what is EFI?
This engine runs by means of a system, called the E.F.I. for Electronic Fuel Injection.
(includes spark in 1991) (1989 to present)
Almost all cars 1988 and newer,
have this system. ( due to the USA EPA/ California laws) effective mandates,
on SMOG laws.
Why we have EFI and no more
CARB'S in USA? , here is a 1980 Carb setup
that passes smog, no words need define the word SUCK here. Just look.
"aka, Vacuum H3LL"
I like to think of EFI as
Distributed, Carburetor. (really
if you think about that hard, IT IS !) And some things (all good) were
added to make this New EFI carb better (like temperature and altitude
corrections)
Fuel pump runs higher pressure, up to 10x more. 6 is now 60,
worst case. (30-40s range normal)
All they really did is spread the parts
out, making them easy to test, and easy to replace and costs way less, like a
new ECT is $25, (ever price a new carb? or try to find parts for
one?)
ANALOGY:
- The Carb fuel nozzels are now Injector(s).
- The Carb jets are now (equations in a computer) making them
adjustable for the first time (that is, never seen an SU carb ? with variable
jets? as most folks never have. (60s British cars?)
- The Carb emulsion jets are now equations (see above)
- The Carbs T.V. is STILL THERE (throttle valve) (no, not television,
sorry)
- The Carbs Choke is gone, replaced by (equations). (I spent way too many
years fixing this junk , the crappy sticking chokes and endless stories
here.... all bad.)
- The Equations are fed by "SENSORS". (MAP/MAF, ECT, TPS , IAT and 02 and RPM)
- The carbs Power valve is gone, and is also equations. (stored in fixed
memory ) and varies by air flow (sensors).
- The carbs float and float valve are now gone and now a FPR regulator.
- The carb could never talk to you, but now the EFI can ! hey buddy
the TPS is stuck at 5v. fix that please. (all you need to do is SCAN
IT)
The carb ?,with a vacuum leak goes lean and surges, the EFI can
self correct ( 3 ways or more...)
If a carb part breaks?, the car stalls
(floods or goes lean and stalls), if the EFI sees a bad sensor it goes to
Failsafe (limphome) and engine runs crappy but runs, and beasts the hell out
of walking.
The EFI
system. is way simpler than any Carb. with all its fussy , complex needles ,
jets, power valves, sticking chokes, or air bleeds and the like !
End
carbs. , carbs are Dead technology today. (I have 1 cars that has a carb still
and a motorcycle) My car is 1968. (runs like new too)
EFI:?
If EFI don't ring a bell ?, please
check out my page below:
The presumptions are, you have engine and drive
line mechanical/electrical(electronic) maintenance, skills. (can do
compression tests. vacuum tests, and fuel pressure tests and a full tuneup,
all are basics.)
A full set of tools and or the desire to buy more.
You can NOT fix a car, with out tools and Tools are free, that is, all tools
net DIVIDENDS ,
to the point of payback!The
desire to dig in and get to the problem, will overcome any hesitations (yes a
pun).
If you want magic or expect to fix a car with no tools or money,
then you need a reality check.(I'm sorry all machines break and need humans to
keep them running, and not one machine on earth has "zero costs of
ownership")
I refuse to guess. (as do all ASE mechanics) See this
master say that clearly, to the students,
DO
NOT ask me to GUESS!
If you want to throw parts and guess, then do so,
it is your nickel , and wasted time, I can not help you guess. In the end, it
is your car and your cash.
There is but one Silver bullet . (but
yes,
do tune up the engine)
(The Lone
Ranger, magic silver bullet, refr) (spark parts and filters do not last over 60,000 miles, )
Imagine paying a mech to
fix your car at $100 and hour + 2x price on parts ,and all that was wrong
?,were bad spark plugs or a clogged fuel filter, (you can do that service (just
those 5 parts) for $25 at home)
Not only that, the dealers charges $15+ for
$2.50 spark plugs. (earning the name stealerships, well earned? huh?)
What
do you thing $25 new spark wires cost there, 400% more. 800% < ask them and
cry.
The EFI will not function correctly with a bad engine (dead
cylinder(s)?) dead spark or bad sensors or actuators. ( or bad gas).
The ECU
will try hard , very very hard to run a bad engine, (low compression?, Air
leaks? etc) but will not do so on a dead engine or one with dead cylinders.
I
call these LIES, if anything lies to the ECU, it will malfunction. Bad
sensors, or leaking or clogged injectors will result in bad fuel
control.
(However the ECU/PCM can adjust to normal wear and compression
losses over time and altitude like no CARB ,ever could by itself. Heck we had to
retune the carbs for Denver, Co.)
Lies to ECU or any computer, are called
GIGO, garbage in , garbage out. ( If sensors lie to it , it will send out
(inject) results, based on those lies)
Bad fuel pressure, is one form of
a vary BIG lie. (bad means out of spec, (short for factory
specifications) 30 PSI is minimum ,but if the
FPR fails and pressure is
55psi , all hope is lost !!!
The ECU (EFI) brain, is not
Deity like or Omnipotant it is really, brick stupid, and has no inputs to true
reality, therefor, it can never make a comparison to truth.
The CHECK engine
LAMP; or CEL:
The false illusion that my engine is ok, if the CEL lamp don't
glow running , IS NOT TRUE at all. (The ECU will report SMOG is bad, or gross
sensor failures, and no newer cars lots more , but on old cars it will never
reliably report a bad running)
The ECU will not report low engine
compression, in 1996+ they do report MISFIRE for the first time
ever.
However, the ECU can detect sensors lines that short or just the wire
fell off of it. "opens and shorts, are reported, for some, but not all
sensors/actuators.
On topic reading
links are here:
You might get help here.
