Knock Reading Of 207!

[White GTS-T]

Well story goes the other night i took my car out for a drive and got a knock reading of 207 on my S-AFCII.

The controller is installed correctly and knock was set correctly and previously the highest reading i had gotten was 26.

At cold start up i get a very small reading as with cold idle. Once the car is fully up to temp i.e after a 3 hour trip and stopping at traffic lights i get a reading in the mid teens.

The reading of 26 occurred when i heel n toed from 5th to 4th to 3rd.

But the reading of 207 happened on a very cold night <10 degrees. I was at 2000rpm and having just previously installed a 3"dump/front pipe and 3" high flow cat i wanted to see how it would pull. Went to 90% throttle and revved it out to 4300rpm before shifting and thats when the reading occurred. Prior to this i hadn't gone past 50% throttle.

To double check i put it into second and did the same thing and got a reading of only 4. I haven't had the car tuned yet since i installed the A/F controller (booked in this Tuesday) but just wanted to hear your thoughts as to why i i got such a high reading.

Car: HCR32

Mods: 3" turbo back exhaust with 3" high flow cat, Greddy VSP-L FMIC, M's Filter with CAI, Walbero Fuel Pump. Everything else is stock.

The car does however run very rich. There's unburnt fuel over my rear bar and inside of the exhaust is i thick lining of carbon build up/soot. I always run it on Bp Ultimate. Apexi TT o2 voltage is constantly in the high .90's and theoretical A/F ratios is usually in the 10's. Is it just that the car is running super rich, or that it was a really cold night?

[r32woohoo]

Shouldnt your motor be dead with a reading like that?

Maybe you went over a bump at that moment and the knock sensor picked it up?

Or a rock flicked up and hit the engine

[White GTS-T]

Shouldnt your motor be dead with a reading like that?

Maybe you went over a bump at that moment and the knock sensor picked it up?

Or a rock flicked up and hit the engine

I don't know. I know its extremely high and that the ecu reads genuine knock at 120 so who knows how much damage was done at 207? The road was flat but rather bumpy so that could have been the cause, a freak reading perhaps, don't know about a stone but quite possible. I guess i'll find out more when i go to the tuners on Tuesday. But for what its worth car has been running fine since...

[R31Nismoid]

It'll just be a cell that needs adjusting. As you said it was a horridly cold night.

Thats the cause.

No real need to worry. Whilst 207 isnt great, a once off shouldnt post any problems.

If you stayed up it and it knocked 207 on and off for a few mins i'd be worried.

[White GTS-T]

Thanks R31Nismoid that puts my mind to rest a great deal.

I'll be able to sleep easy tonight...figuratively speaking...as I'm on my 3rd No-Doz tablet as i have an assignment for uni due this morning...

Anyway I'll let you know how i go with the tune. Thanks guys.

[Cubes]

The black soot over the rear bumper is the lack of a cat.

[White GTS-T]

No it's not, it's just running that rich

[Cubes]

Are you sure?

Mine used to run so rich that I had ignition break down (well in to the 9's); with a cat it never used to spray soot over the rear bar. The cat in that tune/lack of tune only lasted a couple of months before breaking in to bits and blocking. It wasn't noticeble it was stuffed until we checked the cat out next tune. And it was nackered.

So if its running as rich as you say; you cat will be near stuffed.

[SLY33]

i saw 260 knock when my valve guide broke

[White GTS-T]

Are you sure?

Yes i just replaced the stock cat with a 3"high flow item myself last week.

i saw 260 knock when my valve guide broke

[Cubes]

If its running as rich as you say sort it out ASAP as the new cat won't last too long.

OR.. wind the boost up a little

With stock ecu's and a little boost they don't run 'that' rich. If your still getting soot over the rear bar something is up with the car.

[Birnie]

I had one of these years ago and i never found the knock reading to be consistant.

Mine would start low and gradually increase as the car got hotter, and so did the unit with all the lights running thru it.

Cruising down the freeway it would gradually climb to 100 with no change in driving style.

And don't compare it to knock reading on a Power FC either

Once i went to Power FC, even before it was tuned (base map), i drove 1.5 hrs to the Hitman for a tune, same freeway conditions etc, no knock over 15.

Maybe my SACF was FUBAR ?? Who knows.

[White GTS-T]

Yeah thanks, the car is booked in for a tune tomorrow at Geelong Tune-Up Specialists. Hopefully they can sort everything out.

As anyone else had there car tuned there?

Hopefully after only a week of driving it as is the new cat will be fine.

I'll post up a dyno sheet and what not when i get back from the tuners tomorrow.

[WogsRus]

I have seen them that high, but looking at the long, 99.9% of the time, the spike occurs on VCT change over, so what you hear is the change over of the VCT or somethign associated with it.

As long as you don't drive it at such a high knock reading and it was a one off, it was propably a glitch.

[White GTS-T]

Who's comparing it to a Power FC?

Well the highest reading that i had gotten previously was only 26 and that was when i heel n toed twice in quick succession.

Other than that highway and city driving the highest reading was in the mid teens. So i would say that it's pretty accurate.

[White GTS-T]

I agree that it was probably a one off but RB20's don't have VCT...