merchauser

yes, all the fuel here is E10.

for sure, that is the plan. what is puzzling me the most, is yesterday's AM consistent runs at zero???!!
cannot figure out how and why that happened. in my mind, it suggests my car is CAPABLE of this
and that there is a solution at hand...???


so my "testing" at different RPMs, with and w/o WOT is essentially worthless? lol

all my excitement about a new gas station and better fuel has nothing to do with my zero knock runs?

great idea I will be getting a union and some hose to perform this test later today; don't want to spill any fuel in the rear hatch; will report this later. anxious to see the result. as stated, pumps are new, and filter was replaced 01/18. I don't think debris from the in tank hose could have made it past the pump and into the filter?

yes. data sheet showed 2@180, 2@184, 2@188, and 2@192. now all are at 200, and I put them back in the order removed.

merchauser

stock brains and chips


18 was the number of knocks registered.

FredR

So to answer the question- the display on the hammer showed the number 1.8 - correct?

merchauser

no, Fred, the display was eighteen or 18 (per 10,000.) the hammer cannot read out decimals. hope this helps you.

FredR

OK- so what criteria are we going to use to define that there is a problem?

merchauser

I guess for one, jim's statement from post #28, as well as others that have told me I should see zero knocks; only going by what I have been told here and what I read.
from the forum posts. in my mind, I have determined that knocks retard timing, and thus performance. are you suggesting, that nothing it wrong and this is all normal?

also, since I WAS able to record zero knocks, that suggests, that it is possible. what I would like to learn, is why was i able to get that result yesterday. originally, it seemed
as if the common denominator, was the Shell gas. now it seems like that is out the window...….unless, (big stretch) the next few gallons I put in the car diluted the super fuel??
that seems far fetched, but, as we all know, anything is possible????? I am more than curious.

Speedtoys

Zero would be ideal.

But it's not entirely a realistic goal.

We have knock sensors because we have a 'more aggressive' timing map, than say a 32v 5l S3. THEY should never have knock, because they have no way to ID it and manage it.

I can induce knock, just one or two, on demand in almost any driving condition.

Some knock is natural..is just fine.

But there are a staggering amount of variables...logging knock counts only, and throwing very subjective testing at it, is...interesting. But wont lead anyone to more knowledge on how/why/what.

A sharktuner would be very nice here.

merchauser

this and what others are commenting tells me that I have something that needs to resolved. 18 is too many and this is affecting my timing and power.
with all that I have done, I don't think I am far from a solution. I am sure, with this communities help, I can get this sorted.

I will be doing fuel pressure and delivery tests later, and perhaps that will show something? although, the only possible (not likely) item is fuel filter.
Not sure if the FPR or dampers could cause a lean condition??

agreed! without it, all my silly tests are just that...… silly.

wish there was an ST2 nearby...….

merchauser

regarding fuel pressure tests, WSM says jumpered pump and car not running is 2.5 bar + or - 0.2 bar, and 2.0 bar at idle.
is there a spec for pressure under a variety of RPM's?? or are those two measurements adequate??

FredR

The obvious question one has to ask is whether anyone has ever seen a 928 kitted out with the EZK system experience engine failure due to knock damage? I for one have never heard of such . As I am aware the system was integrated into the 928 platform primarily to permit the car to go long distances and still get you home if decent fuel was not available and one had to fall back on filling with Witch ****. The motor is tuned to run on RON98. I have on choice but to run RON95 which is equivalent to your PON91. I had to pull a bit of timing at around 5.2k rpms and somewhere around 3.9k rpms but got gains in other areas. I later found out that my faster than stock exhaust may also have played a part in that a less restrictive exhaust burns faster thus will not take as much advance. Do you have a stock exhaust?

