I have a '91 TII. In the last couple weeks I've been getting a weird operating condition that I'll try my best to describe.

While accellerating normally or even WTFO, from 2000rpms to about 4500rpms my car stutters almost like ignition break up. From 4500rpms up it smooths out like nothing is wrong. Here's the kicker. It only does this until I've been driving around for a while and everything has been hot for a while. If I turn the car off and let it cool down, fire it up, let it warm up, and go for a drive again it does its little hesitation again for a few pulls.

Mod's are Catback, Intake, Stock main cat, NO precats, HKS SQV vented to atmosphere. I just replaced all 4 plugs a few weeks ago. I'm not sure if maybe this could be a fuel issue since it does feel like an ignition issue. Any advice/help on this is appreciated. Possible that my cat is clogging?

 

Do you have an upgraded/tuned ECU along with that atmo BOV? if not, this is a problem!

 

I'm on stock ECU still but this isn't causing the problem. I've run my other TII on stock ECU with a vented BOV and never had an issue. It would only cause an issue if my BOV was leaking pressure under accelleration which would be the same as a vacuum leak.

This isn't as simple as blaming a BOV for poor accelleration.

 

Sounds like the typical hesitations when the secondaries come on.

Stock injectors?

If so i would start to re-do your grounding points.

http://aaroncake.net/RX-7/grounding.htm

that is about the best info around on the subject for our cars. The nice thing about it is it is without all the nonsense about adding a bunch of random grounding wires everywhere....

 

Or, your primary injectors need cleaning.....

 

well it could be breaking up (ignition) becasue you have, basically, a more free flowing exhaust. So, stock ECU + free-flowing exhaust = not enough fuel.

Does this happen at -pressure too? (you say accelerating normally, what is normal for you?)

Since you said this only happens UNTIL the engine is warm, it could be a compression issue. No one wants to jump to dire conclusions, but you are describing symptoms of fading compression.

Never hurts to clean the injectors and run some new wires as well.

 

My injectors are fine and compression is mint. I changed the fuel filter today after work due to me not knowing when it was changed last. Well after changing it I started the car and it was idling like CRAP so I started listening and I heard a loud tick from the area around the coils. I listened closer and found it coming from the Leading Coil pack. After further checking of the coil I saw it was arcing under the plug wire where the coil connects to the wire. I stopped the engine, pulled the wire, and found that the L1 tower was cracked in HALF. This explains why it felt like ignition breakup.... because it WAS. lol

Anyways, now I'm going to be looking into upgrading them. Probably going to look into some MSD Coils as I know a bunch of people have used them with great success. I priced out a new Leading Coil from NAPA and they want over $500 for it so I figure I can upgrade both my leading and trailing for that price and have a mint ignition set up to handle any power level I want.

 

Good job on tracking down the problem

the msd coils are reviewed to be no better than the stock T2 coils.

Lets price it out. roughly $50 per MSD Blaster coil X 4 = 200

Minimum of 3 (but recommended 4) MSD 6A boxes = 300 - 400

Misc wires, connectors, heat shrink = 40

Looks like you could replace your entire ignition system or replace just the leading coil for the same price.

 

Yeah I figured I could upgrade the ignition system to MSD and have everything new for about the same cost of just replacing that one leading coil. It's rather sad really to think about it that way though. Mazda really needs to come down on price for their parts.

Could I not just get 2 Blaster coils for the leading and run them off the factory igniter? I don't see why that shouldn't work.

 

that will NOT work. I tried it.

The factory ignitor doesn't have enough juice to power the blaster coils.

If you read my build thread here... https://www.rx7club.com/showthread.p...&page=21&pp=15

4th post down.

Somewhere in there, I documented what happened.
Basically, the plugs both fired, but very weak. Not enough to run the motor.

 

Thanks for that insight!

I found another Leading Coil locally here so I'll get getting it and I'll be back to 100% again.