Ok. In my introduction, I said my daughter was offered a free 1986 RX-7 (non-turbo). There's only one problem... It won't start. It doesn't appear to have any spark whatsoever. We went down last weekend to take a look, and spent the weekend trying to figure it out. It seems plagued with electrical problems - ignition switch on, no volts, lights in the center info panel didn't light up, but Sunday I suddenly saw the door light and the low coolant light (and the annoying buzzer) came on. I'm mainly stating the above so that if it is related to a no spark problem, it may jog someones memory.
Now the spark issue...
I went down armed with a digital multimeter, and a CD of downloaded wiring diagrams.
I was a little side tracked because I thought the primary coil was in the back at the firewall, and it turns out it is the one in front!
We tested the wires from the ignitors to the EGI - all good

Cleaned all the grounds. The only one I didn't physically disassemble was the one on the top of the motor, due to time. I did however check the grounds going to the EGI with my meter, and all was good.

With the injectors plugged in, I get 12V to the proper pins on the EGI plug.

We checked for "something" coming out of the CAS using the meter. I know this isn't the most accurate way to test, but it was the only way we had. we saw some sort of signal there.

I have since done more searching, found alot of good stuff on the ignition system, but nothing that will stand out as "This is it dummy!!!", anyhow, I'm headed back down Monday for the week to see if I can get this running for her. I will be a little better equipped this time as I'm bringing my electronics test equipment as well (O-Scope, Signal Generator to maybe simulate CAS signals to the EGU, and an adjustable DC power supply just in case)

Can anyone point me in a logical direction for troubleshooting this?
Is there a way to test the ignitors?
Could there be another common point (either wire or ground) that could cause issues like this that I could look at?
Have I asked the right questions, and if I forgot to ask the right one, could you answer those questions as well

Thanks in advance! Hopefully, she'll be an RX-7 owner soon!

By the way... The car is in walterboro South Carolina if anyone is in the area and feels helpful

 

Sorry, I know this isn't going to be the most helpful post, but take a look at the factory service manuals here if you haven't, they will really help you out:

http://foxed.ca/foxed/index.php?page...nual#secondgen

I would start by checking the MAIN RELAY and fuses, then that the crank angle sensor is working properly, if that isn't working properly you will get no signal to the ignition coils.

Some more threads that may help you:

https://www.rx7club.com/showthread.p...ighlight=spark
https://www.rx7club.com/showthread.p...ighlight=spark

 

As suggested check the Main relay. With key to the on position it should click. If it does not click then check the 15 amp Engine fuse in the interior fuse box. The Main relay has a couple of wires running to it that each have constant voltage and they come from the EGI Comp (White/Blue wire) fuse and the EGI Inj (Black/Green wire) fuse both located in the engine fuse box. At the leading coil the two wire white plug needs to be disconnected and check for voltage on the Black/Yellow wire with key to on. Also, with key to on check for voltage on any of the emission solenoids at the Black/White wire. There are four of these solenoids of various colors (blue,orange,.........) located on the driver side of the engine and each of these solenoids have two small hoses connected to them. The solenoids are black in color but they have a colored dot on top of them.

Make sure the Main fuse in the engine fuse box is good. You can check the Black cable/wire coming from the far side of the engine fuse box for constant voltage and if it does then the Main fuse is good. On the battery side of the fuse box the Black cable runs from the battery to this fuse box but on the other side is the Black cable you want to check for power and this cable drops below the fuse box to a Black connector no more than a foot below the fuse box. You could check for voltage here.

 

I did forget to mention the Main relay. The main Relay is working. It clicks when ignition is on, and sends the 12V to the ignitors / coils, and to the fuel pump. The engine will crank, but it appears we don't get either spark, or Fuel Injector signal.
Due to our lack of proper test equipment, our checks may not have been accurate. Hopefully, I'll have better info later tonight or tomorrow.

 

Actually the fuel pump shouldn't have voltage w/key to on unless it has been rewired so it does have voltage w/key to on or the fuel check connector has been jumpered or the AFM vane is opened. Check the B/W previously mentioned as it leads to the ECU and powers it up. W/o power the ECU will prevent spark from occuring as well as a problematic CAS would prevent spark from occuring. The coil/igniters also need to be grounded to the fender or they won't ignite.

 

Ok, been doing some reading, and testing. The main relay is OK. I tested it with continuity tester, and also by checking for 12V on the ignitors and emmissions solenoids. I checked that the CAS signal (both signals) are getting to the computer. What I don't have is that 5V going to the G/Y wire on the ignitor. I checked the wire for continuity, and made sure it wasn't shorted to ground...

 

Put your scope on the G/Y wire on the leading coil when you crank the car. If you don't get a square wave, it is likely that the ECU is dead or there is a break in the wire between the coil and the ECU.

The ECU will fire spark and literally all it needs is 12V and the CAS signal. That will give the car spark during cranking.

 

The wire is good from the ECU to the ignitor. Would that signal come from one of the transistors in the ECU? If I knew which one, I could change it out and test....

