HAILERS

*********I'm curious. I wonder. The Lead coil assy has a small two wire plug. One of the wires is Black/Yellow. That is 12vdc for the coil assy. The other wire triggers the coil ignitor. Forget the trigger wire. If possible, put a meter on the black/yellow wire. Key ON. You should see batt voltage. Put the key to START and let the starter turn the engine over. Does the battery voltage stay on the black/yellow wire as the engine is spun with the starter??? Not that I can think of anyway it would disappear, but....I wonder.
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I think this one is worth doing and it won't take much time. Gone for the day.

Delphince

End of another day. As I made my last post we had been trying the "shadetree" method as you called it, and it seemed to be working like I said. We got the motor to be kicking and bucking, and would run for brief moments at a time, but only for moments on its own fuel and even with starter fluid (which it should have ran on even with the AFM plugged in but seperated). This went on for about a half an hour, then the ecu seemed to cut out like the others and stopped sending spark anymore unless the middle ecu connector is unplugged.

The ecus are 326.

No idea about the harness being turbo or not. I certainly hope not, but I'll look for the plug.

I'll give it a try.

HAILERS

Yes. I missed the two batterys. It was a bit late when I read/wrote that last post.

There's something else that makes no sense. You say in your last post that you only had spark if the middle plug was disconnected. The middle plug supplys the ref voltage to the sensors like the TPS, has the afm signal, tps etc.

Well, that might be a clue. Maybe. The ECU sends that ref v signal to the tps, afm etc and maybe one of those wires is the culprit. You pull the middle plug off and now you have spark again. The ref v is used inside the ECU for spark/injectors pulsing etc and that part seems to work unless the middle plug is connected up. So maybe the TPS, afm, variable resistor, pressure sensor is pulling that ref v down if the middle plug is connected. The engine should start with the afm plug off, just won't stay running.

Pull the plugs off the afm, tps, variable resistor, pressure sensor and then see if you have spark if the middle (all) plug is connected up.

Another thought is to pull the middle and small plugs off. Go to the ground wires in the PLUG. With a meter see if they are less than one ohm with the key OFF. They should all be pure black wires. 2R, 3A, 3G, and 2C. In other words I'm wondering if the ECU is properly grounded. Its gnd is on the top of the rear rotor housing. Intake has to be off to check that area, but using a meter on those wires I just mentioned should verify it or not.

Look at the online FSM, Fuel section and a subsection called Control Unit. It shows what each wire in the middle plug goes to. It might give you ideas. Any plug going to the solenoids on the rack can be removed along with any connected to the ACV, tps, boost sensor.

I don't know. I do know I'd go to the middle plug and compare the signal at each wire, especially at the middle plug and or actually ohm them out from end to end i.e. from the ECU to the item in the engine bay and check each wire for being shorted to gnd while doing so.

Wow. Two battey car. humor.

HAILERS

Here:

The plug is read from top far right to the left, in an up/down manner. 2A is on the top row, far right. 2B is just below it.

2A is the ref voltage output of the ECU. I'd bet big bucks this voltage goes to zip when the key is put to Start. That means the internal ref voltage also goes to zip and there will be no spark/fuel

2A feeds the TPS, ATP, Pressure Sensor, variable resistor, afm. The afm will NOT work without that voltage from 2A therefore it won't stay running if started.

2B...not required for running.

2c....a gnd that IS required.

2D....definetly not needed.

2E...required for running

2F....not required

2G....not required

2H....not required

2I....not required but will make the start mixture lean if the engine is cold.

2J....not required

2K....not required

2L.....not required

2M....not required

2N....not required

2O....not required

2P.....not required

2Q....not required although it will make starting a little more difficult. Adds a large amount of air during start.

2R....Gotta have that.

Saying in my own way, that you could unplug those Not Required and the engine should start. Some effect the actual running down the street, but do not effect Starting and idling on the whole.

Delphince

I ran out of time and had to get my brother a plane ticket home; not an easy thing to get one 24 hours before departure for that matter, either.

