Options to improve 14CUX running.

[blaze_away]

I have a slightly chim 400

Its 4.6 with stealth cam custom decat manifolds and y piece. Standard 14CUX with Tornado chip. It running well does 1/4 mile in 12s ie its doing about as well as it should.

BUT fuel consumption is and alwaus has been not very good. ie about 18.7 mpg doing brim to brim on two tank fulls.

What would be the best way forward to improve mpg figure assuming I should be getting around 21 mpg

Full Remap with lambdas ?
or
Change tune resistor to non cat fuel map ?

Or what else ?

[ITVRI]

Book in a session with Joolz at Kits and Classics

He can put your car on the rolling road and tune the 14CUX to suit your modifications or ensure everything is running as it should.
Give him a call he's always happy to help.

http://www.kitsandclassics.co.uk

Edited by ITVRI on Tuesday 22 August 20:14

[QBee]

ITVRI said:

Book in a session with Joolz at Kits and Classics

He can put your car on the rolling road and tune the 14CUX to suit your modifications or ensure everything is running as it should.
Give him a call he's always happy to help.

http://www.kitsandclassics.co.uk

Edited by ITVRI on Tuesday 22 August 20:14

Beat me to it. Jools is your man to remap the 14 CUX. Easy drive from where you live, being that he is only about 10 miles off the M1. And he is not expensive, and has his own rolling road.

[jojackson4]

As above there's no guessing

[Sardonicus]

What they all said

[blaze_away]

Right....I think I need to call Joolz.

Cheers all

[Classic Chim]

He's a really good guy and will get the best out of it.
I've covered 78 miles today early morning then late evening Frank. Rugby to A45/A46/A4189 to Reddich and back. At least 16-18 miles on the A4189 each way with 50/40/30 speed limits and winding road.

I'm doing a test on almost exactly 4 gallons of fuel (tvr Gauge willing)
78 miles so far and I'm sure I'll get another 22 before the gauge is back to 1/4
So that suggests 25 mpg but that is constant running rather than stop start!
I'm using google maps to calculate the exact mileage to check against my milometer
I'll confirm tomorrow. 95 Ron fuel too!
I'm then going to do the same around town which will be low 20's at best.

Edited by Classic Chim on Tuesday 22 August 23:38

[TV8]

Not sure where you live (where I live involves lots of stationary traffic) or how you use the car, but curious why you think the car should do 21MPG?

More than happy to recommend Jools for remapping (my car was his first chargeable remap!) but i would not be using MPG as an indicator of where such a remap was required. Depending on how mine is used - around town, I don't fill the car up or reset the trip meter to avoid such potential up setting calculations but on a run, I recently drove back from Spa to Sarf London on a tank full with the roof down and a good turn of speed which is over 300 miles.

I do not know what the tornado chip actually does but assuming it keeps all the features of the 14CUX, then get a roverguage lead, down load the software and go for a drive whilst logging the actual results. You will see what is happening with the trim on the map as you drive. If the mapping of the ecu is showing the fuelling trim going outside of its ability to correct itself, then it will be running to lean or to rich and will need a remap - this is essentially what Jules does - make sure that the car is running within tolerance of the map for lots of different driving scenarios.

All this is assuming that the car is running fine - good ignition, set-up etc etc.

[Belle427]

You could try a fresh set of plugs before you have it looked at, won't hurt.
I'd probably fit the iridium type that seem to have some great feedback on this forum.

[blaze_away]

Belle427 said:

You could try a fresh set of plugs before you have it looked at, won't hurt.
I'd probably fit the iridium type that seem to have some great feedback on this forum.

Good point thanks, serviced about 2k miles ago and new plugs fitted. They are fouled though which also tells me its rich.

[blaze_away]

TV8 said:

Not sure where you live (where I live involves lots of stationary traffic) or how you use the car, but curious why you think the car should do 21MPG?

More than happy to recommend Jools for remapping (my car was his first chargeable remap!) but i would not be using MPG as an indicator of where such a remap was required. Depending on how mine is used - around town, I don't fill the car up or reset the trip meter to avoid such potential up setting calculations but on a run, I recently drove back from Spa to Sarf London on a tank full with the roof down and a good turn of speed which is over 300 miles.

