Some thoughts on towing in new cars

So over the last few days we went away to test out our new camper, and this put the LDV T60 through it’s paces, and we noticed a few things.

Now the LDV T60 Owners Australia Facebook Page is full of people that have had issues with overheating while towing. So here’s a few things that I noticed on our 500km round trip away towing a 2,000kg camper trailer.

Cruise Control can be great

Cruise control has to be one of the best things to happen to cars since the invention of cars, no joke, it makes maintaining a constant speed easy on the driver, easy on the driveline, and just an absolute pleasure to use on long trips. That’s if it is used correctly.

One thing that I noticed when using the TorquePro app is that Cruise Control can make the driver complacent on what they are doing with the vehicle, it’s really easy to just point the car at a hill and just leave it alone to do it’s own merry thing and get itself over the hill, which may not necessarily be the best thing for the car.

A few hills I pointed the car at, 5th gear, 100kmh, the car could easily crest the hill doing it, however a watch of the gauges showed that I was pushing the car to 100% load and watching the EGT start to climb rapidly, the car was working, it wasn’t in it’s optimal torque spot for the hill, and this was pushing her too hard, even though it wasn’t pushing her “beyond” her limits.

Knowing your torque band

So according to the LDV website, the T60 with it’s 2.8l VM Motori Sourced Diesel produces 360nm @ 1600-2800 rpm, and sitting at 100kmh in 5th gear sits me at around the 2,000RPM mark, which should ideally be right in the middle of the torque band, which is where it would have it’s best pulling power.

In reality though, as I said above, you point her at a hill and she’s under some pretty tough loads. Dropping her back a cog and getting closer to the 2,500-2,800 mark caused the car to be closer to the height of it’s torque band as advertised, however dropped the load back to the 65-70% mark according to torque, and kept the EGT’s down from the high 450-500 degree mark, back to a much better 400-450 degree mark.

So I’d say despite what LDV is claiming to get out of the RA428 motor, and where they get it, the best spot for the torque is higher in the claimed torque band than lower or middle of that band.

Though this could also be measured against the claimed kilowatt rating of the car, because when you look closer, the RA428 as it is tuned in the T60 is only hitting it’s peak of 100kW at around the 3,400RPM mark.

Exhaust Gas Temperature

So one thing a lot of people don’t like to keep an eye on is the Exhaust Gas Temperature, instead wanting to trust the coolant temperature, which is a pretty laggy way of measuring the temperature.

Now in Torque, the EGT probes are listed as CATS1B1 and CATS1B2, and from some nutting out, the CATS1B1 seems to be the pre-DPF gauge, while the S1B2 seems to be post-DPF judging from where they both sit in regards to load and what the car seems to be doing at the time. I watch the S1B1 as it seems to be the more responsive of the two sensors, and doesn’t seem to go through the roof when the car is doing a burn, unlike S1B2 which really get’s hot when the car is doing a DPF Burn.

Now for Coolant to spike, the block has to heat up, the coolant has to run through the galleries, get heated up by the block, and then carry that heat from the block, past the sensor, and the transfer that heat to the sensor, the Exhaust Gas Temperature is a more accurate and fast way as it’s taking the hot exhaust gas and reading it from a probe directly in the exhaust stream.

So this is where I like to watch my load from, Load and EGT seem to be a really good way of watching what the engine is doing, once you start going past 450 Degrees on this motor, and on the load you start getting up past the 75-80% mark, you’ll start to climb, if you’re at 100%, that means you are getting all of the cars power at any one spot on the band.

90-100% load isn’t always bad

So, one thing to point out is that the car is calculating the load for you based on the parameters you have punched into the vehicle profile, you get that wrong and your load will be up the shit.

Likewise, load is relative to what you are doing, I found load at the lights, taking off with the car, doing a hill start, will generally sit at the 90-100% range, because you’re moving the entire mass of the car, load, trailer, etc to get it up to speed. As long as you aren’t pushing it to speed over a super long distance, these are transient loads on your vehicle.

Likewise, if you say you have a bigger or smaller engine (Torque defaults to a 1.9l petrol from memory) then your load calculation is pointless, as it’s comparing the other values from the ECU to an entirely wrong idea of what it is looking at.