Even better, is Wiki
If you don't have a scan tool,
you must learn to test your sensors and learn to convert the readings to human
terms. .
Take one example, the ECT, the
hot
engine with ECT unplugged will read about 250 ohms. 250 ohms is 180 degrees F.
(revised 2015 with Excel plots )
Here are my sensors test page.
Consider the below block diagram for EFI. (I made it up as a universal system
for TBI and MPI and the adding of spark in 1991, SEE BLACK "X" for that
addition)
My drawing is crude , I'm no artist or writer , only a retired
mechanic. (I did only electronic controls, last 10 years and PLC's, and
computers and chip testing for over 50years.)
The system is simple , if
you just look at the whole system engine with EFI.
Suzuki ECU History: (USA
evolution only)
The below shows a basic fuel system, (The
89/90 year, there is only 1 injector and the ECU don't create or control spark,
but it DOES monitor spark and cut fuel if spark goes bye-bye)
1989-90' EFI
is a fuel only system.!
The 89/90 has a stand alone Distributor (old
school, mech. vacuum and advancement weights) , and a coil, the ECU does not
create or regulate spark, in these 2 early years.
In 1991 the TBI 8v ECU, now
creates and controls all spark and advancement of same.
For EFI skeptics
, if you drove 2 cars for 20 years both 1.6L the gas savings (10,000 miles per
year) 1990 to present would be a fuel savings of $5000.00 (some of the V8s
SBC/ LBC Chevy's report gains over 20% ! (quadrajet sickness)
Digging in to EFI: ( ECU is Engine Control Unit)
The ECU is a processor
and as such has inputs , outputs and if the inputs lie , the outputs lie.
If any input goes bad (detected it) the ECU will attempt (very poorly)
to mimic that bad sensor ( simulate is the correct word and works better
starting in 1996+, that is, less crude)
If the ECU knows what is wrong it
will throw
DTC errors and glow
the CEL lamp.
The ECU can do 4 things, work perfect, run in Failsafe, run
in Backup mode, and be LOST.
See Backup and
Failsafe here, this will kill economy and
power and RPM limits. (spark retraded, and 15MPG horrid fuel
economy
What does lost mean?, it means that something horrid is bad, but
the ECU does not know what it is, (like fuel pressure at 60PSI) and the ECU can
not control fueling at all, it just runs rich. (do to lack of sensor command
Authority)
The ECU is NOT all powerful and knowing , it is not Artificial
Intelligence as some think.
It can't be , "because it has little to no
redundancy in the sensors., and lacks necessary quantity of sensors to do that.,
for example, it has no wide band oxygen sensor"
I like to think of the below
drawing as a FLAT carburettor or distributed..,, with the parts all laid out
and easy to test and replace. because it IS.
The 89/90' just controls
fuel see that "X:" the X path was added in 1991 to NOW.
So as you can see ,
only the 7 inputs below control injections.
If the 7 inputs(counting CMP
(CAS) are good, then the output (injections) will be good. The 7th input is
fuel pressure ,
it must be in the specified
range.
The word CAS below is for either or both the CMP or CKP sensors
(cam and crank) that I show as ONE sensor. CAS. (crank/cam angle sensors)
CKP
started in 1996 for SMOG and misfire detection, the engine runs with the CKP
unplugged 1996-98. (not tried later)
The ECU brain, will mimic all detected
dead sensors.
(but never can it mimic a dead CMP (cas) CAS means cam angle
sensor here.
if the CMP dies , RPM is 0 and there can be no spark or
injection timing ever with a dead CMP)
The ECU can get lost if any sensors
are wrong (weak) or fuel pressure wrong. or VUCUUM bouncing
like a mexican jumping bean.(or a 10 year old kid
on
a Pogo stick)
If the spark is bad, the engine can not burn fuel correctly
and NO EFI system can cure that.(not yet)
The injectors must not leak or be
clogged.
IF the exhuast leaks (cracks?) near the 02 , the 02 lies, and the
ECU goes , NUTS.
IF the air meters (MAF/MAP ) are not dead but lie? AFR will
suffer. (but will run in most cases) (on a carb car, if the Carb can't feel (if
you will) air flow?, the engine dies) (AFR means the Air/ Fuel flow
ratios.)
Case in point, unplug the MAF/MAP engine runs but real rich. Try to
run engine with each sensor unplugged and learn what happens?
The below, is the 8 valve TBI system total;
( the 89/90 Kick, only does injection ,
never does it do, spark, but does cut fuel of the tacho wire A1 goes dead.)
All Suzuki ECU's kill injection if spark is lost. No exceptions. (same with CMP, and a dead Tachmeter
signal pin A1 (oddly missing on Suzuki drawing below) but is here.
Starting in 1991 the ECU took over FULL
spark generation duties. see that below. (91-95 USA)
This system will run your
engine , even if the motor is old and tired.
It will not run your engine
correctly, if the engine has dead cylinders , or you have bad sensors,
actuators or bad fuel pressure. Nor clogged injectors or leaking ones.
A bad
engine is discovered by poor compression, weak or bouncing vacuum at idle.
The ECU can NOT adjust for
dead cylinders, nor gross cam timing issues or gross Ignition timing
errors.
Here is
the 16v 1992-95 (N.American) ECU. with my markup's It has 3 more injectors and
the MAP is replaced with a MAF.Here are my sensors test
page.
end basics, G16 EFI.
The Jargon is not made up , it is SAE/ASE standard terms.
(Society of Automotive Engineers)
I made a very short list of 40 of the 4000 terms or
Jargon used by
SAE.
We use Jargon,
because nobody wants to read, or type, Engine Coolant Temperature sensors 1000
times. over and over.... it's ECT (every technology has its Jargon , or worse
latin, ask your Doctor that.... omg)
Source : Fixkick.com
rev 4 1-5-11
