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I think the early versions of MegaLogViewer you had to but not now as it filters out AE and overrun fuel cut events:

http://www.ideasandsolutions.biz/MegaLogVi...isFAQ.html#gego

From what i understand (i may be wrong here):

If wideband is used and EGO Correction is on, it will try to adjust the fuelling in the usual closed loop way so the EGO matches the Target AFR table.

Below 90kpa it will adjust fuelling up to the value specified in Controller Authority (+/- 15% on mine).

Over 90kpa it will adjust +/-5% (value set under Lambda AFR Targets).

If Narrowband then it would need to go open loop over a certain load value (otherwise i guess it'd try and adjust to 14.7 on WOT which would be bad)

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Hmmmm

On the subject of AE and tuning have just read a very very lengthy article on datalogging and tuning.

Basically it was saying when you datalog and tune with megatune, switch OFF AE Enrichment, but leave EGO Correction ON.

Whilst I understand the logic of this, whats the risks to the engine whilst logging and driving when you hit WOT ??

Thoughts please ?

Nige

AE is only for changes in throttle position

For logging and tuning you want to try and hold steady state so you get clean samples. lots of throttle changes mess this all up and should be avoided. you can drive around at WOT without needing AE, so where is the problem? you just get there a little more gently than perhaps your usual driving style :lol:

Bill

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Yep AE is about right methinks after some playing, I have done a load of reading seems the later versions of MLV aren't infected with AE switcvhed on , but Bill may have a point in try not to have too much AE one when data logging.

Anyway, on to the current project within me MS :lol:

Starting

PITFA - it does, and runs horribly until over 72 Degrees, and until now I have put up with it.

Today I needed to get out of the house fast, and the MS starting meant it didn't like being driven until warm, but it drove, coughed and sneezed, and I thought, I can get this better (this seem to be a comment MS Cry from the fiddlers - me now included :lol:)

SO, mucho reading I had done I turned myself to the starting.

Yes I do need a PWM Valve, and one is due to go one soon, but, even without that it runs dreadfully untill warmed up, even if I manually keep the throttle open - it doesn't like it, and takes around 10 cranks to start :(

From my reading I understand(ish) :P:lol:

there are 3 levels to starting :

  • Cranking to getting engine to fire
  • Then when it fires - Afterstart enrichment to keep running short time
  • Then a table of Temp vs fuelling called Warm up Enrichment - to warmed up engine

Then the engine goes to the VE Table. The MS ECU uses a VAST amount of its computing power in the 3x areas above (inc the PWM needs)

I have massively altered the tables, enclosed are before and afters of these 3x tables above.

I have just popped the 90 back in the Garage, it started on the 5th crank, and sounded HUGELY happier, it would actually tick over on it own when it reached around 60ish degrees, (didn't before until nearer 75+ degrees) and sounded sweeter and happier generally, I think I can improve more, but you only get a 2x try a day on cold starting :lol:

Enclosed are the before and after pics,

Cranking settings :

post-22-1207501857_thumb.jpgpost-22-1207501866_thumb.jpg

After Start Enrichment (ASE) :

post-22-1207501873_thumb.jpgpost-22-1207501882_thumb.jpg

Warm Up Wizard :

post-22-1207501890_thumb.jpgpost-22-1207501899_thumb.jpg

I would be interested in comments thoughts advice and views please :)

Nige

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  • 2 weeks later...

Hi Nige,

I do appreciate this thread a lot. Was a good idea. Unfortunately work was and is taking its toll. So I´m not able to keep my test mule running ..

What I managed was to start it for charging the battery today. I tinkered with the advance at idle. As said, I´m inclined toward 20° figures at idle and low MAP to improve fuel consumption. With that advance I had an idle RPM of 950, MAP was 36. When I reduced the advance to 11° the RPM dropped to 870 and MAP seemed to stay at 36 if not was raising a tad.

What were your observations that led to the lower advance ?

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Hi Nige,

I do appreciate this thread a lot. Was a good idea. Unfortunately work was and is taking its toll. So I´m not able to keep my test mule running ..

What I managed was to start it for charging the battery today. I tinkered with the advance at idle. As said, I´m inclined toward 20° figures at idle and low MAP to improve fuel consumption. With that advance I had an idle RPM of 950, MAP was 36. When I reduced the advance to 11° the RPM dropped to 870 and MAP seemed to stay at 36 if not was raising a tad.

What were your observations that led to the lower advance ?

Hmmmm :unsure:

Ignition timing and all that goes with it is tricky to put up in a single post, could wear a keyboard out :lol:

Basically you must stop thinking in terms of "My Dizzy Had" and look to more "What the engine would really run best with" type of thinking.

