Jkludy

I have a 86 4runner 22re turbo that I bought in December. I test drove, was a little rough but thought I could tune it up and not that big of a deal. Drove up on trailer and toed it home. Started up find off trailer and into garage. Sat for 2 weeks, started up fine and drove ok. Then parked another week until I had the time to work on it. Replaced radiator, timing chain, dist. cap and rotor, replaced rear and front brakes, and axels on front. Went to it and it would run for 10-20 seconds and then shut off. Checked timing- right on, replaced circuit open relay, main relay, and AFM, tried again- still will not run. Went through all wiring and grounds repaired as needed, still no run. Replaced fuel filter and checked inside of fuel tank for debris and nothing, still not running. Doesn't appear to be any injector pulse- I checked the injector resistor checks (ohms) ok.There seems to be power on both sides of injector connector off the main harness is this strange? I would have thought there would be a ground on 1 side??? I have 12v to fuel pump until it cranks over and fires and then loose 12v. ?? Hooked 12v directly to fuel pump still no difference. I'm at a loss-- think it could be the ECU- just don't want to spend the money (because I have already dumped a lot in here) if it isn't that. Any suggestions would be greatly appreciated.

Thanks!

Co_94_PU

iTrader: (-1)

Q&A,
The system (s) are primarily switched ground. Specifically the injector should have voltage on both sides and the ECU grounds them to trigger the pulses. No problem.
(?? Is code for what the hell I assume you don't want answers for those)

first the simple things, battery voltage over 12v, clean firm ground at the battery terminal the small wire to the body and the large one to the lower intake. Solid sensor and ECU grounds located at the rear half of the lower intake. No stored codes. Air meter plug fully seated and in the correct orientation. Firm connectors along the intake piping (I tend to forget to cinch the intake pipe at the throttle body). Verify vacuum lines firm and routed per the diagram under the hood.
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OK verify the injector resistor if you haven't already. To high a resistance here will effect to injector open time. To low of a resistance will damage the ECU. I don't recall the Ohm spec, it's somewhere in your manual. You should have more than 9volts for a minimum with the key on between the resistor output and ground. Test lamp between injector and ground flashes during run or cranking.

There is a file pump test connector, if you haven't located it already, in the diagnostic harness. It's a two place "T" configuration with female Spade connectors, located along the left hand inner fender. Where there are two rubber boots attached. You can jumper this plug together to bypass the COR and VAFM (circuit opening relay, and volumetric/game air flow meter) and directly power the pump. One side is B+ (constant power with key on from the EFI relay) and the otherside is FP( battery voltage while running or cranking, it's the pumps positive lead). A test lamp between these indicates proper functioning during cranking and running (as you noticed above, no voltage at crank or run state)

Put a volt meter to one side of the signal generator (distributor pickup coil, plug on the side of dizzy) test for an AC voltage while cranking and run state. I don't remember the voltage range start high and work low, I think it's around 4vAC peak to trough. Follow up with a spark check via timing light and manual (old school spark test, wire less than 1cm from plug top)

Now the fun parts.

You could be building excessive back pressure plugged cat, or failing turbo.

remove the intake pipe from the turbo and inspect for damage, excessive play fore-aft and up-down/left-right no visible contact damage to housing or compressor wheel. Freely rotates.

Relieve pressure: Loosen the turbo from the manifold, if it runs do the the exhaust from the converter to isolate it.
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That should get you somewhere pointed in the right direction.

scope103

While I have little experience with the '86, I believe the following applies to all 2d gen:

1. One terminal of the injector has constant 12v (with key-on); the injector is opened when the ECU GROUNDS the other side. So with the ECU NOT calling for open, you can measure 12v on both side of the injector.

2. "Runs 10 seconds and shuts off" is the classic sign of a COR-VAF circuit problem. You replaced a lot of those parts, but why? You say that you get 12v at pump until it cranks over and fires, then lose 12v. This is exactly what happens when the key to STA (start) closes the COR, then once it starts (and you let go of the key) a defect in the COR-VAF circuit allows the COR to open, cutting off 12v to the pump. But you say applying 12v directly to the pump (so the pump is running ALL the time) makes no difference.

3. At least on later 4runners, the igniter sends the IGF signal to the ECU to confirm the plug fired, and if the ECU doesn't get IGF it throws a code, and cuts off power to the injectors. Do you have any codes?

Co_94_PU

iTrader: (-1)

Confirming, ignition feedback failure presents as the COR does. Start run die promptly after releasing the key.

Thank you sir!

Jkludy

I have tried all the above things- and have gotten nowhere.

Code 3 and 11 & 14. Are you thinking we have an ECU issue and need a new one? I have a new COR and I have another used AFM, that worked in another truck. Possibly an ignition signal issue? thanks!