Just because you have an Auto, doesn’t mean don’t worry

In fact, a huge number of the reported issues with overheating have been in the Automatic transmission. And I think I know why.

A lot of people with an Auto are less “Driving” the car, and more “Operating” the car, they are attending to the car, moving the steering wheel to point the car down the highway, there is less thinking and more doing.

The car really doesn’t know what is going on, and without extra inputs from the driver, is operating within a set amount of software parameters to try and decide what is best for it’s given set of circumstances, and like the Trolly Problem, a software engineer can only code so much into the architecture of the programming. The rest is left up to the learning aspect of a modern transmission, and then how the driver drives it.

Now the thing is, we aren’t always towing, what the transmission learns from street driving in the city, or highway driving in the country, or offroad driving in the bush, or dragging a trailer through these will never be a one size fits all kind of system.

There are very few cars on the market these days that have a “perfect” automatic transmission (cough CVT cough) that can always be in the optimum gear for the revs and road speed, there will always be points where you have to actually pick “Do I want to go fast, or do I need to slow down and have the right gear for this obstacle”, and that’s what you need to think of the road as, and the roads features, as obstacles to the car.

Just like you won’t go flying up a hill offroad in 4th gear revving off the limiter at full speed, likewise pushing the car on the limiter in 4th to get 110kmh, or labouring it in 6th at 80kmh won’t be good for it either, and leaving that up to the transmission to decide may not be the best course of action.

You’ve said labouring a bit, what do you actually mean?

Well labouring is where the car is going slower than it wants to for the load that it is pulling, now labourting doesn’t necessarily mean the car is “chugging” along, like if you try and short shit the car, take off in second gear and once rolling try and go to third before you’re really even moving, making the car feel like it’s about to stall (I wouldn’t suggest trying this, but most manual drivers will know what I am talking about, everyone has done it at some point, grabbed the wrong gear, like 1st to 4th or 2nd to 5th on a standard H pattern shifter)

Labouring can mean the car is trying it’s utmost to give you what you want, however it just can’t get there. I mean, you can feed it all the right foot you want, but you’re just not getting a response, that can be a symptom of labour.

Will a throttle controller help me here?

In cruise control? Nope. Not in most fly by wire setups anyway.

Generally the flowchart on a fly by wire looks like this:

Pedal ->ECU->Throttle Body

And the Cruise control sits within the ECU, taking the wheel speed feedbacks into account, and adjusting the throttle to where you want, if you want using a throttle controller, it is sitting around here:

Pedal->Throttle Controller->ECU->Throttle Body

Now I say Throttle Body as that’s what a lot of people think of, now cars don’t have what you would think of as a throttle body these days for the most part, which traditionally looked like this:

However a modern diesel throttle body looks more like this:

Image Courtesy of Bosch GMBH

So it’s more computer controlled, and it will take what it wants from the engine, sensors, loads, wheel speeds, etc and figure out where it needs to go, there’s no longer a physically direct link between your foot and the engine. It’s all going through a computer.

What a throttle controller can help you with

What a throttle controller did help me with was more power when I was driving manually, I found that using my HikeIt Controller I set it to Sports 1 or Sports 2, and I had the right amount of response when taking off, overtaking. The throttle wasn’t too laggy for my circumstances, and wasn’t too touchy for me, I was able to precisely find the “Sweet spot” in responsiveness and drive it from there.

I don’t have enough power, I’ll get a throttle controller

We refer you to this video from Ultimate Diesel Tuning:

What you do get is improved response from the throttle, as far as power at the actual wheels, you don’t get more, but what you do get is more response. It takes the lag out, or it puts the lag in. It’s the difference between getting that oomph instantly, or waiting a second or two for the car to agree “Oh, you want power?”

So what we reccomend:

Get the torque app. Seriously, it’s really simple to get, and it’s only a couple of bucks, if you have a car that is OBD-II Compliant, which is most cars built after around 2004, and support the ELM27 protocol (Again, most stuff post 2004) you can use Torque.

If you want to, you can check if your car is OBDII Compliant by going to this list from Fuel Economy Solutions.

If you want to Download TorquePro, you can get it from this link to the Google Play Store.

There is also a free version of Torque Available by clicking this link.

Tags: , , , , , , , , ,

Leave a Reply