Target AFR tables iwth a wideband LC-1

[Bowie69]

Thanks to Mr BBC I have a new toy to play with (Innovate LC-1), and frankly I am very chuffed with the results so far, engine seems to be running very nicely, the over-fuelling I was getting under high RPM/Load has gone, and the VE map is looking MUCH healthier:

The above map took 5, 20 min sessions to get, from an archived map I had saved from January. I logged, saved, MLV -VE Analysed the current MSQ with the log file and then burnt it to the ECU, repeat 5 times On the last run, the largest cell change was just 4, and had been slowly improving on each run(first run was over 20!). I was a happy bunny

The problem with new toys is that when you get into using them, you realise you know sweet fa about them, hence this post

Now, whilst this is a f-huge improvement on before, and it is running nicely, I have been tuning against an AFR table which I think is what you would call 'safe', there is no allowance for light throttle cruising, and am unsure how to go about this, especially for a RV8 which can be a bit finnicky

Current target AFR table is as follows:

Current tune is here: http://www.thebowate...CurrentTune.msq

Most recent log file is here: http://www.thebowate...msq/datalog.xls

So.... any tips, tricks or advice? My current thought is I should go for a cruise at 50/60MPH and note the RPM/MAP and then tune it down a bit in those cells, but it seems like there should be a more scientific way to about this

Oh, before I forget, the engine is in a mild state of tune, ported, bulleted valve guides, 9.35:1 comp pistons (real comp probably nearer 10), Kent H200 cam, Rhoads lifters, and is 4.0 serp block/heads out of a P38 (cross-bolted etc), and is installed in the RRC in my sig, weighing at 2500Kg

Thanks for any help

Pete.

[zoltan]

How have you run the sensor? Have you taken an analogue output from the LC1 to the MS ECU or are you using it stand alone?

[Paul_VR6]

Sounds like it's output straight to the MS from the MLV VE tweaking

I would do exactly as you say, just creep down on the afr in your cruise area (once you've identified the specific map/rpm).

You will know 'too lean' when it starts surging a bit. You can add a bit of timing to get rid of it, and then go a little leaner. Then repeat. Once you get to a point that no more timing will help, that's your lean misfire limit, Add a bit more fuel back and you're done.

I also suggest monitoring your duty cycle at cruise as well, min duty = min fuel

Hope that helps!

[Bowie69]

How have you run the sensor? Have you taken an analogue output from the LC1 to the MS ECU or are you using it stand alone?

Straight to the MS ECU

Sounds like it's output straight to the MS from the MLV VE tweaking

I would do exactly as you say, just creep down on the afr in your cruise area (once you've identified the specific map/rpm).

You will know 'too lean' when it starts surging a bit. You can add a bit of timing to get rid of it, and then go a little leaner. Then repeat. Once you get to a point that no more timing will help, that's your lean misfire limit, Add a bit more fuel back and you're done.

I also suggest monitoring your duty cycle at cruise as well, min duty = min fuel

Hope that helps!

Cool, yes, it does, and good to know I am not a million miles out in my thinking

Any ideas as to what is 'safe' on a RV8? Really really don't want to break this one

Also, full MAP AFRs... are they too high, low, about right?

I realise this may be slightly outside of LR4x4, but I think wideband tuning is missing a little from this sub-forum... plus I couldn't find it via even advanced googling...

I'm in no massive hurry to get this right, I won't be tuning again until the weekend, in the meantime it is making a lovely run-around

TIA

Pete.

[FridgeFreezer]

I found this on my puter the other day, it may be of interest:

Note I have no idea where it came from or what engine it's for so it may be totally wrong for an RV8. I suspect the cruise is a bit on the lean side but I know nuffink about tuning, once it's running I lose interest

[Bowie69]

Cheers FF, I seem to remember that one from HfH's epic thread, but had completely forgotten about it

As it is rich on idle, it could well be for a V8, which would be handy

[Quagmire]

Peeps on v8forum have said previously that the rover likes 13.5:1 at idle so looks like it must be...

[FridgeFreezer]

I've always found with narrowbands that the RV8 likes to be on the rich side at idle, certainly when V8Bertha mistakenly set his NBO2 correction all the way down to 500rpm it hunted like hell at idle.

