no injection ...ECU? 92 tracker 8v TBI

[fixkick]

you ask such great questions, the car will run soon, i promise.

Hi great stuff here, so much detail. you are obviously mad scientist smart. I've read many of your pages many times.
Im glad to help, im not so smart if my jeep SKIM dies , im sunk.

welcome ./
1992 Tracker 1.6 8v TBI 4x4 just died while driving. no start.

short story it runs on test fuel, Good you have spark.

TPS 1.1 v, B1 yellow connector ecu 11.65 v key on or 7.5 v cranking, battery reads 12.75v
is it ecu? I have tried 3
there are 4 pins.



Long story.... many tests
fuses dmm tested.
compression ok(50psi) for cold engine sat for weeks in -10 c. im sure you meant 150. and is good.
Timing is good checked cam to dist. to crank on #4.watched timing belt its ok.
all 4 spark plugs gapped. spark test ok.
No fuel spray in Throttle. (we will fix this)
injector wires disconnect at ecu 1.8 ohms. injector disconnect at TPS connector 1.6- 1.8 ohms.(to high?) yes. that is injector coil ohms
Noid test fail no light. (im sure its TPS bad or open ground)
TPS a-d 5110 ohms b-d 1200 ohms, @ no throttle 1.1v full 4v +.

Tach does not seem to move. tach wire at ecu B1 brown wire 11.65v key on 7.5 v cranking. good.
remote start installed by me 4 yrs ago all plugs disconnected no joy. (this may be it, need to do 1 test or 2)
runs on test fuel.
ecu flashes code 12.

ECU story complicated.
Mine dies flashes code 12. I replace 2 caps No joy flashes code 12. BAD ECU, you broke the trace or feed thru under corner cap, im sure.... sorry.!!!
I find another ecu for sale though he is not sure it works. It has had all 3 caps and 3 transistors changed.mica backed transistors by the way. Tried it, no joy flashed 12. It did register a 42 code when the battery got to low. 42 means the love battery cause the CMP to go dead)
The code went back to 12 after charging battery.change last cap in original ecu no joy.
This one my be good. we will see later.
Found virgin ECU at wreckers Looks fine on inside no joy flashes 12 (its bad,)
and also registered and cleared 42 same as other ecu. all caps and transistors on all 3 show no burn marks or suspect markings.
no code 12 means the ECU is dead. (this code 12 means , simple self test are ok) if no 12 ,it means the simple self test all failed.
it must flash some code or its a dead ECU.
this is like on new cars the scan tools is dead. no comms. and fuses good.

So the main questions I have are: 3 ecu are all bad?
the tach needs more attention on your pages. I see some one else has recently asked and you have not answered their question.
How do you test the tach? is it the tach guage in the car must run or only that the ECU get a signal (B1?)?
the tach just shows the coil pulses. the ecu watches the tacho brown wire if it dies it kills the injector, and sets a code 41.

The readings seem wrong to me. should a tach signal not be a pulse? yes it does. in fact 40v pulses. (scope)
Why with key on is it 12 v if not turning? (easy the coil is hot, and the ignitor is off, this causes the line to pull up to 12v. via the primary coil resistance.

Is the 7.5 v cranking really the pulse and my DMM slow? pages say it should be 12 v is this the problem? (the dmm averages the 0v and 12v and gets 7v cranking, this is what a dMM does, the scope shows the real signal. see bottom of post.
what sensor (and where is it) that will throw a code to a 8v TBI ecu?
41 spark, dead, 42, CMP dead. or misfiring.

and of course what else could be wrong? thanks for your time and all the effort into the pages.

ECU , no code 12 or some other code means the ECU is brick dead. (or in backup mode , but is same deal, dead)
no lie , lots of dead ECU about.... and worse every year.


lets look hard at the TPS. the TPS can set DTCs but not all fail modes.
that is its greatest weakness.

what are you 4 pins doing.
key on.
connected, back probing only, and volts.
PIN A must be 5vdc at all times, or the ECU is bad or the line is shorted to ground.
Pin B will be at 1v, idling and more key on not running due to Dash pot vacuum device holding throttle open at tad.
if pin be goes much over 3.0 volts the ECU thinks you are asking for WOT unflood mode and kills all injections. this you?
Bin C, idle mode. (0v idling, but key on, engine off, will be 12, due to above dash pot actions. this pin does not stop injections, ever.
Pin D , is ground 0v. if not you will not get injections and throw DTC codes.

my guess, is PIN B will read wrong. and the ECU only warns on this pin if near 5vdc, (tps too high errors) there is no unflood warning DTC, (weakness)





tacho sigs (key on is 12v, if it was 0v the coil would burn to a crisp with infinite dwell. (im sure this is good on your car as spark is good)

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the keyffail path there, is Dead NOID lamp.
the ECU is NOT injecting, we need to find out way
and there are only these causes.
1-TPS stuck high.
2-No cmp signal (no its ok you have spark on no 42s)
3: no spark (nah your is ok)
4-ECU power pin dead or ECU not grounded, there are 3 EFI fuses, ig-coil, FI, and dome. all must be good. and ECU grounded and 12s spit out.
4-bad ECU. (some of yours are in fact dead)

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I see some one else has recently asked and you have not answered their question.

what question, i might have missed it... ill check. thanks.
just the tachometer>?

thanks or asking.. sure....

the tachometer has 3 pins.
one is ground .
one is 12v battery (those 2 pins are just power to operate the tacho electronics board in the tachometer.)

if those are good and the 3rd pin does not look like above scope signals.
if signal is good, tacho is bad. (very common) Some even get the bad caps disease,too.
if signal is dead or weak the ignitor or coil are bad, (or fuse power to coil blown) no spark. supressor missing, code 41s.