rotaeng

Got rebuilt distributor and installed. Check coils for proper trailing and leading connection. Getting Vacuum to trailing vacuum control unit on the distributor. Spark plug wires double checked for proper connections trailing and leading spark plugs. I can set leading timing without problem to yellow timing mark. Trailing timing (with a timing light connected to trailing plug wire) is also at yellow leading timing mark. Adjusting Vacuum control unit does not change timing. Car starts easily and idles well. Any suggestions or thoughts?

OneEyeMick

If you can move the vacuum pot and it doesn't change the timing for the trailing check to see if it is connected in the distributor correctly. Just pull the distributor cap off. When you move the vacuum pot back and forth one of the magnetic pickups should move back and forth. If nothing moves, check the rod that connects from the vacuum pot into the inside of the distributor. It should hook up on the inside. It might be easier to explain with pictures.

If you can adjust the trailing timing but not within spec. Maybe your distributor is off a tooth.

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rotaeng

Thanks for your help!! Vacuum pot is connected. Magnetic pickups move back and forth with vacuum pot movement. I checked vacuum pot with vacuum tester and it appears to be moving OK. Rod is connected. Check vacuum to trailing vacuum pot running and is 30cm Hg. I pulled out the distributor several more times and aligned tally mark and timing mark. Set timing for leading. When I test trailing there is a small movement toward the trailing timing mark but is it only about 1/20 of the distance.
If any other ideas, I would greatly appreciate it.

OneEyeMick

This is strange. The vacuum pot should be able to move fully within the grooved slots of the screws that hold it on. It looks to be about a centimeter of movement back and forth on the one I checked.
I know there are quite a few slight variations over the various RX-7 models. Possibly a mismatch of parts in the rebuild is causing the problem. But that is just mere speculation.

t_g_farrell

iTrader: (1)

What are you hooking up to when measuring the timing for trailing? Details on exactly how you r doing this may help us help you.

Benjamin4456

When you checked for vacuum, were you at idle? If so, there's an issue there somewhere (unless it's some sort of smog thing I don't know about). The vacuum pots are for advance, and should only see vacuum around part throttle.

Like others have said, the movement is fairly large (as in it should be noticable), so my thought would be that the arm connecting the pick-up to the pot is either loose or somehow worn, or that the pot is damaged/the bearing that the pick-up is attached to - I can't remember if it's leading or trailing that is physically attached to the large 'bearing' - is frozen and that is causing limited movement....?

Does the mechanical advance work? ie, disconnect the lines to the vacuum pots and plug them (the lines, not the ports on the pots), and then rev up to 4k-ish and see if the timing advances.

My last thought is that your timing light is picking up the leading signal. I know this has happened to me before, so try changing where the inductive clip is located on the plug wire or move the plug wire away from the others while testing to see if that makes a difference.

t_g_farrell

iTrader: (1)

So you know you need to put the timing pickup on the front rotors trailing plug wire right? If not that would explain your results.

GSLSEforme

rotaeng

Thank you for everyone's thoughts and recommendations. In answer to some of the questions
1) I am using KAL inductive timing light and putting it on (Front rotor)T1 and L1 spark plug wires to check trailing and leading timings respectively. I don't believe the trailing connection is picking up the leading wire signal. I moved the connection as far as possible away from the leading spark plug wire and it did not make any difference. Moving the trailing vacuum control unit setting does not affect the trailing timing. Note the trailing time is not exactly at the leading mark. It is probably about 4mm toward the trailing timing mark.

2) With manual vacuum tester, both vacuum control units (Pots) move easily and completely. The Trailing vacuum control unit fully moves and the signal rotor shaft lines up with trailing pick up coil when manually advanced (Engine lined up with Leading timing mark). All connections appear normal and secure and I have compared this to my old distributor. I feel both vacuum control units are working properly. This is a "new" rebuilt distributor from Rock Auto.

3) There is a constant vacuum to the trailing vacuum control unit when at idle. There is no vacuum to the leading vacuum control unit at idle although steadily increases with any increase in RPM's From my manuals I cannot determine if this is normal or not. When I pull the vacuum hose off the trailing vacuum control unit (idling) there is no change in trailing timing. When I manually move the trailing vacuum unit (idling) there is no change in trailing timing.

4) I have reinstalled and check the distributor tally mark several times, so I am confident it is installed correctly.

