Scoob+Bike=Fun

after reading all this, i come to the same conclusion that i had before.... I still want one, because im supersticious, i want lights just in case I dont notice, maybe a distraction, but that red led in the corner of my eye will help me keep my mind at rest.....but....what happens if the K/L fails??? what am I going to do???? how will I know if it is working or not????oh no!!!!oh no!!! oh no!!!!

New_scooby_04

iTrader: (4)

If I understand correctly, the std test for a KL is to grab a spanner or similar implement and lightly tap an area of the engine near the sensor. That should register as KL activity. If it doesn't, your KL may not be operating correctly. IIRC they often pick up starter motor activity as knock, so if you sudenly loose all activity upon starting the car up, that may well be an indication too!

NS04

Graz

Ignore PSL, he's just come on here to troll as usual. For a standard UK car a KnockLink isn't really necessary. However for piece of mind that you haven't picked up a duff batch of fuel, or a sensor (MAF) is on it's way out and gone out of spec, it's worthwhile. I've got one, yes my car is a fairly standard MY00 (for now ), but it's now out of warranty so anything I can do for reasonable cost to ensure it's running okay is good for me. I've also had a dying MAF which luckily enough I was able to spot before it did any serious damage.

The factory ECU does tend to ignore the OEM knock sensor above 5k rpm, it may be better on the new ages. This "feature" is well documented. The ECU is unable to determine knock from general background noise at high rpm so the sensor is largely ignored. You will see this on the KnockLink, I can generally light the first couple of LED's at high revs.

You'll be able to tell if its working, firstly test the install by tapping the sensor and ensuring all the LEDs light. Mine tends to light most and sometimes all the LEDs when I start the car.

If he's getting audiable knock then that's pretty serious, okay it might only be on NUL, but you shouldn't get it at all on an electronically managed engine. It may well be detting like crazy on boost, you might not be able to hear it so easily then. Sounds like a dodgy sensor to me, be it MAF or Lamda.

My old Chavilier (not a turbo) used to pink audiably, put a hole through one of the pistons after a few months.

New_scooby_04

iTrader: (4)

Just out of curisoty, what does Pinking sound like?

Best wishes,

NS04

Graz

The typical description is like pins being rattled around in a tin can.

It was quite noticable in that instance, metallic knocking / rattling noise. Suspect it needed a proper tune up, no engine managment on that car, had one of those funny carberetta things

morpheous

iTrader: (9)

Skeleton Wa@king in a biscuit tin

tath

que?

New_scooby_04

iTrader: (4)

lol If I hear that I'll panic rather than laugh though!!

NS04

pslewis

No sorry, fails to address the question:-

"Where is the evidence/report/data sheet that states the ECU can only retard 'a certain amount'"??

Just because, sometime, somewhere, someone burnt a hole in a piston - when,maybe? using 95RON fuel ............. does NOT, repeat NOT, conclusively point to an ECU that has a limited retard ability!

Pete

john banks

Pete, I don't sell knocklinks, never have.

The 99/00 ECU runs a pair of base timing maps for high and low octane. You can see them here: http://www.ecutek.com/tuning/oemcompare/

It then runs up to 16/16ths of a compensation map's contents, which typically is up to a further 6 degrees, and there is a fine learning matrix on top of that. The minimum timing is what is in the low octane ignition map. It is not surprising that the learning range is limited, how else would you stop an errant knock sensor or noise on the signal retarding the timing until it was ridiculous?

With sustained knock which the above system can't work around, the wastegate solenoid can be cut to zero duty which will drop the boost to about 0.5 bar.

In the standard car this all works quite well. With your favourite Scoobynet failure, the MAF sensor, the zones accessed on the map can be wrong and it can struggle though - it thinks you are at much lower engine load than you really are. The failsafes for reporting MAF errors are nothing like as sophisticated as on say a Bosch Motronic as in a lot of European motors. Given that the ECU does stop listening for knock at high revs (there are maps in the ECU for it which I've adjusted), then it is certainly possible for a car to be in that situation that the factory ECU should be able to avoid. I think that you place excessive faith in the ECU's abilities to save the engine in extremis.

Additionally, as pointed out, there are airflow limits to knock detection, as well as some manifolds that do stop the ECU correcting any apparent knock at all. On tuned motors you may want to be able to adjust more parameters for knock control than are available to you.

The stock system on 99/00 being deaf at high RPM relies on knock occurring in the midrange, and extrapolating results to already cautious mapping with trivial boost at high RPM. However, you don't double the power on the engine by cautiously mapping at high RPM with low boost

However, it is possible to operate the engine hard at approx double the stock power and have it survive, but obviously it needs some care, we are talking >200 BHP/litre here after all.

You can dispute all I say if you like, I'm not being dishonest, have nothing to gain, nothing to hide. I'm reasonably experienced in understanding and managing knock, as well as building my own circuits to take over the whole load control of the ECU, so I have an inkling as to what is going on. Good enough for you?