I do not know what the tornado chip actually does but assuming it keeps all the features of the 14CUX, then get a roverguage lead, down load the software and go for a drive whilst logging the actual results. You will see what is happening with the trim on the map as you drive. If the mapping of the ecu is showing the fuelling trim going outside of its ability to correct itself, then it will be running to lean or to rich and will need a remap - this is essentially what Jules does - make sure that the car is running within tolerance of the map for lots of different driving scenarios.

All this is assuming that the car is running fine - good ignition, set-up etc etc.

Cheers Graham. My test run was all done on A roads no stop starts and very light right foot too, specifically to see what was the best mpg I could get. Rover gauge shows long term trim is zero. So, I'm no expert but this makes me think why is my mpg so much lower than everyone I talk to and so I suspect the map is wrong is that a valid conclusion ?
The car is running really well other than that.

[N7GTX]

Classic Chim said:

95 Ron fuel too!

Tight git.

I have to use 97 at £1.25/litre

[ChimpOnGas]

Classic Chim said:

I'm doing a test on almost exactly 4 gallons of fuel (tvr Gauge willing)

Mate, forget the TVR gauge!

Being a motorcyclist I'm sure you know the only way to get a true MPG figure is to use the brim to brim method.

1. Brim the thank

2. Drive the car for a number of days under differing conditions (urban, motorway, A&B roads, driving like a pussy sometimes but spanking it occasionally others)

3. Make sure you are properly recording your mileage, Google Maps is OK but a Sat nav or mobile phone app is much better

4. After approximately 240 miles fill the tank again and record the litres needed to brim it as in your first fill

5. Divide the miles you've accurately recorded during the brim to brim test period with the litres needed to brim the tank again

6. Divide the figure by 4.546 to get your true and accurate imperial MPG

Example: 253.233 miles divided by the litres required to brim the tank on your second fill = 51.369 litres, multiplied buy 4.546

And these figures shown in the formula: 253.233 / 51.369 x 4.546 = 22.41mpg (Imperial)

Top tips:

• Use a mobile phone odometer app to record your mileage during the brim to brim test period, this is by far the most accurate method of precisely recording the exact distance you have traveled to the last foot

• Make sure you cover a mixture of driving styles and traffic conditions during the brim to brim test period

• Try to be honest with yourself to brim the tank properly on the second fill, clicking off short will give you a better MPG figure but you'll just be kidding yourself

If you really want get a truly accurate figure the brim to brim test should be repeated over and over again and over many thousands of miles, you can then take the average of all your mpg figures which will allow for different driving styles, climatic and traffic conditions

Forget the best figure recorded in perfect conditions, it will make you feel happy but the truth is it's your average MPG over many tank fills that's the important figure

As you might imagine I've done literally hundreds of accurately recorded brim to brim tests in 'Ol Gasbag', taking the average shows me she consumes LPG at a rate of 21.341mpg, I then take the average difference between the petrol price and the LPG price over all those fills to give me my average petrol cost equivalent fuel consumption.

The result looks like this: 21.341 x 1.921 = 40.99

Meaning I would need to be achieving a true average of 41mpg in a petrol car to match the average fuel economy of my TVR Chimaera, if you study true mpg figures this compares favorably with a five year old petrol super-mini (Fiat 500, Nissan Micra, Ford Fiesta ect ect).

And I know which one I'd rather be driving

[blitzracing]

Quite simply the catalyst fuel map uses extra fuel to heat the catalysts to break down pollutants, that does nothing for the MPG whats so ever. You can get 30 mpg out of a 4ltr engine by switching to the green map without lambda control, and then remapping to lean the mixture off to about 15.5:1 AFR for light cruse. The problem is that the car will no longer pass the emission tests (unless you have a TVR friendly tester) as the catalyst are not getting the correct fuel cycle any more to keep the chemistry working as it should. Even if Joolz remaps the catalyst map to be as close as possible to ideal, the 14CUX lambda control is not that good, combined with the fact that TVR puts the probes downwind of the precats, so the lambda cycling is quite ragged. This has the effect of overshooting the mixture both richer and leaner than needs be, so you loose out on both economy and drivability. Its dead easy to put a switchable resistor into the tune resistor to switch between the green non cat and white cat' map, so that bits not a problem at least. I dont know if its possible to overheat the catalysts on green tune however, but it may be worth trying green tune after a remap and keep an eye on the catalyst body temperature. If its glowing red hot- its too hot! If you can get away without overheating the catalyst, you don't have an emissions problem, just switch back to the white map at MOT time. Cant say I know if Joolz has tried a green tune with the catalysts fitted, as its normal practice to remove them and find an "appropriate" MOT tester!

