The "Tuning MS V8 for Economy" Thread

[Hybrid_From_Hell]

Sam (Mr Noisey) and a few others have posted / asked about "Economy" tuning on Megasquirt.

As I have a few mins here is a start to a thread which will give peeps interested some ideas background tech knowledge

and thoughts as to what they can do, I will warn everyone now, Running an engine to lean will = damage and very quickly,

take extreme care what you are doing, and go easy.

Also too rich can equally dmage you engine, too lean = heat = melted pistons, seized engines etc, too

rich = bore wipe = wear = damage, this isthe risk you take playing around with MSQs, but for those that want

to learn here is a starter for 10.

Before you start going into advanced tuning / autotune / leaning off / economy etc, FIRST make sure that

The engine is in good condition - ie

Emmissions are about right MOT wise,

tick over is solid,

the engine drives well with no black smoke

there are no faults within the MSQ

The timing is SPOT ON check with timing light vs Trigger wheel / pulley markings

The leads plugs etc are correct type (NGK BPR6ES) and gapped properly

VR sensor equally gapped

Fuel pressure is correct in rnages

Filters are clean - air and fuel and air filter is BIG ENOUGH (many are not)

ALL sensors are working and showing correct readings on MLV

the exhaust is leak free and good for purpose ie big enough

4>2>1 is better for power and mid range than 4>1 each side

You have a known good NB Lambda sensor

The fuel is of a decent RON Rating

You can keep the engine temperatures under control (too high = lost power and false tuning)

Your TPS is calibrated and saved in the ECU

Freash oil change so no fuel in oil, no black smoke on booting it up the road ..........

OK

Some background, this is esp around V8s.

There is a lot of snake oil and nonsense taked around tuning and BHP, much is over egged,

and max horsepower is as a result of a good condition engine being tunned properly through all the steps without

jumping any methodoligy and patience is required, there are no short cuts.

There are 2 main tables for working in, VE (Fuel) and Spark

These are interconnected, and are also linked to AFR (*air Fuel ratio)

Spark - or MORE spark = Heat, more spark also needs MORE fuel to get the target AFR

The lower the number on the AFR the richer it is, and the HIGHer the number on AFR the leaner.

An AFR of 14.7:1 is known and refferred to as a Stoich as is frankly as lean as you should go esp on a Rover V8,

and a rover V8 (any size) won't run properly on part throttle at more than 16:1, experts say max economy is

around 15.5-16:1 AFRs but posionous gases are produced at this level so often Lucas ECUs were set to 14.35 : 1

richer than stoicch !

If you have to have cats super lean is also a bad idea cats need ARFs on cruise of around 14.7, but a Rover V8 will

run hot at 14.7 or higher, so a richer mixture of say 14.3:1 will give more fuel and help cooling - GEMS ecu set up

actually have a internal ECU setting of 11.1 on WOT to keep engine cooler. AFR tables are key to economy power and

temperature. With MS the MLV or Tuner studio tunes TO THE AFR DATA STORED

Therefore to make major changes to economy you need to change the AFR Target table.

All of the above relates toVE ? Fuelling. MLV / Tuner studio will rewrite cell values via the algorithmic processing

it has to match the AFR table targets with the MS datalogs and rewrite cells accordingly. However, spark is NOT altered.

More spark or less sprk with the same VE cell value = differing heat BHP and economy, they are interlinked, as such you

also need to tune spark along with the AFR table to get the matching and corresponding VE cell value, you CAN'T tune

spark with MS without a Knock sensor.

There is a load of guff about adding spark in until you hear pinking and knocking and back off etc, this is real nonsense,

and should be avioded at all costs, either use a known good ASpark table or purchase Knock sensor setups or use a rolling

road. RR charges can be £150 per hr or more and a session can be 4 hrs !

So, make sure I would say that you spark table is good, and then tune to VE table to AFR targets. also note that the

bigger the cc of the V8 the less advance at WOT the engine can take, and also max advance can be fully in at =/-3000 RPM, no lower.

As a simple guide, WOT and pedal to the metal MUST have more fuel to get BHP and Cooling etc, and aviod being super lean,

but cruising you can tune down to say 14.3ish:1 and for a greater rnage of cells, this way you can have you ckae and eat it,

foot down = fuel + power, and cruise = economy, but there will be a step, where is will feel that there is a hole as the

engine goes from lean settings to rich settings with what can feel like a mineshaft whilst it moves from one to another.

