Knock???

[Bass Junky]

Hey ppls.

Well, I had to fill my car with Vortex on Sunday night because I was too far away from a BP station and didn't have the fuel to try to get where i was going.

Anyway, later in the night, I'm driving back from seeing "Saw" (sick arse movie, it was great) and something interesting happened.....

LESS than 2000 rpm, almost 80 kph, just accelerating up to 80 after somebody slowed down in front of me and the engine light starts flashing......

Engine just comeing on boost, probably about 5 or 6 pounds on tap.

So I slow down and try again, and same thing.

Happens again in 4th, at around 2000 rpm, sometimes stops with the pedal down, sometimes not.

Doesn't happen in third, or at full throttle anywhere else in the rev range.

I'm assuming this is knock, but I'm not sure.

Can you make an enginee knock at 2000 rpm?

How much damage am I doing at those rpms anyway??

Does this mean I should go out and buy new cams and get my turbo highflowed and put in a built engine to stop it from even happening

All help appreciated.

I'm off to buy some octane booster....

BASS OUT

[Scooby]

Bass;

knock is not your friend at any rpm but obviously high levels are worse than low levels

what mods do you have. seems that timing is 'on the edge' with 98, if your ecu has been tuned did the tuner give you any safety margin for bad fuel etc

even the best built engine will knock if the tuning is not right so cams and turbos are not likely to help if there is something fundamentaly wrong

might have been just a bad fuel batch

have you checked wastegate connections etc (although you said it knocked @ low psi boost)

regards

[Bass Junky]

the Afrs are good, no leaner than 12:1 at the hot bits.

Obviously at lower rpm they lean out a bit, but not much.

Have a look at the charts.

[3R1K]

Bass, it has happened to me. I accelerate on 4th gear on around 90 then I see the engine light flashed.

It happened randomly for me , so I'm not sure to be honest

[NickR33]

I was on holiday in Apollo Bay recently and had to fill up with that crap 96 octane 'premium' at BP... I was so paranoid that the motor would ping but I wouldn't put octane booster in as it fouls the plugs, if I had coppers in I wouldn't mind... but not with platinums

Hey Bass I have some cams sitting on the floor at home, if ya want them

[Zebbie]

Just to add to the thread......

I ended up having to fill up with the Caltex 'Premium' the other day, and in concert with the warm temps atm (40+ Deg in Bathurst) - I had plenty evil pinging/knocking moments, under mild boost <>5-8psi...

It was just like a tin can full of pebbles... :-/ !!!

As soon as I could mix what was in the tank with real BP fuel, no pinging at all, even when given a good flogging to see if it was the fuel.

I've heard of a few reports of this, especially with the cheaper fuel (Serves me right, tbh)

feed thy beast properly!!!

[GTRgeoff]

Bass I have 11.6:1 and a crappy batch of Optimax has me listening for every sound. Didn't see the light but heard it.

[SLY33]

zebbie, on those hot days, be careful of ANY sort of flogging no matter how good fuel youve got in the tank! with ambient temps of 40+ intake temps would be frying! especially if youve got a tuned ecu as they are often tuned closer to the limit than a factory ecu. PLUS while your factory temp guage might be sitting sweet in the middle, i guarantee you youll see water temps over 100deg! even more so if with the a/c pumping!!

[Zebbie]

I was guessing something along those lines.... I am trying to get a standard airbox atm, for modding as my input temps were high on a standard day (hks pod/mushroom - 20 deg c ambient, 40 deg c actual input - on a decent probe)

God only knows what the real input temps are on a day like the last few.

When i've got a standard airbox, we're modding it into a ram input from the underneath of the indicator cluster, which'll help a lot.

I've also got a mines ecu, which is running rich atm, just to add to the rest of it.