No Spark for my 7M-GE

[rfurgy]

I don't know if anyone here has done this or not and I might even get made fun of for doing it but oh well. My first Supra was NA with the 7M-GE but was wrecked in an accident but the car ran beautiful. I managed to find a clean donor shell close by which needed a heart transplant. The problem is that the Supra that the NA motor went into was a Turbo car. I have successfully installed everything I need from my first Supra to the other. Motor, tranny, drive train, wiring harness, computer, etc... Even did all the gaskets and seals while it was out.

I'm having a problem now though because I have no spark. I've been going over stuff and can't seem to find where the problem is. I just reset the crank, cams and timing belt to make sure everything is lined up there. I also made sure that the distributor is in correctly as well as my spark plug wires. I've checked over the engine harness and have everything hooked up. I even researched the earths that are located near the starter. By the wiring schematics I figured out that the white ones go to the intake and through forums that the brown ones should be bolted to the head. I didn't change the secondary harnesses that run through the fenders though but as far as I can tell that shouldn't make a difference but I could be wrong. I've narrowed it down to the coil so far which means I'm not getting spark there. I'll be testing the coil but I'll bet it is good because it came off the other car which was running fine. So even without testing the coil yet, I'm wondering if anyone could possibly help. I'm starting to think it has something with the wiring in some way. I've even changed all the little components like relays to make sure it wasn't that.

Is there something I'm overlooking?

Thanks,
Rob

 

[CyFi6]

Check the green connector at the coil and the distributor, a lot of times one of the wires will pull out of the connector slightly and youl get no spark at all. Just make sure theyre both tight and use some needle nose pliers to make sure alll of the actual wires are pushed into the connector all the way.

 

[rfurgy]

I have now made a closer check of the green plugs. They are in working order with tight connections. I have also changed out the IGN and EFI fuses to make sure that wasn't it.

I keep thinking that it's something simple but can't put my finger on it.

 

[AJ'S 88NA]

I have now made a closer check of the green plugs. They are in working order with tight connections. I have also changed out the IGN and EFI fuses to make sure that wasn't it.

I keep thinking that it's something simple but can't put my finger on it.

There is only 2 wires that go to the starter. The hot from the baterry and the one that goes to the selenoid. The grouped wires that look like they could go there are grounds attached to the manifold. I just posted that in the other NA/T thread.

 

[Kckazdude]

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=IG&P=5

It will probably be something you find that was forgotten. I just performed this same swap into another car. With the exception of all the other wiring nightmares it went smoothly.

 

[castrol supra]

:aigo:WOW:aigo:

Save that to favorites.

I was just about to give him the same thing.

 

[rfurgy]

Ok, the coil checks out (ohms are good), the distributor checks out (ohms are good). I've checked for wiring breaks to the igniter and I have good harness wires there (the IGT, IGF, E1, and of course the 12v pos from the Ignition switch). I'm in the process of checking the distributor harness for breaks. I have voltage to the coil (12v) but don't have anything coming out when turning over the engine. The EFI and ING fuses were checked and good.

It's starting to look as if the worst possible situation is happening. A bad Igniter (Ignition Module). Hope I find a break in a wire somewhere because I don't have an extra ECU or Igniter to try on the car.

Is there ANY way to test the Igniter? The Cygnus manual says to try another ECU or Igniter if the wiring checks out. Which I don't want to go buying either of them just for a 50/50 chance of it working. These parts aren't cheap at all and don't really know how they could go bad from sitting around. Not to mention I made darn sure that I was careful while handling them.

Oh yeah, I would also like to test the signals from the computer to see if they are correct but it seems that the Cygnus manual says that the car is suppose to be Idling but how can that be when I'm trying to find why the car has no spark. Is it simply stating that the car has to be turning over?

I'll update if I find more and any help is greatly appreciated.

Thank You All

Almost forgot, does anyone know how the pickup coils work in conjunction with the signal to the computer for it to send the signal for it to fire? I noticed there are 3 pickups in there. I'm assuming the G1 and G2 pickups are to determine when cylinder one is at TDC on the compression stroke and when it isn't. I am also assuming that the NE pickup is close to what a cam or crank sensor would be doing. Could it be possible that I need to make a 180 degree turn on the distributor in order to get spark? Although I'm pretty sure that I have it at TDC for cylinder one, this has crossed my mind. I guess it wouldn't hurt to try at this point.

 

[Nick M]

Did you pull codes yet? You are looking for 12 or 14. 14 is specifically igntion failure. That doesn't mean component failure, just that you didn't get IGf to the ECU.

 

[rfurgy]

Haven't pulled codes yet but not sure if there will be any because the computer has not experienced the problem while running. Which in most cases the car normally has to start and run for like 10 seconds before any codes will be stored by a diagnostics system. I will still be giving it a try just to exhaust every angle.

Things I've Checked and Found

1. Wires from ECU to distributor and igniter - Ok
2. Pickup coils - Good Ohm readings at distributor and at ECU end of harness
3. Igniter - 12V coming out of igniter to go to the coil
4. Coil - Ohm readings check out good
5. Grounds - In place and seem to have good ground at least for main circuit
6. Timing - Crank notch at zero and cam gears line up with the plate notches indicating TDC.

I just read on a website from someone who rebuilt a supra and encountered this same problem and also went through a bunch of troubleshooting with it. The person came to find out that he had a bad ground to the ECU that when fixed, the car started right up. I will be checking into this because my situation sounds very close to what that site was saying. I'm no electrical expert and not even how the ECU is suppose to be grounded.

