EFI Index:       Electronic Fuel Injection System (and spark)              

   Joking !                  
Running your Sidekick under water is not all that successful with EFI,  (above is Diesel)
The EFI starting in 1991 has spark creation and generation , prior to that year, the Distributor creates and does all spark advancements, by its lonesome.
The fuel injection rates are all controlled by the ECU via Inputs.   (ECU = Engine controller Unit)
The ECU measures many parameters and decides the injection rates.  (Air flow, RPM, load, Manifold pressure, Coolant temperatures, etc)
The ECU can correct for  many changing factors like,a tad lower compression,  altitude, colder air, a dirty air cleaner, and sensors just a tad off,  but little else.
The EFI excels at adaptation, like nothing else, like no Carb. ever made.

  1. EFI simple block diagram (see below)
  2. EFI trouble shooting
  3. EFI sensors and actuators  (sensors are inputs, acutators are output slaves)
  4. Testing all EFI sensor ,etc.
  5. Using the full scan tool to see what going on.
The Achilles heels of EFI below:  (this is because, it (ECU) don't know these are  bad, or is happening)

The EFI falls flat on its face with low or too high fuel pressure #1 top !  30 PSI running or bust!
bad Engine (say 90 PSI compression) Timing belt slipped?  Got Bouncing vacuum?   150 to 200PSI is normal. not 90. (90 is lawn mower compression)
Bad spark. (a tune up at 60k is manditory ) that means timed right too.
Leaking injectors or badly clogged. ( yes, the ECU can compesate for slightly clogged injectors using Closed Loop controls)
Bad sensors, or weak. (dead sensors are reported , mostly , but not too well with the TPS, only shorted or opens are reported for most sensors)
A Bad ECU.
A bad 02 sensor. (one that fibs, grossly is the worst) 02s last about 100k miles, that is it. The heater usually dies first wrecking MPG.
A melted closed CAT.
The EGR stuck open.

Go back one page and put a symptom in my search box.  like: bogging, or misfire, or power loss,?

This simple diagram shows how EFI works.
The ECU assumes fuel pressure is correct (about 30PSI) and that the injectors are not clogged or leaking, if not?, big trouble for EFI.
Notice how the fuel travels in a non ending loop.
Note too, how a clogged fuel filter , lowers pressure to the injector(s) (an they fail) and overloads the poor pump. (lost power?)


TPS is Throttle Position (aka: throttle angle, TP sensor)
ECT is coolant temperture
02 is the exh oxygen sensor. (front)
IAT is air (induction) air temperature, (not found on some pre 93 16v Sidekicks)
CAS is cam angle sensors (and or crank)
MAF (air meter) is MAS Air flow (on non USA cars, it can be a Air volume not mass) sensor
MAP, is the plenum baro sensor, manifold air pressure (vacuum) sensor. 8v cars only.



ver 1    1-1-2013


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