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Old 06-04-2003, 04:34 PM   #1
ANZAC_1915
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On 92 or 94?

I think the JDM 2.0 would be worse on 92.... it is running higher boost and similar compression.

Glenn
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Old 06-04-2003, 06:47 PM   #2
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Quote:
Originally posted by TypeC


It comes from huge ignition advance during tq peak. Specifically, 22-24 Deg BTC in the midrange. See the FFI board for specifics from the tuners who are logging this.
Ok, add the ignition advance... 22-24 is pretty agressive.
I think a lot has to do with combustion chamber and piston dome design as well.... perhaps these are also areas that need improvment.

It's interesting though, if subaru found it necessary to advance timing so agressively, makes me wonder if you bring it back down to say 18-20 deg, how much performance one would be giving up....
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Old 06-04-2003, 07:33 PM   #3
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We get some detonation but not each time. Very odd. I have to run some more tests, just been too busy. Yes timing is setup aggressively but remember that boost response is lazy as all heck stock too. Another thing. We got no more than 15 PSI stock whereas others have reported 15.5-16 PSI.
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Old 06-04-2003, 09:28 PM   #4
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Quote:
Originally posted by hatchy
What specifically is wrong with the combustion chamber and the piston design? These two things usually don't cause detonation, they affect fuel and air mixture as it enters the cylinder but I don't see how this would cause detonation.

Poor piston and combustion chamber design can cause hot spots which will cause det.

I don't know if there is a problem, but just going by what I know of the other engines... listing things that can cause det.

Since I am in line for an STi - I'd hate for it to det itself to death you know?

-S
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Old 06-04-2003, 09:37 PM   #5
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Doesn't the ECU have some knock correcting function on it? I know the S.E.C.S. unit some have installed shows this parameter so maybe someone could hook one of these up to an STI and see if the ECU is pulling timing when knock is detected. Just an idea.
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Old 06-04-2003, 10:47 PM   #6
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Quote:
Originally posted by StealthWagon
Doesn't the ECU have some knock correcting function on it?
Others have called that function "Einstein" in the past. I've always maintained the correct name should have been "Billy Bob" or something similar. With the our STI the car basically ignores small detonation that is audible though a knock sensor with a head set attached. It will continue to advance timing up to what Iíve called the "big bang" in another post then it will yank back timing on the very next dyno run. Every 4-5 runs it repeats the process.

Our new STI has detonation problems. Two other tuners that I know who own the car have reported theirs has the same issues.

Ours will detonate in bone stock condition on 93-octane fuel. It doesn't do it on every run, due to its highly variable timing curve between peak torque and peak power. With any luck Iíll put a tech article with a few data logs on our web page in the next day or so to give a little better background information on our STI.

The short of it is that it's running a lot of boost stock, with a lot of advance, and making a lot of power, but for some reason or another the STI ecu isn't happy enough and keeps advancing timing in the midrange which eventually leads to audible detonation. It's almost as if it's memory is only good for about 4 full dyno runs.

This is something that Iíll be able to tune around at some point, but there is NO EXCUSE for Subaru letting this car out on the streets with its current ECU map.
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Old 06-04-2003, 11:03 PM   #7
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Quote:
Originally posted by shingles
what was the intake temp like during the tuning sessions? perhaps the IC isn't enough?

-S
The intake temp sensor is in the MAF sensor, and as such its readings are not really of much use. The temperature of the shop was however in the mid to low 60s.
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Old 06-05-2003, 01:51 AM   #8
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Perhaps we should have a poll of who is experiencing det in stock trim, what AKI gas they're running?
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Old 06-05-2003, 02:05 AM   #9
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For the people who DO know what it sounds like, here is the poll:
http://forums.nasioc.com/forums/show...hreadid=372340

I was able to hear pinging in RSquire's 22B on the track with a helmet on. Only when we got a set of mechanical det cans on it was someone else able to confirm it.

Glenn
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Old 06-05-2003, 02:09 AM   #10
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On the WRX, Einstein aka the "knock correction" in reality defines how aggresively the engine advances ignition and maintains boost (when it shows a positive value).

