Ignition system trouble

B

Boswoj

New member
Hi all -

I've got a first gen 12A with an 81-85 distributor that is down on power and breaks up at 5500 rpm, really refusing to rev any further in racing conditions. I think the problem must be ignition - the previous owner had the positive side of the coils linked together, then one wire running to the positive side of one ignitor, and both positive ignitor terminals wired together. I cut out a piece of the stock harness and ran separate positive and negative wires from the terminals on the respective coils to the ignitors without linking the coild orthe ignitors. The car then ran like crap, and tach stopped working. Is this an indicator of a bad ignitor? Any good suggestions?

Thanks for your help!
 
If you are running an aftermarket tach., and a shift light, run one from the leading coil and the other from the trailing coil. When one of the ignitors crap out, you can tell by what isn't working, and which one it is.

Use 2 MSD Blaster Coils for the best in spark. Keep the stock ones in your parts for back-ups. Check junkyards for ignitors, as they are expensive form the dealership/parts house.

------------------
Corey L. Clough
ITS RX7 Soon-To-Be
[email protected]
 
Boswoj, check out your coils. I had a 6 race old MSD Blaster coil take a crap & the car would run to 4-5,000 & shut off. It was a bitch to restart.

David
 
Do you know the part# on the coils??


Originally posted by TURN9:
If you are running an aftermarket tach., and a shift light, run one from the leading coil and the other from the trailing coil. When one of the ignitors crap out, you can tell by what isn't working, and which one it is.

Use 2 MSD Blaster Coils for the best in spark. Keep the stock ones in your parts for back-ups. Check junkyards for ignitors, as they are expensive form the dealership/parts house.
Click to expand...
 
Go hit my web site and go to the RX7EngineSwap directory and look at some of the older dated pics and you'll see how to wire them.

The car was wired correctly to begin with. I would do the following....

1. Get a timing light, and hook it to the leading ignition of each cylinder and watch the timing as you rev the car....if the timing light does not light you have a bad ignitor...reverse the process for trailing...if the timing light start to behave badly on one or the other (lead or trail) at RPM then its a "potentially" a coil problem.

2. Seperate ALL of your positive and negative wires going from your coils to your ignitors INDIVIDUALLY in their own wire loom (1/4 size) and then put the trail and lead in their own wire looms respectively to isolate and potential bleed through of "juice".

3. Seperate, see me for cheap method, all of your plug wires from each other to prevent same as number two...

4. Using the timing light method, check the leading and trailing plug wires at RPM to see if you are having problems in a particular area...I.E...both trailing plugs wires (could be wires, ignitors, coil or wiring) use methods above to isolate and trouble shoot.

Typically, your coils will last a long time. Look at your wires, and wiring first, then ignitors, then coils.

Sorry I repeated 1...but it is kinda tough to explain after a FULL DAY, after a FULL WEEK, after a FULL MONTH of work (GRIN).

Drop me an e-mail with your phone number if you want me to help talk you through it.

Frank
#67 IT-7
www.balz.myip.org

[email protected]
 
OK - newest installment of my ongoing problems:

I have a parts car that I drove on the road for many years that has a lot of nice new parts on it so I started substituting things hoping to cure the problem. At this point I have replaced cap and rotor, plugs, both coils, and spliced in a new section of wiring harness obtained from a wrecked car from the coils to the distributor and ignitors. In addition, I have recently replaced the '79 carb with an '81-'85 model. It had much the same problems with that carb, only in slightly different RPM ranges - so I don't think it is a pure carbueration issue - although at this point I can't rule anything out! At the same time I installed a new fuel pump, pressure regulator and gauge and adjusted my float levels. The car still breaks up at around 5500 and will not pull cleanly. When it breaks up it smokes like crazy until it clears out again, nearly leading to a black flag. I was subjected to not being able to pass a lightly modified Fiesta on the straights! Please - any suggestions that can prevent this from happening again would be greatly appreciated!
 
OK - one more update, anyone got any suggestions?

Retimed the car and found that both leading and trailing were set to 30 - so I reset leading to 24 and trailing to 16 which an earlier post I found said was a good place to start. Car is still breaking up like crazy at about 5500. Timing light showed good strong flash on both coil wires and all four plug leads. I'm completely stumped. It must be a carb problem, or a very mysterious ignition miss that only surfaces at high RPM's. I've got a race this week-end and am not looking forward to being a moving chicane again. Has anyone ever experienced something similar to this?
 
Boswoj, here comes an answer (maybe) with a question. If you were to take your race car to a garage with diagnostic equipment would the equipment point to the bad guy or at least narrow the choices ?

I know this is extra cost but so is pi$$ing entrance fee money down the drain when the car don't run.

Me am
confused.gif
with all the ideas forwarded.

David

Battery, they do some funny stuff ???????
 
That it smokes like crazy when the car breaks up is your biggest clue. What kind of smoke is it?

Likely it's oil. Sounds like you may have a fundamental engine issue where the side seals are giving out, causing a loss of compression (no more acceleration), and dumping oil into the works. Do a Mazda compression test with the engine warm for yuks - though often these items don't show up unless you've got the rotors spinng madly...
 
Not sure if this helps. have you tried a new or different distibutor. possible the weights inside are sticking or not spinning properly enough to advance the timing. Just a thought but my car is timed at 20 both leading and trailing. 79 Mazsport carb and intake. 85 motor. pulls well past 8k.
You may want to contact Scott @ Mazsport, ph# 727-530-9960. If he cant help ya, dont know who can. Good luck.

Chris
IT7 #88
PowerTrip Racing
 
First of all - thanks to all who have tried to help! It's really great how everybody pulls together and helps the guy with the problems.

I went to the local guru and he noticed that the exhaust pressure (super scientific hand behind tailpipe method) started out strong then went cut to about half at 2000. Possibly internal structure of muffler collapsing under high pressure? Removed muffler and tried again. Same result along with bleeding holes where eardrums used to be. Next step, take apart carbs to verify jetting - AH! whats this? Fuel jets that you can stick your arm down! Rejet, and much crisper. Acid test wil be under load at track on Saturday morning, but I am confident that I am now headed in right direction, if a little red-faced. It sounded like a jetting problem from the beginning, but I eliminated that from consideration after having carb built. Then replaced coils, plugs, rotor, cap, wires, wiring, ignitors, fuel pump, filters, and added pressure regulator and gauge only to find -------- it's a jetting problem. To paraphrase Sherlock Holmes: "Once all possible explainations are exhausted - it must be one of the impossible explainations"

Thanks again everybody - I'll let you know how it comes out.
 
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