Knocklink sensor position

[peter thomson]

For those who have fitted a knocklink, where is the best place to locate the sensor on our engines.

[Nutter_John]

the best place is in the center of the V , but getting it in there is real hard unless you strip it down . I have mine places on the front head , there is a bolt hole near the front on the passenger side . Just blot it up there and it should pick up knock for the whole engine

[peter thomson]

Thanks John ,will do

[phosty]

I've been umming and ahhing about a knock monitor - the thing that has put me off is that the MAP2 doesn't recommend active knock control via the MAP2 if the factory ECU does it too (double-dipping I guess)

Or are you just planning to use it as a visual aid only?

[peter thomson]

It's as a visual aid only Phil as I'll be setting up my SAFC shortly as I have an LM1 hardwired into the VR4 as well. It's not very easy to watch what's happening with evoscan .

[Eurospec]

Evoscan is by far the best method of detecting knock, the next best, and better for you to monitor while driving would be a knock link.

Dont use active knock control on the map2 on a mitsu ecu, as phosty says its a double dip. The stock ecu will be dragging the timing out anyway and you will just pull even more out.

as i learn more about these ecu's i learn that the actual strategy is that when a predefined knock sum (5) is reached, the stock ecu will start to use a separate and more conservative timing map, the effect being a timing pull (retardation). There is also a separate afr map which is richer that goes with it too.

The effect is to dump fuel and retard timing. Clever stuff. For those tuning, it is also a good indication that you shouldnt run your injeectors too close to 100% IDC on full chat. If you do and there is a knock event, the ecu cant dump fuel since the injectors are already fully open.

I would expect 100% IDC to occur at a power output of around 420 ish horse power based upon an 11.5afr. Richer and it will occur sooner. Actually thinking about it, that is irrelivant since you would have hit fuel cut long before. The thing is so fappin conservative in terms of airflow!

Cheers,

Ben.

[peter thomson]

Thanks Ben. Any advice on the hi and lo throttle settings to use and any other advice would be gratefully received.

[Eurospec]

Hi and low throttle settings? I'm assuming safc?

If so and assuming stock injector car, boost control etc, filter, exhaust, stock fuel pressure that kind of stuff, then i would set low as high as it will go (prolly 49%) and High at 70%.

Leave all the lo stuff alone, and tune high. It will be purely a fuel removal. This will give you stock driveability and behaviour, but when you gun it, off it will go.

Cheers,

Ben.

[peter thomson]

Yes SAFC2 thanks Ben

[phosty]

Benh, slightly off the topic of the thread but you did bring it up - what AFM Hz value does the VR4 ecu fuel cut at then?

[Kieran]

Benh, slightly off the topic of the thread but you did bring it up - what AFM Hz value does the VR4 ecu fuel cut at then?

It's not quite as simple as that - Fuel Cut depends on the load/rpm cell the car's looking at - EG, foot to the floor at high RPM will take a very high value before it cuts. At lower RPM a lower Hz reading will trigger it.

As for the 'Range' of the MAF, All the Evoscan logs I've done and seen from other high boost cars in the club suggest the ceiling's around 1400Hz... But I'm not 100% on that.

[Eurospec]

Kieran is right, its not so much a hz value, more like a calculated load.

Of course the primary driver of load is the kvf hz value, but obviously this is rpm dependant.

If you are thinking of where to set the kvf clamp on your map 2, i would set it high, use the table to get the afr's where you want them. The usual issue is between 3 and 4000 rpm where the stock ecu runs very rich. The air flow value in there will need to be lower to try and pull fuel out, which will have the effect of moving it out of the fuel cut range. Also be aware that a throttle pump (ie flooring it) in this range will give you a higher kvf value if you are using map or tps based enrichment at that point. The same affect is observed if you are in the turbos spool range and you nail it. The boost pressure will shoot up and the b/c will try and regulate it, but the rapid change in manifold pressure will result in map enrichment if you have it enabled.

Once you have the afr where you want it, then decide if you want to use the kvf clamp at all. If you do- i normally dont- set it a small amount higher than your maximum value in the last load line that you are using. Be aware of how it works though- if the output value exceeds the kvf clamp value, then only the kvf clamp number will be sent. Pottentially that could make you run lean.

Hope that helps,

Cheers,

Ben.

[phosty]

Thanks guys. I did not plan on using the clamp - the MAP2 manual suggests the best way is just to ensure the max Hz value in the tables is lower than that at which fuel cut occurs to avoid potentially lean situations as you describe. But I was hoping it would be a simple number and not a moving limit.

Not set up any enrichment tables yet - taking it nice an easy so far.

All interesting stuff - but I'll stop hijacking Peter's thread now and stick to MAP2 threads for more.

[peter thomson]

No problem Phil it's all interesting to me as well