still can't figure out ignition breakup. ideas?
 

This is a bit long but I am just trying to answer all the obvious questions and tell the story.

First, here's my setup: 1988 Turbo II with big streetport, T04S turbo, running 18psi on straight 100 unleaded gas. AFR's are low 11's, ignition advance is around 16 degrees, at least at peak torque. Ignition system consists of stock FC coils with MSD 6AL on the leading and 8mm Magnecore wires. I have the Banzai Racing Power FC kit, which means the trailing coil is custom wired (because the FC and FD trigger them differently).

I am still getting intermittent spark blowout, at least after I drive a fresh set of plugs more than about 20-30 miles. The blowout usually occurs over 10psi and 4000rpm. Sometimes I can go WOT and feel none at all, sometimes I feel a little bit, sometimes I can hear it audibly (sounds like a piston engine with 1 cylinder not firing) when my atmospheric wastegate opens. Most of the blowout occurs at part throttle actually, and there doesn't seem to be any real pattern besides that.

I have been using BR10EIX plugs, the fine wire irridium ones. I have tried it at stock gap (~.30) and have tried gapping them down, but gapping them down to .24 didn't help blowout and just made the car idle worse. Should I try using the B10EGV plugs, which I think have a tighter gap than that stock?

I've also tested the resistance on my plug wires and they are well within FSM specs, and I tested the resistance on the leading coil per the 2nd gen FSM and it's well within in spec as well. So what do I do now? Right now the plan is to switch to B10EGV... I shouldn't need new coils right, not with low 400's whp (hopefully) and 18psi? Could the lack of an ignition amplifier on the trailing (due to cost and the fact that I don't know how to wire it with the Banzai trailing coil setup) be causing this? Should I try swapping in another leading coil even though my current one is in spec?

This just really sucks because I literally get 20 miles out of a set of plugs before they start getting breakup. The last set I removed after about 100 miles looked good, a nice tanish color that was pretty uniform on the outer ring, the insulator, and the ground strap. These current ones I even torqued with a torque wrench to 12 or 13 foot pounds.

The modified coil doesn't change anything, installation of ignition amps on the trailing coils is the same as it has always been, you would need 2 more MSD6A amps, wired in just like you did on the leading.

It is more than likely the plugs, switch back to all 9's and see if the break up goes away.

I didn't mention this, but what got me to change plugs was ignition breakup on the 9's in the first place, but that was before I had installed an MSD box. I'm going to give the B10EGV a shot first, and if that doesn't work I'll try the BUR9EQ again. With that level of boost (18psi) I am just more comfortable running colder plugs.

Can you really get intermittent breakup like that from trailing ignition? I know plenty of people amplify the trailing, but that wasn't necessarily because they found it absolutely necessary to prevent breakup. I can see myself dropping $300 on two MSD boxes and have them not solve anything.

Try changing the fuel! I have had problems with break up on the old set up every time i ran the 110 oct it would break up!
Now i run 93 oct at 20psi no break up and mix above 20psi with no break up, but i also run low compression rotors.

Does the PFC have the ability to change the dwell in the coils?

^ Yes it does, but nobody's really tried to do it. I've been thinking about experimenting actually.

It does. I've been told the values in the Datalogit represent charge time in degrees of crank shaft rotation. Makes sense. I've experimented with it and posted some results in the PFC forum. I hooked the scope up this past weekend but something came up and I never got to run a full test to verify input values versus results.

I read your thread and it inspired me to mess with it just a little bit. Today I increased the dwell values from the AP engineering numbers (which are curiously 30 all the way down the columns for both leading and trailing) to something a little closer to the FD numbers from Apex'i. I kept it at 30 all the way up to 4000 rpm. At 4000 rpm (same settings for leading and trailing) I put it to 40, then 55 for 8000 and 10000

so it was something like

55
55
40
30
30
30

on both leading and trailing. It made no difference in the spark blowout problem and I noticed no change in driveability. I'm not sure if I'll keep it that way or not. The next thing I will try is the B10EGV plugs (as opposed to the BR10EIX I have now). After that I will be looking into HKS twin power (as opposed to one MSD 6AL on leading) or even aftermarket coils.

It's really frustrating though, reading in all these threads about how powerful the FC ignition is and it keeps crapping out on me.

Ok here is a few things i have done to troubleshoot ignition breakup. Check your voltage under boost. If it drops u got your problem there. Check your wiering from the PFC, or just redoo it all the way. That has helped before.

