ATTN: all RHD GTO turn down your boost!

[rez604]

what? why?
well, are you data logging your car? no? turn it down! if you are datalogging and not getting any knock, disregard this thread.

on stock boost (8.7psi) you will get knock counts as high as 14, if you've done the free boost mod (raising to 11.6psi) you are knocking as high as 20 count. even more psi and you peg the knock sensor at 28count on a stock fuel system+94oct! this is even true when hotwiring and doing a relay bypass on the stock pump.

if you are running stock ecu with no fuel management or fuel mods please turn down your boost. I guarantee you are knocking like crazy. after a bunch of tests on 4 different gto's with stock fuel systems+stock boost including mine, I've come to the conclusion that the jdm ecu is mapped for higher octane than we have available here in Canada at the pumps. yes, 94 from chevron isn't enough. all 4 cars gave same results. the main test was a 3rd gear WOT run from 1500rpm to red line. a sticker on one of the cars gas cap shows a rating of 100, assuming this is a RON rating, its equivalent to ~96aki.

please don't be stubborn, unless you are logging your car, you have knock and are damaging your engine under boost! the skylines have known this for a while and can reflash their ecu for our gas...but unfortunately we cannot.

how can you turn down boost if you don't have a boost controller?
unplug both vacuum lines to the solenoid and cap them. it will return your boost to waste gate (5.8psi) and save your engine until you can figure out an alternative.

what are the alternatives?
meth/water injection, usdm ecu, race gas, fuel management etc.
find a way to get that octane up at least 2 count and your good to go until you upgrade your fuel. swapping for a fed spec usdm ecu is also an option, though i have not tested this yet.


edit: update june 15
my solution
meth kit. no more knock. check post #17 in this thread.

[TT Eric]

Wow...

Eric

[Vr4Much?]

this is news to me...
will let everyone on beyond.ca and 780tuners know soon

If I have a boost controller hooked up, can I just disconnect the boost controller selenoid?

[BlackStealth]

If you have a 91-92 GTO you can counter the "aggressive timing map" by pulling back some timing by adjusting your Crank Angle Sensor for free. 93 and newer can have their timing adjusted by adding a Greddy Emanage or some other controller.

[rez604]

Originally Posted by Vr4Much?

this is news to me...
will let everyone on beyond.ca and 780tuners know soon
If I have a boost controller hooked up, can I just disconnect the boost controller selenoid?

yes, you just need your wastegates directly routed to one of your vacuum ports (good spot is the nipple on the back of the ypipe before the throttle plate)
if you got electronic, just turn it off and you should be good to go.

Originally Posted by BlackStealth

If you have a 91-92 GTO you can counter the "aggressive timing map" by pulling back some timing by adjusting your Crank Angle Sensor for free. 93 and newer can have their timing adjusted by adding a Greddy Emanage or some other controller.

i would love to see proof of this if it worked for someone. my base timing was 10deg advanced, i turned it back to 4deg and still same results. even turned back to 1deg still same results. its not the timing map, cause i compared it with a usdm log and had same timing.

[BlackStealth]

When you modify the CAS, the results won't be reflected in the OBDI datalogger (timing) because the base timing isn't included.

[rez604]

i think there is a misunderstanding here.

i realize the logger only shows what the ecu is doing to the timing, whatever it may be. what i explained was done to the CAS directly (ie. with a timing light and turning it manually).

i'm trying to say adjusting the actual base timing back [as you suggested] even -5deg (so your sitting at 0deg base) still does not remove enough to compensate for the knock. remember this is all still at 8.7psi! if you have actual proof of this working i would like to see so i can compare it with my logs. i have logs of my own car at 0deg base still producing considerable amount of knock at stock boost.

removing timing from what the ecu does (ie. using timing control) WILL remove the knock.

[freakosaurus]

attention: *Semi-ignorant reply*

I have noticed this on my 91 GTO as well while data logging. HOWEVER, even at stock boost I get ~<10 knock count. But I refuse to take this wildly fun car back to wastegate pressure. I'm now running ~13 lbs and watch my ECU pull timing as it sees knock. As long as the ECU pulls timing if it sees knock, I'm not going to worry about engine damage. Again, please, mind the flames, as I have already acknowledged the fact that this is a semi-ignorant reply lol.

[cpearsall]

just to clarify, this only applies to rhd drive cars imported form japan? north american lhd cars are okay? are their ecu's programmed differently?

[rez604]

cpearsall you are correct. rest easy. (get a datalogger package if you havent already though, they are worth their weight in gold)

freakosaurus, its your car so you do what you want with it. im actually interested in your logs, send me a pm.

edit: look what i found lol http://www.3si.org/forum/f35/knock-11-psi-458619/ your log is almost exactly like the 4 cars ive logged.

your ecu is further pulling timing from base 15 during WOT to try to remove the knock, which is not happening. the knock is real, its damaging your engine.

[freakosaurus]

So what are you suggesting then? USDM ECU? I know knock is bad...I thought I'd be able to hear it... it sounds to be about 6kHz right?

[BlackStealth]

Wow, it's hard to believe -5 degree timing removal across the board isn't enough. Is it possible that you're reading false knock because of aging motor mounts?

[cpearsall]

Originally Posted by rez604

cpearsall you are correct. rest easy. (get a datalogger package if you havent already though, they are worth their weight in gold)

freakosaurus, its your car so you do what you want with it. im actually interested in your logs, send me a pm.

edit: look what i found lol http://www.3si.org/forum/f35/knock-11-psi-458619/ your log is almost exactly like the 4 cars ive logged.

your ecu is further pulling timing from base 15 during WOT to try to remove the knock, which is not happening. the knock is real, its damaging your engine.

thanks for clearing that up. an aem ems has been in the works for a while.

[rez604]

Originally Posted by freakosaurus

So what are you suggesting then? USDM ECU? I know knock is bad...I thought I'd be able to hear it... it sounds to be about 6kHz right?

i think for most ppl a fed spec usdm ecu will suffice. for myself though ive decided on meth injection instead.

i found with the higher octane, right when the injectors run out (past 100%IDC) the knock returns. this further supports my findings.

Originally Posted by BlackStealth

Wow, it's hard to believe -5 degree timing removal across the board isn't enough. Is it possible that you're reading false knock because of aging motor mounts?

you know, im honestly not sure. even after testing my mounts with various methods i still dont believe i can cross this out. the fact that this happened so similarly on all the cars is what bothers me. once i get solids i will be running a few tests again.

[freakosaurus]

Originally Posted by rez604

you know, im honestly not sure. even after testing my mounts with various methods i still dont believe i can cross this out. the fact that this happened so similarly on all the cars is what bothers me. once i get solids i will be running a few tests again.

I can tell you for a fact that mine was not due to motor mounts. by retarding timing ~10 degrees with my CAS, I noticed a substantial drop in knock count.