Samurai TBI | No Injector Pulse

Samurai TBI | No Injector Pulse - Printable Version

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Samurai TBI | No Injector Pulse - d8nk - 08-16-2020

Hello all, new to this forum but have been reading a ton, thx for all the info!

Backstory: Driving along and suddenly engine died. Spark test - pass, Fuel pressure near 50 psi at intake, basic NOID test, failed. Replaced caps on ECU. Still no NOID pulse. Did more extensive testing, TPS good, injector at 1ohm, wiring good from ecu to harness at TBI. Here are where my questions begin.

Doing the pulse signal tests on positive side (red wire), I get no signal, key on dead, turning over no signal.

Doing the test on negative side (yellow wire) I get no signal, key on dead, turning over dead.

I'm pretty convinced one of the transistors is bad. Curious if there is an simple DMM test I can do on the transistors to determine if one is bad? If the plus side (red wire, B8, Q101) transistor is bad will this always kill the signal on negative side? Is it both work or both fail?

Trying to do as much testing as I can before I go the route of replacing the transistors. Thanks for any input!

1992 Samurai TBI 8v
-80CXX ECU

RE: Samurai TBI | No Injector Pulse - fixkick - 08-16-2020

(08-16-2020, 01:14 AM)d8nk Wrote: Hello all, new to this forum but have been reading a ton, thx for all the info!

Backstory: Driving along and suddenly engine died. Spark test - pass, Fuel pressure near 50 psi at intake, basic NOID test, failed. Replaced caps on ECU. Still no NOID pulse. Did more extensive testing, TPS good, injector at 1ohm, wiring good from ecu to harness at TBI. Here are where my questions begin.

Doing the pulse signal tests on positive side (red wire), I get no signal, key on dead, turning over no signal.

Doing the test on negative side (yellow wire) I get no signal, key on dead, turning over dead.

I'm pretty convinced one of the transistors is bad. Curious if there is an simple DMM test I can do on the transistors to determine if one is bad? If the plus side (red wire, B8, Q101) transistor is bad will this always kill the signal on negative side? Is it both work or both fail?

Trying to do as much testing as I can before I go the route of replacing the transistors. Thanks for any input!

1992 Samurai TBI 8v
-80CXX ECU

before doing all that radical things to ECU , know that the injectors can cut fuel for other reasons.
I presume engine runs on test fuel and spark plugs dry? sure , no injections sure. but sparks good means test fuel works (hand sprayed in the air horn of TB)
The test fuel; test tells more things, ECU not dead, Engine timed ok, and runs on test fuel proves that easy. Timing belt not snapped, or spark or cam timing way the hell off time. compression ok, if 80psi WOT the cam belt slipped 155 is par.

here is how the ECU logic works

FI and IGCOIL fuse not blown.

insert the diagnosic, jumper in the DLC jack.
key on CEL glows must,
and will flash code 12, good, code 41 or 42 means spark failure.

if yes crank the engine for 5 full seconds. release key
and see if code 41 or 42 show up now, the long cranking lets the spark test run out. fully. or any other code related to TPS is bad.

injections are last things in the chain of logic to work.
first is the idle switch closed, at 0vdc. key on.
then TPS TP pin at 1v not 3 ,4 or 5vdc, if yes, the ECU goes to CUT FUEL mode this is UNFLOOD mode in the users guide called WOT cranking to unflood.
then all spark test both, of them CMP not dead or missing or the coil feed back wire called tachometer not dead or missing.
if any of that fails, NO INJECTIONS are going to happen to keep As seen on TV crash and burn.
the ECU does not want you are car to burn up. injecting with bad spark.

that includes, intermittent spark of any kind. (code 41, code 42)

I do not see how both transistors can fail, but the low side transistor must have pull up to test it. the injector 1ohm coil meets that need.

12vdc on all power pins of ECU and grounds. too. Im sure they are but to be full here yes.

I have never tested the ECU for cut fuel if only timing is way off, some cars in fact do that. for sure. mostly newer cars
dead spark or intermittant, CMP not dead, coil brown wire not dead.
TPS at idle not WOT 5vdc. TP pin 1v, idle pin 0v.
are the top causes of lost injection, dead injector,
if you are lucky the key on test, for prime pulse at tip of injector horn off, seen to shoot very tiny fuel just keyon each time the 3 second rule happens.
key hear pump run 3sec, and this very tiny squirt happens. but not guaranteed, but if seen, is super good information if seen.

tell me more? this can be fixed easy based on tests.

RE: Samurai TBI | No Injector Pulse - fixkick - 08-16-2020

the pump must run for 3 seconds key on, if not find out why, fuel pump relay bad or FI fuse blown or IGcoil fuse blown.
just listen as you key on for the 3 second fuel prime sound.
im sure it is ok, and you checked PSI but just hearing that sound tells me the priming pulse happened, and any relays that chatter , ECU CAPS are bad.
Im always looking for other odd things any ECU does in the logic, if injectors are dead, look for other oddities.
like, CEL dead. or
blinks out code 12 and repeats or as it repeats, halts mid flashing code sequence, this is ECU crashing for bad CAPs. seen that many times. and relay chatter sounds.

