I've always had an issue running decent boost on my car, the spark just gets 'blown' out at anything over 350lbft torque, causing a chronic misfire.
I changed the plug gap down to 0.5mm and this helped, allowing 0.2 bar more boost. I changed to Bosch coils and it made no difference, I changed from JECS to Apexi PFC ECU and no difference. I tried different heat setting plugs and still no difference.
I tried 0.4mm plug gap and it allowed more boost before misfire but cruise and idle suffered badly so I returned it to 0.5mm.

I have worked around this torque limit by tapering boost pressure rise and holding the 350lbft to 6500 gave my 432 bhp at Well Lane.
Problem now is that with the new headers fitted the engine is making its power at much lower boost and I'm hitting the ceiling at 1.45 bar.

What can I do next ?

 

Are you using 8b's with the 0.5mm gap?

 

Go for a Capacative Discharge system ?? MSD, and Autronics seem to do multi channel amplifier thingies. Dont really know how good tho. But I think the Rigolis use the MSD DIS-4

 

Tried 8b's and 7b's at 0.5mm
The later coil packs seem to run ok, I've been in Harveys car at 2.2 bar boost and it was clean as a whistle on std coils.
Any idea the impedence of the 99/00 coils ? I could perhaps pair up my outputs and run them ?
Would the MSD run with the Bosch coils ? I'm not sure that these coils are very good ? If you check the OEM listings they are all old gutless cars !

 

I take it you are running the new ECU?

Are you sure you're getting a proper 12v (or more like 14v) at the coil?

Are you using the std subaru ignitor/amp module? Are all the connections good, earthing?

Spark strength seems to be the issue.

Also, how are your breathers done? Rob had a misfire he solved be temporarily blocking off the crank case breather point on the inlet, although I suspect you have this sorted.

A CDI module could be the ticket for the system, as the coils themselves don't seem to the the problem. Although you say they are for old cars OEM etc etc, they are not. The listing I have shows them as replacement uprated parts for older cars, although probably equal in technology and performance as the Subaru OEM coilpacks?

Paul

 

Yes, I think they probably are similar to the OEM coils in terms of spark strength.
The breathers are sorted.
I'm back on the JECS (with your latest map Paul ) until I get the Microtech handset (soon)
It's now going as well at 1.4 bar as it was previously at 1.65bar which is nice but I want more ! The ign is not up to it though

Are the coils are insulated from earth ? I think they go to/from the ECU.
Where does the ECU earth go ? Direct to battery or to the shell somewhere ? I think a big earth ring is on the cards.

 

Big earth ring is a good idea I think. It could even be that some of the ignition circuits are wired via the keyswitch too, in which case improved wiring in that area may help too.

I don't have a clue how the ignition as a whole is wired, other than ECU->AMP->COIL->PLUG

Need to check wiring diagram.

Paul

 

Earth ring now fitted, no difference to spark collapse threshhold

The maximum torque/boost still seems to be limited to approx 330lbft at Star or 350lbft at Well Lane (probably the same value)

Would racing plugs help ? Do they fire easier due to the fine tip ?

 

Andy,

I'm using the standard Subaru coil packs on mine, but they are driven by the Pectel ECU ignition drivers.

First time on the dyno, we did suffer a little ignition breakdown, and we had to close the plugs down to .5mm (racing 8's). this helped, but was only cured when we increased the ignition dwell time. This was using the '97/98 ignition block/leads.

I then switched to the early coil packs, still driven by the Pectel ignition drivers, and have now been able to open the gaps back to .7mm. This appeared to be happy at 2.75bar on the dyno.

I'm goimg to be trying another set up on the dyno, to see if it gives any gains.

Mark.

 

Andy

Im worried now..

Ive had the dwell board fitted to my ecu so Im running wasted spark...

Im seriously considering using Crane or MSD CDI...

I know the coil packs can do over 500lbft of torque.. No bullsh1t for once.. you know roughly marks figures.. that was using coilpacks.. unsure whether the pectel drives them direct.. if so could be the bosch ignitor module thats not up to it??

Its an interesting thought this as trout has a similar problem.. we thought it maybe fuelling related..

David

 

duplicate post there mark...

http://www.cranecams.com/ignition/intro.htm

 

Cheers Mark

I had considered the drivers but the Apexi ECU with its own drivers suffered the same Also the Bosch coils reacted the same way as the original coil packs, the original coil packs which were in good condition were slightly better in my opinion !

I mapped a car recently on early coil packs and when the AVC-r went mad it quite happily ran 2 bar without protest !

It's all a bit strange !

Andy

 

ign module??

I can send you mine to try if you want??

 

Where's the Ign Module ? Is that it by the MAP sensor ?

