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Discussion Starter #1
ok i will start with an intro, 86 4 runner, 22re, manual trans. bone stock all original. I bought it for my son months ago and it had 278k and ran decent so we pulled the engine and dropped in a new 22re due to milage and had the injectors rebuilt.
now, new engine is in, starts up and runs perfect 100%. for only 2 complete seconds. as in counting 1thousand1 1thousand2, dies.
now, ill give you my diagnostic run down (career mechanic with certifications all the way from briggs, john deer, detroit diesel, cat, honda, chevrolet, ford, etc) but im not the best ecm guy.

1-no the distributor is not 180 out
2-yes it has new clean fuel
3 new filters
4 new TPS
5 all fuses and relays have been verified
6 the MAF is opening and sending proper signal to the CO
7 the CO is sending proper signal to the FP ( fuel pump)
8 the fuel pump is opening and sending 42lbs pressure to the fuel rail KOEO
9 noid lights flash on all injector plugs
10 CSI (cold start injector) works.
11 3 injectors =3.59ohms and one is at 5.50ohms on the 20k scale

now. since it only runs for 2 seconds then dies i assume the CSI is priming it but the injectors are not spraying even though there there is pressure and noid lights flash.
yes i have also tried jumping the FP in the engine bay plug to make it run nonstop and still dies in 2 seconds so we know its not the pump or that whole circuit cutting out.
BUT if i stand and give it a shot of carb clean in the MAF it will keep running perfect so this is why i think the EFI driver in the ecm is not working ?

so my questions,
1 is there something in the MAF that sensing the carb cleaner makes it keep running?
2 how do i test the fuel injection driver in the ecm,
3 or am i on the wrong track beating a dead horse and its ignition dropping after 2 seconds?
 

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Discussion Starter #2
update. assuming it is the NE or IGF circuit, do i test those for ohms or power? and also can they be KOEO or ve to be KOER?
 

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rock crawler
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You have a lot of good questions that I can't answer now as I don't have enough my FSM handy.
Your assuming you have adequate fuel delivery as the CSI seems to work, but is it really OK?

The noid says the injectors are working, but are they? Maybe they are getting a pulse but something else is preventing them from operating.
 

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rock crawler
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and i dont know if im looking for voltage or what?
It depends, if you are looking for a signal with power on, you're looking for a voltage, using a DMM on the volts setting.
If you're checking continuity of a wire or something, you're measuring ohms on the resistance setting of a DMM.
 

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1990 Toyota Corolla Wagon
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What happens if you hold the ignition key in the start position? Does it still die? Does it try to restart immediately or does it just crank with no start after it dies?

Have you tried disconnecting the CSI to see if it starts at all? Sounds like a fuel delivery issue. Do you still have the old injectors to try?
 

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Discussion Starter #10
It depends, if you are looking for a signal with power on, you're looking for a voltage, using a DMM on the volts setting.
If you're checking continuity of a wire or something, you're measuring ohms on the resistance setting of a DMM.
i need to know what im looking for at the ecm on the IGF wire, i have been told i must have an oscilloscope?
 

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rock crawler
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According to FSM there should be 0.7-1.0V from IGt to E1 (grnd) at idle.
Doesn't mention NE or IGf.
IGt = Blk/wht stripe
IGf = Black/yellow stripe
NE = Black/red stripe
 

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When I had my engine installed the same thing happened to me. It turned out to be the wire was broken that got the pulse signal to the ignition control unit. The car will run for exactly 2 seconds without this signal. I found the below post by sb5walker. He claims that the engine should run without this signal minus the advance but in my case, the engine would die after exactly 2 seconds. I hope I'm not steering you in the wrong direction but maybe this will be a small breadcrumb toward your solution.


sb5walker
Senior TN Member


On the 22RE the signal coil is fired by a four lobed magnetic "reluctor" in the distrib as Victor said; it provides a pulse at each cyl's compression stroke TDC, (meaning, two pulses per crank rotation). It attaches to the igniter, and the igniter passes the signal on to the ecu on the "NE" wire, which enables the ecu to know when a cyl is at TDC and to set timing as mentioned. The interesting thing is that the ecu has no idea WHICH cylinder is at TDC; it just sends a spark trigger signal to the igniter on IGT, with advance relative to the NE signal based on rpm (from the NE wire), and other inputs (not sure, but believe the VS signal from the air meter, possibly VTA from the tps, and the knock sensor if there is one. Maybe also based on engine coolant temp (THW from the ect). It's the position of the rotor in the distrib that directs the spark to the appropriate cylinder.

Even though that NE signal is not a crankshaft position signal in that it carries no information about the position of the crank (only gives pulses every time a cyl hits TDC on its compression stroke) and in fact there is no such sensor on the motor, I have often seen the signal coil or it's pulses referred to (incorrectly) as crank position. I may even have done so myself. I can see how that would naturally be confusing, but basically people are referring to the mechanical spark reference signal that any ecu needs in order to time spark.

