auzivision

Well that makes sense. When I disassembled the EZK up in Michigan over the weekend (added an EPROM with different tune), the electronics inside looked fairly ‘low powered’… no big wires or any large heat sinks.

So a low lever signal is sent to an amplifier up front (assuming still a solid state device) which is then sent to a coil which is in essence another amplifier with some ‘momentum’.

I’m guessing this amplifier is also acting as some sort of isolator since the windings on the low side will also have inductance and all the unique characteristics that go along with that?

I’m not a gambling man, but if I were to bet money… I’d bet I’m not the only one that thought that the rotor spinning around in the cap is what created the timing.

Thanks for the clarification!

davek9

Hey Kurt, just a few additions

"The 86+ 928's are the same, except the breaker points are replaced by electronic switches, and the rotors live on the ends of the cams instead of in a separate distributor. "

Actually it is ’85 and up (in the USA) and ‘87 and up in ROW.

And the EZF/EZK can not adjust individual cylinder spark, only a COP or some other type of system can do that, not a stock 928.

The use of multiple Knock sensors IIRC is for detecting which cylinders are knocking front two, middle two, or rear two not individual, as eng temps and fuel and hot air distribution can be a knock factor.
However w/ the use of the Hall sensor it can deduce which cyl is firing and give a reading for it, but then can or could only adjust one distributor bank (1,4,6,7) or (2,3,5,8).

On the ‘85’/’86 it would be all 8 as they do not have Knock sensors, hence the default no-aggressive factory timing.

I'm sure one of the Shark Tuner guys could give you more or correct me

Dave

auzivision

Hey Dave,

I know I don’t know much about the EZF and just enough to be dangerous about the EZK, but I'm fairly certain the EZK has the ability to retard just one cylinder (or max one pair) at a time.

I was reading the shark tuner manual last night when I learned this. That’s when I became so curious because I couldn't conceive in my mind how this could be done.

Now I’m pretty clear on this systems operation and will trust that when the EZK retards the spark… it happens.

It's still rather amazing how it all ties together.

Landseer

We can also add the 84/5/6 Euro 16V cars as well. Basically the (early) 32V engine management system on a 16 V engine.

jcorenman

Dave, thanks for the clarification on the rotor locations.

And I am happy to correct you on the knock retard

The EZK does indeed retard individual cylinders as needed, assuming the hall sensor and knock sensors are working.

The two knock sensors do not sense the front/middle/rear cylinders, instead they both listen to the engine block as a whole.

The detection of which cylinder is knocking-- and needs retarding-- is done by timing. If a knock sound occurs when the #1 cylinder is fired, then cylinder #1 is the one that needs retarding.

The CPS tells the EZK precisely where the engine crankshaft is, during its rotation. Since the engine rotates twice for each cycle, while the cams (and rotors) rotate once, the EZK needs to know which stroke the engine is on-- is #1 cylinder approaching TDC on the compression stroke, or the exhaust stroke? That's where the hall sensor comes in, identifying where the camshaft is for the EZK.

You can see the individual cylinder knock-retard numbers on the sharktuner, so there is no question about what it is doing.

The EZF doesn't have knock-sensors (or a hall sensor if I recall correctly) and can't do knock-retard, at all.

Here's a screen-shot of ST's EZK-monitor page showing the knock-retards:

AO

What a cool thread. I knew most of the bits and pieces of it, but this ties it all together with a pretty bow.

Planning on doing some sharktuning this Friday. I'll see if I can get a screen shot of some individual cylinder knock retard action.

John Speake

Just log KR1 -8 with your ST2 and you will see what is going on everythime you hear the audilble knock alarm on your ST2 :-)

Landseer

How should timing progress on a 32V car under moderate throttle as it moves from idle up through 3000 rpm or so? Does the vac module on the EZF have major input in this rpm range? i just can't shake this low power flat spot I'm getting on takeoff.

John Speake

The vertical axis on this map is due to the vacuum feed to the MAP sensor in the EZ-F.

John Speake

Have you tried a good MAF ?

Landseer

Yes. I've got an 86 that runs wonderfully. Switched in LH, MAF and Temp II alternately and got no difference in 85 behavior.

Thank you for that chart. Need to do some testing. Have 18.5 mm hg or so at idle, BTW, at the computer.

Landseer

Am literally getting a massive burst of power at 2100 RPM or so.

John Speake

Shouldn't you have more like 21 inch Hg ?

PorKen

Did you check the cam timing? (I can't remember if I asked you already.)

Landseer

I'm zero on DS

Minus one degree on PS

Had the gauge on it again last week.

(FYI, it had similar behavior before the chips also. No change on the low end that I can recall)

It continues to mock me. But its given up most of its petty little secrets. Just this left.