It shows a 0 or negative value when it retards both due to det.

The tech line (I heard) at least on the WRX is able to put some boundaries on how high it starts on the + side.

I've seen it read with the SSM (Subaru Select Monitor). I expect this is not a public OBDII command.

Glenn
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Old 06-05-2003, 11:13 AM   #11
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Quote:
Originally posted by Glenn Wallace
On the WRX, Einstein aka the "knock correction" in reality defines how aggresively the engine advances ignition and maintains boost (when it shows a positive value).

It shows a 0 or negative value when it retards both due to det.

The tech line (I heard) at least on the WRX is able to put some boundaries on how high it starts on the + side.

I've seen it read with the SSM (Subaru Select Monitor). I expect this is not a public OBDII command.

Glenn
Glenn,
The system has quite a few positive sides to it, but they all rest on the premise that it can identify detonation and remember where it occurred.

I have never heard a completely stock WRX detonate, so I would expect that for stock tuning the authority range of the system seems to work.

However on the STI it is only reacting to the largest of detonation events, and doesn't seem to really remember them long enough to make the needed changes to the fluid ignition and fuel maps. When it finally recognizes an event, it will pull back the advance, but 3-4 runs later it tries to run the same advance that caused the detonation in the first place. It then gets the same results as it had the first time.

Someone once told me that the definition of insanity is doing the same thing over and over again and expecting different results. I think Einstein might be insane.

Clearly Subaru needs to remove some of the ignition advance authority from the stock ECU in an effort to keep these motors in one piece.

-Nathan
www.turboxs.com
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Old 06-05-2003, 11:33 AM   #12
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Quote:
Originally posted by hatchy
Okay, educate me, what exactly about the STI combustion chamber and piston that would cause hot spots and detonation? Be specific in your response, please.


http://www.theoldone.com/articles/

read the articles and archieves there, lots of good information about piston design and head designs.

No one is saying there's anything wrong with STi's head, mearly that it could be a contributor to the situation. Just bring ideas to the table.
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Old 06-06-2003, 02:47 PM   #13
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Ok from what Ive been reading is that its most likely a crap tune from FHI- most specifically too high of an ignition advanve authority in the ECM at peak torque. While this seem strange from the factory I can see were the attention and testing to the USDM STi might have been rushed or misunderstood initially due to the new EJ25t. So Will the Ecutek rom files work yet with the STi? Or are new STi owners going to have to go without a "jimmy" and wait on FHI or the aftermarket? Has anyone mixed in some toululene and had consistant results?

BTW I understand the issues with the EJ 207. I dont understand the issues with the EJ25t. Wasnt that the point? To releive det and make safe power with the US gas? WTH happened?
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Old 06-06-2003, 04:26 PM   #14
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Hmm, well no det problems here yet, but I've only driven it hard in 70-75 degree temps with a decent bit of humidity around to help keep it happy.
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Old 06-06-2003, 08:23 PM   #15
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The WRX in stock from does not have det because the ECU is tuned "very conservatively" according to some of the tuners. So people paid roughly closed to 1K to have it tuned "more aggressively" and have some det. Now the STI is tuned "aggressively" stock and people will pay...roughly one grand to make tune it more "conservative"?
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Old 06-06-2003, 08:44 PM   #16
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Quote:
Originally posted by WRXBob
The WRX in stock from does not have det because the ECU is tuned "very conservatively" according to some of the tuners. So people paid roughly closed to 1K to have it tuned "more aggressively" and have some det. Now the STI is tuned "aggressively" stock and people will pay...roughly one grand to make tune it more "conservative"?
Essentially correct. Hilarious isn't it? What a wierd job they did on the STi ECU. I don't get it.
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Old 06-07-2003, 10:41 AM   #17
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Let's hope this doesn't turn into a melted piston disaster.

Here's a reminder of what happened with the first STi's in Australia in 1999. And then Subaru blamed the owners (at least initially)



PULP friction: petrol stymies
Subaru WRX STi
First Published: The Sydney Morning Herald
Friday, April 30, 1999

The $60,000 instant sell-out "supercar" has run into
problems. Low-grade fuel or an engineering shortcut may be to blame, writes JOSHUA DOWLING.