 

Do you know if the ECU is being powered up? If pin 3I has battery voltage w/key to on then you know it is.

 

ECU does have power on 3I.

 

Did you go through the procedure of cranking the main pulley which can usually be achieved by turning the alternator pulley and watch the voltage on the G/Y wire to see if it changed from 0 volts to 5 volts in a repititious manner? This can be measured at both coils. If it is not present, a used ECU are fairly cheap.

 

I have an extra ecu , and I'm in goose creek PM me if you want to come buy and get it.

 

I did that and got nothing, so I also threw my scope on it just to make sure. no signal at all.

 

Got spark today!!! Now to start putting her back together!!
Huge thanks to Chris (Slevin FD) for having an ECU and coil local!!!

Many Thanks!!!

Most likely, more questions to follow... I'm a newbie to these cars without pistons...

 

It's not problem Dave. Just doing my part to keep the rotors spinning.

 

Glad you got it sorted out.

You'll find that of all the issues with the car, the engine block itself will be of almost no consequence. Most issues are external to the core of the engine and just stem from age/abuse.

 

Well, I have spark, but now no fuel it appears. Fuel pump was bad, so I replaced that today, but it still won't start. At times it sounds like it really wants to, but no apples. I first figured that it was flooded from all the cranking, but when I pulled the plugs, they were dry.

 

You want 30 psi with the fuel pressure gauge teed in after the fuel filter and 40 psi with the vacuum hose disconnected from the FPR and higher than 70 psi with the gauge deadheaded to the fuel line before the filter. You also want to see voltage on the Blue wire which connects to the fuel pump at start or w/key to on "and" the fuel check connector jumpered. If you don't have that then you need to look at the Circuit Opening relay near the steering wheel (just to the right of it) which has a white plug connected to a yellow relay. Top right wire (Blue) connects to the fuel pump. Top left wire (either B/W or B/R) should have voltage w/key to start. Top center wire (B/W) should have voltage w/key to on.

 

fuel pump is working. I'll have to rig the Tee up to test the pressure. When I jump the yellow test connector to turn on the fuel pump, should it build pressure and shut off? It doesn't do that, it just keeps running, and I see fuel coming back through the return line.
I'm used to the "other" fuel injected cars that will turn the pump off after pressure is built, but don't know if this is the case with this setup. There are no leaks, but I can hear flow through the fuel pressure regulator.

 

It, being the fuel, should just run as far as I know.

 

When you jumper the yellow test connector on the passenger side you are essentially saying "run the fuel pump, period".

All cars when the key is turned to ON and engine OFF, will run the fuel pump for about 5 seconds and then shut off. Jumpering the yellow plug just turns the fuel pump ON manually, bypassing everything else.

I would check that your injectors are opening with a scope back probed into the secondary injectors located on the upper intake manifold (though primary injectors would be best too, but they are under the intake manifold on the block). That will give you a quick and dirty test since it seems you have fuel flowing already. Check fuel pressure too if you can, but having a new fuel pump would dictate good pressure, I hardly have heard of the regulator failing on these cars, but not impossible.

If both of those are good, I would double check that it really isn't just flooded (to which I think thats your issue honestly).

http://rx7.com/techarticles_unfloodFC.html Take a look at this, PLEASE when cranking, let your starter rest, do 10-15seconds MAX, not 20seconds like they say on there, and use engine oil, not ATF. I gave this link to another member and he burned out his starter!!!! You seem like you know better though : )

 

OK. Chapter 3.
I finally got my first rotary engine to come to life!!! After doing the deflooding, she smoked bad... no biggie, I expected it, but the idle RPM never went below 3000.

 

Ahhh flooded.... just what I thought. These cars can fool you when they flood.

Ok, if the RPM isn't steady at 750rpm after the smoking stopped (did it stop?), next think to check is vacuum lines. If you forget vacuum lines, the car will idle higher, if you forget a decent sized vacuum line, the car will idle high and smoke a bit from it trying to richen itself up to keep the engine running.

Check over all the lines going to the throttle body, the upper intake manifolds, and the black intake tube.

Then, at the top of the throttle body is a flathead screw under a black rubber cap if its still there. With the BAC disconnected (the bypass air control valve located on the upper intake manifold with a WHITE plug, right in the middle of the fuel injectors), adjust the idle when the car is warm and A/C OFF. Clockwise to decrease idle, counterclockwise to increase idle. Set to 750rpm.

How long did you run it for? It has an accelerated warm-up system that will keep the car idling high until it is warmed up! (Ignore this if you let it warm up, then the issue is with a vacuum leak or idle set too high).

Oh and an old method of checking for vacuum leaks is having a small propane bottle and spraying around the engine bay. When the engine moves the propane in the air through the vacuum leak, it will burn it and will idle HIGHER. Propane can be substituted for carb cleaner. Do at your own risk : )

 

Did you try to close the throttle by hand just in case it was stuck?

 

Good point. If the idle comes down when you close the throttle by hand, check the cable that goes to the accelerator pedal and the cruise control cable. They both can be adjusted.