Rokpapaziz

Hi all

I've recently noticed that when logging with my tactrix I've found some high knock sums (10-20) when the engine is around 60 load and 1500rpm.

That's basically when I am cruising on the speed limit of 60kms (Australia) in 6th gear.

I was using the GST boost pill map and now reverted to the stock pill and tune. I'm getting the same knock sum happening in the same areas of the maps. I've refilled the fuel using both BP ultimate and Shell V Power (98RON)

So does anyone have any ideas on how to tune this out? Less timing? More/less fuel? Mivec?

Any help would be appreciated.

sstevojr

iTrader: (7)

60-70 load and 1500-2000 rpm, yeah.
You can try and smooth out the area of the timing map that transitions away from idle (less ramp up basically). I personally think it's a "phantom knock" of sorts, especially when first acceleration off the line. I was able to reduce the knock sum, but not the occurrence (especially when the engine is still coldish); I still get counts of up to 6 right there all the time.
Also, for me that is too low a rpm to cruise in, try dropping to 5th gear (I can't stand cruising at less than 2200).

Rokpapaziz

Thanks so much for your reply sstevojr 1 out 138 views isn't bad is it??

Glad to know my car is not the only one, actually that's not really anything to be happy about.

So maybe I should ask a different question.

Is everyone else with a tactrix logging constantly and not seeing knock at that 60/70 load, 1500 to 2000 rpm range??

Or

Is everyone else doing the same as me and just doing 3rd gear pulls with evoscan with very little to no knock sum and thinking everything is fine and dandy?

majinfajita

I'm not saying this isn't useful to pursue for some, but the lazy man's solution is to downshift (I am rarely higher than 4th gear unless I'm doing over 70km/h, at which point I'm in 5th and even shifting at that point feels like I should have ridden 4th a bit longer).

As you can tell, like sstevojr said, cruising at under 2200rpm is somewhat foreign to me as well....so in response to the quoted question, I think the people who are logging (and thus running custom or basemap tunes) typically don't run the revs so low and thus aren't noticing those problems as those occur in situations they wouldn't normally put their car in.

richardjh

Yeah, he and I are going to pursue this as an exercise in Lurning What the Engine Wants.

To start with, I've suggested he do the following:

- Pour some good (name brand) octane booster in with the next tank of 98RON, and see if it makes any difference at all. I contemplated suggesting a treasure hunt for higher octane fuel, but a can of booster will hopefully suffice. If nothing else, it'll act as extra injector cleaner, lol.

- Check under-car area for metal rattling bits - stuff that might vibrate like mad at a harmonic around 1500rpm and make the knock sensor go ape.

- Review his logs of a "stock tune with mode23 logging" ROM I provided, and compare to logs of Bryan's Base Maps in the same area. Bryan uses less timing advance at 60-70 load, 1250-1750rpm, so if the stock tune knocks MORE, it tells us a whole lot.


I'll also go back over his logs and see if the standard ECU behaviour of retarding 1* per 3 knocksum appears to improve things momentarily, or if it makes bog-all difference to the knocksum.


I've checked my own open-loop tables around 1500rpm, and it's switching over at 85 load. Those came in as part of Golden's preferred settings for open loop, and it's a country mile from the 60-70 load knocking seen here. So I doubt blurting more fuel in is the answer.

If it turns out to be as straightforward as giving it more timing retard there, great. But real life is rarely that accommodating.


I guess we'll see. Will welcome constructive suggestions, of course.


I, too, wouldn't drive so as to see 70 load below 2000rpm... but my wife could easily do this if she borrows the car, just driving normally. NORMAL/AUTO is rubbish at downshifting, and will happily lug the motor in 6th.

So... I'd want combustion to behave itself, should those circumstances arise.


Guess I can test out timing (and possibly MIVEC) on my car's ROM too...

Rich

majinfajita

Seriously Richard, guys like you are what keep this community going.

Rokpapaziz

Ok this is a good reply, I'm sort of trying to gauge how people who have used the GST maps are driving their cars.

I can understand why you would only use 5th or 6th gear as an overdrive gear.

But I'm actually interested in fuel economy too. I will usually get 400k's out of a tank before the refuel warning comes on. How does cruising in 4th affect your fuel usage?

Also i'm wondering if these engines with a stock tune are actually going to blow up if you drive it as it is programmed from the factory.

sstevojr

iTrader: (7)

I'm assuming this is an Australian version of humor??

The SST "Automatic" mode was an after thought in production. It's designed for silly people who buy race cars and want "good gas mileage" (just get a Prius; in fact buy a Prius and ask their forum "how can I make my car fast"). This is something that has been talked about endlessly, you can find MANY good threads (as the SST is now 4+ years old, with just as many years of speculation).
Shocking news break: Stock Cars Have Engine Knock. It's the "what kind" and how much" that are important, as turbo's build a whole lot more pressure a whole lot more quickly.
As a "safe" idea, don't cruise under 2000rpm, unless you are in a parking lot. You get maybe 1 more mpg but a higher "risk" of breaking something.

Rokpapaziz

Thanks for the tip Yeah I do get this only use lower gear sentiment.

However I bought my car second hand and I'm pretty sure that the previous owners would have not used manual mode all that much. Therefore my car has already done a few years being driven in normal auto mode.

So if this knock happens in stock tune, it has also been going on for a couple years.

I would get a prius but you know what? I stupidly spent all my money on a race car.

richardjh

Oh, trust me, you really don't want to open that door...

Yes, indeed.

The "what kind" is still negative-boost area, low rpm. The "how much" is knocksum of 20. Big number. That's why I'm keen to find out more...

Rich

majinfajita

I'm actually still running the stock map for now (until I get a wideband). Well, city driving for extended periods in lower gears than the auto program has negatively affected my mileage, but not as much as you'd think. I used to get about 430kms in a tank before the first refuel warning, about 460km before the second. Now it's between 385 and 400km before the first warning, about 410-430kms before the second warning.

Bear in mind, us North Americans don't necessarily appreciate how expensive gas is in other parts of the world -- right now (where I am in Canada), premium is approx. $1.27 a liter, and stateside, people outside of California pay way less than that, so that drop in mileage is easily rationalized for us.

richardjh

Was $1.65 a litre here last fill.

Rich

crak

iTrader: (3)

1.39 here in winnipeg

majinfajita

To be fair, the AUSDM/JDM Prius with the sport package uses the same tires as the FR-S/BR-Z

There's nothing wrong with wanting better fuel economy, and it's not like you said you wanted 50mpg (look at the new Bentley GT with the V8 - it gets like 25% better economy but is as fast or faster than the outgoing W12, so even millionaires are concerned about gas prices )

Rokpapaziz

I do have a bombed Prius on Forza 4 on Xbox, it was a bit.... underwhelming I'm pretty sure it only uses a single gear

When I first bought my car i used normal auto all the time, fuel economy was pretty good. Best figure was 8.7litres per 100k's on the highway.

Since I starting flashing the ECU I used manual sport. Of course the fuel economy was not as good, even though I was shifting manually into 6th gear at 60k's.

Lately I've been doing logs doing all kinds of driving styles. I'm getting a general idea of where I'm seeing knocksum in normal driving conditions.

So after I'm satisfied with knowing how my car drives on stock tune I'll reflash with the latest GST base map and start tuning from there. I get the feeling it's better to wait because every few weeks Rich seems to find out something new and would prefer to wait until he and Razorlab release a new official ROM.