Hello i am new to this mazda rx7 club but i have been having issues with my rx7 and cant get to an answer to my problem . Ok so i have no spark from the spark plug wires i have tooken 1 off at a time and checked for spark when cranking engine and it doesnt have spark . I have checked for voltage at the plug that has two wires for the igniter with coil , 2 black and yellow stripe wire at the trailing both of them have power and trailing not sparking . Also tach not working . NOW leading also has 2 wires to the ignition coil to power it. It has the black and yellow stripe and another green wire . The black and yellow stripe has power . The other one just has nothing but 951 ohm of resistance . I am aware that i need to be getting power to both wires but i have read that the power on the green wire is suppose to get 5 volts. Im not gettimg the 5 volts . So i baught the car like that its been sitting for about 15 years . Another thing i have checked the resistance to both coils with igniters the leading one reads 1.6 ohms and the trailing both read 2.3 ohms . According to Manual im suppose to be at .02 - 1 ohms for those igniters with coil . So im stuck between two things i can buy the leading and trailing igmiter with coils since i did the resistance test on them and MAYBE that might fix my no spark issue . But what if i buy them i still get no spark due to the green wire not getting the 5 volts it needs( on the leading coil with igniter plug ) so there is one wierd thing i feel i need to mention . I am almost certain that the spark plug wires are good because for some weird reason when i grab my test light and start poking the wire with no power (951ohm) i start to get spark come out of the wires ??? So thats what throws me off completely. How do i get spark coming out of both leading coil wires by touching that green wire with some power ?? PLEASE HELP

 

The car is a 1986 Mazda Rx7 . When i baught the car off a lady she said its been sitting more than 10 years . Also im afraid i might have mestup something by poking the green wire with 12 volts of + side of battery . And yes when i poke it it starts to make sparks come out of the spark plug wires (leading ones) i feel like i shouldnt have done that . ONE thing i have not tried that i need to try asap is to turn over the engine by hand or even crank it and see if i get 5 volts to the green wire on the leading coil igniter . Because i have check it and it just reads resistance . However i have not spun over the engine by hand while checking if it gets 5 volts . I need HAILERS help is he still around here in 2024 december !?!?!

 

The car is a 1986 Mazda Rx7 . When i baught the car off a lady she said its been sitting more than 10 years . Also im afraid i might have mestup something by poking the green wire with 12 volts of + side of battery . And yes when i poke it it starts to make sparks come out of the spark plug wires (leading ones) i feel like i shouldnt have done that . ONE thing i have not tried that i need to try asap is to turn over the engine by hand or even crank it and see if i get 5 volts to the green wire on the leading coil igniter . Because i have check it and it just reads resistance . However i have not spun over the engine by hand while checking if it gets 5 volts . I need HAILERS help is he still around here in 2024 december !?!?!

 

Check all your grounding points?

 

Hi thank you for the reply and i have actually not done that only the one to the starter and the one that goes to the top of the rotor housing. Can you please help me identify the rest of the grounding points so i can check them

 

I don't have wiring diagrams for FC. I suggest you try to find a link to them somewhere on here.

I think you can probably also find the Haynes for Series 4 and Series 5 manuals on ebay.

 

Ok sounds good i will search threads on here or looks at the fsm for information. And i will get back to you in a couple days and let you know . Because i have work today unfortunately and i will get to the car tomorrow

 

repair manuals and wiring diagrams can be found here

https://www.foxed.ca/index.php?page=rx7manual

 

The coil trigger signal from the ECU is very brief, usually less than 0.01 seconds so you will not see it when measuring voltage on most multimeters. Most people don't have access to an oscilloscope and don't know how to use one, but if you happen know someone who does that is the best way to measure the trigger signal. If your multimeter has a frequency mode, that might be useful.

I'm not familiar with what voltage will damage the ignitor, but if you were able to trigger it by briefly tapping 12V to the signal wire that might not damage it. Some automotive parts that were designed for 0-5V can survive being connected to 12V. Before checking grounds, I would check all the fuses visually, and use your multimeter to confirm that the ECU and CAS (crank angle sensor) have power when the key is on. I'm not familiar with the electrical system of that model year RX7, but hopefully you can find wiring diagrams or old posts online showing what pins or wire colors you should be checking. Good luck.