Co_94_PU

iTrader: (-1)

​​​​​You sir, need to go buy a manual! Code 3 is the NE signal transmitted to the ECU via the Igf..

Dizzy signal generator, ignitor, or broke wire between ECU and ignitor.

Jkludy

I know what the codes are- I am just stating the facts of what I have tried and done. I have gotten my code information off the internet- code 3 stated 'No signal from igniter 4 times in succession'.

sorry for the dumb questions- but what do you mean by dizzy signal generator ?

I've check all my wires between ECU and igniter all good.

Co_94_PU

iTrader: (-1)

Distributor signal generator..

Jkludy

CO_94_PU - the simple things have all been gone through for the 2nd time to make sure all good. Battery 12v (check), clean firm ground at battery terminal (check), solid sensor and ECU grounds (check), Stored codes 3,11,14, I have removed these codes and still same issue. Air meter plug fully seated & correct orientation (check) Firm connector along the intake piping (check) Verified vacuum lines firm and routed per diagram under the hood (check).

injector resistor fell within the Ohms test. output is 11v- between ground and B+ wire.. one is 3.7 to 3.8 and the other is 3.4 to 3.5. The test lamp between injector and ground did not flash like you said it should on crank or run- it stayed a solid light- is this good or bad? so to me this sounds as if it is not getting ground through the computer?

fuel pump test connector- constant 12v I would loose power at the fuel pump after trying to start it-- but sounds if you and the others said this is normal...??

Could be building excessive back pressure in the cat- we don't have one. We checked the intake pipe from the turbo and inspected it for damage and excessive play fore-aft and up and down and left and right and saw no visible damage.

We put a volt meter (Fluke 88 multimeter) and on the primary coil resistance we got .08 to .09 according to others the FMS states .04-.05, my Haynes manual shows .05-.07... Is this an ok reading being higher?

Distributor signal generator p/u coil resistance was 155.2 with key off

Spark test was bright orange/yellow when turning over

Only other thing I did not mention in original post was I removed the A/C unit which consisted of 1 wire and didn't think nothing would affect my removal.

Thanks for any help!

Co_94_PU

iTrader: (-1)

Good morning,

Confirm please you no longer are getting code 3?

Noid light to injector. Seems wrong, someone else want to confirm please, it should be flashing with injector pulses.

Fuel pump, is getting power from either the air meter or COR ( and confirms noid light cycles when circuit is grounded )

I can't confirm the resistance checks for our 86 models, I think close enough is good enough for now.

AC clutch wire shouldn't be any issue unless it was live and contacted something important..

OK back to the injector signal. Which does seem to be the issue like you suspected, They should be triggering during cranking using the startup table in ECU memory. It's possible they cycle faster than the test lamp can respond to, if you want to try an analog meter that would rule that out.

Assuming no code 3 reappeared were looking for a bad ground ( "ground b - engine block"), a loose/damaged wire in the injector harness, or there IS an internal issue with the computer. A bad driver circuit which could be a simple resistor loose or fried, dry and/or blown out capacitor, or a dead transistor. Which are repairable. If it is a problem in the injector timing table it's not reasonable to repair.

Google
site:yotatech.com ground locations "the guide"
And it will give a good post where all those are located. Primarily concerned with the one on the intake, head to body, and then body to battery.

Test resistance between the ECU grounds to the body
e10 and e20 are located on the left-hand side of the plug next to the injector wires #10 and #20.

Verify little to no resistance between the down stream(ground) side of the injector pigtails to the ECU pins "#10" and "#20" (note those are the signal names not a pin number).

If they have good ground and good trigger wires. You'll have to start sniffing around in the computer if you are comfortable with that. The RTE being a smaller production run they can be difficult to replace, so be very cautious.

​​​​​​​Located along the injector circuit there will be a transistor driver circuit. Inspect for scorch marks and similar signs of failure.

Jkludy

Good morning,

Confirm please you no longer are getting code 3?

Noid light to injector. Seems wrong, someone else want to confirm please, it should be flashing with injector pulses.

Fuel pump, is getting power from either the air meter or COR ( and confirms noid light cycles when circuit is grounded )

I can't confirm the resistance checks for our 86 models, I think close enough is good enough for now.

AC clutch wire shouldn't be any issue unless it was live and contacted something important..

OK back to the injector signal. Which does seem to be the issue like you suspected, They should be triggering during cranking using the startup table in ECU memory. It's possible they cycle faster than the test lamp can respond to, if you want to try an analog meter that would rule that out.

Assuming no code 3 reappeared were looking for a bad ground ( "ground b - engine block"), a loose/damaged wire in the injector harness, or there IS an internal issue with the computer. A bad driver circuit which could be a simple resistor loose or fried, dry and/or blown out capacitor, or a dead transistor. Which are repairable. If it is a problem in the injector timing table it's not reasonable to repair.

