injector problem

[mjbalogh]

NOID test failed, injector's not being fired and I get a code 12 from ECU. Would I still get a code 12 if the capacitors were no good in the ECU or if the transistors required to fire injector were kaput? Kinda stumped

92 GEO tracker 1.6L EFI, automatic 4wd

[kick-fix]

ecu cant test injectors. this is a dumb ecu.
only check limited things and only for catastrophic fails (opens and shorts of sensors)
exceptions are fuel , EGR is quazi tested. Quazimoto? hahahah

on this ecu before you condem the ECU.
(yes, those caps need to be fresh but ecu will still try to inject no matter)
be adviced, many noid lamps draw too much current that is why i recommend the radio scratch lamp, it is only 20 miliamp light (very very tiny ).

i have a box of NOID and they all fail on 8v. (commerical set)

Before condeming ECU.

1: the TPS MOST NEVER Signal WOT full time ( how ever) including the loss of the ground wire to the TPS . THIS SIGNALS, UNFLOOD MODE FULL TIME.
no injection, no noid, no NUTTN. (hahahah)

2: The CMP must be firing.

3: there MUST be spark read back.


you will not find these facts out in many places.

if NOID is dead. check for spark.

if spark looks good, still be suspisious.

Place the DLC , diagnosic jumper, crank motor for 10 seconds (5 is spec)
release key (DO NOT POWER OFF KEY) just let the spring return do its THING.
CEL will flash 12.

if it flashes 41, 42 or others, then you have a bad input to the ECU.

if you get code 12, the change CAPS but dont expect this to fix injection.

if it is bad transitor they are only 70 cents each.



make sure injector reads 1ohm ( .8 to 1.2 ohms is spec)
never hot wire it you WILL BLOW IT TO KINGDOME come.

this is a Low impedance injector ( in fact it is the lowest of the lowest and must be respected for this fact)

lets do some more tests.
they are all easy.
ready?

[Bex]

Originally Posted by kick-fix

EGR is quazi tested. Quazimoto? hahahah

You can be so funny...

I read these things with great interest...when my injector wire shorted out, no CEL light came on, etc. In situation like the above, would you recommend opening ECU to see if those injector transistors are fried, or just test red injector wire?

[kick-fix]

sure ,all the above and more ,
your car was an exception maybe 1 or 2 harness shorts in 2 years on this forum. yes, inspect the harness at both ends (FSM says that on every single page of the diagnosis for sensors and actuators)

the ECU can in fact stop injection if the inputs to it, are wrong.
"GIGO" , in computer parlance, Garbage in , Garbage out.

yes, many people make the mistake( even top mechanics) of looking at these old cars through the lens if modern OBD2 , technology.
this is bogus.

the biggest differences are: OBD2 , must detect 50% increase of Smog.
this is not even on the list , in OBD1.!
this ECU only checks the most obvious errors. and is missing all but one of the 13 OBD2 monitors. (code 51 > becomes P0400 with brains)

did you know the OBD2 even compares , load and air flow using many ways.
and if they Diverge , it sets a code.
case in point. it models air flow just with the TPS , RPM , Vacuum and VE.
it then compares this model with the readings on the MAF.
if they are greatly off you get a MAF performance FAIL.
this is fancy stuff by comparison to 1991 OBD1 cars.
case in point:
misfire (not in 91)
lean fail (sort or long term fuel trim) ( stores it inside but never reports it,91)
rich fail, same story.
advanced mfg. DTC codes, (none,91)
the list is huge.


i have posted here 100 times.
all 95, kicks and older.
pop the ECU lid, look of smoke, look for burning ,look for Electrolytic CAPS leaking boric acid. check the caps visually under bright light and magnifying glass. (splits,bulges, cracks,warpages,tiny volcanos,etc)

if you have cap meter test them. (removed) dont forget polarity and antistatic rules, bla bla....
if really smart ,get them out of there,fast . this originals are all junk.
we have same ECUs from other countries and diff , brand caps,same year and no issues at all. (all I say is USA ,Canada cars)

If they look changed? (see solder pads with flux, or newer type caps (with crosses on top?) or removed conformal coatings on the pads. they were changed.


This old ECU is dumb as a brick. If it does complain , then believe it)


the key TESTS ,on a dead injector:
1: use the correct Noid lamp ( 12vdc, 0.020 amps or close)
2: check all wiring at both ends.
3: ring out the wire for continuity and shorts to 12v and ground.
4: check TPS output volts. 1vdc typ., key on. at TPS POT tap.
5: check for spark, injection never happens unless it can make spark.
6:check for code 41and42 ,cranking. (keep key on ,crank for 10 secs)
7:check the coil for 1 ohm.
8:listen for clicking ( all this is on my injector page but .....)
9: if you have a scope you can see it open under power.
(very advanced tests here, the back EMF on the coil tells the story)
10: plug in an injector pulser ($100 tool) and look for injections!
[ never try a bubba and hot wire it, it will burn up]

11: if all checks out ok, above , then your pressure testing was bogus. do over.


and questions for how to do any above,just ask.

the guy in the shop knows these because he/she when to ASE school.

so how is that ,compressive ? IIRC. Im old and retired. hahahahahehehehe

[kick-fix]

oh, forgot.
no injector test ,monitors or DTCs , ZIPPO , all years.to 12/95'.


NO ACTUATOR DIAGNOSIcTS AT ALL,ZIPPO
and injectors are , Actuators.