Mads

Hi

I just bougt this LH + EZK chip.
http://cgi.ebay.com/ebaymotors/87-91...#ht_2153wt_939

Does anybody know if this chip is a copy of a good performance chip ? or if its just a bad hack

I have only driven the car about 10 km, but i don't think there is any performance increase should i run with the chip for a while, og just go back to stock ?
How long does it take the ECU to 'learn' after it's been disconnected ?

I also found out that my LH unit was partnumber 928.618.123.25, acording to JDS LH chart that should be from a 91 S4, but mine is from 89 is that a good thing ?

The car is af 89' S4 auto, with Airpump delete, X-pipe and RMB.

Mads

jcorenman

There is no way to tell what it is from the ad, but the reference to "$400 chips" would be Autothority. Those are stock chips with a higher idle speed (not needed), higher rev limit (which may or may not be safe), more fuel (which the S4 does NOT need, it is already too rich in the higher-load areas) and more spark advance.

The spark advance is the only thing that would add any power. My concern is that the Autothority chips add more advance than may be safe.

The situation is this: The EZK senses the beginning of knocking (pinging, pinking) if the ignition is too far advanced, and retards up to 9 degrees of ignition advance if the engine starts to knock. (The stock EZK does this 3 degrees at a time, for each cylinder independently).

The amount if ignition advance that can be used without knocking depends on engine condition (particularly carbon buildup), altitude, temperature, fuel octane, etc. And that is the beauty of the EZK system, the ignition-advance can be more aggressive without compromising the safety of the engine.

The ignition advance for a stock EZK is rather conservative, which you would expect from Porsche-- it needs to work in a wide variety of conditions. And an S4 in good condition with good fuel rarely exercises the EZK's knock-retard-- only a few knock-retard's in normal operation. So there is some opportunity there for more power, but not a lot-- typically only a few degrees of advance before the EZK just starts taking it all back out.

The Autothority EZK chip adds up to 12 degrees of advance, with the largest change in the area of highest torque-- and also the area which is the most prone to knocking. And of course the stock EZK can only retard up to 9 degrees.

So there is a real possibility, I think, that if the timing is close with the stock chip (which is the usual case) then adding 12 degrees of advance means that the EZK can no longer control knocking-- it is out of adjustment range. And at best, the EZK will simply remove most of the added advance.

So, depending on fuel, altitude, etc. there should be some gain, but there is also some risk. The problem is that without a Sharktuner, you do not know what the EZK is doing, and you don't know how much knock-retard there may already be. If the EZK is already doing some knock-retard with stock chips then it the Autothority chips will add more advance than the EZK can control, and the engine will certainly knock. It is also hard to hear, especially with an X-pipe and RMB.

On the other hand, if the idle speed did not change (from 675 to 775) then maybe these are simply stock chips. In which case they are safe, but not worth anything.

And as far as I know, the LH for '89-91 are interchangeable-- different part#'s but work exactly the same, except perhaps for some diagnostics functions.

John Speake

+1 on what Jim says.

If the chips were a rip off of the Autothority chips, then their LH chip was based on MY88.

inactiveuser1

When I bought the 87S4 back in 1994 drove the car for about 2 months then upgraded to the Autothority chips.The low end drivability was alot better in throttle responce most likely what Jim says with the advance.Redline was alittle over 6,000rpm after.Same Autothority chips are in there now and wouldn't want to go back to stock chips.Still have airpump,stock exhaust etc.On 93 octane it runs good,never tried any octane lower in the car than that always ran 93.Chips that have alot of advance aren't good thou if going to Nitrous or similar mods with boost.X-pipe and RMB which I don't have may lean it out more which isn't good with advanced timing from the chips.The one difference with the Autothority chips that I could definently feel was the low end throttle responce if you can't feel that the chip set you have may not be doing much.

Mads

Thanks for the input
I run 95 octane, but we have 99 octane also. I always use 99 on my Audi a4 b7 1,8T (with chip).
Would it make any difference with octane on the 928 ?

Mads

John Speake

If they have advance the igntion timing as much as suspected in your EZK chip, then under hard acceleraqtion on 95 octane the igntion will be retarded and you may end up with less power than a stock chip.

On the other hand with 928 octane you should notice an increase in perframnce due to less knock retard.

But all depends what fuel grade those chips were developed for. But there are large variations from car to car as to where detonation will occurr. That's why a SharkTuner is the only way to really remap the EZK correctly.

When knock retard is activated, timing is quickly reatrded in large 3deg steps. But it recovers on a very long time constant in 0.1 degree steps if detonation has ceased. This can take up to 15 seconds for the timing to return to stock.

With the ST you can edit those two parameters

Eturbo924

Quick question. Reading on the rev limit. What should a stock S4 (1987) rev out at in 1st,2nd and the like? Is it always 6k... or is each gear different. Oh this is an auto. My 87 seems to go past 6200 in 1st at least. I have not noted the other gears... but definately in 1st.

Was wondering if the chips were changed.

SeanR

I've had to replace a few of these chips here in Texas, they wouldn't allow the car to pass state inspection.

PorKen

Don't know about the S4 chips, but on the S3 chips, the AT=eBay chips have the stock rev limit, 6400 rpm (as well as stock WOT fuel and ignition maps, IE. they cannot dyno higher than stock).

S3 and S4 computers don't factor the gear used or road speed. At WOT, the first gear shift on the 4-speed is hydraulically programmed to a certain speed, and the other shifts are controlled by the kickdown relay, shifting just before redline.

John Speake

Standard Rev limit on S4 is to 6510 rpm.

dcrasta

Sorry i cant see the value in gambling on a 30 $ chip from Ebay in a car like a 928. Maybe a throw-a-way Honda or Toyota, but not a P car..

mark kibort

are you sure the rev limit is 6510rpm, I thought it was 6600rpm and 6800rpm for the GT

John Speake

Quite sure... for the S4