5) I drove the car today and it seems to run fine and normal. Could not detect any misfire.

Could there be a problem with the orange vacuum control valve(solenoid), as this is what the trailing vacuum control unit connects to? If this is bad, where would you be able to obtain this?

Any other thoughts will be greatly appreciated.
Thanks again, to everyone.

GSLSEforme

OneEyeMick

I had connected my distributor wrong once. I think i mixed up the trailing and leading coils. Albeit I was running a Direct Fire Ignition setup but ran the trailing through the distributor. This setup ran fine. I didn't even realize that it was a problem until I took my distributor cap off and saw melted plastic pieces.
So that was a little of a tangent but double check your wire placement on the distributor cap. Also make sure that the magnetic pickups are signaling the correct coils.
So if your coils are being signaled by the wrong magnetic pickup, moving the trailing pickup would make no difference.

rotaeng

Again, thanks for all the help.
this is what I have done and some answers to your questions.

Distributor was replaced due to wire broken on pick up coil and bad vacuum units.

Remember car starts easily and is driveable.

Regarding coils and ohms
I have read some different recommendations for readings. (primary resistance 1.35 +/- 10% both coils)


here is what I am getting (car had not been started prior)
Trailing
Primary 1.7
Secondary 6.63K

Leading
Primary 1.8
Secondary 9.04K

I think I will just replace both of these.

The distributor cap and rotor are brand new.
Plug and coil wires are not new, but I will get new ones. They have not had too much use, several years old. Do not drive this car daily.

Checked solenoids.
I have three (front to back Orange, blue, white marked)
Orange (vacuum control): Not working
Blue (relief valve) WORKING OK
White (air conditioner valve) Not working
Let me know if anyone feels this could relate to the original problem: cannot adjust trailing timing. Note: manual adjustment of trailing vacuum unit with handheld vacuum device(while running) makes no difference.
Lastly, where would I get another solenoid valve?

Have not checked the primary ignition wiring but I suspect it is OK. I did rewire years ago and have not changed anything in years.

GSLSEforme

Benjamin4456

Based on the vacuum rack, it sounds like you have an SA. How did you determine the advance and AC solenoids are kaput? Are they not receiving power, or are they not operating when powered? Also the AC and the relief solenoid's operation will not affect timing whatsoever.
Edit: Just checked and you've got an '80 - same here

The SA's do have a system that messes with the trailing under certain conditions. First off, I would say get some new plugs, but that's it. Like GSLSEforme stated, it's not a good method to replace parts in order to confirm if they're the issue without having diagnosed it first. Second, I would try unplugging a little connector that runs to the ignition control box located on the drivers fender well. The connector in question has - I believe - a yellow and orange wire and is just a simple two wire block connector. It will be somewhere by the brake line that runs in that area. This connection is what allows the trailing ignition to be disabled off idle and on deceleration in order to maintain the temperature of the thermal reactor. While you should reconnect it after the fact (unless you have done away with the stock exhaust and installed a header), it may help reduce the number of factors that may be messing with things. It shouldn't affect timing, but who knows, it could be causing some other sort of false positive elsewhere.

In what way did you rewire the primary system? The 1980's system is by far the most intricate, so I'm curious if something could have happened there.

Edit: I just had a thought. I know the leading spots on the dizzy can be used for trailing, such as when you go DLIDFIS. Perhaps then the trailing could also fire at the same time as the leading (just thinking out-loud here) if given the same input. My thought is that if the trailing is somehow using the reluctor signal from the leading (which may have happened due to your rewiring), the trailing would fire in sync with the leading. To test this, check the timing of each leading and trailing, and then adjust the leading vacuum pot to move the leading (make sure you can see a difference) and then go and check the trailing and see if it's moved. Now that's just a theory, but heck, doesn't hurt to try.

rotaeng

Everybody thanks again!
Let me give you some history of this car, as it had slipped my memory, as it has been many years. Keep in mind, this car has been stored most of the time. I have owned it since about 1982(bought it from a friend who was original owner) It is a 1980. The reason anything is coming up now is I had an oil leak in the front cover and had to pull the engine to replace gaskets.
About 9 years ago, I rebuilt the engine. I had to put 1981 rotor housing replacements, as I could not get 1980. I got rid of the old thermal reactor. It has a regular exhaust manifold now. Because of other problems that I cannot remember, I could only find a 1981-2 distributor from junkyard(note: now have the rebuilt one installed). Through my books and pictures of the 81-2 wiring on the car I pulled it from, I installed this. I cannot remember if trailing time was a problem at that time. The ignition control box on the fender is gone since the ignitors are now on the distributor. I am now suspicious that this is where the problem lies: possibly in how it is wired. I do have stored (I believe) the old ignitor box and distributor. I may have to pull this out and experiment. I will get the books (Haynes and Mazda workshop manual) out and start going through the wiring diagrams. If any suggestions or if you know that this conversion of the ignition system is not compatible with the 1980, let me know.

