What Have You Done to Your Ingition for the WI?

[PuntoRex]

Hi there,

Have you experienced any faults caused by the not-so-powerful stock ignition while running WI? And what did you do?

I know the basics of narrowing the plug gaps & installing a more powerful 3rd party ignition, etc. I'd like to know what 'exactly' you guys did to your car & how it worked for you.

Recently I got some fluctuations on 5th gear WOT pull (in the midrange rpm, not yet have the chance to take it higher than 5000, I don't want to lose my license). Once or twice on 4th while running very well from 1st to 3rd.


I've thought the possibilities:

1. Improper fueling, as Richard mentioned. I've tried richening a little by rising the fuel pressure, but situations got worse, still fluctuating & even with shudder. While with the stock ECU, I couldn't make it leaner for the trial.

2. Compressor surge, which I'm not sure if it really is by hotrod's descriptions & my limited knowledge. And my car had similar symptoms before I installed the pre-compressor jet. Is it that on higher gears, engine load is also higher, thus higher EGT, higher back pressure, & worsen VE? So the engine can't swallow the same amount of air as when on lower gears? (Higher EGT makes more energy be trasfered to the compressor, thus larger mass air flow & higher boost which the worsened VE can not take, a vicious circle )

3. Miss fire. In the last 1~2 months, I'd suffered from this fluctuation occasionally. About 3 weeks ago, I changed the plugs & got a satisfying result. Now it's back again after I installed the pre-compressor jet. Maybe the improved compressor efficiency makes larger flow, thus higher cylinder pressure which is harder to be ignited? Those plugs are quite new, so I'm not sure if these plugs are still not good enough or anything else, like fatigue coils, bad HT wires (which shouldn't be, they are Magnecor KV85 & only 1 year old)....?

Any thoughts?
Thanks a lot for your time & experience sharing.

[JohnA]

Originally Posted by PuntoRex

1. Improper fueling, .

That's easy to check with a wide-band sensor
.

..Higher EGT makes more energy be trasfered to the compressor, thus larger mass air flow & higher boost which the worsened VE can not take, a vicious circle ).

EGTs are measured on the exhaust side (obviouly :lol: ) so the compressor is not directly affected. Just the turbine.
Try a smaller jet, 0.4mm, activated a bit later as well.
.

...3. Miss fire. In the last 1~2 months, I'd suffered from this fluctuation occasionally..

I'd try iridium plugs, perhaps one grade colder and slightly smaller gaps as well (I don't believe the myth that iridiums need wider gaps)

[PuntoRex]

Thanks for reply.

I've tried platinum plugs for quite a while, mostly working fine. Colder ones seemed not necessary & not suitable for my car. My experiences show the stock heat range still works the best. Since there's water for help in cooling.

I've also tried shortening the gaps. That worked fine in the higher rev range, but suffered a little in startup & low down torque. And I felt, with shortened gaps, the engine ran smoother, kind of iron-out-the-edges effect. However, with that smoothness, seemed not as powerful. A trade-off anyway, I guess.

Originally Posted by JohnA

....

EGTs are measured on the exhaust side (obviouly :lol: ) so the compressor is not directly affected. Just the turbine.....

What I was saying is - the compressor is driven by turbine, & turbine is driven by EG, higher EGT means higher energy, so the turbine is driven harder, so is the compressor...


Where I live is a sub-tropical zone, ambient temp is rather high, now still 20-ish 'C averagely, & almost 30 'C around noon! It's mid Nov!

And my tiny ancient engine & tiny turbo working at a rather high pressure ratio could not have the same efficiency as yours. Under the current setting - 0.5 before turbo + 0.5 before throttle - I still got once or twice audible knock when sudden boost rise rushing past 20psi at 5th. So I need that much water.

[JohnA]

Originally Posted by PuntoRex

I've also tried shortening the gaps. That worked fine in the higher rev range, but suffered a little in startup & low down torque..

That could mean that the mixture is a bit off low down.
Either too lean or too rich.

.

What I was saying is - the compressor is driven by turbine, & turbine is driven by EG, higher EGT means higher energy, so the turbine is driven harder, so is the compressor... .

Ah, gotcha now.
Yes, indirectly connected they are indeed :wink:

.

Where I live is a sub-tropical zone, ambient temp is rather high, now still 20-ish 'C averagely, & almost 30 'C around noon! It's mid Nov!.

you're in Taiwan, just realised now :lol:

[PuntoRex]

Well, has anyone ever done any mods to the ignition other than just plugs/wires?

Simply put, are those "upgrade" ignition like MSD or others any worthy?

Or, sticking to the stock system would be just fine, as long as it's not malfunctional & the engine comes with turbo in stock form, instead of modified from an NA engine. Because that's already powerful enough with certain margin?

Any thoughts?

[DuMaurier 7]

I use a pair of MSD 6A amps on both my leading plugs (1 pair of leading plugs fire together and a pair of trailing ones fire separately) with Magnecor Wires. I have run at a fuel ratio of 10.0/1 (maybe richer ! , my wb only goes down to 10:1 ) and a big 0.9mm jet at 75% + (duty cycle of the HSV) WITHOUT any tipe of break up . When you introduce water into the combustion chamber you need a stronger spark , because of higher in cylinder pressures , additional conductivity caused by the presence of water and cooler temps , with an ignition amp. you can even use colder plugs without the associated problems

[ubcnme]

Hi I have an dual MSD on my veh. With my water inejection I have the aquamist 1s system Im running 2 .4mm jets with it. check out my ride on web site ill be posting. http://members.cardomain.com/pocketchange

[PuntoRex]

Thanks DuMaurier 7 & ubcnme :smile:

Seems you guys really enjoy your MSD

One more question:
Did you experience any insufficient of the stock ignition then upgrade it to MSD, or install it the same time along with other mods as a whole project?

If you did experience the insufficient of the stock ignition, what were the symtoms?

Thanks again :wink:

[DuMaurier 7]

Didn't wait to experience it myself , many went that way before so I learned from their experiences , but what they described is exactly what you describe . :!:

[SaabTuner]

Originally Posted by PuntoRex

2. Compressor surge, which I'm not sure if it really is by hotrod's descriptions & my limited knowledge. And my car had similar symptoms before I installed the pre-compressor jet. Is it that on higher gears, engine load is also higher, thus higher EGT, higher back pressure, & worsen VE? So the engine can't swallow the same amount of air as when on lower gears? (Higher EGT makes more energy be trasfered to the compressor, thus larger mass air flow & higher boost which the worsened VE can not take, a vicious circle )

That is possible, higher backpressure does lower VE, but higher EGT doesn't necessarily mean higher backpressure. So I doubt that's the cause.

Compressor surge usually happens in the higher gears because there is more time for the turbo to spool. Therefore in higher gears you tend to get boost at lower RPM and voila: compressor surge.

When I instal water injection on my Saab I'm not sure how I'll adjust the ignition. The ECU controls the voltage to the direct ignition rack and varies it with boost pressure so that there isn't any more voltage than necessary to ignite the STOCK a/f mixtures. Unless I can adjust the ECU output, plug gap will be my only adjustable factor; it's a bit disconcerting.

Good luck though with your project!

Adrian~