The more pronounced your AFR table is for economy at cruise and part trouttle the worse the cravass will feel.

Increase cruise to 16:1 and it will increase the hole further and can make for a tiring drive.

There is also an arguement that the sort of issuesd above means you drive it differently, and thius use MORE fuel than if

you set the target AFR at say 13:1 at cruise gain more power less of a hole and thus a sweeter engine to drive so you don't

hoof it all the time ...

However, too much fuel on part WOT or cruise = less power as it bogs the engine. This is why you need to have a good solid MSQ

to create leaner than try it all at the same time.

I have found that having a base map, changing AFRs dataloging resetting and then driving and feeling the engine can give me as

much if not more info and feedback than just the MLV doing its stuff.

A recent trick I have discovered is setting the tickover cells to a target of 13:1 - 13.5:1

u gives a rock solid tickover, although you might chase the cells about a bi before you know which one your engine really wnats

to use, once you know change the values and set in the AFR log, and then whtever tuning you do your tickover will remain solid.

There are 2 ways you can have a more econmoical MSQ

Method 1

Run 2 x MSQs

On MSQ1 tune for power, have WOT at lower AFrs and cruising above stoich, say 14.3:1, set the AFR table, set the spark table with

max advance in at 3000_+ rpm, and tune tune and tune until happy.

Then

MSQ2 take MSQ1 back off the spark table across the board by say 4-7% lower backing off at low to mid rnage higher backing off a WOT.

then set AFR table to lower settings at WOT a BIT, More at Cruise and even more on overrun, then retune.

The above is what I have done, the other option is to try to tune the MS as just one setting as noted above where you have max Spark

and fuel at WOT and part WOT lean on Part and cruise and a ferking great annoying hole when moving to power from cruise, which is

why I have got Option 1.

Enough brain dump for now, I'll also bung up some stuff and AE enrichment, which is a hugely complex section that you need to get to

grips with for the power side of tuning

Hiope the above is of help and interest feel free to add to this as a useful future thread ?

Nige

[Mr Noisy]

Thankyou Nige

It is only after a few months of running MS that i ahve realised that tuning for power does mean that one does tend to use more fuel than they might otherwise want to.

This is partly/,ainly due to the fact that the engine is SO much more powerful/driveable, it persuades you to put your foot down a lot.

However, i do have the option to work on my motorway economy so why not try to save soem money hey? I'm confident in my car enough now to take it on a 500 mile round trip but when youre looking at £200 in fuel its a bit off putting.

Hence, raising the point the other day that has partly inspired this thread.

I havent had chance to look at my laptop yet, but one evening will have a fiddle.

I have a nicely dialed MSQ now which i have driven a thousand miles on probably and off roaded a lot and its great, no smoke, no troubles, as much power as i can reasonably expect no doubt.

As such, i can use it as a basis for an ECO table.

My AFR table is mostly 14.7 in the midranges, climbing to 12.8 WOT gradually. It runs lean to 17:1 on overrun, and 13.5 for all tickover rpms.

The plan is to work out what cells i use for cruising and then alter the AFR accordingly. I was planning 15:1 for a lean cruise but if this is not recommended for RV8 then i'd be sorely tempted by 14.7:1

Regards the spark table, all accounts say that one needs more advance to allow for the slower burn of a lean mix, but of course this all starts to add heat.

So are we saying that advancing the spark means i will require more fuel to reach target AFR? ie retard spark, less fuel, less heat, target AFR reached BUT LESS POWER?

Obviously the ECO map is purely to provide enough power to maintain cruising speed whilst using as little fuel as possible right?

The only thing i am quite confuddled about is how the spark advance relates to the resultant AFR, unless i have just figured it out a few lines above.

Thanks again for starting this thread Nige

[elbekko]

I think you've pretty much got it, earlier spark = more burn = more fuel = more power (in simple terms, not quite that black and white).

You mostly have to worry about leanness when the motor is actually working. Now in your case I'm a bit skeptical that leaning it out will do much, since you mention the MAP is pretty high at cruise. If you lean it out, you'll just move up the map to more load and more fuel, eventually reaching the same point probably.

