rotaeng

I had previously set timing on my 1980 Rx7 a few months ago. After getting my carburetor problem fixed, I decided to recheck timing. Leading plug is perfectly lined up with 1st yellow pulley timing mark. When I attach to trailing plug it is also at 1st yellow timing mark. When I try to adjust with the vacuum unit, it will not adjust to 2nd red timing mark. I am confused. The engine seems to be running ok and with the prior timing I did there was no problem with timing marks(trailing with red 2nd mark). I would appreciate any thoughts on why this is occurring or what I am overlooking. I relooked at plug wiring and see no problems.

rxtasy3

iTrader: (2)

the trailing timing is an internal adjustment on the dist. if u or someone else has messed with that adjustment it's probably still ok. i could be wrong but i just can't see how both leading and trailing can line up on the same mark.

gsl-se addict

iTrader: (3)

Most common issue is that the inductive timing lights can pickup the leading signal, even when connected to trailing. Try moving the pickup and see if you can lock on to the trailing.

Other issues:

- the '79/'80 cars only fire trailing part time in order for the thermal reactor (SA's version of a cat) working. It should be firing for you, but the circuit box that controls this might be bad

- the '79/'80 get their tach signal from leading (since trailing sometimes does not fire). Because of this, it is hard to know if trailing is working at all

If the trailing isn't moving when moving the pot (and it is lined up with leading), it is likely that your light is triggering on leading. As I mentioned, try moving the timing light pickup and also check for spark on the trailing plugs.

rotaeng

Thanks for your time and advice! I greatly appreciate it. I tried moving the pickup on the timing light multiple times and no help. I did have another "electronics" box, that the ignitors attach to, and I changed this out. No help.

By chance, I located the following information from Racing Beat about Cross triggering in 1980's Rx7's.
If this is the problem, do you have have any recommendations on how to remedy this?

As stated earlier, Mazda began equipping their rotary engines with "breakerless" ignitions in 1980. With the 1980 model RX-7 the electronic components were located in a separate box, while the 1981-85 RX-7 models’ electronics were mounted on the distributor housing. Aside from simplifying the ignition, this change has eliminated a major problem we had seen in the earlier 1980 ignition system - a tendency to "cross trigger" between the leading and trailing ignitions.

This cross-triggering, which occurs randomly, causes the trailing ignition to fire at the same time as the leading ignition. The result is very dangerous to the engine at higher power output.

Cross-triggering is a very common problem with "aftermarket" ignitions used on rotary engines. The problem arises because Mazda's rotaries have two complete ignition systems that normally do not fire at the same time, while virtually all the other cars in the world either have only one ignition or, if they have dual ignition, the ignitions fire at the same time. This problem can be observed with a timing light connected to the trailing ignition, and will show up as a variation in timing, occasionally switching between the leading and trailing timing settings.

Copyright 2007-2012 Racing Beat, Inc ©

gsl-se addict

iTrader: (3)

Have you verified that you are actually getting spark on trailing? You could take a trailing spark plug wire and insert a spare sparkplug or a screwdriver and lay on the strut tower. Crank the car over and see if you have spark.

Kentetsu

Doesn't the trailing only fire part time on SAs?

Upgrade to an electronic dizzy, much easier.

Make sure your plug wires are routed correctly. Top is trailing, bottom is leading.




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rotaeng

Again, much thanks for your ideas and recommendations!

Checked for spark in trailing and leading plugs and both are good. Any other thoughts?

Re: electronic dizzy. Can you Explain what you mean or how this is done? I thought the 1980 distributor is electronic (no points).

Kentetsu

Hmm, you may be correct. Not sure if the 80s came with points or not...

gsl-se addict

iTrader: (3)

The '80 is electronic, but the ignitors are mounted away from the dizzy (on the strut tower). It is the only RX-7 like that. The '79 was points and then the '81-'85 are all about the same.

However, because of the remote mounting, the '80 has more problems with interference on the signal wires between the dizzy and the ignitors.

rotaeng

Do you think upgrading the ignition with a Jacob's FC 1000 Fire Control Ignition System might help remedy this cross triggering problem, or can you think of any other solution?



From Rotary Perfomance, Inc.:
Need ignition? Jacob’s rotary FC1000 is the one to have. We’ve installed this system on countless RX-7s and have been nothing but pleased with the results. Cleaner plugs and no misfires. This is a true capacitive discharge system, not just a simple restrike system like the HKS Twin-Power. This system actually amplifies the spark with up to three times the spark intensity. The FC1000 can be used with the factory ignition coil, but many often maximize the system with the addition of a performance coil. An additional feature is a dedicated tachometer output. This lead can be used for a shift light input, rpm activated switch, additional injector controller input, etc. Priced reasonably, this system installs easily with standard MSD connections. Install one today.

