Hi guys, have a thoughts to share to see if a few heads together can resolve this.

 

Since been involved with zeds (some 4 years)

it has only been a recent (this year) that I have got involved with pinking or detonation call it what you may at a level which is odd.

 

I know of at least 4 cars on this forum and many others who have posted that detonation is a slight or in other cases a major concern.I myself can occassionaly hear it on my own car when the correct load conditions are present.

 

My first thought is that I know this was not a big problem when I had my first zed 4 years ago, is it a continued degregation in petrol quality maybe?

 

My second thought is concerning the knock sensor,as the purpose of this sensor is to detect pinking and retard the ignition to prevent it, why then does it still present itself?

 

My third thought is when this occurs on auto cars it would seem it is outside the change down parameter of the gearbox which would concour that the engine is not under duress load or the box would change down,this either points again to the poor quality petrol theory or have these engines the ability to mimic a sound similar to pinking / detonation.

 

Final thought if a Tectom was connected whilst running through the detonation / pinking sound would the Tectom be able to show if the knock sensor is activating and timing been retarded?

 

Well there you are chaps a few things to mull over eh? all answers on a post card first out of the bag gets a big kiss of my German Shepard.

 

Cheers Jeff TT Happy Xmas all

 

 

 

 

[This message has been edited by Jeff TT (edited 16-12-2001).]

Jeff,

 

Not sure on the cause of more detonation but everyone going for mega boost might be part of it !

 

However, re the knock sensor, I believe this only operates at low revs and as most people's det happens higher up, that's why it doesn't get stopped.

 

Dave

From memory, the knock sensor is ignored above 3500RPM - there's too much background noise for the ECU to pick out any knock from then on.

 

As for using the Techtom - yep, if you look at the parameter for the BCSV, it should toggle if/when knock is detected - because you'll go into safety boost.

If I recall correctly, the BCSV should be "ON" (open) when running, unless;

 

You're in safety boost (temp sensor, knock sensor)

You're at idle

 

There are so many variables with knock though - it could be petrol quality, it could be injectors getting tired, or covered in crap..

 

Anyway HTH.

Az

Hi Jeff,

From my limited experience of detonation (apart from blowing the engine up on my old Calibra Turbo) I was having safety boost problems recently on my standard T.T auto which I assumed to be a faulty sensor as (a) it's a standard engine and (b)I'm running cold heat range plugs, but three days ago I filled up with super unleaded (97 octane) and have encountered no safety boost problems since, which may validate your fuel quality theory.

Regards,

Brian

I was getting detonation even on super unleaded. I changed to Optimax and that cured everything.

 

AFAIK the problem is down to running big boost on hybrid turbos whilst stuck with a shitty Superchips chip. I'm sure most people will agree that this is a recipe for disaster. Hoping to change to a JWT chip early in the new year.

 

Mike

From what I've read on here thats a recipie for a hole in a piston... Heck you might as well put the stock ECU back in!

As I don't know how much you know this might be a little simple, but:

 

1) Make sure that your Injectors are not gunked up and they are big enough to keep up with the boost you are running.

 

2) Make sure that your chip is set up to the same configuration as your current upgrades.

 

3) Check your lambda sensor is working properly.

 

I won't go into more detail because I don't know what I'm talking about!!!

 

Phil

aaronjb interesting that knock sensor may not function over 3500 revs,however in my experience if the load is right in top gear about 40mph / 1700revs a slight tinkle is audiable you do have to listen out for it though but it is there,given that the auto box is not changing down and this occurs when re appling a very light throttle as a slight incline is encountered then is it likely that the retardation available to the ecu is limited and cannot reduce the problem that may be more about the fuel than an engine that to all intent and purposes works and performs ok in all other aspects, thoughts guys?

Jeff TT

I would have thought that if the problem is at low revs then it's a fuelling problem rather than an ignition retarding problem. If the ECU can deal with higher revs (and higher boost) then it's capable of higher fuelling. For optimum power at any revs, detonation is better resolved through increased fuelling instead of further ignition retarding - retarding reduces power.

 

In terms of checking the lambda sensors are operating correctly (which can be done using built in ECU diagnostics), that won't actually help with high rev detonation as the sensors are not used to determine fuelling at high revs on Jap cars (and not at all on UK cars).

 

This starts to get complex as UK and Jap spec cars use lambda sensors differently. I apologise now because I may have got the following the wrong way round - I can't remember is it's UK or Jap cars which have closed loop processing but I'm fairly sure that it's Jap. Anyway, assuming I'm right ...

 

Closed loop processing will monitor the mixture using the lambda sensors and adjust fuelling accordingly. However, there is a time lag involved in this (due to time taken for lambda sensors to pick up the effect of a mixture change PLUS the processing time of the ECU). As a result of this, even in cars where closed loop IS used, it is not used at high revs because the delays would be unacceptable and cause risk of engine damage. Therefore, the hard maps in the chip are used to determine fuelling (these are based on the volume of air going through the air flow sensor and the engine revs).

 

Still assuming that I haven't got UK / Jap cars the wrong way round, UK cars don't use closed loop at all. The lamba sensors are just used as a warning for the ECU to go into safety modes if things are getting nasty.

 

Not sure how much this helps but, being a bit of a weirdo, I think it's interesting !

 

The attached is all based on someone's research of Jap & UK ECUs and watching them operate - unsuprisingly, it has not been validated by Nissan who I suspect would be somewhat reluctant to validate it ! However, the person who did the research knows more than a little about the subject.

 

Dave

Jeff, just looked at your profile. What is a boost jet?

 

Thanks,

Phil.

I have heard of instances with boost jets of boost spikes, which can cause detonation, retarding the timing will help to minimize detonation as it is recommended by Jim Wolf that timing be cut back to 13.5o BTC (as opposed to 15o BTC standard) to minimize detonation when upping boost levels, and when the car is running in safety boost the timing is retarded by the ECU, so I reckon these people know something we don't!.

Have also noticed a slight trend here, mostly Autos!!!

 

Could it be a slight rattle being heard from the Auto box as it's put under load? Reason I say this is my old mans Caprice Lazy used to do it going up a steep road to his house, my Kirk does it ALL the time and has done since I got it!!! Tried everything in that thinking it's pinking/detonating but it's not a Turbo so I ain't overly arsed. Plus that's covered mega montey mileage.

 

Just a thought!

 

As the Auto gets a tad tired could start making some interesting noises?