No longer pushed by a deadline, I'm tired of it and tired of chasing ghosts that can kill an ecu. The engine and everything running it is going to be ripped out and thrown in a very dark corner. I guess this string of posts is going to be added to the very small number of threads that have been written for this problem and never figured out. I'll probably just drop in my existing engine and harnesses once I get this turbo swap done, and rip the problem motor to pieces and put it back together with new stuff or just throw it off a long cliff. Dragging my brother away from work and across the country for nothing more than a few long nights in a garage and a couple drinks has been nothing short of both embarrassing and infuriating.

HAILERS, dude, thanks for sticking with me on this one. Maybe someday I'll figure out what went wrong, but not today. In the meantime, your input was both inspiring and motivational.

Edit: One other thing I noticed. On the last day I scooted the driver's seat forward to look for a dropped tool, and found a bottle of No Smoke under the seat. I promptly unbolted the cats and about a pint of oil drooled out. Oil control rings must be toast and have been for awhile. I want to smack the guy that sold me the car upside his head. "Ran fine and parked last year" my posterior.

HAILERS

As they say, Cool.

Just remember something about a turbo swap into a non turbo. The Turbo EM harness (one that fits on the engine) is not pinned the same as the Non Turbo EM harness. In other words, a turbo EM harness will be mating with a Non Turbo FRONT harness, and the wires in the EM harness will not be mating with the right wires in the Front harness.


Some wiring changes have to be made for it to work right.

On Rotary Resurrections site he tells how to make these small changes so things will work right.

Somehow I think that's the last thing you needed to hear at this point in time.

I've no idea what was killing the spark in your car. Eternal Infernal mystery. Later

helghast7

iTrader: (6)

you know in my experiences i have found that electricity is extreamly lazy, so after your statement about all the oil being in the exhaust, it makes me think that the wire running off the ecu that controls the tps nad all that could be rubbing the wire for spark and one of those wires or sensors could be saturated with oil, or any liquid.

since , like i said, electricity is lazy, it could be traveling to the saturated wire. if this is the case then it would be something on one of the other wires or sensors and only travel there, since al the other sensors would activate when on the start position...

my logic is a littly looney i know, but thats because its late, im just trying to help

theonlygreat

I fixed this same exact problem yesterday on an 86 that has been sitting for 2 years. It would only give one spark right when you stopped cranking. All it took was cleaning up and tightening the main grounding points (and the negative battery terminal), then adding the extra ground at the boost/pressure sensor on the passenger side shock tower. It sparks like a champion now.

RotaMan99

HAILERS, if the vref voltage dropped from a faulty sensor, could that also cause the trailing ignition not to work at all?

I am suspicious about the vref voltage wire since it seems we had a short in the harness when I first got the car running after swapping manifold and wiring 2 rpm switchs and a relay box, I narrowed it down to about a 6" area near the TPS plug but with the plug depined, the original problem seemed to almost disapear and then moving wires around, the problem vanished. This problem im talking about was one of the primary injectors doing equal rapid clicks in even waves, very strange. Anyways, its not doing it any more but I can make the engine rev a few rpm higher and lower by moving the TPS plug which is slightly odd, even when its not plugged into the TPS.

Sorry to hijack the thread but im looking for any possibilities.

The two Black/Yellow wires in a single 2 pin connector, am I supposed to get 12v+ on both those wires?

HAILERS

Where is there a two pin connector with two black/yellow wires?????? That's not ringing a bell with me.

And about THE ONLY GREAT's remark. The boost/pressure sensor isn't needed for spark or starting the car. I Wonder if adding the extra gnd to the sensor didn't do something else all together. What I'm saying is, is that all the gnds for all the sensors in the engine bay are all connected together inside the EM harness and all terminate together at pin 2C on a series four car. So, maybe the ECU gnds are not bolted to gnd on your engine. That gnd is located on the rear rotor housing just to left of center line.

That makes sense if you grounded the brown/black wire on the pressure sensors plug (could be pure black on a later car). Series four.

Primary injectors clicking without the engine running and the cas not being turned????? Only if the wire from the injector to the ECU was touching gnd somewhere inbetween. Usually when I hear someone asking about unusual clicking, I think it's just the BAC doing it duty cycle. Normal. Engine does not have to run for the bac to click.

TPS plug off and movement of the plug itself makes the engine rev different???? Shouldn't do that unless one of the three wires is bare and touching *something*.

