Hey guys, i have a 84 GSL-SE that is having some troubles. recently the alternator died on me and then the battery dropped to 8V and the car stopped running. I tried bump starting it on a huge hill but it only sputtered at the beginning then nothing. I swapped in a spare alternator and charged the battery then when i tired starting it, only one rotor would fire. I checked compression and spark on both rotors. The weird thing is itll run on either rotor but not both at the same time. I checked the gas coming into the intake and it looks like its flowing fine. Does anyone have any idea why both rotors wont fire at once?

Thanks,
Nathan

 

I was able to get it running on both as far as i can tell but it has a hard time idling and doesn't want to rev up. It doesn't sound right. My dad who doesn't know anything about rx7's says it sounds like the timing is off. I cant see how it could have changed by its self though... Could the air/fuel mixture have changed at all? What could have gone wrong when the alternator died? Could something have fried?

Thanks,
Nathan

 

After it runs, if i pull out the trailing plugs, they are drenched in oil/gas. The Leading plugs are fine though. Any ideas?

Thanks,
Nathan

 

Alright - welcome to the wonderful world of the -SE.

"Running on One Rotor" - is out here if you search. I know, because I wrote the damn thing! What this came down to for me is that the Fuel Injector pigtails (those wires that energize the fuel injectors and come from the harness) need to be replaced. Over time, the hard plastic insulation on these pigtails gets cut or frayed, or the internal wire cracks, and then you get a fuel injector that won't fire. You can help diagnose this by grabbing the wiring harness where it splits off behind the alternator when it's misbehaving, and pulling the harness back and forth. If it magically runs fine and then runs crappy when you move the harness - BINGO! Borg-Warner pigtais were all of $7.50 each (x2), so save up your lunch money for a few days and there you go.

Plus, didn't you say you just replaced the alternator recently? That wire harness is the same one with the injector plugs on it, so my guess is that it got torqued or tweeked and cracked the wire somewhere along the way.

"Trailing Plugs are Wet" - Well, this gets a little more complicated. I'm not sure what your technical ability might be, but Trailing Ignition has an effect on idle quality (smoothness), power, and fuel economy. The engine will run on Leading Ignition, only - but won't idle well, power will feel 'down' at lower RPM, and fuel economy will probably drop off, as the engine isn't burning all of the Air/Fuel mixture. In order of likelihood of being the problem, follow these simple steps;

1) Plug wires/Coil wires - plugged in correctly? Fairly new? Corroded or missing? Replace with a set of known good and make sure they're wired up correctly (Psst - they're labeled on the distributor cap!). Also, Leading is on the bottom, Trailing is on the top - not trying to insult you, just making sure we're clear about these things...

2) Swap Ignitors - These are located on the sides of your distributor, and 2 screws per ignitor hold them in place (*the one facing the alternator is Trailing, and is a pain to get to those screws). Take the one facing the front of the car (Leading), and swap it for the one facing the alternator (Trailing). Car won't run? Then it's a bad ignitor that you just swapped to where it counts (see above re: spark). Replace the Ignitor, and you should be good. If the car runs just as bad as before - then your ignitors are probably not the issue.

3) Is your tachometer working on the dash? Because if not, it gets it's signal from the Trailing Coil, and if the Trailing Coil isn't firing, you're not going to get Trailing spark, either. You could swap the coils if you're feeling up to it (*note: The coil toward the front of the car is the TRAILING coil, and the one closer to the back is the LEADING coil - Mazda is kinda screwy like that, aren't they???). Car won't run now? Probably a bad coil now on the Leading Side, since you need Leading spark for the engine to run. Tach working now? Yep, that's the Trailing Coil sending a good signal to the computer. Replace the bad coil.

Don't mess with your timing. If it was running fine before all of this alternator/dead battery/messing with it, then the timing is probably fine. Tell your Dad that American Idol is on, and get back to the steps, above.

Good luck, and reply back if you find it - I'm sure someone will stumble on this thread in the year 2054 and be pleased that it was well-documented.

