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The info conserning my can be found on this board, what happened when I did the custom IC project to my viggen. The car ran helthy rich prior to the IC change, but it ran crazy lean right afterwards. At the time when I posted this there seemed to be very few people out here who actully believed what I wrote. My findings are based on broadband lambda reding, no guessing or approximation. Any way that was then, so lets contenue with the present and Steve88SiS's car.
If I recall correctly steve posted that he dynoed his viggin with the new IC and there wasn't anything wrong with the mixtures?
The following is just guessing and if I have it wrong, could somebody who knows better correct my statements. One could think that changing the IC will have the same affect as driving during the winter here in the nort (-30 deg C sometimes). I believe this is only one side of the coin, due to the better flow of after market IC's. We know for a fact that a good after market IC will flow about 4 times better than the stock x-flow.
So what does this do?
Since the MAF is located very far away from the engine, there will be lag and deviation to the value compared to the actual airmass going into the engine. This would not happed if conditions would remain costant, drive with same rpm, boost aso. We all know that a car engine does not work this way. Things will get tricky when we do a hard acceleration, lets say WOT in third gear from 100-150km/h, this will take about 4-4.2 s. with a stage III+ viggen. Once the pedal is punched to the medal airflow will increase dramatically under a very short time period. Under these conditions ECU should relie on the reading from MAP and temp, because there is no way the MAF reading will tell the ECU what the heck is going on. We should be in the clear, but I believe we are not. This is because my engine broduced an extra 12bhp with the new cooler. This will happen is the engine overall efficiency is gets better or more airmass will find it way into the engine. I would place my bet on the second choice, because my engine started to run lean. T7 will boost to a target airmass, so there should not be a possibility for more airmass, but there is.
Like I wrote above I do not know what happens, but I think it has to do something with the better flow and IC volume.
I havent had the change to look into my car with TECH so I dont know what one could find. If more airmass is getting into the engine one should be able to read it from TECH, actuall airmass and calculated airmass or the ratio of these two. If the ratio is not the same with std IC and new then something has changed.
One other thing to keep in mind is T7's will to compensate for added fuel pressure and other changes as well. ECU will do the compensation under closed loop lamda conditions, but it will have a affect for all the maps.
For instace if you add more fuel pressure to get the engine to run rich under WOT, it wont stick to long. Extra fuel pressure will force the engine to run rich under close loop also and ECU will not tolerate it very long. So T7 will adjust the injector open times to get mixttures to land in the right spot. The same compensation will take place under WOT also, so you will end up with about the same ammount of fuel.
posted by 195.237.1...
, Sat, 17 Apr 2004 03:25:42
, Fri, 16 Apr 2004 10:40:47, Fri, 16 Apr 2004 09:38:22, Fri, 16 Apr 2004 02:42:52, Sat, 17 Apr 2004 03:14:00, Thu, 15 Apr 2004 15:44:57
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