2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

no start problem, only sparks 1/3 CAS rotations

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Old Mar 13, 2012 | 07:14 PM
  #26  
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Originally Posted by durtled
cursed fc
I've been operating under that theory for awhile now. For many reasons.
Originally Posted by gxl90rx7
a standalone ems is the only solution. FC wiring sucks
Yep. I agree with that 100%. Still better than the FD though.
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Old Mar 14, 2012 | 06:52 AM
  #27  
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Where are the grounding wires under the dash? And anyone know what wires go to the coils and Injectors?
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Old Mar 14, 2012 | 10:32 AM
  #28  
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Originally Posted by Walker04950
Where are the grounding wires under the dash? And anyone know what wires go to the coils and Injectors?
Oh I have a wonderful Factory wiring diagram ... Mad rare and splindifferously complicated.
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Old Mar 14, 2012 | 11:07 AM
  #29  
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Four firings of one turn of the CAS is normal. Yours isn't.

Pull the CAS out of the engine and leave the elect plug on it.

Pull the small white, two wire connector off the Lead coil assy. Backprobe the black/yellow wire in that plug.

Turn the CAS by hand while watching the meter (key On, engine OFF). See how many 0-5 signals you see when turning one full turn. Matters not which direction you spin the CAS, same results.

Each time the meter goes from 0vdc to 5vdc you should get a firing and you should see that four times when doing this.

Let's say you see four trigger signals (5vdc shows up). Then it isn't the ECU or wiring or CAS as the problem, it's further downsteam i.e. coils assy.

On a series four car, the wires b/t the coils and the ECU are a straight shot with no connector inbetween at all. On a series five that is NOT the case.

MY guess is that those wires are ok. Now the CAS four wires have a connector b/t the CAS and the ECU. Make SURE this connector is in place and connected together properly and also ohm out the CAS wires from the ECU plug to the CAS plug and while there make sure none of those four wires is going to gnd (both ECU plug and CAS plugs disconnected doing so).

The plug that is inbetween the CAS and ECU is called FE-04 (front harness to engine harness)
and if memory serves is somewhere below the brake booster/master cylinder area.

Also answer this.................when you get in the car and stare at the tach needle.....does the tach needle make one bump upwards when the key is initially turned to just ON???? Should.

Series our TURBO EM harness in a NON TURBO car???? Yes or no. Yes from what I understand. How did you handle the alternator wiring if that is the case. How did you handle the boost sensor wiring that is different than the non turbo vs the turbo em harness?

Nothing wrong with stk Mazda RX wiring at all in general, if someone has not buggered up the connectors.

http://rx7.pw.cx/guides_manuals/coll...ystifying.html
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Old Mar 14, 2012 | 11:20 AM
  #30  
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******* Therefore, and this is important, in one eccentric shaft (crank) revolution, an ignition event occurs every 180 crank degrees.********

The above from the attachment in my other post above.

And we know the CAS rotates at 1/2 eccentric shaft speed............so in my mind four firing events with one full CAS rotation is normal and makes sense.

And just in case.........either of the coil assys MUST have at least one of their attach fasterners in place. The ignitor in each pack gets it's gnd from the body of the coil assy touching the chassis for a gnd point. Also the battery neg cable has a splice off it that attaches just at the base of the left front strut tower.This is the main CHASSIS gnd point on the car.
Attached Thumbnails no start problem, only sparks 1/3 CAS rotations-feofour.jpg   no start problem, only sparks 1/3 CAS rotations-feohfour.jpg  
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Old Mar 14, 2012 | 12:21 PM
  #31  
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From: jordan ny
its not a ton of money to build a mega squirt. aaron has a write-up. also. maybe go crazy and run some grounds. id hit the fire wall, alt bracket, keg, maybe one on the frame somewhere. had a towncar once....kept blowing throttle cables...after the 3rd cable i figured out that the throttle cable was the best ground to the fire wall....from that day i hook up grounds everywhere. better safe than pissed.

Last edited by durtled; Mar 14, 2012 at 12:25 PM.
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Old Mar 14, 2012 | 03:45 PM
  #32  
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Haliers,

The car is an S4 Turbo with an S4 NON-Turbo EM harness.
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Old Mar 14, 2012 | 04:10 PM
  #33  
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From: FORT WORTH TEXAS
Originally Posted by 20B10AE
Haliers,

The car is an S4 Turbo with an S4 NON-Turbo EM harness.
Ok. But remember that turbo and non turbo EM harness wiring does not match up unless steps are taken to make them match up.

And were the harnesses on the left side of the engine changed out for any reason?

Also..........on non turbo the alt wires are in the EM harness and on a Turbo car the alt wires are in the ENGINE harness on the left side of the engine. So the question is......is the two wire plug meant for the altenator in the EM harness connected to ANYTHING at all? That plug has one black/white wire and one white/black wire.
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Old Mar 14, 2012 | 04:18 PM
  #34  
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Originally Posted by HAILERS2
******* Therefore, and this is important, in one eccentric shaft (crank) revolution, an ignition event occurs every 180 crank degrees.********

The above from the attachment in my other post above.

