coulty

On my MY96 sti I am experiencing lift-off det. It doesn't light the knocklink under full throttle but when i lift off the KL lights right up. This is only at high revs ie 5.5k to 7k. The only mods are a green panel filter, centre decat and a ecu upgrade (similar to scoobyecu). Before i installed the new ecu i tested my KL and it was doing the exact same thing using optimax and millers.

Does anyone know if lift-off det is just as bad and how do i prevent it???

Thanks
Stuart

coulty

c'mon someone must know! Greasemonkey where are you when i need you !!

Stuart

ozzy

Is it definetely det?

Does it happen only when shutting the throttle or is it more to do with gear changes at high-revs?

Stefan

coulty

It happens when just backing right off the throttle or when backing off to change gear. Can i adjust the sensitivity of the knocklink if it is just gearbox noise?

ozzy

There's a little pot at the top of the KL for adjusting the sensitivity (default is maximum IIRC). Personally, I would run the car on something like DeltaDash to see if the ECU is actually seeing knock (and pulling back timing) and also some det-cans just to check if it's actual det or other gearbox/engine noise.

Stefan

coulty

Cheers Ozzy

could you please point me in the right direction to have her checked out then because i really don't want her to go boom!
Who has deltadash or det cans that could help me!

Many thanks
Stuart

dnb

Delta dash doesn't work on MY96 cars... (MY99 and onwards only)

I have made det cans out of ear defenders and hose pipe to good effect before now - I'd suggest that this is more reliable than seeing if the ECU is doing anything about the apparent knock, as the ECU can be deaf at times!

I have a "select monitor" of sorts for my laptop that works for MY93 to MY97 cars.

coulty

dnb where are you based?

Stuart

dnb

Very south!! (The Isle of Wight)

coulty

LOL oh well at least i asked!!

Anyone else want to try to help!!

Stuart

ozzy

Sorry, Stuart forgot you had a MY96.

Only place I know of would be a dealer for the Select Monitor

Stefan

coulty

you dont know anyone with det cans?

The_Judge

So you say it was definitely doing exactly the same, prior to fitting the ECU upgrade...? Has it done it since you owned the car? Did you buy the car with the knocklink already fitted? Or did you fit it yourself, and have been getting this activity from day one of fitting? Have you always used Optimax and Millers...? Does it only do it in the rev range you've stated? What activity (if any) further down the rev range?

One thing to check is that there are no splits in any of the induction tract/turbo/intercooler pipes...

ozzy

Whereabouts are you in Scotland Stuart?

Stefan

coulty

Ozzy i am in glasgow.

Judge
So you say it was definitely doing exactly the same, prior to fitting the ECU upgrade...? YES
Has it done it since you owned the car? DONT KNOW CAUSE I ONLY FITTED THE KNOCKLINK ABOUT A WEEK AGO
Did you buy the car with the knocklink already fitted? NO
Or did you fit it yourself, YES
and have been getting this activity from day one of fitting? YES
Have you always used Optimax and Millers...? SINCE DAY ONE OF THE CAR BEING IMPORTED
Does it only do it in the rev range you've stated? YES
What activity (if any) further down the rev range? NONE WHATSOEVER

I will check the pipes tonight but why would it be them when the throttle shuts?

Stuart

I appreciate the help i am getting from you both!

The_Judge

I was wondering whether it was sucking in more air than the MAF knew about... but if you're not getting any activity further down the rev range, it's unlikely to be that.

coulty

My lambdalink shows that at these revs it is still running rich so that would not be the case if there was more air being drawn in surely ???

Help!!
lol
Stuart

greasemonkey

Sorry I'm a bit late to the party Stu, will have to complain to boss about work compromising my ability to post on Scoobynet!

Caution is always the way to proceed here. Assume it's det until you can prove otherwise.

How, exactly, does the LambdaLink behave on WOT, and when you lift off? Does it richen up for a fraction of a second after you lift, or does it immediately drop down into the lean area? Could concievably be that the ECU is reducing fuel injection too soon after it detects you lifting, which could point to the TPS not reading properly, among other potential causes...

Bob Rawle

Lift off det is caused when you drop onto a part of the map that has high timing and a possible lower area of fuel numbers, as temperatures are high as you shift from high revs this will cause lift off det due to pre-ignition and a kind of dieseling effect, hang it on the over run under these conditions and you can melt a piston, the early cars are particularly prone, I used to get it on my Sti2 wagon even running 98 ron and booster on the track, it can be mapped out easily enough if you change to a programmable ecu or if the std ecu maps are tweaked accordingly.

What plugs do you have in there, a set of cold ones may well fix it, at least heat grade 7's better with'8's I would say.

bob

coulty

GM i am going to go out and see exactly what it is doing and report back in a little while.

Bob thanks for the input. I have no idea how cold the plugs are as they were replaced by JVS for me when they imported the car for me. I believe they are iridium plugs but that is about it. Tell me the ones do get (part no please) and i will have them replaced as soon as.

Many many thanks
Stuart

coulty

Ok i have been out and once it was up to temp (oil that is!) i gave it some and the first thing that happened was the knocklink lit up at about 4.5k for the first ever time. I got it up past 5.5k and let off while watching the lambdalink and the lambdalink shot down before the revs went down so therefore it immediately dropped into the lean area.
The map i got from Alex Hill was for my model code of ecu (6K) and year. It was a map for running at 16.4psi (up from 14.5) and for using just optimax and no booster as i used to do.

What is the best plan of action now?

Stuart

greasemonkey

Confirmation from someone with det cans that what you're seeing is "real" det would be helpful, but for the time being I'd suggest that looking into a remap/Scoobyecu etc. would be a good idea.

ozzy

Stuart,

Some of the lads around Glasgow may know of someone with a set of det cans. Do you know Alan Garrod, Dougster or Scoty?

I think John Banks and T-UK (Fife) were making some DIY det cans for monitoring their cars. It could be worth asking in the Scotland forum for some local help.

Stefan

dnb

DIY detcans will not cost you more than £10. Well worth doing - it's not difficult! Must get mine back, then I can post a pic.

If you want software to examine your ECU then email or PM me.

torment

Please ignore my ignorance ...But when you guys refer to det cans...What the hell are these please....?.

greasemonkey

Think of a stethoscope... for car engines!

coulty

Just to update the ongoing saga, I am getting a new map sent from Alex Hill that he says should clear the problem.....heres hoping!

Stuart

coulty

Ok so heres the final part to this. It turned out that it wasn't true det but was the clutch release bearing spinning when i went to change gear ie lift-off throttle. Hope that shows there are more than just det problems that light up the KL, but always make sure you get it checked by someone who knows!

Stuart