Adding an A2A Intercooler to L67

[ev351]

Hi all,

I am continuing development on the l67 Suzuki Sierra, I came across a bargain deal on an A2A Intercooler plate and core and associated parts, so I could not resist wasting some money.
Im not sure if this is the right place to ask this, but I have seen people posting videos of A2A installs on commodores, and I have noticed that some people relocate the MAF sensor to just before the inlet to the manifold but after the Intercooler? Can anyone tell me, is this a requirement? I would have thought not as I used to have a factory supercharged / intercooled MR2 which had the MAF at the beginning of the inlet tract as normal. Could anyone bust the myth and explain for me please?

Ev.

[jenko]

I would think that placing the maf at the manifold would give a better reading of air density entering the engine and give more accurate fuel calcs , as opposed to further upstream where the incoming air would be colder and more dense .
So the further away the maf is from the manifold the greater the tendancy to run richer at idle (low air speed greater heat soak) and leaner at high rpm( fast air speed less heat soak) of course this can be fixed with tunning, but will not always be 100% right

[antus]

I agree, the MAF also contains the air temp sensor, which affects timing, so the pcm wont know how much the intercooler has cooled the air if it is before it. As Jenko says you can tune around it to some degree, but I would put it after if possible.

[jenko]

Also just because the manufacturer put somthing somewhere certainly does not mean it is the best place.
They have to deal with a lot of compromises to make their vehicle meet a budget,to add a sensor 500mm from where their stock harness puts it ends up costing lots of dollars when you take into account it is only $1.00 x 100,000 + vehicles .So the "engineers" are told by the bean counters no you cant do that modification!

[krusty]

A2A is a strange animal. Air flow and pressure just don't get real close at low throttle openings and boost pressures which can make it real dangerous. I'd suggest some form of MAP based software tbh

[charlay86]

L67 IAT is not in the MAF so location of the MAF won't have a huge effect on spark timing. Putting the IAT in the LIM is a good idea but needs a bit of work in the tune.

MAF location is a trade off between how quickly the sensor responds to flow changes vs how sensitive it is to pulsations/reversion in the inlet tract.
A2A intercooler setup increases the inlet tract length and volume between the compressor and inlet manifold, which was otherwise very short in stock setup.

The closer MAF is to the inlet valve (downstream of the compressor), the faster the sensor will respond to air flow changes but it will also be subject to pulsations of greater amplitude, potentially causing air to be metered more than once as it goes back and forth past the sensor element (causing it to be rich at particular engine speeds). for improved throttle response and better idle control you could also move the throttlebody downstream of the compressor (this causes a few issues as you will now have boost on your TB vacuum ports).

If the MAF is upstream of the compressor (factory location) the engine pulsations are almost entirely removed by the compressor and the throttle plate (although we now have the pulses from the compressor to deal with, but they are at a much higher frequency). The problem with this setup is mainly due to the delay in density change in the inlet manifold.
The supercharger itself responds instantly engine speed changes so the flow past the MAF changes quickly, but with an A2A intercooler system the intercooler and associated piping has to be be pressurised so the density change that the engine sees is delayed. This delay also affects any delta tps functions and it causes a similar problem at idle, as it takes longer for the engine to respond to the change in IAC position, causing the engine to hunt.

It is also important to note that MAFs work best when they have nice laminar flow through them, this means that you should avoid locating them next to any sharp bends or sudden changes in pipe diameter.

[charlay86]

Remember that it is a MASS Air Flow meter, it effectively measures the number of air molecules flowing past it.

[antus]

Good info

[ev351]

Ok thank you everyone for the input. Looks like its not as simple as may seem. Also, maybe im getting in over my head here in terms of tuning. I know a local tuner suggested that if he tunes this setup he would want to remove the MAF and just use a map sensor, Im not sure about the IAT, I did not consider that. And yes it makes perfect sense that it should be close to the LIM, as what use is knowing the temp of the air at the filter.
Im certainly not keen on doing it, but for safety maybe I should be letting some else tune this thing now. Shame it will probably end up a Kalmaker job... No one in Sydney seems to want to do anything else.

[kojab]

When you say "Shame it will probably end up a Kalmaker job" what most people don't realise is that the Kalmaker tune contains 98% data of the original factory tune.