A nice thing about the 22RE ignition system is that the igniter can provide a spark without the ecu just by using the signal straight from the signal coil. Of course, that has no advance. In fact, when the 22RE first starts, that's what's happening; the igniter starts out triggering spark at TDC using the signal coil input, and it takes a rotation or two for the ecu to figure things out and start sending a trigger on IGT, at which point the igniter starts using that signal to trigger spark, instead of the signal coil input. If the IGT wire were to lose connection between ecu and igniter, the motor can still run, but without any advance.

Then there's the IGF, or ignition confirmation signal, sent from the igniter back to the ecu, confirming that a spark took place. Some folks have suggested that the igniter is able to determine if the coil actually produced a spark that actually got grounded out (hopefully at the spark plug), and that the igniter will only send an IGF if there actually was a spark. I don't know if that's true, or if the igniter generates IGF simply based on it's triggering of a spark, which it does by grounding the primary winding in the coil. I suspect it's the latter. Anyway, the purpose of IGF is to let the ecu know there was a spark; if it doesn't receive IGF for 4 sparks, it will stop firing the injectors (and throw a code 14).

All that is the way the 22RE's VAST (variable advance spark timing) ignition system works. The 3VZE's ESA (electronic spark advance) system is a little different. In addition to the NE signal, there are also two camshaft position signal coils in the distrib, G1 and G2. Those actually ARE cam position signals; how the ecu uses that info I have no idea. Another difference is that those signal coils connect directly to the ecu; the only spark trigger the igniter receives is IGT from the ecu, so there's no spark and the motor can't run if there's no good IGT connection from the ecu. Otherwise, the igniter functions pretty much the same; the ecu will stop firing the injectors if it doesn't receive IGF.

The two ignition systems are explained in more detail, with diagrams, here:
http://www.autoshop101.com/forms/h23.pdf
 

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ok i will start with an intro, 86 4 runner, 22re, manual trans. bone stock all original. I bought it for my son months ago and it had 278k and ran decent so we pulled the engine and dropped in a new 22re due to milage and had the injectors rebuilt.
now, new engine is in, starts up and runs perfect 100%. for only 2 complete seconds. as in counting 1thousand1 1thousand2, dies.
now, ill give you my diagnostic run down (career mechanic with certifications all the way from briggs, john deer, detroit diesel, cat, honda, chevrolet, ford, etc) but im not the best ecm guy.

1-no the distributor is not 180 out
2-yes it has new clean fuel
3 new filters
4 new TPS
5 all fuses and relays have been verified
6 the MAF is opening and sending proper signal to the CO
7 the CO is sending proper signal to the FP ( fuel pump)
8 the fuel pump is opening and sending 42lbs pressure to the fuel rail KOEO
9 noid lights flash on all injector plugs
10 CSI (cold start injector) works.
11 3 injectors =3.59ohms and one is at 5.50ohms on the 20k scale

now. since it only runs for 2 seconds then dies i assume the CSI is priming it but the injectors are not spraying even though there there is pressure and noid lights flash.
yes i have also tried jumping the FP in the engine bay plug to make it run nonstop and still dies in 2 seconds so we know its not the pump or that whole circuit cutting out.
BUT if i stand and give it a shot of carb clean in the MAF it will keep running perfect so this is why i think the EFI driver in the ecm is not working ?

so my questions,
1 is there something in the MAF that sensing the carb cleaner makes it keep running?
2 how do i test the fuel injection driver in the ecm,
3 or am i on the wrong track beating a dead horse and its ignition dropping after 2 seconds?

You haven't mentioned the number 1 possibility, which may cause some of your "electrical concerns". I wouldn't be surprised if your problem is actually quite simple.


The air flow meter is crucial in the early Toyota EFI systems (that utilize an AFM).

There is a "STA" circuit, which is the starter circuit - which overrides the EFI system from it's "safety" (I'll get to this) and ignores some values - particularly the air flow meter - which allows the fuel pump to run without the engine running.

Running for 2-3 seconds indicates to me that there isn't anything wrong with your ignition system - if there was a fault, it wouldn't run at all.

Instead, my assumption is fuel.


The air flow meter is crucial to the fuel pump. It's a safety feature - in that if something happens to the engine (causing it to shut off) then the fuel pump shuts off.

The air flow meter, especially after just starting (and at idle) is sensitive - and anything like a crack in the tube between the AFM and the throttle body, or even a very mild vacuum leak, can be enough of a leak to allow air to enter the engine at idle, and close the AFM enough to shut down the fuel pump.

However, when the STA circuit is started, it will run the fuel pump - and most likely after you return to a "run" position in the key, there is just enough fuel in the system to keep it running for 2-3 seconds. I've seen it time and again.

You can test this by simply going to the diag port and jumpering 12v to the fuel pump port. It may run, but not well. If it runs longer, find the problem in a vacuum leak or the tube (many times the crack is hidden, hard to see, or on the underside where you can't see it).
 
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