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Old 01-17-2003, 05:42 PM   #1
Red Rocket
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Default A few tough ECUTEK questions....

I guess this is directed to Shiv because he's the only one offering them at this time.

I'm leaning very heavily towards getting a ECUTEK reflash in a month or two. I have a VF29, and will be getting fuel mods. I have a catless up and downpipe, with an exhaust cutout installed before the stock third cat. So at the track I take the cover off and have a 4 foot long open exhaust after the turbo. How will the ECUTEK's boost control deal with this? Do I need to mess around with restricors in the lines to control boost? Not a big deal I have a needle valve already installed to prevent boost spiking with the stock boost control.

What does the ECU rely on to determine timing? There is no post turbo IAT sensor, so how does it determine the quality of the intake charge, if it is hot or cold? MAP/MAF/RPM/cc's + the ideal gas law? I have read here that with the stock ecu there is no active control of timing after 6200 RPM's and that it is basicly set from feedback from the knock sensor...is this true? I felt this in my car when I installed the large turbo - very agressive timing up top at about 12 psi - for a little while. Does this continue to be true with the ECUTEK, or is the active timing range extended? Can the rev limit be raised slightly, say to 7400 or 7500 RPM?

What about high octane or race fuel? Not leaded fuel, but a few gallons of 100 oct at the track, or 94 oct plus Toulene on the street. Will the ECU respond with strong timing or to a change in AF ratio from the fuel?

Shiv seems to be the only one offering this right now. Will you be travelling to the east coast at all for dyno tunes? I live close to Adreniline Motorsports (which has a Dyno Dynamics) in Worcester, MA. I belive Vishnu has offered unichips through them in the past. I'm sure there would be enough interest for many people in the area to get custom tunes over a few days.

Thanks,

Kevin
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Old 01-17-2003, 07:14 PM   #2
Delicious Tuning
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Default

Quote:
So at the track I take the cover off and have a 4 foot long open exhaust after the turbo. How will the ECUTEK's boost control deal with this?
The ECUTek's boost control is based primarly on wastegate duty cycle's. They are set dependant on the setup of your car. If minor changes are made to the engine, intake, exhuast, etc... the ECU can adapt to them. If a lot of minor changes are made or more major changes are made then more tuning will be involved to regain the optimal setup for a car. A 4 foot long open exhaust is little more than minor and will probably need tweeking for optimal use.

Quote:
What does the ECU rely on to determine timing?
The ECU basis a lot of it's timing values off the knock sensor. If the knock value is set very conservative, or a low number then the timing will not move to much as there is not much room to advance if needed. If the knock value is higher then more timing can be used as there is a wider range of play. For the first run on a dyno you will produce X amount of Hp. The 2nd time through more then likely you will produce more than X. This is due to the fact, that timing values have advanced a little because the knock values were lower then daily driving which takes it's toll on a car.

Quote:
What about high octane or race fuel? Not leaded fuel, but a few gallons of 100 oct at the track, or 94 oct plus Toulene on the street. Will the ECU respond with strong timing or to a change in AF ratio from the fuel?
The stock ECU map will respond from say 91 to 95, but not as quickley as you might hope. It is not an instant hp upgrade but the ECU will lower the A/F ratio's (since they are far to rich with higher octane) and advance the timing. The timing of course based primarly on the knock values which are returned from the knock sensor which will be lower with higher octanes. Be very careful going back to 91 octane, as the car also has to update the maps. Raise the A/F ratios that are being returned from the O1 sensor and lower the timing.

Cheers,
Bill at www.I-SpeedUSA.com

Last edited by Delicious Tuning; 01-17-2003 at 07:23 PM.
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Old 01-17-2003, 09:56 PM   #3
Jon [in CT]
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Bill at www.I-SpeedUSA.com (aka skywalker),

Just curious to know whether you guys are currently using an ECUTEK reflasher and have the benefit of access to their guides, training materials, etc. If not, what is the basis of your assertions in the post above?
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Old 01-18-2003, 01:15 AM   #4
Vishnu Performance
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Default

Hi Kevin,

Those are good questions. I'll do my best at answering them...

