GMECM 1227749

Bed Raised

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.  These 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.

MAP and MATCoolant Temp Sensor installed

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 Temperature 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, with the 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.

Knock Sensor

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 this area.

MAP sensor and solenoids

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 idle.

Power Steering SensorFuel Pressure Fittiing

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.

DIS Trigger wheelCrank Sensor

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.

DIS Ignition Module

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 steering hoses. 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.




Distributor PlugCrank sensor and bracket

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 web page.

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