 

Hello guys thank you all so much for your recent suggestions and help . So today i was testing a couple things out on the Rx7 . Im testing with my multimeter and my power probe hook . When i turn the engine over by hand i am not getting the 5volts to the green and yellow wire at the leading coil i have spun engine slowly and not getting it for sure . Ive read on forums where hailers does this exact test and hes able to get the 5 volts . That 5 volts come from the ECU . So i did check 3 grounding points . #1 The one from Negative of battery to the strut tower then goes to starter bolt connected to engine . #2 there is one right by firewall by the trailing coil. #3 the on on top of the rotor housing . Ididnt remove them but when i touch those point with my power probe right away it says i have ground. But i will clean them up and double check again . Not sure if there is a #4 grounding point . NOW i removed the carpet at the passenger side and i backprobed the Ecu and i verified im getting 12 volts with key ON . However i am not getting Ground to any of the 3 grounding points on the Ecu not sure why but when i check i read 9volts with my power probe hook to the ground wires so somethings not right . Also i have done resistance check on CAS plug and check withing spec at 160 . I have not checked for continuity to ground from the cas to the ecu pins but i have read on forums that the cas is like bulletproof . I will do that next also. But i think my main problem here is that the ECU is not getting the ground it needs . I have a bad ground . So im going to recheck everything worst case scenario i am probably going to rewire the ground points from the Ecu straight to my own ground near the passenger footwell but that is where i am at . Any suggestions what i should do next .

 

There are 4 ground wires at the computer in the 1986 Rx7 N326 Ecu . 2 in the small plug and 2 in the medium size Plug and None at the Large plug . NOW when i backprobe all 4 with key off ONE wire at the medium connector does read ground . The other 3 read like .860 volts (less than1 volt) . But with key on all 4 wires read around 9.6 volts including the one that is ground when key is off . With that being said i believe one of my grounding points might be connected with a positive wire or something like that im gonna stop for today and figure it out later today or next day off .

 

At some point you may want to look in the ecu for any corrosion of the motherboard(s)..

Look for any bent pins.

Look for damage of the harness as it passes through the firewall. It can get damaged, say when someone jams aftermarket gauge wires through the same hole.

 

Hey guys i couldnt wait till next time so i stayed out a little longer and i was able to run a ground directly from the battery to the ecu and that solved my problem . I can now spin the engine by hand and at some point i get 5 volts on my power probe and now i have spark at my leading coil and also my trailing ! Car has not started yet sadly but im getting good spark. I did bring down fuel tank and cleaned fuel tank and added new fuel like a week ago . Also replaced fuel filter installed it in the correct flow direction and verified that im getting fuel out of the filter line . Not sure if im getting fuel direvtly thru the injectors though . Does anyone know an easy way to check if fuel is going into the injectors or maybe i just dont have compression im gonna keep trying to figure it out and eventually order a compression tester . But for now the initial problem is solved thank you all for your help

 

Nice work so far... From what I can remember all grounds from the ECU converge into on wire in the passenger foot well. You will need to peel back tape to find it. If you know how to solider, adding another wire from the point where they converge to the chassis will be a work around and it is actually recommended by some. I don't like adding extra grounds due to ground loops but it has worked for many here.

Here is Aaron's grounding tutorial: Grounding

The easiest way that I know how to check for fuel delivery is to smell for it, most can smell it after some cranking. Take off your plugs and do both, look and smell after some cranking.
Also, using some starting fluid is an easy/cheap test for fuel delivery as well.

Hang in there, with some skill and proper guidance, hopefully another RX7 will be resurrected.

 

HI there i have sprayed a whole lotta starting fluid in it and it doesnt start but it sure sounds like it wants too it even sputters like really fast like its about to fire up but it still has not fired up . It smokes out the tail pipe after that and it smells like starting fluid . Not fuel . So maybe i will pull off the fuel rail and check if the fuel injectors are firing and getting power. It has new fuel pump also and fuel pump strainer forgot to mention .

 

Hi guys the rx7 started up clogged fuel injectors looks to be the problem as soon as igave her straight gas where the fuel injectors go she fired up .