 

yeah, theres also something on the chassis leg..

David

 

I'll check the earths around that area and see if it helps. The Microtech ECU has a dwell adjustment so I can also try that when I get it fitted.

 

Curious... Andy, is your ignitor module the really early 4 channel type or the slightly later 4 channel type?

I've seen a similar thing happen with another car, and when I lent the owner my ignitor module we found that it isn't plug compatible. The really early type is a large module with an aluminium heat sink integral to the back of it. The later module is just plastic, and presumably uses the bracket as a heat sink.

Perhaps the older ignitor module doesn't achieve quite the same slew rate and hence has trouble ionising the gap at the higher boost levels... remeber in those days the boost really was quite low!

We were "lucky" with Mark's car, because one of the main reasons we decided to drive the coils directly is that the T6 cannot be supplied with high side drives, which are necessary to drive the Subaru ignitor module, so we said to hell with the Subaru ignitor, we'll just drive the coils directly from the T6. It is possible to stuff a buffer in the loom adapter to drive the Subaru ignitor module but it was extra hassle we didn't need. And as Mark has already pointed out, the T6 driving the Subaru coils was fine even at 2.75 bar

This begs the question, that if the coils themselves are up to the job, what other part of the ignition system isn't ? It can't be earthing because that is a constant between the two different types of setup, so it leaves only one thing... the ignitor! I'll try to swap out the ignitor on the "problem" car and see what effect that has, may just go for a Bosch module for simplicity.

Cheers,

Pat.

 

What does the ignitor consist of? Can it not be replaced with a home made or aftermarket part?

I think I asked this before, but I'm assuming the ecu has low level ignition triggering and the ignition amp is a 4 channel open collector arrangement?

What is the deal with the newer wasted spark systems? Or in fact, is there now a 4 channel module on the new cars? As they run coil on plug again.

Paul

 

I think mine is the black plastic type. Are the alloy fins visible without removing the module ? I can't see any alloy.

David has offered me the use of his igniter module to try out so as this is looking favourite at the moment, I'll take him up on his kind offer

Andy

 

Mine is alloy, and seeing as Pat has a Legacy like me (even the same colour) I assume this was the source of the one he lent out.

Some cool air to said module might improve it's chances too.

Paul

 

On my old nova and pug, I have had problems with these dying due to heat..

The intermotor replacement ones dont last.. used to just simply die..

Its also important to use a heat transfer compound with these if they need them..

Like paul says.. maybe improved airflow or cooling - heatsink?

Talking to my dad about this problem, he doesnt think it is an issue with blowing the spark out, more so that its harder to generate a spark at higher pressure, in the fact that it takes more energy.. (had been drinking when he was expaining..)

David
David

 

David,

not enough energy to create the spark is more accurate, but it's what I would call "blowing the spark out" anyway.

The problem is made worse at high RPM as there is less time to charge the coils. But proper 4 coil set up has double the time of dual wasted spark, and that works fine on the newer cars.

You can get those bosch amps, but they are pricey, especially getting 4.

Paul

 

about 90quid each iirc.

Im now running wasted spark

Not what I specced.. I thought I was getting 4 coil drivers... but..

Going to look into CDI systems..

Group buy???

David

 

I'd agree with that The air/fuel mix has increased density and therefore requires more energy to ionise. That's why closing the gap helps but it is the law of diminishing returns as the spark gets smaller
I think it starts by getting partially 'blown out' and misfires slightly as it weakens then fails to fire completely giving a sensation like fuel cut if you take the boost high enough !

 

The MSD dis2/4 comes in at around $320 and looks an excellent piece of kit Lots of little features (like launch rpm soft cut) for us guys with the basic ECU's

[Edited by Andy.F - 5/27/2003 10:45:41 AM]

 

andy... where from, thats cheaper than I have found..

David

 

http://www.summitracing.com/

Search for

MSD-62111 2 coil unit $329
MSD-62151 4 coil unit $331
MSD-8230 High Output Coils $44 (single, but twins available)

This is the cheapest place I have found in the US. I bought all my V8 car parts there, one of which was a MSD ignition system which happily ran all 8 cylinders off one coil at 7500 rpm.... even with 175bhp of NOS on

If you're thinking of buying, let me know as I may be interested in sharing the shipping

Andy


[Edited by Andy.F - 5/27/2003 11:19:22 AM]

 

http://www.msdignition.com/sn2000.htm

this also looks interesting, a CD primary side booster.

Paul

 

Andy,

How did you identify an ignition failure in the first place? What symptoms etc?

Thanks

 

Simple to install with no cutting or disconnecting wires.


How do they figure that one ??????