Having said all that, I would fit a knock sensor onto any Subaru I ran that was worth very much that wasn't under warranty, whether than be modified beyond PPP, or an older car.

Knock is not an all or nothing phenomenon. Brief light knock will not likely do any damage at all, but without acoustic aids even to my experienced knock detecting ears I cannot hear light knock in the cabin. With a knocklink you often get some warning of the bigger knock to come and can do something about it. At high specific outputs (even 100 BHP/litre is high enough), severe knock can punch out headgaskets, crack ring lands, big end bearings no problem, the typical combustion pressure can be ten times that of normal combustion.

I used to tune in ignorance trusting the factory knock control. Thankfully this was when I was tuning my own motor, on a small turbo with fairly weedy outputs so it could take it fairly well. Fitting a knocklink was a revelation, it was prompted because whilst the ECU was reporting no knock correction I could hear it clunking in the cabin. Knocklink was then a revelation. I thought I didn't need it, but this saved my first engine and allowed it to go on to do 406 BHP. It still runs today in lower tune in another car. I have subsequently damaged 2.5 litre engines, I think partly from knock, since being very careful on the latest one the outputs are just rising, and so far it is holding together knocking on the door of 500 BHP, on Optimax. Yes I have several gauges, I'd rather I didn't need them.

New_scooby_04

iTrader: (4)

Interesting read, John.

Thanks for taking the time and effort to explain things for those of us who aren't technically inclined!

Best,

NS04

tath

pmsl...

i don't know which planet you're from but a degree in mechanical engineering is not required to see that there are obvious limits to retardation, although apparently not in your case...

pslewis

john banks ..... very interesting explaination and much appreciated.

It makes a nice change from the kiddies just spouting 'what they heard at the local McDonalds meet' ..... like tath

Looking at those graphs is interesting ..... I VERY rarely take my engine over about 3500RPM ... certainlt not up to 6000RPM!! no wonder engines let go if thats what happens to them!!

I am still of the opinion, and I'm not just being simply pig-headed about it, that the Standard ECU can manage whatever fuel is used (unless its clearly weasel pee!) - a 6 degree shift is quite a marked from the 'standard' BTDC angle .... more than enough to cope with all known pinking I would guess??

The flashing lights are great to some owners, it serves to make them think they are somehow in control and it looks good to their teenage mates ...... no mature driver would be seen dead with them, surely to god?

I'm going to keep my £150 KnockLink money firmly in my Bank Account .... I like to think I can drive properly without idiot lights (cos thats what they are!)

Thanks again for the blurb John!

Pete

Roojai

Pete,

Just continue thinking what you like. It is VERY arrogant just to assume you are right (based on nothing but a hunch), and ask everybody else to provide documented evidence of their facts.

And then, just ignore the documented facts, and still believe you are right.

You should find some evidence for your beliefs first.

Science not religion mate!

Roojai

You are missing out so much of the potential of your car. You need to get a bentley.

tath

mate i'm telling you what i know to be true - if you don't want to listen please try at least not to condescend to me. from what i've seen of your posts, you're an **** who delights in starting arguments so please - keep it to yourself. In future, i'd advise you to stick to what you know, whatever that may be.

john banks

LOL. If you VERY rarely go over 3500 RPM, surely you would be better with a diesel or a 1.6? (or getting your thyroid checked LOL) Are you sure you are not dead? You're only getting significant boost for the upper 1/4 of your rev band. There are lots of nice VAG petrol or diesel cars that would be giving you more real world torque.

6 degrees won't cope with all known detonation, but will for the vast majority of it unless there is a collection of unfavourable circumstances such as very hot intake temperatures and a failed MAF sensor for example.

On modified cars it is totally different, and I can see why you don't need to modify.

The flashing lights actually look dreadful, I only have them there because they have a purpose, but I'm only 30 so not matured yet However, if I was your age I wouldn't be seen dead in a Subaru

tath

and in response to your 3.5k comment i sincerely hope your taking the ****. however if indeed you are not, then i'm afraid your right. knock is very easy to detect unless your running a stupidly loud exhaust and any sane driver will immediately back off.

in my limited experience of subarus, i have heard pinking a few times at low revs when using 'questionable' super instead of optimax - i have never driven my car hard with petrol i was not sure about and as soon as funds permit i will buy a knock link.

David MY99

"I VERY rarely take my engine over about 3500RPM ... certainlt not up to 6000RPM!! "

Isn't a Fiat Multipla more your style then
What's the use of having a 'sportscar' and not using it. That sounds to me like you are the one at the local MacDonalds showing off but affraid to use it, or call it old and wise. But you're absolutely right that you don't need a KL if you're not using the potential of the car...

crusher

PMLOL!...