[Hybrid_From_Hell]

Few Tips

1. DO NOT have too lean an AFR on cruise, the 4.6s ECUs had this and they run far too hot

causing liner issues, I read somewhere that 17:1 was in the maps somewhere, V8s don't like more than 14.7:1

and many have made comment that for high speed cruising this toio is too lean

2. Hot days and cold days will give differing values, make sure you account for the hot days, as on these

it will run leaner than a cold day etc, if your AFR Table is on the edge and done mid to cold day, a super hot

day can see you engine running too lean - I think I have that right ?

3. If the engine has a hot cam, Valve over lap can cause hunting issues and the Table settings for Tickover are often best done by ear and feel,

4. Watch engine temperature, too lean = hot = damage, fuel economy wise lean vs F lean = not much.

in a 2 ton truck with the areodynamics of a detached bunglaow

5. DO NOT let the LC1 go into deep water when on - it will die !

6. When you have finished post up you NB VE Table vs the LC1 WB VE Table

Hope the above helps

Nige

[Bowie69]

Cheers Nige/FF/Quag, nice to have some confirmation from people on this

Nige, I think you may have it backwards, working from first principles, colder air = denser, for the same MAP you would get more oxygen into the cylinders, leaning out the mix, but I am open to correction about this

Just went out and tweaked the VE table at idle, and when idling in gear, and brought it to around 13.5:1, from around 14:1 (which I thought would be rich enough), and much much smoother idle, seems v8forum guys know their onions

Engine temp is very good in all honesty, mostly around 80-85C depending on ram air, traffic, fans running(on @85) etc, don't think I am running too lean atm.

Some tentative thoughts on this....

• Do some logging, cruise at 30, 40, 50, 60, 70 mph
• For 30mph, I should be able to get away with a bit leaner, something like 15.5:1?
• 60/70mph something closer to 14.5:1
• Smooth the steps for 40, 50 mph
• 13.5:1 ish at idle (already done) and
• 12.5:1 at 95Kpa and 12:1 at 100Kpa?
• Smooth out the section between cruise and WOT
• Smooth the section to the right of cruise
• No point leaning off the deceleration area, as I run fuel cut off under 1500rpm/25Kpa

Reckon I overcomplicated it again, but there you go   

Anyone anything to add?

Cheers muchly

Pete.

*edit* Almost forgot, here's my old NB table, but I think at this point it was starting to go a bit squiffy:

[Quagmire]

I think Bowie is right- tuning on a very cold day means you are working at the leanest end of the spectrum (if you see what I mean) as you are getting denser air drawn in.

Hence on a hot day you will then run into the richer side of things as you are getting less oxygen sucked in for the same amount of fuel being injected..

[FridgeFreezer]

I thought this was what the inlet air temperature sensor was for

[Bowie69]

I thought this was what the inlet air temperature sensor was for  

Good point, well made!

However... I regularly see IAT at 40C+ which is just down to heat soak when coming to rest, but then it is idling, and not really a problem, I think

[Paul_VR6]

The first AFR table posted above is good, but will vary slightly for every engine/vehicle combination. If anything my major feedback on that is the 'cruise' region goes to too high a MAP (in general) but it might be fine for the exact combination it's being used on.

Temps at 'lean cruise' .. running leaner then stoichiometric actually reduces EGT's (they peak at stoich) so if engines do run hotter, I have no idea why. It is possible that running lean without increasing spark advance can cause higher EGTs, which is one of the reasons you increase timing as well.

The IAT will trim the table for varying temperatures but some users report that this doesn't work perfectly. I have had it 'not' work well before and it was because my injector dead time was *way* off for the injectors I was using and skewed the results of the fueling algorithm. Typical high imp injectors (big body EV1) will be around .9-1.1ms, if you're running low impedance with resistor packs it can be even larger and newer style EV6 injectors can be much quicker around .75ms.

I would turn off decel fuel cut and tune at least one map bin for decel. Usually you want to run decel at a slight delay (1-2sec) so it's not jumpy. Tuning one bin down there will allow you to hit decel anywhere and be 'in tune' before you do.

Hope that helps!