If I find that my grounds are good then I will conclude that I have a bad component in the system. With the wires being good my findings would indicate that either the signal to the igniter is bad which would be the ECU or the igniter itself has somehow gone bad. Which I find it absolutely strange that either of those would go bad. The battery was removed from the car before disassembly and I made sure to handle all my parts with care to avoid damage while out of the car.

 

[jetjock]

1) NE (Number of Engine revolutions) provides rpm and crank position information. G1 and G2 provide reference signals used in conjunction with NE to determine TDC. Output of all three should be a minimum of 1 volt p/p at cranking speeds.

2) The ECU is grounded at the intake manifold. If the CEL comes on with the key the ECU has at least one ground but you should check E1 at the connector to make sure that one is there.

3) Measuring resistance is a poor way to check things.

4) All that is required to output IGt is a powered ECU, working NE and at least one G signal, and good wiring. Timing is irrelevant in a no spark situation.

5) Removing the distributor and spinning it by hand while monitoring the primary ignition circuit is a lot easier on the starter and battery than cranking.

in most cases the car normally has to start and run for like 10 seconds before any codes will be stored by a diagnostics system.

There are several codes that can be set on cranking alone. Checking for them should have been one of the first things you did.

 

[Nick M]

There are several codes that can be set on cranking alone. Checking for them should have been one of the first things you did.

Does no STA shut down EFI?

 

[jetjock]

^ Can the car be push started?

 

[Nick M]

Unlike these clowns, I have never had to push a Supra. I think they have said they parked it on a hill before now that I think about it.

 

[jetjock]

Clowns? On SM? Say it ain't so

No STA doesn't kill EFI. STA only effects duration and timing and those effects get dumped once rpm crosses 500 rpm. In fact a whole bunch of things happen at 500 but that's another story.

 

[Nick M]

::dunce::

Yes and no on the timing. Timing is retarded with the STA signal, but you have it turned up. Considering all the people that run advanced, I don't think it is the problem, even though it is a problem.

I wouldn't worry about the STA signal too much, since it stalled while driving. The STA signal is to retard timing during cranking.

:slap:

 

[kwutzo]

This sounds like pretty much exactly the issue my car is having at the moment. If you could keep this updated I would appreciate it, and if I get mine running I'll let you know

 

[rfurgy]

Well, another week has gone by and still no spark. :3d_frown:

I'll do a recap for anyone just coming in on this post. I have no spark for my 7M-GE in an 87 Supra which had the 7M-GTE but had everything swapped from the NA car. The NA car was in an accident 2 months ago but was still running then. So in theory the car should be starting because I have everything I need.

I now have the motor, tranny, computer, wiring harnesses (motor harness and main relay harness [the one that runs through the driver side fender and to the battery]). I haven't changed the harness inside the car yet though. I was hoping I could avoid that, but I'm thinking that the Turbo harnesses might be that much different that they all need to be changed. Which if anyone know for a fact that they do, just let me know so I can try to bypass the harness for the time being till I get the harness out of the other car.

With some voltage and ohms checks, I discovered some weak grounds to the computer (which are repaired) and some missing/dropping voltage which I don't know how is happening. With checking cygnusx1.net I realized that the part of the computer that controls the EFI is tied into the part that controls the spark. Which makes sense, you need fuel and spark to get the bang. So I decided to trouble shoot some of the EFI circuits to see if I was having a problem there (even though I have no spark I was curious) The part I found and chose to check into is at this page -> http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=33

By going through the steps I discovered (while ignition was to the ON position)
BATT - E1 = Getting proper voltage
IG SW - E1 = .01 Volts (way out of range), should be 10 - 14
+B/+B1/M-REL - E1 = Starts at .3 Volts (way out of range), should be 10 - 14 but then drops about one thousandth of a volt per second. Electrical noob here but isn't that what is called a Voltage Drop? If so, any tips as to finding it?

Also found that my Check Engine Light is not coming on. Haven't checked the bulb for it but my guess the bulb is good and I have a problem getting power/signals to the computer to run the part of the system which controls the Ignition and Fuel.

Pretty much everything under the hood is from a running car. I ended up swapping out the EFI main relay harness because of this, thinking that the harness that came with the donor shell may have been bad. Unfortunately it didn't do the trick but was worth a shot.

Going over this in my head, any of the components from the running car shouldn't be the problem. I'm not leaving them out because I know all too well how sometimes things just happen. Chances of it though are very slim. I bought this car off someone who had done a bunch of stuff to it and I don't think the person really knew what they were doing exactly and halfed on the efforts that were needed. I can only assume that there is most likely a problem somewhere in the car that I have yet to get to.

I've been working on this car for over a month and really need to get this thing running. I'll have to be using it to replace my beater (which is getting worse by the week). Please, anyone who can suggest things to try or check into then bring it on. Plus I thank all of you who have at least read this thread and thank those who have suggested things even more. If it wasn't for the help I don't think I would be this far in the troubleshooting process.

 

[cuel]

I doubt this could be the problem, but the tach. is different between the turbo and n/a. I have this pic to show the differences, and how to change the n/a tach. for a turbo swap. You could probably do it the opposite way, or just swap in your n/a gauges.



As far as the problem at hand, I don't have any help to offer.

 

[Nick M]

If your check engine light doesn't come on, and you have no spark, I would think a little harder about a bulb being burned out or not.

 

[jetjock]

Based on the post no IGSW means no Main Relay closure means no +B to the ECU. No wonder the MIL isn't coming on and there's no spark: the EFI system is dead. Stop focusing on spark and start focusing on getting the ECU powered up.