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 Inläggsrubrik: Ways to increase the fuel
InläggPostat: fre 07-06-01 10:43 
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http://www.max-boost.co.uk/max-boost/fuelling_20LET.htm

Since we need about 30% more fuel than stock, this page can be of use..

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InläggPostat: sön 07-11-11 21:59 
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Blev medlem: lör 07-11-10 22:05
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Hi

French newbie on E85 writing

Well I've thru the forum and read the link given in the above mentionned post

I went thru the various methods to increase fuel : fuel regulator, bigger injectors, cold start fouling the water temperature sensor, etc...

However, I am quite surprised nobody tries to foul the Air Intake Temperature sensor. This method is very well used by Tuning fans to increase engine power.

As a summary, cold air weights more that hot air : although it also depends on humidity, the average is around 1.3gram/liter at 0° ... 1.2g à 20°C, 1.15gram at 30° .. so by fouling the Air Intake temperature by some 20°, you get +9% fuel (because the ECU, thinking the air is colder, will inject more fuel) ... By 30° .. you get + 12%

You might argue that +9 and +12% is not that fantastic when compared with other methods .. which is right ... but for instance modifying the fuel pressure regulation leads to +7.5% per 1/2 bar, however with some risk on the fuel pump mainly above 4 bars (so ... with +1 bar, you get "only" 15% more fuel versus 12% by fouling the AIT by some 30°)

But the main advantage of such a method is that it is mathematically assesed ... so you can calculate the add on resistor/potentiometer to be installed very precisely

So Why nobody is proposing that ? Is there any good reason for that ?

Fouling the Air intake temperature is easy as the sender is generally a CTN. For instance on Volvo 440/460/480 B20F, renault F3R like engine it takes the following values :
-50° : 80.000 Ohms
-40° : 45.000 Ohms
-30° : 26.000 Ohms
-20° : 15.000 Ohms
-10° : 9000 Ohms
0° : 6000 Ohms
10° : 4000 Ohms
20° : 2500 Ohms
40° : 1250 Ohms
55° : 680 Ohms
60° : 600 Ohms
80° : 300 Ohms
90° : 230 Ohms
100° : 180 Ohms
The ECU (Fenix 3B on these Volvo 440/460/480 B20F) will then take the air temperature detected into account to inject more or less fuel

Nevertheless, please have in mind that most ECUs will not accept any input value. For instance Fenix 3B (at least those on XM V6 engine in France .. it is likely but not 100% ascertained all Fenix 3B will react the same) will not accept AIT below -40°C ... it will then consider such a value as erroneous and have it replaced by the water temperature if below 20°C then by 20°c when water above 20°C

Best

Bye


Senast redigerad av Ceyal35 sön 07-11-11 22:21, redigerad totalt 1 gång.

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InläggPostat: sön 07-11-11 22:16 
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Blev medlem: ons 07-01-03 13:14
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Hi, and welcome to the forum :)

I can assure you that people have thought about it. The IAT sensor is not a very important one in the engine, it is mainly used for some correction of the MAF-sensor, and to some extent ignition advance correction.
As you mention, an "unlikely" reading from the IAT sensor compared to what other sensors say is likely to throw up a fault code.

If you're thinking about the IAT-mod sold on ebay and elsewhere, it is useless in my opinion. If it causes any overfueling it will be corrected by the oxygen sensor quite rapidly.

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InläggPostat: sön 07-11-11 22:29 
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magnul skrev:
Hi, and welcome to the forum :)
If you're thinking about the IAT-mod sold on ebay and elsewhere, it is useless in my opinion. If it causes any overfueling it will be corrected by the oxygen sensor quite rapidly.


You see this kind of stuff on eBay for a few Euros ... I agree with you : I do not see the benefit for SP95 running .. but for E85 running : yes

The table weight/volume air is scientifically established and used as you said by the MAF sensor for some corrections (As I mentionned above some 12% more fuel with an AIT lowered by some 30°C)

On the opposite, I see many people fouling the water temperature sensor ... But, because there is a big BUT ... it is very difficult to know the relation between Injector opening and water temperature ... so you are more or less forced to go with a try/error method (my understanding is that ECU adds some 50% more fuel at 55°C than at 90°C ... But maybe I am wrong)

Best


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InläggPostat: sön 07-11-11 22:37 
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The reason why people fool the coolant temperature sensor is just for cold starts. It's just used for at few seconds or minutes to start the engine and keep it running. It's not a viable way of converting, i.e. to get +30% fuel permanently. The cold start enrichment increases a lot with decreasing engine temperature. In this sense, the ECU doesn't care about the air temperature. An engine that has been in -20C overnight will need alot of cold start enrichment, whereas a warm engine doesn't (even if it's still -20 air temperature).

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InläggPostat: sön 08-04-20 23:41 
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Hello

The trick of a resistor in the IAT (Intake Air temperature connector) does not work with SP95 because when indicating to the ECU that the air is colder than the reality, the ECU makes the fuel mixture a little bit more rich .... but the O2 sensor (or lambda sensor) sees that slightlly enriched mixture and opens a little less the injectors. So the overall result is NIL

But with E85, without any other modification, the mixture is naturally poor by some 30%-40% ... so when indicating to the ECU that the air temperature is 40, 50 or 60 degrees below the reality it is possible to enrich the mixture by some 15, 20 or 25% .. as good as adding 1, 1.5 or 2 bars on the fuel pressure regulator

Why does that trick work ?
because when reading (sorry only in French) http://www.thermexcel.com/french/tables/massair.htm you can see that air density is higher when cold. Sibling values are given in http://en.wikipedia.org/wiki/Density_of_air roughly
1,34g per liter at -10°C
1,29 at 0°
1,24 at 10°
1,20 at 20°
1,15 at 30°
so it should be around
1,44g per liter at -30° C
1,39 g per liter at -20°C


For 100 liters of air entering thru a vane meter sensor, when reading -30°C on the IAT sender, ECU will then call for 1.44 *100/14.7 = 9,79g of fuel
If the external temperature is in fact +10°C, that is to say with 1.24g/air liter … it should only call for 1.24*100/14.7 = 8,43g of fuel … so with the additional resistor fitted in the IAT sender connector .. the overall enrichment is roughly around +16%
If the external temperature is in fact +20°C/+30°C ... then the overall enrichment is around 20/25% respectively
Not a too bad result with a such an easy to do modification ... unplug the IAT sensor and fit a resistor in its connector : done ... provided the outside temperature is always above +10°C

As with E85, the mixture is poor by some 30-40%, the O2 sensor will in fact appreciate this enrichment and not play against

Such a modification does not work in cars having a hotwire mass air flow sensor because their ECU do not take into account the air temperature ...

It works very well in case of Air Vane Meter sensor ( see http://en.wikipedia.org/wiki/Mass_flow_sensor ) because air density is used to compute the air mass entering the engine
It works also a little bit in MAP sensor ( http://en.wikipedia.org/wiki/MAP_sensor ) where temperature is used to correct MAP

When so doing, the resistor should be selected with caution because many ECUs, when reading an air temperature of say -40°C will consider the sender is not running properly and have its indication replaced by a fixed value (e.g. the water temperature at cold start)

Of course it is easier to play that trick in the South of Spain that in North of Europe ... sorry for the Swedes .. and it works better and better with hot air taken from the engine bay and not from the outside ... playing again the same game as "tuning" people with a washable air intake located in the engine bay

Any comment ?
Bye
Best


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