Google
site:yotatech.com ground locations "the guide"
And it will give a good post where all those are located. Primarily concerned with the one on the intake, head to body, and then body to battery.

Test resistance between the ECU grounds to the body
e10 and e20 are located on the left-hand side of the plug next to the injector wires #10 and #20.

Verify little to no resistance between the down stream(ground) side of the injector pigtails to the ECU pins "#10" and "#20" (note those are the signal names not a pin number).

If they have good ground and good trigger wires. You'll have to start sniffing around in the computer if you are comfortable with that. The RTE being a smaller production run they can be difficult to replace, so be very cautious.

​​​​​​​Located along the injector circuit there will be a transistor driver circuit. Inspect for scorch marks and similar signs of failure.[/QUOTE]

AC clutch didn't have anything connected to it other than 1 wire and the AC was dead so I removed.

I cleared all the codes and then relooked and I have code 3 (which states ignition signal) and code 11 (switch signal). I have power on both sides of the injector connector. I put a noid light in injector connector and have no pulse while cranking.
I opened up ECU and noticed a couple areas that look a bit different than the rest of the panel- I have pics but couldn't upload them. there is a couple areas on the back side of the panel that looked a bit different with the solder. on the other side I have an area D002 and D003 area that only have power on 1 side, I would think there should be power on both??

I checked all the grounds per the drawing from google "the guide" and the intake- ohms .3 resistance, head to body - ohms .4 resistance, body to battery - ohms .4 resistance. The one ground "#3 ground goes directly from cylinder head and runs to the firewall" wasn't on the truck when I bought it- but I installed one to have all 4 complete grounds. One other interesting note on the #4 it states that there is 2 wires that bolt together- I actually have 3-- 1 brown and 2 white w/black tracers- all grounds.

I am leaning towards a bad component in the ECU- hoping to find someone locally to repair. Found one for sale for $325 if needed. Just want to make sure before throwing more money into it.

Thank you for your help and support online- it has been helpful.

Jkludy

AC clutch didn't have anything connected to it other than 1 wire and the AC was dead so I removed.

I cleared all the codes and then relooked and I have code 3 (which states ignition signal) and code 11 (switch signal). I have power on both sides of the injector connector. I put a noid light in injector connector and have no pulse while cranking.
I opened up ECU and noticed a couple areas that look a bit different than the rest of the panel- I have pics but couldn't upload them. there is a couple areas on the back side of the panel that looked a bit different with the solder. on the other side I have an area D002 and D003 area that only have power on 1 side, I would think there should be power on both??

I checked all the grounds per the drawing from google "the guide" and the intake- ohms .3 resistance, head to body - ohms .4 resistance, body to battery - ohms .4 resistance. The one ground "#3 ground goes directly from cylinder head and runs to the firewall" wasn't on the truck when I bought it- but I installed one to have all 4 complete grounds. One other interesting note on the #4 it states that there is 2 wires that bolt together- I actually have 3-- 1 brown and 2 white w/black tracers- all grounds.

I am leaning towards a bad component in the ECU- hoping to find someone locally to repair. Found one for sale for $325 if needed. Just want to make sure before throwing more money into it.

Thank you for your help and support online- it has been helpful.

Co_94_PU

iTrader: (-1)

Check continuity, ECU Igf (middle pin upper row center plug) to the ignitor module. Black-yellow wire.

It's not going to run with a code 3..

Co_94_PU

iTrader: (-1)

You missed this one, or I didn't see the answer.

If you're "done diagnosing" just get a megasquirt PNP. Best bang for your buck ECU wise.

Jkludy

I went out and tested for continuity- my color of wires were different colors-- but found the correct ones and had high resistance on someone elses previous repair I pulled a wire and it came apart- so spliced them back together and WOW--- I cranked it and it is now running! You are a life saver- thanks for the direction and helping me! I truly appreciate!

Jkludy

I did see this and had done this prior. THANKS!

space-junk

iTrader: (1)

Co is the guy to talk to when trying to diagnose electrical issues. And he's always willing to help. Glad you got it sorted! Now, let's see a build thread!

Co_94_PU

iTrader: (-1)

Which one was bad, injector or ignitor wires?

Thinking the last one but wanted a clear answer for the "record",
When others are searching.
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PS, at idle there is less than 10% duty cycle on the injector, so a tiny test lamp is needed around 1.2 volts or less and it needs to stay within the resistance band the ECU is designed for. So the STD 12v noise light isn't going to cut it. Analog volt meter...

Jkludy

igniter wires were bad.

Thanks for your help

I thought I posted a response and I didn't sorry.