I will work on this and let you know how it goes.

GLSEforme: Haven't checked the spark but will do.

Benjamin4456

The swap will work just fine if wired correctly - I'm running a 1982 dizzy with DLIDFIS on my '80. The trailing deactivation will no longer work with the later system as there is no provision for it, however as you no longer have the thermal reactor, there is no need for it.

I would definitely suggest going through the wiring diagrams (like you stated) and fortunately, the later systems are much more straight forward. Perhaps you could also post a couple pictures of the situation.

GSLSEforme

Benjamin4456

^^^^this, and it also works much better for DLIDFIS if you ever choose to go that route.

rotaeng

Thanks again! I haven't started sorting through the wiring yet.
Benjamin4456: I did some reading about the 2GCDFIS and DLIDFIS. Is there a specific set of instructions on doing this, that you recommend? Also, I assume this improved your car performance significantly?

Benjamin4456

Well as you have certainly noticed, there a quite a few threads on the subject. The different systems are really down to your choice depending on how many new (or used) parts you want to find, and also just what you are interested in. When I did mine I just read through a few of the more descriptive threads, and then compiled the information in order to make my 'own' design. That's another important thing to consider: just because one member mounted theirs somewhere or did some particular detail doesn't mean you have to either, I chose to put mine on a vertical plate with standoffs on the shock tower, for example.

As for benefits between systems... I don't know as much as others about 2GCDFIS, although I believe there has been some recognized improvement (albeit somewhat small) in using the second gen coils. I would suggest against SLIDFIS as you put a fair amount of load on a single igniter, and increase the chance of it dying prematurely. Personally I'm an advocate of DLIDFIS with GM HEI igniters (PN DR-100). The system provides improved spark thanks of course to the DFI but also as the HEI's can flow a few more amps than the J-109's. The HEI igniters are also readily available at most local stores for $20 or so, compared to the increasingly rare and expensive J-109' and J-105's.

General benefits of any DFI wasted spark system are: potentially quicker start-ups, easier de-flooding, better or reduced exhaust smell, fewer emissions, potentially increased gas mileage, and a potential gain in overall torque (particularly the low end). You may also notice a changed exhaust note and better throttle response.

I will say this however, I strongly suggest you try and find the current issue first before going on to any major mods. That way you don't somehow cover up the issue with the new work, and it will also help you to fix or diagnose the issue in the future if there ever comes a need.

Edit: While this is not necessarily the most in-depth thread on the subject, here's mine on DLIDFIS that I did just recently (note that I did not end up using an SA dizzy). Hopefully I can still remember most of my reasoning in case you have some questions. Otherwise, just do all the searching and reading you can

http://​​​​​​www.rx7club.com/1st-gen...dizzy-1132011/

rotaeng

Thanks, Benjamin 4456 for the info.

I did get wiring diagrams and looked at 1980 and 1981 as a comparison.
I went through the wiring on the car. Verified locations of trailing and leading coils (trailing one is toward the front), and trailing and leading ignitors(Leading is toward the front, trailing to passenger side). Wiring is correct. I am baffled.
I did read this on Racing Beat - Mazda Performance Specialists

Distributor Upgrades

If you wish to install the 1981-85 RX-7 breakerless distributor in a stock 1974-79 engine, there is one potential problem: the centrifugal and vacuum advance characteristics of this distributor are slightly different from the original equipment "breaker point" style distributors. The easiest way to deal with this is to set the timing to: Leading - 24° BTC / Trailing - 14° BTC at 5,000 RPM and use this as a starting point (vacuum disconnected). If you wish to use this distributor for racing purposes, the vacuum advance should not be used, and the timing should be set to the proper total advance setting (Timing Chart - PDF).
Rotary Tech Tips: Ignition Systems

I will keep working to see if a solution can be found, otherwise will drive the car as is.

thanks to all!