***Glanced and saw... your Trailing Plugs are drenched in OIL??? Explain.

 

Hello, thanks for the reply. I tried wiggeling the harness but it goes to the left of engine adn then back around the front of car to get to underneath the intake. Dident seem to make a differnece. Both ignitors work and i did a coil swap. Front rotor is 1 rear is 2. I made sure of this when i hooked the the plugs/wires. wires and dizzy/rotor is a week old. Plugs are 10K old. All spark. Tach works and bounces. SO i pulled off the intake last night and am gonna replace all vac hoses underneath. What am i looking for at the injectors? Anything i need to remember to do?

Thanks,
Nathan

 

I got the injectors out. The one over the rear rotor appears to have a cracked plastic seal at the top. I dunno how this would affect it however as the small o-ring is still intact. The picture may be hard to see, but the plug that connects into the injector with the cracked seal, is also partly broken. Are these "pigtails" you are referring too? Also the picture of the injector has a red arrow on it where the crack is. Would a crack like that affect the injector? I have some spare injectors off of a parts car that i took that plastic piece off and swapped it back onto the injector. What would cause this plastic piece to break other then the heat? I also notice that what i think it the temperature gauge sensor is cracked, its green sensor thing as shown in the photo. The temp gauge worked last time the car ran though. That is the water temp sensor right? Should it be replaced?

Thanks,
Nathan

 

Excellent LongDuck! This info is exactly what I've been searching for. Well written. It's 2015 not 2054, so you got to see someone appreciate your post in your lifetime

 

Glad I could help (3 years ago!).

 

Hey LongDuck,

1. Watch my recording of my dashboard tach while trying to start the car. Does it tell you anything about anything? (functioning normal? trailing coil? trailing ignitor? etc.)

2. I assume the ignitors are the same whether for leading or trailing. I have a used one that has been tested and the seller told me to put a thin film of dia-electric grease on the silver side of the ignitor before mounting on the distributor (something about dissipating the heat and preventing hot spots on the ignitor thus improving reliability.) Is this a common practice?

Thanks for reading and any helpful advice!

 

Well, since this 3-year old topic is kind of in the same realm, I'll respond here.

You video shows me a few things;
1) Your battery is low, possibly from cranking it - it should show above 12V when cranking, and when still should be around 13.5 volts or so, which leads me to...

2) Your cranking speed is slow - due to your tired battery. In order for the engine to develop compression quickly to the degree it needs to start, you need to crank that thing over pretty rapidly, especially when cold and/or the seals (apex-, corner-, oil-control-, etc.) are going out. The less compression you have, the faster you need to spin the engine which is why a rotary that won't start with the starter can sometimes start through push/pull starting - as the road speed helps to spin the engine over faster.

3) Your battery gauge flickers when you go 'Ignition/Crank' - which could be a tired/old fusible link (driver's side wheelwheel forward of the strut top). Fusible links can sometimes pass low voltage but fail at higher voltage - which is why they're designed as fuses. Pay close attention to the 'IGN' and 'MAIN' links.

4) Your engine builds oil pressure during cranking, which is good.

That's all I can tell from your short video. On the separate issue of the ignitors, it's pretty common to add some dielectric grease to the back of the ignitor to help it dissipate some heat to the distributor, but it's not necessary. The ignitors are identical and can be swapped at-will to check function - which is more accurate than the FSM suggested test rig, which isn't 100% as a diagnostic tool.

The fact that the tach is bumping at all is a good sign that the trailing ignitor/coil is probably firing properly, but I'd feel more confident if the tach was showing 1000rpm during cranking instead of just bouncing off the peg from vibration - which it could be. And which would indicate a problem with the ignitor/coil on the trailing side, which if you recall also tells the ECU when to trigger the fuel injection.

 

BIG SMILE. Thank you, LongDuck! The tach used to bounce (spike) up to about 1000 RPM about every second or so when cranking but now the needle just sits on the peg and flutters a little. I thought that might be a sign of something not working properly (coil, ignitor?)

I had no idea about the other things (batt should be 12V+ when cranking, tired/old fusible link, tach should show 1000 rpm, etc.)

You're right about how difficult it is to remove the trailing ignitor. Looks like you need to remove the alternator.

I'll work on this project later. Now I have rats in the attic to deal with... Good grief.

Thanks again, and I'll keep everyone posted :-)