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Thread: No Spark
12-28-2011, 06:29 PM #1
I am in the process of putting a 5m out of an 83 supra in my 85 pickup.
So I had some ignition yesterday, then I did some checks on the igniter and fixed a wire on my afm which I realized was Incorrectly wired. Now I have no ignition. The primary and secondary resistances on the coil check out, as well as the distributer coil. Also I do have 12V at the coil.
The 5V IGF signal from my ecu is not present though, I only get ~0.2V on the green wire coming from the ecu and no apparent voltage on IGT when cranking.
The TSRM's advice is to try a new ECU, I am on a pretty tight schedule right now and tracking down another ECU probably isn't going to happen in time.
I have done all the wiring myself so if the ECU isn't shot it could be a mistake I've made, however I can't for the life of me think what it could be.
Here is the pinout I found for an 83 5M. The far right connector is the only one I have touched. I have 12V at IG/SW Bat and +B. All relevant AFM wires are hooked up.
M-Rel isn't connected as my main relay is hooked up directly to the trucks ignition switch. Could this cause trouble?
It would appear that wiring this thing to run is painfully simple but it's giving me nothing but headaches.
My grounds seem okay, I have gone over every inch of the head, block, and Intake manifold with a multimeter and there is continuity throughout. All ecu grounds have continuity with the body as well.
The Distributor is stabbed correctly, timing belt is fine and set correctly.
Any advice would be welcome, I really don't want to have to give up on this.
12-29-2011, 01:31 PM #2
b, +b, batt, and ig/sw all should have power. also, make sure e1(both), e2, e01, e02, all have continuity to ground. check these at the ecu itself with the key in the "on" position. once those are verified, then go from there. btw, that main relay needs to be on during cranking, otherwise itll never start.
12-30-2011, 01:22 PM #3
b, +b and ig/sw all have power. All e's coming from the ecu have continuity with ground.
Igt and Igf are the issues I've found so far. Igt has no voltage when cranking and Igf does not have the ~5 or 6 volts it should.
That is the thread I used for some guidance on checking out the igniter circuit, see tech26's post. That green wire does not have 5v in my car.
Top is how it was wired in the car, bottom is how it is now wired in the truck.
Here's how my wiring is set up for b+ and such. It is how the ecu was powered in the truck previously. All the switched 12V signals are powered by a physical ignition switch not a relay which the ecu controls. Hence my M-Rel not being connected. The //---- indicates that nothing is connected, not that it grounds or connects anywhere else. Would the ecu require some current through M-Rel to turn something on internally maybe?
12-30-2011, 01:43 PM #4
its possible. i havent seen an internal schematic for the ecu itself. mrel might need to be hooked to the coil of a relay and the other side grounded(for resistance so it isnt a dead short to ground). however, so far its sounding like the ecu got fried. have you run the tests on the igniter itself? id run those. if it checks out. sounds like the ecu took a dump. wether it was something wired wrong or what i cant say as i didnt wire it.
12-30-2011, 04:39 PM #5
What did you do with the wiring of the AFM? For the R to M series swap (minus the 82 setup), you have to repin 2 wires, or you will not get ignition.
Here is what the AFM plug should look like after you swap the brown, blue/red, and black/yellow wires, and just leave the black/yellow wire disconnected.
Last edited by 83CelWA; 12-30-2011 at 04:59 PM.-Chris
1983 Celipra GTS:
6M bored .50 over. 250cc injectors. Delta 272 regrind cams. Carter HF fuel pump.
Pacesetter header w/2.5" cutsom exhaust. Open air intake filter. 3" piping to TB. 65mm TB & ported AFM.
4:10 rear from Supra. BillyM shifter kit. Swapped most interior over to black. T3 camber plates.
935 Budget Coilover kit. KYB AGX struts. T3 Needle bearing upper perch kit. Eibach Sport rear supra springs. SF Ford TFI Performance coil.
Almost finished with the fiberglass hatch!
12-30-2011, 05:30 PM #6
Initially I had forgot to change the afm wiring. After it wouldn't start at first I realized my mistake and changed the wiring on the ecu side not directly at the afm. I'll look over it and make sure that one of the wires I left connected doesn't go to ground somewhere else in the harness or anything foolish like that.
I also tried another igniter last night and didn't get anything. Not completely ruling out the new igniter being bad as well but the guy I got it off of seemed to think it worked.
12-30-2011, 07:30 PM #7
its sounding more and more like a fried ecu im afraid.
12-30-2011, 07:58 PM #8
There's always a silver lining to every bad situation. I'm quite certain my ecu is fried but at least I think I know what happened. On my harness that black and yellow wire is just black so it didn't occur to me that it
was actual a 12v hot wire. So I used it for my vc. Which then fried the ecu.
Thanks for your help will and 83cellwa. At least now whenever I manage to find another ecu it isn't gonna fry too.
12-31-2011, 01:09 AM #9
Got your private message. Looks like you've already figured it out though. If you're not getting the 5 volt reference from the ECU then there's something wrong with the ECU. Double check the power wires AND the ground wires for the ECU. If the ECU doesn't have a good ground it wont work either. I think it's understood without saying, but, giving 12v power to a signal wire is bad. At this point, I would open the ECU case and look for spots that look like they got really hot and burned / melted. You can also try smelling the ECU after it's opened to make sure it's a dead ECU.
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