After numerous engine problems - including four melt-downs
- Subaru's Impreza WRX STi seems more fragile than its
rugged, rally-bred image suggests.

Acclaimed for its Porsche-like performance at a fraction of
the price, the car is sensitive to changes in the octane levels
of premium unleaded petrol (PULP), Subaru Australia has
admitted.

The highly strung, high performance turbocharged engine
can be stymied by a combination of low-grade fuel, hot
weather and and high engine revs. It is believed the STi
could now be paying the price for a technical shortcut.

Subaru acknowledges the STi has not been modified to suit
Australian fuel. It is believed part of the deal to import the
limited edition involved certain concessions, including
making few mechanical changes.

In Japan, the STi is designed to run on 100 RON
(recommended octane number) fuel but in Australia must
settle for premium unleaded which is rated between 95 and
96 RON.

When tested locally, Subaru found, the STi adapted to
Australian fuel because the engine's computer adjusts the
combustion timing according to fuel quality. But as STis
have been distributed across the country, a small but
significant number of the shipment of 399 has run into
problems. (For a performance car this is unusual, because
most manufacturers make allowances for Australia's low
grade fuel.)

Some have developed engine "pinging", a symptom of the
engine not getting enough fuel or getting fuel with insufficient
levels of octane. In extreme cases this can overheat the
engine or melt a piston.

Subaru Australia is sending a selection of fuel additives to
Japan for testing and is also considering "detuning" STi
engine computers during routine servicing. Ironically, the
latter would decrease the performance for which owners paid
a $20,000 premium.

Drive has learned of about a dozen examples of fuel-related
problems with the STi. The maker claims it has received
calls from "less than 1 per cent" of owners.

A straw poll of 22 STi owners in the Subaru WRX Club of
NSW showed about half have experienced problems. "We
did an informal survey via e-mail and found it's happening to
some STis and not others," said club president Tony Stott.
"There's definitely something unusual happening ... more
than it should given that these cars are supposed to be
bulletproof."

Subaru Australia recommends that STi owners who plan to
drive "enthusiastically" should add five litres of methyl
benzene to each tank of fuel to improve the octane rating.
Shell sells 20-litre drums for about $35.

One owner, whose STi was repaired under warranty after
"melting" a piston, said: "Subaru told me the car's not
supposed to be driven hard because our fuel is so iffy but the
car can barely run on it. Other performance cars don't suffer.
If I wanted a car to buy bread and milk in I would've spent
$20,000. The biggest joke of all is you could run a Hyundai
around a track all day and [not] blow up."

Some STis have melted a piston after being driven near the
rev limit for sustained periods. One owner said: "I don't think
my problem was fuel-related. The computer starves the
engine of fuel between 7,500 and 7,900 rpm when it needs it
most. I'm no engineer, but that seems absurd."

Subaru Australia's technical manager, Derek Ashby, said he
believed driver abuse was to blame.

"We've given most owners the benefit of the doubt," he said.

"However, we will be looking very closely at future cases
because driving on the rev-limiter is not how you drive a
motor car. That's not considered to be a fault with the
vehicle."
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Old 06-07-2003, 12:43 PM   #18
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Quote:
Originally posted by Glenn Wallace
Subaru Australia recommends that STi owners who plan to
drive "enthusiastically" should add five litres of methyl
benzene to each tank of fuel to improve the octane rating.
Shell sells 20-litre drums for about $35.
Methyl Benzene, AKA Toluene.

Since it's illegal in the US to add things like Toluene to your fuel tank, SOA won't be able to get out of it this way...
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Old 06-08-2003, 02:14 PM   #19
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Quote:
Originally posted by Grant
Wow, I can't believe that response from Subaru.
In North America, both Subaru of America (SOA) and Subaru Canada, Inc. (SCI) are wholely-owned subsidiaries of Fuji Heavy Industries (FHI), the company that manufactures Subarus. Additionally, FHI owns Subaru Research and Development, Inc. (SRDI) in Ann Arbor, Michigan, whose Power Plant Group runs durability and emissions testing of engines, transmissions and emissions systems for future Subaru models.

