pban

Yesterday had my downpipe and backbox fitted, I watched the knock link intensely every time I managed some WOT wondering if it was going to det running FMIC and Millers. Hit 4000 RPM in 3rd and WOT, a full spread of lights

This morning I was going to post the fact that a decat on a Version 5 needs to watched. Full spec is STI V5, APS FMIC, K&N cone filter; H&S decat downpipe and back box, standard centre and a bottle of Miller per tanks.

Anyway just to confirm I plugged the DeltaDash in this morning to see if I was getting any knock correction and there is none at all. After the full spread of lights 4-4.5k I see just the two greens with a flicker of amber much further up the rev range.

Now I'm left wondering is it det? Do any of the experts have an opinion? Am I seeing det? Should the ECU be picking this up and attempting to correct if it is or is there something else that will cause the knock link to react like this? The sensor is in the usual place under the intercooler (where is was anyway)

And before anyone tells me I need a remap I will be booking the car in for a Tek 3 from THE MAN very shortly, its next on the list of mods.

Paul

babber

I thought the OEM ECU knock sensor was ****e, and even ignored knock above a certain RPM, as it could simply be engine noise ?? I'm no expert here.

Delta dash should only show you knock correction when the sensor senses the knock then retards the ignition....Doesn't that mean knock won't really be noticed by delta dash and hence the need to have a more accurate sensor (Bosch) and the knocklink ?

Phill

john banks

Can't tell from the other end of a Scoobynet thread I'm afraid.

The ECU often does not pick up overboost related det on decat STis for some reason. What boost does it peak to when it dets?

Bob will listen with det cans to confirm if it is det or not. Meantime if you are not sure do not provoke it.

It could of course just be a noise it is picking up that resonates at that frequency - for example a heat shield. Without you being able to fiddle with the ignition and fuelling can be tricky to tell, but does it do it on part throttle through the same area? Does it do it if you block off the solenoid vent pipe to make it run lower boost?

pban

John

Peak boost was 1.27 bar at around 4500 RPM, in fact the lights came on as she reached peak boost as I remember. I just thought that with a FMIC charge temp would be lower so I figured the car would be less prone to det!

I will see if she still does it at part throttle. Like I said remap is on its way so I shall be very careful with the right foot until that’s done.

Isn't this why we fit knock links to give max warning of anything that could damage our engine?

Paul

Dizzy

The problem is when u fit a fmic (or uprated tmic) you will increase the (air)charge into the piston and therefor potentially leaninig it out

pban

Dizzy

Is that because the FMIC is less restrictive? Does the MAF not compensate for this to some extent or with the decat I am now flowing loads more air, too much for the MAF to compensate for. I'm not arguing just curious.

Paul

Jack0

Agree entirely with John Banks.
You need to verify whether it is KNOCK or NOISE!
Knock is most likely to occur in 4th and 5th under certain load conditions with the sweet spot at approx. 3K-4.5Krpm when the cams are singing.
Load conditions can be interpreted as inclines, high ambient temps, heavy payload (get out of my car you fat b@rst@rd!) etc. etc.

What ever you do, do not trust most of the b0ll0x you read on here. It is your engine not theirs. Get someone who can use Det cans to differentiate between Knock and noise ASAP.

Jacko (my 2p worth!)

pban

Jack0

Thanks, will certainly be careful until Bob had done the business.

Paul

john banks

Well, given that the timing is acceptable for 100 RON at 1.1 bar (the target boost), with 1.27 bar and as Dizzy says a denser charge (so higher load which can be thought of as air charge per cycle) plus it happening at peak boost, it is IMHO very likely to be detonation.

Probably just needs more appropriate timing in these zones. The denser, cooler charge gives a higher dynamic compression ratio which requires less ignition advance for the same or a greater BMEP. Just because the ignition may have to be retarded is not necessarily a bad thing. It is often whether the effect of the dynamic CR is opposed by the reduction in charge temperature - sometimes it is, sometimes not.

This all assumes that your fuel pump isn't knackered, MAF is OK etc etc.

[Edited by john banks - 5/13/2003 10:14:57 AM]

pban

Thanks everyone for your imput. Like I said before, I shall treat with care until remap is done.

Slightly off topic, I have the H&S centre pipe available to go on the car but am planning to send it back to have a slight mod done to make it quieter. The exhaust is pretty loud now (H&S DP and BB, standard centre with resonator)I can't imagine the modified H&S centre pipe will be as quiet at the standard pipe so the question. What performance gain with the H&S centre give over standard resonator centre as an approximate percentage? Basically shall I leave the car as is or go for the de-resonatored centre pipe?

Paul

Dizzy

this may sound REALLY dum but where are you getting your earth from for the Knocklink? I got my earth from the sterio and I find the base "0 volts" creeps up when I switched the sterio on thereby confusing the poor lambda link.

pban

Dizzy

Earth is from the ECU bottom stud also connected back to battery.

Paul

Leslie

Dizzy

The earth is pretty important for the AFR measuring device since it is working on low voltage from the Lambda sensor. Maybe a wire direct to the battery earth post would sort it.

Les

Dizzy

Dont worry I know how to sort it was just pointing out it could have been a potential problem