[Bowie69]

Thanks Paul, gave me something to think on, I know I do it too much, but if I think really hard the people inside my head start speaking back to me -they keep me company

I read up on weak mixtures and burning etc, with aluminium pistons and leaner mixtures, as there is oxygen left in the and given the high temperatures and explosions going on you can actually start to burn the piston, hence a melted piston, overheated top end and kaboom -something I want to avoid ofc Localised heat is bad for engine tolerances, so it could well be this that gives the slipping liner syndrome, I may of course be completely wrong, and I don't want to start a discussion about that here!

Anyways..... some success -I finally got some time to do a bit of tuning!

I went with this AFR table, after analysing log files and working out where my cruise zone is, I changed a couple of things, some AFRs and an RPM bin, and of course idle AFR, which I of course tweak manually, but it is there for reference. I also switched off overrun fuel cut off so I could get a ball park tune for the <30Kpa figures. My cruise figures varied from 1900/68 to 2400/88 to 3000/60 (locked in 2nd gear) so I think this AFR table makes some sense:

This is the tune it has now given me:

Looking pretty good, I think...? There's a bit of a spike at 1000/90, very high value.... I take it this means I probably need to up my Acceleration Enrichment a bit?

Another question..... I was scanning the log files with MLV, and noticed something happening at WOT, MAP is decreasing as RPM increases, I wondered if this was a common thing across installations, or is the standard Rangie air filter strangling things? Quick SS:

I got home tonight, and thought I'd tweak the AFR table some more, this time for the overrun figures, and ended up with this:

Any thoughts? Pretty close?

Gonna do some more logging soon with the above AFR table, and tweak AE values, and will post results

Cheers,

Pete.

[Paul_VR6]

It'll only cause damage at higher loads, you can ping all day at low loads and just get a funny noise out of it. I ran my VW like that for *years* because the vacuum advance was to aggressive for the total timing I needed to run for the cam I had. Sometimes you learn these things because you have no choice then to run a sub-optimal setup. Had I had MS at the time, I would have taken some timing out! I would read up on EGT and the effect of AFR, I'll link up a good aircraft related article that helped me understand it a good bit.

I think the VE table looks good, it seems to follow the afr table smoothly, which is how it should be. I wouldn't bother with that last one, just tune to 14.7 in decel for now then turn overrun fuel cut on when you need it.

That bump in the VE table could be a misfire, or just needing more accel, it's hard to tell without a log that shows what caused the analyzer to do that.

MAP loss at high rpm is intake restriction, could be anything. A motor that breathes looses almost nothing up top, and some see over 100kpa at the resonance points for the intake length they have.

I personally would try to lean out cruise a bit, but that's your call. I have my current motor running just sub 16:1 on light cruise with 42deg timing and it seems to be working quite well. Hard to say the actual AFR as my wideband only goes to 16 on that side. Getting good gas mileage though.

[Bull Bar Cowboy]

TBH I have always felt that vastly better results are obtained when using a WB Lambda. For setting up the NB is really a guesstimate and can lead to all manner of other issues being glossed over as a result of trying to get the mixture to satisfy the NB switching or in some cases trying to get the NB switching to satisfy the mixture.…………… with the WB, what you see is exactly what you get, and this can also be a great help in finding those illusive injection faults.

Out of interest I used the following AFR table to good effect and then manually altered the idle cells in the VE table to my liking (mostly rich).

Pete ………. Keep as long as you like, there is really no hurry ………..

[Bowie69]

Ian, you are a star, thanks again I expect I will be done with it around the end of the month

Not spent much more time tuning, I think just the one run since last update, but it is running very nicely, and getting wheel spin from stationary in first, bearing in mind I have an autobox, to me that is pretty astonishing

For others interest, the reason I went with a WB sensor, even though I had had what I thought were good results with a NB, was that at high MAP, just after changing the transfer box ration from 1.2 to 1.4 it was flooding it with fuel, and knocking the sensor out so it read lean, MT then 'compensated' by making it richer, and the situation worse  . So, WB sensor installed 1 10 minute run and everything looking much rosier, and I went from there. It really has been a huge help

Ian, the spec of your engine is not so dissimilar to mine, if you have it still, would you mind posting your VE table here for comparison?

Cheers,

Pete.

[Bull Bar Cowboy]

As if by magic............. I think this was the latest........