The situation in Australia (and England) is very different. Subaru Australia and Subaru UK aren't owned by FHI, they're owned by a company called Inchcape. Inchcape wanted to sell the STi in Australia (because individuals were importing them privately from Japan already), but FHI was unwilling to spend any R&D to develop STi ECU maps customized for Australian fuel. And FHI likely warned Inchcape that the JDM STi's maps were borderline in their ability to support 96 RON fuel. Inchcape was undeterred and brought a few JDM STi's over to Australia and tested them using the local fuel and decided that the JDM STi would run OK there. But, just in case, Inchcape decided to limit the total number of imported JDM STi's to 399.

Since the STi's 2.5L engine was designed primarily for North America, I presume that SRDI has performed extensive testing on it already. I don't think Australia's experience with the STi in 1999 provides any lessons for owners in North America.
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Old 06-08-2003, 02:32 PM   #20
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I wonder if nmyeti (or anyone) would do the community a favor and publish an audio recording (.wav file) of the STi's knock sensor during a period in which they believe they hear knock, similar to the recording from a WRX with a boost controller at http://www.turboxs.com/_images/12%20...eep%20hill.wav.
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Old 06-08-2003, 07:37 PM   #21
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Quote:
Originally posted by Jon [in CT]
I wonder if nmyeti (or anyone) would do the community a favor and publish an audio recording (.wav file) of the STi's knock sensor during a period in which they believe they hear knock, similar to the recording from a WRX with a boost controller at http://www.turboxs.com/_images/12%20...eep%20hill.wav.

I'd like to do that and Iíll try to go one step further. I'd like to record it from both the STI knock sensor and an aftermarket piece to see if we are dealing with a knock sensor related issue. I need to work out some of the details with Pete (our EE), but if I have a chance Iíll try it this week.

I filled the STI up with 94 this weekend, so I am anxious to get it back on the dyno to see if this makes any difference. I suspect it will just encourage more advance in the 4000rpm range and that will in turn eventually lead to more knock.

-Nathan
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Old 06-09-2003, 08:39 AM   #22
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Quote:
Originally posted by god


Essentially correct. Hilarious isn't it? What a wierd job they did on the STi ECU. I don't get it.

Has anyone tried an gradual increase in octane to determine the STi's peak advance target?

In my experience with Neons -- the ECU behaves exactly the same.
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Old 06-09-2003, 03:10 PM   #23
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Default Is there a problem?

I don't doubt this report from an expert, but I am not seeing the same thing in my Ca car.

Quote:
Our new STI has detonation problems. Two other tuners that I know who own the car have reported theirs has the same issues.
And the Aussies turn faster than the 7K limit we have.
Quote:
Some STis have melted a piston after being driven near the
rev limit for sustained periods. One owner said: "I don't think
my problem was fuel-related. The computer starves the
engine of fuel between 7,500 and 7,900 rpm when it needs it
most. I'm no engineer, but that seems absurd."
So am I missing something or is it variable by car or? This is obviously a serious problem if it exists and one can't be to careful. But are we to quick to judge that FHI and STi have screwed the detonation pooch?

Mike McBride
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Old 06-09-2003, 03:25 PM   #24
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Quote:
Originally posted by MZM
I don't doubt this report from an expert, but I am not seeing the same thing in my Ca car.



And the Aussies turn faster than the 7K limit we have.


So am I missing something or is it variable by car or? This is obviously a serious problem if it exists and one can't be to careful. But are we to quick to judge that FHI and STi have screwed the detonation pooch?

Mike McBride
No I think your right and thats why we started these thread- Not to cause panic or to let the EVO boys relish in our problem but to understand who, what, when and WHY this is occuring to some cars. I think we need to get down and dirty with this new engine so we know what its doing and how we should deal with it.
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Old 06-09-2003, 03:39 PM   #25
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Detonation is less likely to occur at high RPMs than it is at low RPMs.

Detonation is more likely to do some serious damage at high RPMs than at low RPMs.

But low RPM detonation can be a bad thing over a long period of time. It is a cumulative thing.
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