RE: Samurai TBI | No Injector Pulse - d8nk - 08-17-2020

Engine runs perfect with fuel down TB directly.

CEL working good, 12 code, no funny business with flickers or anything. Able to run motor with fuel down TB and have CTS unplugged and throw a code. Plug back in and back to 12. Seems to me that is a good sign ECU is not fried.

TPS tests out good, voltage good, Ohm tests are good. Tested everything you have written on your pages without a scope, the one thing I dont have Sad

I have a tach and it shows rpm while cranking and if it runs with gas down TB. I have not checked for tach signal at the ECU input, not sure how to do that (which wire)

" but the low side transistor must have pull up to test it. the injector 1ohm coil meets that need. " now this is interesting. I had the injector/TPS harness unplugged while doing the positive and negative noid tests. Should I test with it hooked up and probe that way?

I did google that you can test PNP and NPN transistors with ohm meter on DMM. I am seeing that the positive side does not seem to be testing correctly. I am suspicious of that one now.

"12vdc on all power pins of ECU and grounds. too. " -Have not checked that.

"if you are lucky the key on test, for prime pulse at tip of injector horn off, seen to shoot very tiny fuel just keyon each time the 3 second rule happens.
key hear pump run 3sec, and this very tiny squirt happens. but not guaranteed, but if seen, is super good information if seen. " - I'm not quite following you here but yes the fuel pump runs for a short while when i key on.

RE: Samurai TBI | No Injector Pulse - d8nk - 08-17-2020

(08-16-2020, 03:30 AM)fixkick Wrote: the pump must run for 3 seconds key on, if not find out why, fuel pump relay bad or FI fuse blown or IGcoil fuse blown.
just listen as you key on for the 3 second fuel prime sound.
im sure it is ok, and you checked PSI but just hearing that sound tells me the priming pulse happened, and any relays that chatter , ECU CAPS are bad.
Im always looking for other odd things any ECU does in the logic, if injectors are dead, look for other oddities.
like, CEL dead. or
blinks out code 12 and repeats or as it repeats, halts mid flashing code sequence, this is ECU crashing for bad CAPs. seen that many times. and relay chatter sounds.

The pump definitely runs with key on. CEL is good, no funny relay chatter or anything. The code 12 blinks 12, then pauses then repeats 12, pauses, repeats, etc. That is normal right?

RE: Samurai TBI | No Injector Pulse - fixkick - 08-17-2020

(08-17-2020, 04:41 AM)d8nk Wrote:
(08-16-2020, 03:30 AM)fixkick Wrote: the pump must run for 3 seconds key on, if not find out why, fuel pump relay bad or FI fuse blown or IGcoil fuse blown.
just listen as you key on for the 3 second fuel prime sound.
im sure it is ok, and you checked PSI but just hearing that sound tells me the priming pulse happened, and any relays that chatter , ECU CAPS are bad.
Im always looking for other odd things any ECU does in the logic, if injectors are dead, look for other oddities.
like, CEL dead. or
blinks out code 12 and repeats or as it repeats, halts mid flashing code sequence, this is ECU crashing for bad CAPs. seen that many times. and relay chatter sounds.

The pump definitely runs with key on. CEL is good, no funny relay chatter or anything. The code 12 blinks 12, then pauses then repeats 12, pauses, repeats, etc. That is normal right?

ah gees, forgot to say is 5vdc pin on ECU ok> seen also on 5vdc pin of TPS. (key on) Im sure it is but needs to be checked first always. anytime ECU messes up.

CEL Ok, 12 ok and repeat good. pump and pressure good.
the TPS if its ground wire is cut /broken , not a 0vdc, there will be no injection.
the NOID test m must be done (best) with injector pulled, and NOID lamp there,
and not LED NOID the LED flashes faster that humans can see, 5 milliseconds is way to fast for humans.
that is why scopes work best but a real tungsten lamp bulb (as sold for years now, real noid lamps)
I use a 25MA lamp do to my fear of overloaded the transistors. for example a tail lamp uses 40 times more current at 1Amp.

noid dead across the 2 pins. test 1 fails.

to see which transistor is bad.?
connect noid pin battery neg lug., ground and other pin pin of noid to RED injector wire only. (NPN wire) red.
it must flash. if yes transistor is good.
now the PNP trans test.
then test 2, (3 really) connect , noid pin 1 to yellow injector wire, (low side transistor) and other noid to battery wire plus.
the noid flashes now proving down side transistor is good. PNP

yes bipolar NPN/PNP transistors can be tested with dmm, using diode test mode
this is true 1991 up, never on sammi.
as you can see R225 must not be burned open.
[Image: injector-drivers.jpg]

91 TBI flashing , NOID on yellow/red , the tungsten wire in bulb is very slow to cool down and does not actually flash.
[Image: 91-noid-sf1.jpg]

this fast pulse is too fast to see using any LED, 0.7MS is super fast to any eye the scope allows this to be seen this fast pulse. (CRT persistence magic)
[Image: INJ-red-gnd-1w.jpg]

last is I made this drawing below, using vast scope readings. cranking is 2.5mS injector pulse. 0.0025 seconds, fast. and 300RPM x4 is rate.
1/200th second, is a blink most folks can see (eye/brain). 5mS. is that. (the brain also learns this (eye thing), no 2 persons are the same)
[Image: my-TBI.JPG]

as you see the ECU goes to great effort not to overheat the coil in the injector or the 2 transistors.

