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MAP or TPS for load sensing

Practical Standalone Tuning

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In your introduction you say that the engine in this BMW is the M 54 B 30 , a 3 litre straight 6. Does the engine in your car have a plenum chamber with a single throttle body. I looked up on google for the specs on the M54 B30 and it says that it is a 2171 cc six and in the images it shows an engine with 6 individual throttle bodies, which is correct? You are using TPS for load sensing in your example which I thought was the correct thing to do with separate throttle bodies because of the excessive pulsations that you would get with a MAP sensor in a port or do you connect all 6 ports to a common point for the MAP sensor to smooth out the pulsations. In the example you have both MAP and TPS, does the Link use both these inputs to gauge load.

It does actually have a single throttle and plenum. We purposely chose to use TPS as the load axis just to demonstrate how alpha n works. Normally this engine would be tuned using MAP as the load axis. The reason we use TPS as the load axis on ITB equipped engines is because the MAP signal doesn't give us a good indication of load and there isn't sufficient resolution - For example on an N/A engine we're likely to achieve 100 kPa at perhaps only 35% throttle.

Even on ITB engines we do still want to incorporate a MAP signal if possible. The Link ECU uses this for a background fuel calculation and this provides better stability in the fuel delivery.

Our twin cylinder motorcycle engine has ITB So far we have been using TPS only for load axis. If I want to use MAP as well what is the best way of going about it. We have short adaptors between the throttle bodies and the cylinder head ports. We have provision for vacuum tappings in these adaptors. For now we have these plugged up. I could connect the two with a T junction and run a hose direct to the Link which has a pipe for this purpose. Alternatively I could connect the two vacuum tappings to a suitable MAP sensor from a car engine and send an electrical signal to the Link. Do you have any suggestions

Hi Leigh, you pretty much nailed it. You need to connect to the manifold post throttle body and connect this to the MAP sensor. With multi throttles it's a good idea to use a balance tube connecting to each runner and then take the MAP signal off the balance bar to even out any cylinder to cylinder pulsations. In reality for a 2 cylinder engine a y-piece will work just fine in place of a balance tube. Using dual MAP sensors would be nice but there is no way for the Link ECU to natively use this data.

So how about the reference port on the fuel pressure reg with ITB's? Even when using TPS with baro comp for load ref, using a 'collected vacuum source' to keep a constant delta P across the injector? Or do the pulsations in each individual port make this not practical/effective?

With an N/A ITB setup just leave the FPR referenced to atmosphere. The pulsations in MAP signal can make it difficult to achieve good control of the fuel pressure otherwise.

hi there. which video is this?

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