I've lost Trail spark and the tach a couple of times. Each time it had something to do with a dead battery being jumpered and engine starting again. I've no idea why. Started sparking later as normal and tach worked again. I suppose the ECU does not like to see real low voltage. Guessing. No idea why the trail stopped sparking........for a short period of time.

If one of the sensors like the afm or tps or boost sensor or variable resistor causes the ref voltage to short out, you won't/can't have spark because you've killed the ref voltage inside the ECU as well.

RotaMan99

The BACV was not even plugged in. I still hadn't moved the connector from the drivers to the passengers. I was putting on the S5 mani.

It was coming from UNDER the UIM and the only electronic devices under there are the primary injectors. Only one was clicking. It was not random clicks either, it would be 10 rapid clicks, pause for 1 second, 10 rapid clicks, pause, etc. If I moved the harness around it would go down to maybe 2 clicks, pause, 2 clicks, pause, etc. I never heard of anything like this. I would almost understand if the injector was doing random clicks, but these were even numbered of clicks with even pauses over and over again. very strange.

Sorry, might have been black/white, they come from the main relay to the trailing coil?

Thats what I was thinking, I couldn't figure it out. I held the connector so that nothing in the harness would move and only wiggled the connector.

So this would kill spark to both leading and trailing which obveously would cause the engine to not start. Damn, this engine starts, just no trailing at all.

Im thinking of either replacing the harness with another one, or rebuilding it.

HAILERS

Well, there is a two wire connector with two BY wires, but it connects to the Trail Coil assy. The same BY wires are tied to the Lead coil assy also. Yeah, they feed the coil assy 12vdc. Forgot about that. Both should have 12vdc on them. Feeds both coil assy's. One for each coil. Maybe one of those wires isn't carrying it's 12v for some reason? Only one trail coil powered up could cause your problem since the other isn't capable of firing.

The only thing that could make a injector click would be if there was a bare place on that injectors wire that runs b/t the injector and the ECU making contact with bare metal. If the power wire to the injector was bare it'd blow the EGI fuse and not do the click thing.

Did you make that voltage measurement on the Trail coil (at the ECU pins), with the plugs off the Trail Coil??? Maybe forgot to put the trail coil plugs back on. I'm talking the electrical plugs not the sparkplugs. That might account for a high voltagle at the pins 1X, !U, 1M.

RotaMan99

I think I got 12v on both wires but I will have to tell the owner to test it again since he has the car.

Both trailing coils don't fire at all.

If I do a continuity test on the wires, how much resistance is exceptible. I always look for a real low resistance but don't know how much is to much.

Suppose I could use ohms law eh?

Strange, I have no clue. I couldn't understand how it did that. Next time it comes up in the spring, im ripping into it again. I may or may not be installing a megasquirt. Depends how much he has to spend.

I took the measurement at the ECU with the coil mounted and plugged in. Sparks disconnected.

Could the ECU grounds cause issue with the trail coils?

btw, I found out on my car a month ago that you can start and run the engine with only the trailing coil or only the leading coil.

HAILERS

IF you disconnect the plugs at the ECu and at the coil assy and ohm out from end to end on each wire the resistance should read less than a ohm for sure. Then while one meter lead is on one end of the wire, touch the other end to a known ground. There should be no reading showing that the wire isn't shorted to gnd.

Tried another ECU lately?

HAILERS

The only way I can get HIGH readings like you guys did, is if the plugs(small white plugs from the ECU) are off the Trail coil. Then 1M reads 12vdc, 1U reads 5vdc and 1X reads 0.15vdc.

Normal idle readings are 1X-0.72vdc.........1U-2.2vdc.........1M-1.3vdc

About the injector.......are you sure someone didn't connect the water thermo sensor plug to a fuel injector plug and vice versa?

RotaMan99

Yup, I thought that was it but I swapped my ECU into his and the same issue arrised. I then though maybe something in the harness shorted mine out too so I swapped it back into my car and it works fine.

Ya thats fine. I never unplugged the water thermosensor while doing the work. It was really strange, would happen as soon as you turn the key to the ON position.

Its not doing it now, some how I got it to stop before giving it back to him.

Thanks, that gives me numbers to shoot for. More testing needs to be done though.