RE: Samurai TBI | No Injector Pulse - d8nk - 08-17-2020

Ok thanks for the in depth reply.

Yes TPS 5v good. Ground is good. 0Vdc at idle good. (Even installed a different TPS just to dbl check)

I have an actual NOID light testing set. Not LED. I assume those lights work ok for this?

Just want to clarify my next steps:

-I should remove the injector from horn and have it plugged in to the harness to do NOID NPN/PNP test? What does removing it do?

"this is true 1991 up, never on sammi." Are you saying on my 92 Samurai I can't do this test?

"as you can see R225 must not be burned open." I can't find this resistor on the board, do you have a pic showing where it is? Or I can post a pic of mine and you could point it out.

Thanks for helping me figure this out!

RE: Samurai TBI | No Injector Pulse - fixkick - 08-18-2020

(08-17-2020, 10:05 PM)d8nk Wrote: Ok thanks for the in depth reply.

Yes TPS 5v good. Ground is good. 0Vdc at idle good. (Even installed a different TPS just to dbl check)

I have an actual NOID light testing set. Not LED. I assume those lights work ok for this?

Just want to clarify my next steps:

-I should remove the injector from horn and have it plugged in to the harness to do NOID NPN/PNP test? What does removing it do?

"this is true 1991 up, never on sammi." Are you saying on my 92 Samurai I can't do this test?

"as you can see R225 must not be burned open." I can't find this resistor on the board, do you have a pic showing where it is? Or I can post a pic of mine and you could point it out.

Thanks for helping me figure this out!

sammi, what is sammi here? IDK

this is sidekick /tracker forum not sammi
but some sammi's run the tracker engine /harness and ECU and all EFI parts.

what ECU do you have there, sidekick ends in 56B30 (means sidekick + 8valve+ TBI + 1991-95 , + stick shift 5 speed)
what ECU do you have. I sure can not know that, these old cars can be hacked up 100 of ways,,,,,,,
consider I can not see your engine bay at all.

the sammi has no pnP transistor,
some have hidden injector huge resistor block, sammi EFI is very very driffent that sidekicks, or vitara or trackers or sun runners.

is this a FRANKEN SAMMI (or franken KICK)? IDK.

here ours is in all its glory

60axx ecu is 89/90 very different.

https://fixkick.com/ECU/ECU-8v.html

r225 for Npn Q102 this resitor is HUGE, 5 full watts huge. thumb sized and is right next to Q102, white on mine.

1/4" wide, and 1 inch square/ sized seen here clearly
Q102 here, then r224 small blue. the then white monster, R225 , and may cover its ID mark so big. sorry 0.27 ohms ( one quarter of 1 ohm) reads as short sure.)

[Image: 93-56b30-leak1.jpg]

RE: Samurai TBI | No Injector Pulse - fixkick - 08-18-2020

56b40 is A/T
there are more Bxx numbers for each year 91 to 95 but are only year ,modes (smog. etc)( B51 is the most new one.1994 /95 only)8v.

i have them all here. in pdf

USA only sidekick only. (or tracker but no GM numbers by me)

https://fixkick.com/ECU/EPC-ECU96-98/all_other_years/89-95/89-95NA.pdf

RE: Samurai TBI | No Injector Pulse - fixkick - 08-18-2020

(08-17-2020, 10:05 PM)d8nk Wrote: Ok thanks for the in depth reply.

Yes TPS 5v good. Ground is good. 0Vdc at idle good. (Even installed a different TPS just to dbl check)

I have an actual NOID light testing set. Not LED. I assume those lights work ok for this?

Just want to clarify my next steps:

-I should remove the injector from horn and have it plugged in to the harness to do NOID NPN/PNP test? What does removing it do?

"this is true 1991 up, never on sammi." Are you saying on my 92 Samurai I can't do this test?

"as you can see R225 must not be burned open." I can't find this resistor on the board, do you have a pic showing where it is? Or I can post a pic of mine and you could point it out.

Thanks for helping me figure this out!

ok found this, in older post sorry missed that I did. so sorry

-80CXX ECU (1995 sammi ECU)
you have this ECU, and is not used on any sidekick of any kind so is franken sammi.

a whole different beast that, I will see what that is in the EPC, data base files.

see see r127 and R130 (130 large white) that be it. bottom right.
[Image: sammi-80c-2.jpg]

now see this.
the secret injector resistor on only SAMMI used. and it runs spark via ignitor.
pins a8 and a20 find there that goes, some where is the injector load resistor block I think.

[Image: late-sammi-efi-94.jpg]