Newbie question - DTA S60 Pro.

[Paul D]

Hi everyone! This is my first post on here, so make absolutely no assumptions about what I may know - I probably won't!

I have a query, so I'll give as much info as I can and hopefully one of you knowledgeable chaps can give me some input.

I have a DTA S60 Pro set up to run a Rover 3.9 V8 in a racecar. I didn't install or set up the system, it's as I bought it. Here's what I know that may be relevant to my query: as far as I can see, I have various sensors providing input signals. These are:

Engine coolant temp.
Throttle position.
Crank sensor.
Air temp.

I don't appear to have any of the following:

Knock sensor.
Lambda.
MAP.

The engine is running the twin plenum set-up and the ignition is distributorless with two four cyl. coil packs, so the DTA must be running the ignition and injection. The plenum chamber is fed cold air via two lengths of trunking from an airbox mounted at one side behind the front bumper, so this picks up air at ambient temperature.

My question relates to the positioning of the air temp sensor. If I understand things correctly (and maybe I don't!), shouldn't this be measuring the temperature of the air entering the plenum chamber, so that it can inform the ECU of the intake air temperature so that any necessary changes can be made to the fuelling and/or ignition based on the temperature (and therefore density) of the air entering the engine? If that's correct, then I can't understand why mine is mounted on a bracket bolted to the side of the plenum. Please understand this point - it's NOT bolted into the plenum - I could understand that - but rather it sits on a 'L' bracket on the outside of the casting, with its sensor end in mid-air in the engine bay. In other words, it's measuring the temperature of the air under bonnet, right in the middle of the 'V'.

Being a racecar, under bonnet temps are very high - I estimate that towards the end of a race, the air around the sensor could easily be 70C or more, but the air entering the plenum is only going to be around 25C, even on a hot day. I feel that the engine may be losing some power - could this be the cause? If that air temp sensor is telling the ECU that the air entering the engine is at 70C, when in reality its more like 25C, won't the ECU back off the fuelling and maybe the timing too, to allow for what it thinks is less dense and much hotter air than is actually the case?

Should I be moving the sensor to the airbox, or am I missing something here?

Apologies for the long post - any info will be greatly appreciated.

[x30xe]

In your kind of setup it is better to install sensor to pipe which feeds air to throttle(s). Anyway in the airflow rather than outside.

Best would be inside plenum but it depends on sensor insulation. Some sensors have bad insulation between mounting threads and internals and they show constantly too high numbers. For example Bosch 039 which is "standard" DTA sensor suffer from this and it has to be located further away from plenum, somewhere between air fiter and throttle.

[stevieturbo]

Given the airflow through the engine bay, and the fact any corrections would be very small, I doubt it is a major concern. Just log and see what the temperatures are it is actually seeing ?


But yes it would be better placed in the airstream somewhere.

And in reference to the standard supply DTA Bosch sensor with the black plastic tip. Given it's response time is something ridiculous like 20seconds, it's a waste of time anyway

You need an open bulb thermistor style of sensor

You do not need knock ( and DTA cannot do this anyway )
You do not need Lambda ( but yes it would be nice to have, and you can achieve this )
And you do not need MAP. Although it would do no harm to have it as well.

[Paul D]

Thanks for the responses so far.

Stevieturbo - you say any corrections would be small, but on the DTA website on some of their sample software views, there's one that suggests fuelling could be backed off by 10% or more for a large change in intake air temperature. Wouldn't removing that much from the fuelling have a noticeable effect on power, or am I mis-understanding things here?

I think you may be right about which sensor type I have, as it fits the description you gave for a Bosch one - it does have a black plastic tip, almost like a little square cage with a bar at each corner - does that make sense?

As for the lousy response time you gave as 20 seconds - well, I guess that is slow, but I suppose if it's only meant to be measuring the intake air temp, then this would never change that rapidly anyway would it?

Any other thoughts on this will be appreciated.

[ignitionautosport]

The Bosch one with slow response has a solid tip, like a marker pen. Plastic cage with filament inside will respond fine. And yes can change that rapidly, especially when forced induction. Preferable to have an accurate responding sensor anyway.
Don't worry about it changing fueling, that is the whole point - so it maintains the correct mixture for the characteristics of the air going in.

[stevieturbo]

Thanks for the responses so far.

Stevieturbo - you say any corrections would be small, but on the DTA website on some of their sample software views, there's one that suggests fuelling could be backed off by 10% or more for a large change in intake air temperature. Wouldn't removing that much from the fuelling have a noticeable effect on power, or am I mis-understanding things here?

I think you may be right about which sensor type I have, as it fits the description you gave for a Bosch one - it does have a black plastic tip, almost like a little square cage with a bar at each corner - does that make sense?

As for the lousy response time you gave as 20 seconds - well, I guess that is slow, but I suppose if it's only meant to be measuring the intake air temp, then this would never change that rapidly anyway would it?

Any other thoughts on this will be appreciated.

If intake air temps ever see that much variation, then yes 10% is possible. How the main map is tuned will affect how rich or lean it actually goes and what affect it has on power.

And if you are using a sensor with a very sow response time, then mixtures would never be right in the first place, so what's the point ?

And even with normal temperature variations and no air temp compensation, Ive seen very very little change in AFR's
So little so that ive tuned dozens of cars over the years with ecu's that have never even had an IAT input and they run just fine

IMO trying to nail down specific AFR's is more about emissions targets than anything else.

And you havent stated what sort of air temps you are actually seeing when racing from a datalog with the sensor where it is ?
Chances are for the entirety of a race your IAT's will change very little no matter where you place the sensor as the car is always in motion, with lots of airflow everywhere.

[Paul D]

Stevieturbo - there's a very good reason I haven't stated what temps the sensor is seeing in its current location: I have neither the knowledge nor the equipment necessary to check it!

Can I download the necessary software from the DTA website? If so, then I guess the only other thing I need is a laptop and the appropriate lead, right?

Once I have these and can access my ECU, then is the relevant info from the sensor inputs stored in there? Can I simply look to see what temps the sensor saw at my last race? Sorry if these are simple questions to you guys, but as stated earlier, I'm new to this lark, and being an old git, I wasn't exactly brought up in the computer generation either! When I was at school, I think the only computer there filled a room, and it could just about add two and two!

Oh, and when I said that I didn't think intake air temps would change that fast anyway, I was assuming normally aspirated there as I have on my car - of course, I can appreciate that intake temps could change a lot faster in a forced induction set-up.

Thanks again for the replies!

[stevieturbo]

All the information is on the DTA website, all software etc. Including user manuals

mefmotorsport off this site can supply the appropriate cable

The DTA ecu will log all the time, but you need to tell it what to log. So you may need to select a few options then go for a drive before downloading the information.