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If you read the post earlier that Newsh stated, then the homefries keep the ECU temp compensation intact. If this is so then the temperature differences would/could explain the boost differences
No, they don't, because the temperature compensation is about 0.1-0.15 bar.
The data @ s2central.net is from reading only the theoretic target numbers in the ECU. But it is a corrected PI controller with mappable duty cycle, and this is not taken into account.
You will very rarely see more than 0.1-0.15 bar correction. OP is seeing 0.4 bar less boost = boost leak.
I have my car mapped to 1.6 bar right now. Turning on the correction it does not drop below 1.5 bar.
No, they don't, because the temperature compensation is about 0.1-0.15 bar.
The data @ s2central.net is from reading only the theoretic target numbers in the ECU. But it is a corrected PI controller with mappable duty cycle, and this is not taken into account.
You will very rarely see more than 0.1-0.15 bar correction. OP is seeing 0.4 bar less boost = boost leak.
I have my car mapped to 1.6 bar right now. Turning on the correction it does not drop below 1.5 bar.
Probably a good thing cos your country gets colder than most .... i think it would be a good thing to turn off but mines was tinkered with by MRC and i dont think they tinkered with it. But all the same it might be worth him trying to see if it is to do with the cold temps over here at the mo cos even 0.15 bar is not far off his loss of 0.2 bar he was seeing between summer and winter settings. I guess if his car is pulling strongly as ever and is running smooth it may be just down to this? My cars about 3 psi below what i normallly see in the summer months.
You really should try it with a tank of Optimax too, you could well be getting some knock with 95.. You say you can smell unburnt fuel, are you sure its not oil? What oil are you running in the motor?
And make sure the throttle is actually opening all the way when you push the pedal down, get someone in the car to floor it and check under the bonnet if there's any slack in the cable, you can adjust it out if there is.
From the page mentioned above on S2 Central.. This is from a factory manual and applies to a stock ABY.
Of course it could still be wrong..
Boost Pressure Measurement (A rough guide)
One of the most frequently asked questions by S2 owners is how much boost is normal for a healthy engine. This question does not have a simple answer because of the way the ECU controls boost levels in relation to load (air intake), engine speed, air temperature and atmospheric pressure. I have managed to locate the official factory workshop info for measuring boost pressure on the ABY engined S2 and have replicated it on this page along with my own notes that help understand it (hopefully).
I have spent a good chunk of my time datalogging these cars, so I am quite certain.
Stock wg duty cycle mapping is fairly conservative. If you want a car to boost 1.4 bar, you push it more, and in turn it loses more of the regulation.
It is a feedback controller. The initial wg duty cycle is looked up then controlled using PI feedback. The more you push the initial duty, the less the controller can do.
On a chipped ECU the fuel cut limiter has to be raised so high to prevent issues in normal running, that you won't usually have fuel cut due to boost leaks.
The reason for that is, that the maf signal goes so high, it actually maxes out the VFC inside the ECU. This is why there is a different resistor in the RS2 ecu... but this is another topic.
But hey, here is one simple question - if the MAP sensor reads up to 250kpa, how are you going to get 150kpa of boost?
Out of interest, 1 Bar atmospheric pressure plus 1.5 Bar of boost = 2.5 Bar. So why can't you have 1.5 bar of boost on a 2.5Bar sensor? Do you have to keep a margin in reserve? It would certainly make sense to me not to use the whole range but is this the reason?
Out of interest, 1 Bar atmospheric pressure plus 1.5 Bar of boost = 2.5 Bar. So why can't you have 1.5 bar of boost on a 2.5Bar sensor? Do you have to keep a margin in reserve? It would certainly make sense to me not to use the whole range but is this the reason?
Well, you can. You can actually boost as much as you want with a 2.5 bar sensor.
This comes at a price though, you have to completely disable the boost limiter, which for very obvious reasons is a pretty bad idea. You also lose feedback control on your boost.
So, if you want to keep it intact, you have to leave some leeway, so you do not trigger it in normal driving.
For example - if you drive up a steep incline in a lower gear, you can have slightly more boost than specified at a moment, and you can trigger the boost cut.
With a 2.5 bar map sensor, the most boost I'd program is 1.35-1.4 bar. With a 3 bar map sensor, I do not go over 1.8 when mapping.
You can always fit a 4 bar map sensor to the ECU if you want more boost - it is not more expensive than a 3 bar sensor and the accuracy is good enough.
in my map Dmitri, in the motronic i could boost to 1.9-2bar and the rs2 has a 300kpa controller. With the OEM wastegate spring when the car was mapped it could never hit the boost limiter, and the boost limiter was operational, something i checked when i modified the spring screw on the wastegate and i was hitting the boost limiter quite easily.
so maybe to map only up to 280kpa on a 300kpa limiter, maybe its a bit conservative, unless there is another way to set the boost limiter higher somehow, although i doubt it, since the motronic wont know what boost is there when it is above 300kpa.
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