If the system did not work then logic suggests they would not have fitted it. The stock system pulls timing by up to 9 degrees in three incremental steps of 3 degrees. In ST2 we can alter the increment size and the recovery period. When I was setting up my system I did the testing with increments of 1 degree to help me understand exactly what was going on and with patience managed to work out when knock was consistently being detected and thus pulled back as appropriate. I was running my current setup before I acquired ST2. When I lost my late S4 we opened up the motor and visually it was perfect- no signs of damage on the piston crown and very little in the way of deposition. When I first used ST2 I saw some knock events and they were invariably on either No6 or No2. Testing with a programme mod that Ken prepared for me, I was able to ascertain that at high rpms I had to pull about 2 degrees on 6 & 2 to get a more level playing field such that other cylinders started to knock in the same rev band. This then begged the question as to whether we can deliberately set more advance by say 3 degrees and then rely on the system being able to safely pull back some of that if it proves to be too much knowing that there is still 6 degrees of retard in the reserve. This I have not tried. Now I understand RON98 has just arrived in three garages - whether or not I can be bothered to go through the process again remains to be seen.

So, as I recall [but have not checked recently] the Porsche WSM criteria based on knock count is 50 knocks per 10,000 firing events is acceptable. Last time I read about this it said the display reads in numbers like 1.8 which equates to 18 events and if the display reads above 5 [i.e. 50 events] there is a problem. It also said there were two types of tester= whether they are both the same I know not.

Considering the above is your "18 knock count" relevant especially when you have seen smaller numbers and even zero?

FredR

Those numbers are for the earlier 32 valve model- on your engine the same case number should read 3.8 barg if I remember correctly. That is why some earlier models have 24lb injectors

merchauser

I would be an idiot to not be concerned about potential damage due to knocks, but in this instance, I am attempting to get the most power out of this car by finding the source of these knocks,
in an effort to stop timing pull back. as WSM states, I am well within the allowable 50, but, I think I can do better and make the car better as well. I am using the KTS 300, and there are no decimals
in the display. maybe the 301 has this?? so the displayed 18, is a true 18.

fred, regarding your experience, the sharktuner would surely help take the guess work out of my situation.

yes, stock GT exhaust. I have wanted an X pipe for a long time, but I keep finding other, more important things to buy, so the X pipe, keeps getting pushed down the list.
are you saying, an X pipe would help here? (might be a good excuse to move that up the priorities list...lol)

FredR

Paul,

You would only be an idiot if you knew your car was experiencing a potentially destructive mode of operation and ignored it but that is just not the case here. In reality you are probably more concerned about what you have picked up on the subject matter and the real question is whether it is a problem or not . It is a bit like modern medicine- nowadays doctors can see much deeper into our bodies than they could just a few short years ago- trouble is they find things that were simply never found previously- but somehow people survived and life expectancy increased. Trouble is when we know something is not how it should be we tend to worry more about it - a double edged sword as it were.

One thing you should consider is that not all engines are equal- some perform significantly better than others and Porsche knows this but when they tell you your engine develops 330 bhp what they mean is they all develop that and by extension, some develop even more. Now, if a given motor has a tendency to knock is it because it is burning too much oil that causes a reduction in knock resistance or could it be because it is swallowing more air/fuel and thus more prone to knock events happening at a given operating point?

Regarding the X pipe on its own it gives some performance improvement- if it is breathing better at a given operating point, is it going to be more prone to knocking or less prone?

merchauser

wonderfully stated fred!! good form...you are spot on!

all I want to do is put this car in best shape that I possibly can!

just did the fuel volume test and it is near spot on the 1.25L. not sure if that's a good thing? WSM says that is the minimum, so with new bump I was thinking (hoping) it would pump more. did this 3 times and each time was nearly the same

now for the pressure testing. the loaner tester I got does not have the correct fitting for the fuel rail. does anyone have the size thread??

jcorenman

Paul, in post# 28 I said "few if any", not zero. I think Dave (in a previous thread) and others have posted that S4/GTs generally show zero knock-retards, but it is highly variable.

There is one part of your test that I think is significant: You reported some detected knocks in the 3000-4000 RPM range NOT at wide-open throttle. The S4 and GT advance maps have a lot of headroom in the partial-load area, so knocking there is unexpected. Which is why I asked about Autothority chips-- those add a lot of advance in the middle of the map and will certainly make it prone to knocking.

Are you sure that you have stock chips? The only way to know for sure would be if (a) you are the original owner, or (b) you looked inside the EZK. Assuming the first is not the case, you should do the second. Because what you describe would fit those chips. Stock chips will have a paper label with a Bosch part#, post a pic if not sure.