for the sensor. To the left is
the MAP sensor which eliminates the need for the original airflow
sensor. Below the MAP is hole I used to connect the MAP vacuum
line. I believe Toyota uses BST or British Standard Thread for
their sensors and fittings. I tapped hole to 1/8" NPT. To
the left of the MAP is the stock TPS which will be used with the 7749,
exception of the IDL circuit. The RH photo shows the manifold
with two of the TVS' removed. One plug was purchased at the
local parts store in the Drain Plug selection and the other is a
standard metric bolt. The GM Coolant
Temp Sensor is also visible, oriented vertically. This hole also
had to be opened up
from the stock Yota thread to 3/8" NPT.
Here's the GM knock sensor to the left
of the oil filter.
Originally used with a 1989 Olds with 2.3 it's now fitted to the Toyota
block. I re-tapped the engine block so I wouldn't have to
re-thread the sensor if I had to replace it. It also keeps me
from having to argue with the clerk if I have to return the
sensor. This may not have been the best location as the fuel
filter fitting is extremely close, but it is the location for the OE
Toyota sensor. Notice the block heater to the right of the
filter. It's not bad insurance in
Everything is wired in. The loop
in the hose to the MAP sensor helps keep liquid from getting into the
sensor. The two solenoids mounted above the valve cover are for
wastegate control (forward solenoid) and EGR control. The EGR
vacuum line is connected to ported vacuum to ensure it won't operate at
This switch in the LH photo replaces the
Toyota power steering idle air bleed by sending a signal to let the ecm
know when PS
is active. It doesn't thread into the pump directly so I
disassembled the vacuum valve and used my lathe and drill press to make
an adapter fitting out of the old switch, The lathe was nice to
have but the adapter can be made without it. The RH photo shows
the fuel pressure test fitting I installed in the fuel rail after
removing the cold start injector. The fitting came from a GM car
with Tuned Port Injection but I believe it was also found in late '80s
GM's with the 2.8 or 3.1 liter port fuel injected engine.
The DIS trigger wheel and crank
sensor. Picture on right shows revised sensor bracket. I
set this wheel up so I wouldn't have to remove it to change
belts. Keeping wheel OD to a minimum also reduces inertia.
Timing signals are sent 52 deg BTDC which must be programmed into the
ecm. I chose to place the crank sensor bracket above the
crankshaft centerline in order to reduce damage from salt and
mud. The distance between crank sensor and trigger wheel is
adjustable and the sensor can be quickly and easily removed to aid belt
replacement. The bracket's functional and strong but I may build
a cleaner version at a later date.
1993 Cavalier DIS module installed above rear of engine. There aren't
many other places to mount this on the engine block without relocating
other components. Installing the module in the OE Toyota location means
running four long plug wires across the intake piping and power
Keeping the module close to the plugs reduces clutter. There's also the
side benefit of being able to use all four wires in the V8 "custom
length" wire set to make 2 sets of wires.
At $40 for the box, my wires only cost me $20 a set! Standoffs are used
to keep the aluminum mounting plate
above the valve cover which reduces heat transfer to the module.
DIS systems work best with large power supply wires and luckily the
Toyota wiring harness was equipped with a 12 ga power supply wire for
the OE module. Other wires needed to make the connection from ecm
to ignition module were reassigned from the Toyota module. One
additional wire was needed and this was taken from a circuit formerly
used for the airflow sensor. Throttle cable routing is slightly
modified by installing original cable bracket on firewall.
When you remove the distributor you have
to plug the hole with something. I made this on the
lathe out of some bar stock I bought at the scrap metal place.
Without the lathe
I would have taken the distributor apart, cut the housing short, and
tapped the end for a pipe plug. Not as nice looking but still
100% functional. The image on the right is another view of the
crank sensor bracket. The bracket attaches to the front of the
engine and works with the stock a/c compressor. This first
version was not adjustable for sensor height. The second version
uses the same bracket with a sleeve which can be shimmed.
There aren't any other sensors needed to run the engine. To the
ecm, everything is "singnal in, process, signal out." Once the
correct sensors are installed the job is to tune the calibration to
generate the best "signal out" for any engine conditions. And IMO
tuning is a subject better suited for forum discussion than a simple