[Classic Chim]

110 miles from 4 gallons. I'm not slow either. Factoring in tyre size, milometer/ google maps and being conservative that could be as low as 104 miles.
I hear what your saying Dave.
My gauge is quite accurate and I know how to read it if you know what I mean.
This test started when I had a consistent 1/4 tank and added 4 gallons taking Gauge just above 1/2 full.
After doing this test down to 1/4 tank then adding another 4 gallons the gauge is almost exactly where it started so I'm confident I've got a fairly acurate reading.
It's always around 26 mpg when I do these tests.
You are absolutely correct Dave, but this stuff amuses me and I'm always doing these Little tests.
My gut instinct says 27-28 motorway driving 24 on A and B roads, 20 ish around town.
The biggest difference is starting it hot or cold, just purrs and costs very little.
Overall that to me seems the biggest saving on fuel.
I also remember getting 24-25 on CUX with this engine but that would be below 20 around town or start stop it would be worse than that.
I know it's not a lot but it does feel cheaper to run by quite some way when you put the miles on!
What tyre's are you using Frank.
Would cut gears create more or less drag?

ETA. I actually think I've managed 27.5 mpg on this test. But unless I do a more scientific accurate test I'd rather not suggest this,,, but it fking does

Edited by Classic Chim on Wednesday 23 August 21:16

[jojackson4]

15 ish to the gallon

[blaze_away]

I am running toyo proxes on the front 205 55 15 and S02s rear 245 45 16.

Have had direct contact with Blitz and I am going to try a green tune resistor and a remap with Joolz. He has evidence to support this being highly likely to throw up some benefits. Who knows Alun Chris might run a 12.5 up against yours ! haha.

So who has a green tune resistor lying around that I can buy ?

[jazzdude]

blaze_away said:

I am running toyo proxes on the front 205 55 15 and S02s rear 245 45 16.

Have had direct contact with Blitz and I am going to try a green tune resistor and a remap with Joolz. He has evidence to support this being highly likely to throw up some benefits. Who knows Alun Chris might run a 12.5 up against yours ! haha.

So who has a green tune resistor lying around that I can buy ?

They are easy to make, just get a 470 ohm resistor, solder a wire either side of it and then take off the white one from your loom, about halfway up the fat mess of wires that leave your ECU, cut out the white resistor and splice in the 'green' one.

Make sure you then disconnect your ECU (engine off while you are doing all the above) and then restart the car. Leave it to idle for a couple of fan cycles for it to relearn.

Ideally unless you know you have a TVR green tune map get a new chip with it on as some cars have the RR tune which is not the same.

If you have your cats in though this mod will ruin them, and to get the full benefit, you will also need to manually set your AFM.

However, it is a great mod and will transform your 14cux into something very smooth at low revs.

[cp81]

Sorry to jump in on this...

What is best resistor to use with pre-cats out only (main cat still in)??

[blitzracing]

You dont need to worry about the learning bit on green tune, as the AFM Co setting you do manually replaces the "leaning" bit that the ECU does with lambda feedback. So its simply a case of getting the engine warm, and then you can set it by ear. One way the car will run too rich like its on choke, the other way will will start to run lumpy as it leans out, so you want to set it lean, then back it off just far enough for a smooth idle. On getting the best MPG, you can run the map quite lean, as the car is so light it spends a lot of time with low throttle openings- typically around 2k- 2,5k rpm, and this is the area you can lean out to 15.5:1 AFR. If you want then race car pops and bangs, you lean the mixture right of to around 16.5: 1 on the overrun with a small throttle opening- its quite easy to select the RPM you want this to happen at- you just lean off at say 3500 at the correct map row, and the gatling gun will start at this point. If you dont want it, just close the throttle completely.