Quote:
I have a catless up and downpipe, with an exhaust cutout installed before the stock third cat. So at the track I take the cover off and have a 4 foot long open exhaust after the turbo. How will the ECUTEK's boost control deal with this? Do I need to mess around with restricors in the lines to control boost? Not a big deal I have a needle valve already installed to prevent boost spiking with the stock boost control.
I haven't really experiented with making a single set boost control maps (max wastegate duty cycle and boost targets tables- TPS vs RPM) that would perform well with both with both the stock exhaust and a cut-out. However, I would expect there to be a tradeoff. Most likely being slower boost response time with the factory exhaust in order to protect against overboost with the cut-out. This would be done by limiting maximum duty cycle and dropping "Burst" duty cycle which adds a user-definable chunk of additional duty cycle when the thottle suddenly swings open. Going easy on these parameters will make over-boosting/spiking close to impossible. But it will slow down boost response in the stock exhausted system.

Quote:
What does the ECU rely on to determine timing? There is no post turbo IAT sensor, so how does it determine the quality of the intake charge, if it is hot or cold? MAP/MAF/RPM/cc's + the ideal gas law?
Yep. The IAT sensor is in the MAF, not downstream of the TB. The ECU calculates air density by factoring in MAF, MAP, etc,. The IAT sensor is pretty useless by itself unfortunately.

Quote:
I have read here that with the stock ecu there is no active control of timing after 6200 RPM's and that it is basicly set from feedback from the knock sensor...is this true? I felt this in my car when I installed the large turbo - very agressive timing up top at about 12 psi - for a little while. Does this continue to be true with the ECUTEK, or is the active timing range extended?
There is always active timing control. It does not turn-off above any RPM or engine load. Although its authority range does taper off at the highest load and RPM points. Depending on ECU type (there are several different WRX ECUs on the US roads), the maximum load point will be anywhere from ~4 grams of air per cylinder charge to as high as ~4.5 g/cylinder charge. This works out to be not much higher than stock boost levels. So its easy to reach the maximum Load point with a modded and free-er flowing WRX. When this max load is exceeded, the fuel/adv/knock correction values remain static. With our Re-Mapped ECUs, we spread out the load points substantially to provide actual resolution at higher-then-stock airflow rates. Same goes for max RPM points which, depending on ECU model, is as low as 6800rpm or as high as 7600rpm. Of course, the rev limit in all stock WRXs is at 7100 RPM.

Quote:
Can the rev limit be raised slightly, say to 7400 or 7500 RPM?
Yes. As standard practice, we raise rev limits to 7300rpm will all our remaps unless other specified for some reason. It is possible to rise rev limits well beyond the point of sanity, of course...

Quote:
What about high octane or race fuel? Not leaded fuel, but a few gallons of 100 oct at the track, or 94 oct plus Toulene on the street. Will the ECU respond with strong timing or to a change in AF ratio from the fuel?
Timing will be automatically adjusted to account for the added octane. The amount of adjustment will depend on the amount of authority range given to the knock correction maps. In a stock WRX, its very easy to max these limits out with pump gas, let alone race gas which *should* result in little or no added performance. With our Re-Mapped ECUs, I usually bump up authority range a little bit to take advantage of an occasional race gas fill-up. The results won't be staggering. Going too big in the knock correction maps results in knock hysterisis due to too-eager correction activities. It's a give and take. As much as I hate to be a salesperson, our add-on XEDE tuning device would fit the bill nicely when it comes to compensating for race gas, open exhausts, etc,.

Quote:
Will you be travelling to the east coast at all for dyno tunes?
Yesiree. I'll be in NJ in early Feb mapping a dozen or so cars on and off the dyno. Pretty that tune fest is booked up. But I'm not against making more tuning trips in the future. I've been doing such trips for TEC-II/TEC3s for years. But things tend to go a bit smoother with reflashes since there is little or no chance for the usual hardware/sensor/misinstallation/etc, problems that often accompany stand alone ECU set ups.

Hope that answers your questions to some degree.

Best Regards,
Shiv
www.vishnutuning.com
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Old 01-18-2003, 01:46 AM   #5
PunKidd
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Yep I-speed is using the ECUTEK reflasher. I was just looking at the book last weekend.
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Old 01-18-2003, 11:15 AM   #6
Jon [in CT]
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Quote:
Originally posted by PunKidd
Yep I-speed is using the ECUTEK reflasher. I was just looking at the book last weekend.
This is great news. Greater proliferation of the ECUTEK reflasher throughout the US tuning community is a good thing and means that more tuners will have a deeper understanding of how the stock ECU works and can explain it to us, the owner community. I'll have to pay closer attention in the future to Bill's posts about the stock ECU's operation.
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