I have to agree too that the nicely running engine is a big tempation. It's been a fair few months since I've swtiched from a 300TDi to a 4.6 V8, and it's still pretty difficult to keep my foot out of it

[Mr Noisy]

Yes, my biggest problem I think is my MAP at motorway speeds.

Going to look into it thoroughly with my new knowledge and recent experience.

As the reckless engineer mentioned, watching your injector pulse widths gives you a pretty good measure of how much fuel you're actually physically squirting at any given time.

[Hybrid_From_Hell]

Sam

Your gearing may be too tall.

Thios makes you have to work the engine to get it going, and keep your foot down to maintain

What tyres Gearbox T/Box ratio and diffs have yer got chap, and I'll run me programme

Nige

[Bowie69]

3.54, 1.2, 32.5" IIRC Plus a wheezy 3.5 (smaller engines do NOT necessarily mean better fuel economy!)

Think I mentioned gearing being too high on the other thread

With a 1.4 box, cage, 33" JT2s, winch, heavy bumpers etc and heaps of equipment I reckon on a motorway cruise at 60 I would be pulling 18-20, so for Sam, I would guess the fundamentals need sorting first, then a re-datalog

[Mr Noisy]

Yeah Bowie is right on the specs, I mean my tyres are 33x12.5x15 but they are 32" ish in reality.

Amazed how the gearing can be too tall when so many people out so much bigger tyres on!

Agree on small engine not being guaranteed economy, have said for a while I could do with a 4.6 to get my tank moving!

Yeah Nige if you wouldn't mind working out the overall gearing that would be handy, I mean the standard disco is like 29" tyres I think!

Thanks again chaps

[elbekko]

Have a play with the Ashcroft calculator:

http://www.ashcroft-transmissions.co.uk/calc/ratio_calc.html

[Hybrid_From_Hell]

Sam

here is another way to understand the cell values on VE and spark and AFR

But

before that I have had some PMs regarding "Fuel Required" Settings and tuning them

Er "Non"

Fuel Required is a rough claculation, of how much fuelling typically your engine wnats, what it is is

actually not that crucial, what I use is fine for all V8s inc Mine !. VE Table is more the fine tuning,

IE Fuel Req - how big a bucket do I need 1 / 2 3 gallon ?

VE and how big or small a hole in the bottom to pour into the engine ?

Thus, if your Fuel Req is with the rnage of the ENGINE he VE tunes the injector requirements to the 144 cells.

DO NOT f about with Fuel Req !

However, all of the above is why you can't just take some VE table off the t'internet / mate / helper, and shove

in your V8 and expect miracles - if HIS Req Fuel was 50% less than yours you new whizzy table will be 50% richer

than it should be !be carefull of radomly shoving bits of MSQs into your engine and going to give it large ........

Ok, moving on ...

THESE ARE JUST HYPOTETHICAL FIGS to get you mind tuned in .......

Lets say 1 x cell has a value of 14:1

The VE table has a value of 70

The spark has a vlaue of 15

and that this cell is perfectly tuned.

So

With an Target AFR of 14:1 and a Spark of 15 degress the "Perfect" VE cell value is 70

and now you "Do something"

1.

You change the AFR to say 13:1 as the target

Spark remains the same

FUEL ie VE Cell is too LEAN, as its at 14:1, so the retune will recalc the VE table number, and it will be "Higher"

than 70 ....

2.

You leave the AFR at 14, and the fuel VE cell at 70, but drop the spark to say 13.

cell VE is agfain wrong, now its too rich, retuning will see the cell drop lower than 70 .....

3.

You leave the Spark at 15, you leave the AFR at 14, but you manually change the VE cell to another number.

Now, (and this is what many peeps do) the Cell value is wrong based on a retune it will due to spark and AFR table

reset itself to 70, this is why when peeps reset tickover manually and get it right a retune looses that tickover settings !

So, does the above make sense ?

AFR VE cell value and spark are all interrelated

No 2 is where you can tweak a selection of vcells for economy by reducing spark and fuelling to match, but you lose BHP !

Yes, the above is all very simplistic but I am trying not to met minds, more to give understanding and make a very

very complex subject ladybird book simple ??