I ended up replacing all my ignition system with a Autronic 500R and Crane Cams coils before everything worked fine. And also running B11EGV plugs. Remember that the EGV plugs are shorter then the BUR plugs so u would need to turn ur initial timing up between 5-7 degrees for it to run without breakup.

And another thing, running to rich/lean might give u the same problems.

JT

^ I already added a decent amount of timing when I switched plugs, I noticed it needed it for better spool and idle. AFR's are consistent low 11's, that shouldn't be bad. I am thinking about switching to HKS twin power next because I can get them for a good price and just sell my MSD 6AL box. I really did not budget a bunch of money for ignition upgrades, everyone talks about how strong the FC coils are.

The MSD box requires a rising edge trigger to work correctly. The PFC is most likely outputting a falling edge to the ignitor. Do you have the MSD box wired directly off the PFC or off the ignitor output?

Does the PFC even have the required voltage output to trigger a MSD box directly anyway?
Most ECU's were designed to trigger factory igniters 1-5v and don't have the 8-12 volt output MSDs need to be triggered at.

Tried a different coil on the leading?
These coils are starting to show their age now. A leaking coil might be arcing and be undectable to the naked eye when it's daylight. Check for arcing in the dark or night.
Try another set of ignition wires.
Also disconnect the trailing coils and see what happens.

This is the writeup I followed to install it. http://fc3spro.com/TECH/HOWTO/CDI/cdi.html

Remember that I have an FC running an FD power FC using the Banzai Racing adapter kit, so it's a weird hybrid of stuff. I hooked up the MSD box right at the leading ignitor. The FC ignition system is slightly different than the FD with those two separate coilpacks on the driver side fenderwall. I haven't tried a different stock leading coil, I tested the resistance on it and it was in spec but that really doesn't mean anything except that it isn't obviously toast.

When you say check for arcing, do you mean physically look for random visible arcing on the coil? With the engine running and everything plugged in? I checked the resistance on the plug wires and they are good. I'll put some dielectric grease on them when I change the plugs. I think they're relatively low mileage so they're a lower priority here, but I suppose it's still possible that they are the problem.

I actually just ordered an HKS twin power. I am going to remove the MSD from the leading and install that, and run with the B10EGV plugs at their stock .025 gap. At least then I will have both leading and trailing amplified. If that doesn't work I will swap leading coils next. I have a friend with an FD on stock twins running 14psi with FD coils and HKS twin power and he doesn't have any blowout problems, although he did have blowout when he used the Crane Cams Fireball (Hi-6 I think) system.

It is not a weird hybrid.. The MSD should be hooked up between the coil igniter and the coil.. just like you would on any FC3S.

I kept the exact same B10EIX plugs (didn't even remove them) and installed HKS twin power. My spark blowout appears to be gone.

NOICE! good to see you got it fixed!

so are you suspecting the MSD caused all these problems?

No. I don't think there's anything wrong with the MSD. I had the same problem with the MSD as without it (no ignition amplifier). One MSD on the leading didn't do the job of fixing the blowout. I'm not sure why--it could have been a weaker coil on my part, maybe I was just making too much power (have not dyno'd the car, but I suspect I am right around 400whp) or running too much boost (18psi). 3 MSD's might have fixed it too (2 for trailing, 1 for leading), but I decided to go with the HKS because the total cost would be similar but the HKS box is way smaller and easier to install cleanly (5 wires for HKS vs 18 wires for 3 MSD boxes).

thats good to know I was eventually planning on doing an msd setup but this has started to very my opinon a bit the only thing that I am a bit hesitant about is the amount of HKS box failures I have read about do you know of or have any type of warrenty w/ the HKS products?

So are you still runnign ok with the HKW twin power installed. Breakup gone ? Give us some feedback on how things are running now.

Later

After installing the HKS twin power I could boost 21psi with no breakup. Nothing else changed on my setup.

also, remember that you cannot run non-resistor type plugs with the HKS twin power, or at least they specifically warn you not to do so on their website. So the stock plugs are fine, BR10EIX (which I run) are fine, but B10EGV (which is non-resistor) is a non-resistor plug. I'm sure people have run them anyway, but that is what HKS says.

Would you happen to have any datalogs of AFR/boost/knock from your before and after testing?

"Tranny 6" is I believe before I installed the HKS, and "Dyno1" is definitely afterwards. But I'm not sure how useful these will be... they were done under different conditions, I think one is in 2nd gear and one is in 3rd gear, the fuel map wasn't that great (I was still experimenting with different things). Oh and you can see boost creep from the undersized wastegate.