And we know the CAS rotates at 1/2 eccentric shaft speed............so in my mind four firing events with one full CAS rotation is normal and makes sense.

And just in case.........either of the coil assys MUST have at least one of their attach fasterners in place. The ignitor in each pack gets it's gnd from the body of the coil assy touching the chassis for a gnd point. Also the battery neg cable has a splice off it that attaches just at the base of the left front strut tower.This is the main CHASSIS gnd point on the car.
Grounds. The enemy of any FC owner. So if the CAS is verified good, the wiring has been replaced with the proper 4 wire shielded cable (I assume you properly grounded the shield), the ECU has been changed, the wiring to the coils is verified, changed out coils, I'd start with beefing up the ground wires. If that fails, then back probe EVERYTHING on the ecu with the key on. If there's a sensor that's shorted or something, it could be sending weird signals to the ecu. Maybe not even a sensor, but wiring going to a sensor could be shorting out. I've definitely seen some weird signals going through ecus, doing some crazy things to outputs because of a completely unrelated system.

The FSM does have a voltage pinout section for using the breakout box, but a multimeter works the exact same.... just a little slower. Do NOT use a test light, you'll blow stuff up inside the ecu. If you have one, use a logic probe, they're great.

Like I said, if it's not fixed by next weekend, I may be able to drop by and take a look.

-Green
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Old Mar 14, 2012 | 05:53 PM
  #35  
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OOOOPS. I made a big mistake in my posts above. I should have written to backprobe the small white two wire Lead coil plug and backprobe the GREEN/yELLOW wire in that plug NOT the black/yellow (batt voltage with key ON).

I feel the problem lies in the fact you have a non turbo EM harness mated with the Turbo Front harness. Need answers to questions posed in my other posts to try to help out.
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Old Mar 14, 2012 | 06:56 PM
  #36  
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The engine harness isn't the problem I just put in the NA harness last weekend because my s4 TII engine harness was doing the same thing so I thought changing it would fix it guess I not
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Old Mar 14, 2012 | 07:25 PM
  #37  
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I quote myself sometimes too

Originally Posted by AGreen
...If that fails, then back probe EVERYTHING on the ecu with the key on. If there's a sensor that's shorted or something, it could be sending weird signals to the ecu....
-Green
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Old Mar 15, 2012 | 05:24 AM
  #38  
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Originally Posted by Walker04950
Where are the grounding wires under the dash? And anyone know what wires go to the coils and Injectors?
You have to answer questions posed to you to be helped.
Attached Thumbnails no start problem, only sparks 1/3 CAS rotations-wire.jpg  
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Old Mar 16, 2012 | 06:02 PM
  #39  
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Depressed bump
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Old Mar 18, 2012 | 03:03 PM
  #40  
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Ttt any other ideas?
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Old Mar 19, 2012 | 08:30 PM
  #41  
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Start unplugging sensors to see if you get spark when spinning the CAS. It really is worth a shot.

http://www.rotaryheads.com/PDF/2nd_g...tems_turbo.pdf

^Page 32 gives standard voltages for ecu pins.
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Old Mar 21, 2012 | 01:40 PM
  #42  
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Ttt REWARD first person to get her running gets $200
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Old Mar 21, 2012 | 01:42 PM
  #43  
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Update now I have no spark when I spin the CAS
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Old Mar 21, 2012 | 01:50 PM
  #44  
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W/key to on, the Brown wire in the 3 wire TPS plug should have about 5 volts. Does yours?
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Old Mar 21, 2012 | 02:42 PM
  #45  
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Negative its a 4 wire clip black white red and green and I'm pretty sure its 2 signal wires and 2 grounds wires
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Old Mar 21, 2012 | 02:44 PM
  #46  
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My bad thought u meant CAS I don't have a tps on my UIM but that wouldn't effect the CAS and coils
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Old Mar 21, 2012 | 02:53 PM
  #47  
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I have spark again 1/3 CAS spins like before
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Old Mar 21, 2012 | 02:55 PM
  #48  
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I only have spark when my egi fuse is plugged in wo could it be an injector problem?
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Old Mar 21, 2012 | 06:45 PM
  #49  
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The EGI fuses supply power to the coils via the main relay, and the EGI fuses also supply power to the ECU which in turn supplys the trigger signal to the coil ignitors when the CAS signals to the ECU are correct.

EGI INJ fuse supplies power to the individual injectors and coil assys, just like the jpg I attached a number of threads ago show.

EGI COMP supplys power to the ECU and also the numerous solenoids on the engine.

The CAS signal to the ECU determines when each injector fires and when each coil fires.
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Old Mar 22, 2012 | 05:06 PM
  #50  
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Ttt all my voltages check out any other ideas?
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