1984 GSL-SE

My GSL-SE stops randomly while driving around. It idles nicely and has good power. It has stopped while idling in the garage. It has stopped while cruising through the neighborhood. It has cut out while accelerating from a stop sign.

Where do you start looking to cure such a problem?

It had sat for a year after the previous owner installed a battery backwards. It blew the fusible links. I replaced the fusible links. It has a laundry list of other electrical issues now. High beams don't work, hazard switch doesn't work, remote mirrors don't work. Most everything else works.

Thanks.

 

Have you changed your fuel filter? that would be my first guess on a car that sat for a year. It also could be old battery cables. The aluminum ones that came stock internally corrode. I'd start there then check the FAQ for a larger list of things you should probably start replacing...

good luck -ERIk

 

I recall a member stating that there is a plug near the washer fluid bottle for the electronics that could be corroded or loose, which could cause an intermittent problem.
I would not put money on fuel filter. That excuse is overused. Electrical is most likely from your description.

 

I finally got back to the 7 and I did some more diagnostics.

I hooked up my timing light to see what was happening.

1. On normal idle I hooked the light to the trailing coil wire and watched the timing marks - looked good
2. After awhile (~3minutes), the timing light went intermittent. The engine was running fine. Then the engine just quit.
3. I did this several times and each time the timing light stopped and then the engine quit.

I haven't gotten into the ignition wiring and control circuitry yet. Has anyone experienced this yet? Any quick pointers to where to start looking? I had the engine running and pawed through the wires in the vicinity of the coil and the distributor and couldn't get it to fail.

Thanks again for the responses.

 

Get a fuel pressure guage installed and see what happens with your fuel psi when the motor dies.

Next I'd throw all fusable links in the garbage and walmart carries plastic replacements like newer cars have. I've been through too much crap with fusable links cause I has some that if you shake them they would work and not work.

Inspect your ingniton system, mainly under your distributor cap and closely examine the contacts. Make sure they are straight and clean.

Loose or poor spark plug wires, I once found a loose spark plug on mine!! Mazda dealer!!

Keep us posted with any new info!

Over look harnesses aswell.

 

Quick note.... your injectors will close if there is a ingition failure. They are hooked up together so when one works the other works!

 

Sounds like your trailing ignitor is failing (you lose the timing signal when connected there just before the engine dies). There is a black wire crimped in with a yellow/green-trace wire that is the coil fire signal. The black wire goes back to your ECU and triggers the Tachometer signal and Injector Pulse - this is how the ECU knows when to fire the injectors.

If you can see the trailing ignition go out and then the engine dies, then you're losing your tach/injector signal, which then triggers the ECU to shut off injectors.

Quick fix - cut the black wire from the trailing (front) terminal, but leave the yellow/green wire intact to trigger the coil. Crimp on a spade terminal to the black wire and then attach this to the corresponding terminal on the LEADING coil (rear). This will trick your ECU into firing injection off of the leading coil. If your engine then functions without cutting out or shutting down, then you've solved your problem - replace the trailing ignitor.

When you get done with this diagnostic 'quick-fix' be sure to reattach the black wire to your trailing coil - this is the only way that you'll know there's a problem with Trailing ignition which has a marginal effect on torque, power, and fuel economy.

Try that and let us know what you find out - picture here for clarification showing how you should attach the black wire to the Leading Coil terminal (blue spade connector on the right in this picture);

 

Thanks to everyone that have responded. Much appreciated as I come up to speed on this car.

Here is what I've done:
1. A new fuel Filter
2. Replaced all of the battery cables
3. Inspected the distributor cap and the parts under the cap
4. Capt Murphy - I checked under the fluid containers - I couldn't find the connector you were referencing. The cable bundle under it does look good.
5. I haven't gotten to the fuel pressure
6. I did the fusible link trick. Very cool. Replaced the hack job the previous owner had done.
7. Wires, plugs, distributor cap - next payday.