FC1000 by Jacobs Electronics

Thank you!!

rotaeng

As noted in my prior posts, I was having a cross-triggering of trailing and leading with my 1980 Rx7. Since I could not resolve this, I got a used 1984 distributor and installed this. Initially it seemed to be working well, then I rechecked leading and trailing timing. Leading adjusts perfectly. Trailing timing was off, so I attempted to adjust through the vacuum advance component on the distributor. The timing mark will not move at all. I pulled the distributor cap and looked at the timing adjustment connection which is good. As I moved the trailing lead adjustment the ignition pickup moves freely and with no apparent problem.
I am baffled as to the problem. Is it the ignition pickup that needs to be replaced?

rotaeng

I was having a cross-triggering of trailing and leading with my 1980 Rx7. Since I could not resolve this, I got a used 1984 distributor and installed this. Initially it seemed to be working well, then I rechecked leading and trailing timing. Leading adjusts perfectly. Trailing timing was off, so I attempted to adjust through the vacuum advance component on the distributor. The timing mark will not move at all. I pulled the distributor cap and looked at the timing adjustment connection which is good. As I moved the trailing lead adjustment the ignition pickup moves freely and with no apparent problem.
I am baffled as to the problem. Is it the ignition pickup that needs to be replaced?

gracer7-rx7

iTrader: (16)

merged into existing thread. please do not start new threads on the same topic. thanks.

Kentetsu

I really hate to ask this, and I hope you forgive me, but I'd hate to see you split your scalp on a brick wall while chasing the wrong dog...

Are you 100% positive that all spark plug wires, and the ones from the coils to the dizzy, are wired correctly. Are you sure that your trailing plug is not receiving a signal from the leading (not just cross-talk)?


I only feel compelled to ask that question due to the fact that you have installed another dizzy and still have the same issue. I suppose that maybe your ignitors could be wired wrong, both producing a leading signal. Hmm.
Anyway, I hope it turns out to be something simple. Best of luck.




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gerald m

^^^ And also if the two wires on either pickup are reversed it will give you a progressive retarded effect .. I also believe that in this type of system that will fire even on an interupted signal that the condenser on the dist. be hooked up to help stop any spikes from the coil system .. I think I have only had one or two people agree that this is possible ,, That condenser is not for the radio although it may help static and if so that shows that is helps stop spikes .. JMO

rotaeng

Thanks for the recommendations! I really appreciate everyone on this forum. Working on this RX7 has been a learning experience like i have never had on other cars. I am going to recheck the wiring again.

Kentetsu

Switched wires can happen to the best of us. I was doing some testing a few years back for a new ignition system that was under development, and at some point when I was switching back and forth I ended up reversing the ignitors.

I spent the next year or so trying to figure out why it was so hard to get good performance out of the motor without running in to spark knock issues. Needless to say, when I finally stumbled across the answer, I felt like a total dope. But, I will never laugh at anybody when it happens to them now.

DTech

Hello I've just joined as a new member and I am having the same problem! I just discovered it tonight.

I recently bought an RX7 and have been tidying it up a bit. Someone has previously rebuilt parts of it and there were lots of things only half bolted on so I have been going over it all and fixing it up. Otherwise it is a neat little car.

It is a 1980 or 1981 model (the stamping on the compliance plate is hard to read) - either way it is a Series 2 with an electronic ignition.

The motor had been running a bit rough so I thought I would check the timing. First thing I found was that two of the ignition leads had been switched so that the leading plug was connected to the trailing terminal on the distributor and vice-versa. It's amazing the engine was running at all.

After fixing up the leads I tried to adjust the timing and found that the leading and trailing plugs both fire at the same time (same problem as rotaeng). I guess that explains why the crossed ignition leads didn't cause any major problems. I tried moving the vacuum advance unit to alter the trailing timing and found that this had no effect. Both leading and trailing plugs still fire simultaneously. And the exhaust is smelly a bit like unburned fuel.

Is this the same cross-triggering problem? Is it a common problem with the early electronic distributors?

gerald m

Make a short movie so we can hear what it sounds like and maybe see something that is not correct .. Even a bad plug wire can cause all kinds of problems .. dist cap cracks , bad coil wiring , bad plug wires , incorrect wiring ..

rotaeng

Boogieman: Thanks for the response. I have all new wires, dist cap, rotor. I will make a video, although now I am having a problem with the carburetor flooding, which I thought I had this fixed.

DTech: Are your ignitors mounted on the side of the distributor? If so then you should not be having this cross-triggering problem.
If your ignitors are mount behind a gold electronic box on the strut tower, then you do have a 1980 model and I would bet your problem is the cross triggering. I am in the process of installing a 1981-85 Distributor where the ignitors are mounted on the distributor. I could not find any other solution to this problem. If you find one, please let me know.

DTech

rotaeng my dizzy is wired up to a black box over on the strut tower so it is a little different again. Mine is an Australian delivered model so that might make the difference. But it does look like an external set-up. I'm having someone look at it tomorrow.

gerald m thanks I'll take a few photos and give everyone an idea of what I am talking about.

Car failed its roadworthy certificate today. Rear windscreen wiper didn't work! Come on - half these cars never even had a rear wiper - it was just an option. So what does it matter if it doesn't work?

Kentetsu

Both trailing spark plugs are supposed to fire at the same time. They fire once when they need to, and then once again when they don't need to.

Leading plugs should still fire separately though...

gerald m

Kentetsu is correct and very knowledgeable on this stuff .I am not so sure you have corrected anything at this point .. but good luck

DTech

My problem is that the leading plug is firing at the same time as the trailing plug. And I have found the reason - the external black module mounted on the strut tower is off a V6 engine!. Apparently the original modules were mounted on the distributor but have been removed. Someone must have been feeling industrious to install this set-up. It works but only just. Looks like I need a new dizzy.

Kentetsu

For 1980 only, the ignitors were mounted on the fender. Only later years were mounted directly on the dizzy.