Nige

[Mr Noisy]

That is just what I needed, I now grasp the interrelation.

I think what I hadn't previously considered was the last variable, bhp.

Ie you can run the engine in good tune and simply make less bhp.

If you run the engine with less fuel, you need more spark advance to make same bhp but you then make heat.

It's grasping the interrelation between all the inputs (fuel supply/spark advance) and outputs (smoke/heat/bhp/pinking etc) that is difficult.

Luckily with the help of you guys it slowly becomes clear.

Had a play on Ashcroft calculator and swapping to 1.4 transfer box would undergear slightly on 33" tyres.

However, I wonder if it would help with my MAP at 75mph (I am aiming for 75mph cruise speed but need to get on the motorway to read some data to check this on my current gearibg to see when the MAP climbs up too far)

I mean 75mph on 1.4 box is like 3100 rpm as opposed to 2700 on a 1.2 box.

Could experiment with higher road speeds in 4th gear and see how my MAP levels are.

Time is short at the moment but will get my findings posted up ASAP!

Thankyou!!

[Hybrid_From_Hell]

No prob glad it helped !

Now you'll understand the frustration I have when peeps say MLV and TS don't work,

and I ask what AFR Target table they are using and say "Don't know but so what ? .......

I'm talking about it not tunning ...." ...come here ....nice wall......

The MSQs I supply are more for performance BHP etc...and as you have learnt can be tunned to your own engine even better....

Nige

[Bowie69]

Sam, I'm on 33" and a 1.4 albiet with an auto, it is SO much nicer to drive, doing it again though, I would have changed diff ratios, more choice and drops your low range back to standard.

[Hybrid_From_Hell]

Sam

Here you go

1st factory standard, look at 2000 RPM in 5th !

then your truck as is now - 12% out

Then change of TBox - sorted

or

Change of CW&P sort high and low boxes also 4.1s are hugely stronger than 3.54s

This will make MAP drop as you won't need to have as much trottle to power truck on cruise !

12% will be like a standard car and a car with 5 adults and a hugely foot boot of stuff..... dead dog time

Hope the above makes sense

I built the above to do massive calcs for me own truck, I have on the 4.5 a top speed ao 159 MPH - I was a tad over geared !

Nige

[Mr Noisy]

Thanks chaps.

Yes I had looked at diff ratios, the ideal is 1:1 transfer case with super low diffs, for much lower low and standard high.

Financially, 1.4 case will prevail however.

Going to look at doing this, ideally swap with a defender owner!

[Mr Noisy]

Ahhh! Great post Nige!

So, 1.4 box or 4.11 CWP it is!

As above, lt230 is cheaper and I am poor but I will try my best!

[Mr Noisy]

£200 per gearset!

1.4 transfer case anyone??

[Hybrid_From_Hell]

Either will transform your truck on the road !

[Bowie69]

*IF* you can find a good LT230, then great, if you then need to refurb it, the diffs make much more sense, and upgrade strength all at the same time, only a matter of time before all those extra horses do some damage

[Hybrid_From_Hell]

^^

I'm with Bowie, a PROP fix is CW&Ps, it also will amaze you the difference off road as well !!

Nige

[Mr Noisy]

Out of a stock 3.5 chance would be a fine thing!!

Thankyou for your valued help gennulmen, this economy thread will be revisited when running 1.4 ratio.

I expect to pick up a transfer case for not too much bother!

(Famous last words)

[Mr Noisy]

Oh yeah fully aware the diffs are the best solution whereas transfer box is a "fix" but it's 400 quid and a load of graft I don't need right now, just can't justify it I'm afraid

[Hybrid_From_Hell]

I have just sold a s/h 4/.11 just to rub it in

As bowie says, make sure the 1.4 TBOX is a good one or that will empty your pocket nearly as badly !

Nige

[Hybrid_From_Hell]

Got some mint s/h HD 4.75:1s, if you fancy a rocket pocketship

Nige

[Bowie69]

Don't temp me Nige :x

1.4+ 4.75s... hmmm smokin

Won't be wanting to 90 in it again though

[Hybrid_From_Hell]

I run 35" simex, 1.193 TBox LT85 5 speed and 4.75s !

so re the above for Sam its not totally mad !

But 1.4 TBox, whiplash here we come !