After this, this the stalling still persists.

LongDuck - Thanks much for the post. I think you have me pointed in the correct direction. I did the tach wire switch to the leading coil. I haven't driven it extensively, but it didn't die at all. It died every few minutes before. It idled in the garage for 20 minutes without quitting (a record). However, the tach does flick to zero and then back to normal on occasion. With the tach wire on the trailing coil, it went to zero and stayed there until the engine stopped.

All in all, I think it is the igniters. Both seem to be sick, but the leading igniter seems to be stronger.

All of this is probably a consequence of the previous owner reversing the battery cables.

Now, where do you get a good set of igniters? I'll hit the local junk yards. Victoria British wants $189 each. Any other sources?

Again, thanks much to all.

 

For what its worth. I took some pictures of my oscilloscope showing the electrical waveforms on the negative terminals of my coils. I don't know what they are supposed to look like, so if someone can provide interpretation, please do. Since my scope is uncalibrated, time and voltage are not defined.

 

The scope traces look right. Here is an example of what they should look like (bottom of page):

https://www.rx7club.com/1st-generation-specific-1979-1985-18/transistor-trick-2gcdfis-411312/page2/

For ignitors, try the 1st gen for sale section on here or ebay. $15 or so is a common price for them used. Any ignitor from 81-85 RX-7 will work. They are labeled J-109. Also when installing the ignitors, get some heatsink compound (RadioShack, computer stores) to put on the back of the ignitor. This help transfer heat away.

There is also a connector, as capt murph mentioned, under the washer fluid reservoir. It is a yellow connector with 4 wires. There is a YG and black wire that conencts to the trailing -. These then go to the ECU, which fires the injectors.

When connecting the wire to the leading, you should unplug the trailing ignitor (black box on distributor closest to the alt). The black and the yellow/green wire eventually connect together at the ECU. If you keep it connected the problems with the trailing could be influencing the leading.

 

The weekends were made for fixing RX-7s.

Latest update.

1. Drove the RX this last week - no hiccups. (the tach still occasionally drops to zero with the sense wire on the leading coil)
2. The weather turned cooler - 32 deg at night. Not northern latitude cold.
3. Failure to start in the morning
4. I got it running this morning after cranking for several minutes - thanks to the new battery cable setup. It smoked a lot - Normal? I got some neat pictures and a video clip if someone is interested.
5. It ran and started well until it cooled off again
6. I tried to restart and it failed after much cranking
7. Checked the plugs - wet, wet, wet with fuel
8. Cranked the engine and sat the plug on the shock tower. Excellent fire on the plugs. A fog of misted fuel was blown out of the plug hole, so looks like it has compression (I haven't done a pressure check)

Sorry for the enumeration, force of habit.

To me it seems that the injectors are getting turned on. Both rotors were wet with fuel, so that would indicate that both are on.(?) Hard to believe that both would fail simultaneously. I keep thinking about the battery reversal that shelved the car for the last year. Could that have affected the ECU? Any ideas?

OBTW, I found the connector under the windshield washer fluid tank. It looks very good. This is a California desert car, so rust and corrosion are very limited.

I still haven't checked the fuel pressure, but with the current situation, I don't think that is the problem.

Thanks,
kerniew

 

Here is the latest on my 7.

1. New spark plug and coil wires.
2. Inspected the fuel injectors - good rail pressure and good spray pattern.
3. 10 feet of new vacuum hose - the old stuff was breaking like porcelin.
4. Installed a different (ebay) trailing igniter.

Despite 1,2 and 3. The igniter was the dominant issue. I have the tach sense wire back on the trailing coil. It started well and the tach no longer drops out. WooHoo! I drove it several miles and idled in the garage for several minutes and it didn't die once. It doesn't stumble coming off the line either. I have another set of igniters on order and I'll then replace the leading one also. That one is sick also.

Thanks much to all of the people who contributed to this! It saved me a lot of time and money.

kerniew