Most dizzys operate in a restricted environment - ie it is a mechanical unit and the advance curve is limited by what it possible in a dizzy. As such When I had set in the dizzy what i NEEDED at say 3500 rpm (around 32 degrees) tickover ended up at whatever tickover was as the bob weights and advance settled down, thus my tickover was around 16-17 degrees lumpy and horrible. What it NEEDED at tickover was less advance (and less fuel and less map too) around 14 ish degrees and thats partly due to the wild cam, a std cam should be NEEDING around 10-12ish dependant on the individual engine.

And thats another point :unsure:

As you now have a fully programmable ignition, you can actaully take 2x 3.9 factory V8s with some mileage and find that each NEEDS something different to the other - they SHOULD be identical, but not definately. Think about the V8 or any other engine owner who says "Mine starts on the button every time no probs" and yet the same engine spec can give the "mines always been a pig to start" problem (and here I mean that evrything on both engines is in good condiotn)

Hence to a degree (jeeez - no pun intended :lol: ) you'll need to discover what advance you engine is happiest with. this is a bit trial and error, but I would say for tickover 20 degrees is too much. You wnat to try to get the Map low, and also you need a CO2 reader up the exhaustr pipe, and then work on the ignition and the VE to get to the setting for CO2 you wnat.

With my engine the valve overlap means that I have set the VE Buckets around tickover far far far too high (near 40) just to get it to behave on the CO2 machine, with the valve overlap some of the fuel is coming straight out of the exhaust ports before detonation, so I have to over richebn it to get the MOT % and smooth running, changing the advance affects the MAP AND the VE. Too lean also feels and behaves like too rich, don't be fooled !

I would suggest you should aim for around 10-15 degrees advance, (a dizzys static was around 2-6 and can be improved on by more advance this is done as say a std dizzy with say 6 degrees BTDCand then the normal 22 degrees advance on top giving you 28 degrees adance in total which is all the mechanical unit can do) and fiddle the VE and as you do this see what the MAP does. bear in mind auto don't like as much advance as it causes labouring problems and detonation rather than the manual where you drop a gear. on idle static timing bigger cc V8s need less sp say a 3.5 13-16, 4.5 10-12 and similarly in between, hairy cam can alter this, as does high compression engine- for HC engines (10.5+:1 less advance. I have previous posted up MAXIMUM Adavnce number by V8 engine cc, so bear this in mind too. You should also check you EDIS is 100% set at 10 degrees - set all Ignition buckets to 10 and then do a timing light strobe check, ensure its 10 exactly. To help HC Engines run advance run high grade fuel, mine much prefers 98 ron vs std ron.

Tickover esp on a tuned engine is a compromise. I am assuming you have set the plenum chamber butterfly correctly with a feeler guage (if not see tech arvive and 3.9 hotwire diagnostic manual I have posted in there) and then adjust the allen scre in the front part of the butterfly part of the plenum.

As you fiddle with the VE Advance and tickover recheck the plenum settings - its like trying sometimes to level up a three legged chair :lol:

HTH

Nige

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Just to re-state something Nige said, dizzy timing is only ever the relatively clumsy product of two curves: The curve of the bob weights and their springs against RPM, and the pull of the vacuum unit against MAP. True over the years manufacturers have got it to be a pretty decent result, but you're still governed by the basic curves of the two things, when your engine may need a more complicated shape than a curve.

The same holds true for carburettors, although with added complexity they can be tuned a bit further they still can't match a fully mapped ECU.

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  • 2 weeks later...

Specifically @ fridge,

Cos he's met me, I was the nutter who saw you at bunny lane and asked all kind of questions about how to MS a V8....

I have gone down the MegaJolt route for now (paupers choice) and I have the option for MegaSquirt later.

Has your map changed a lot since the last one you posted?

Cos thats the basis for the map I'm using on my MJ unit.

If it has can I leech?

Please...

@ anyone else who has a spark table that they feel is working well, please share

I have played with mine all over but cannot hear detonation ever!

Checking with a timing light shows it working though.

SO worried about blowing the thing up when all I wanted was a waterproofed V8

which it is....

I know I can use the safe map, but that seems lame after the graft to put the thing in.

RR

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Nige/fridge

Thanks for the PM's and posts. I only need the ignition side, as I don't have all the MS stuff on yet.

I will have to tweak the map anyway as I have only got 10 x 10 bins (pauper)

Thanks guys.

Nige, did u ever sort the fuel consumption probs that I remember reading about some time ago?

rr

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Sub Topic: Wading......

Not exactly high end tuning but a problem to me all the same:

Typical of my lastest wading antics is to be able to wade to full height of the snorkel without issue or the slightest miss-fire for any short length of time - the time it takes to reduce the engine coolant temp to about 30°, then it seems that the warmup fueling starts to flood the previously warm engine.

So, how do I set the ecu to allow me to wade, cool the engine, and yet not overfuel?

Im thinking of making use of the fuel map switching, i.e. having the second map (which is currently used for economy) set to a "false table" where the ve buckets are say (guess) 50% down, this combined with the automatic warmup would then give me a normal fuel amount?

I must admit to being slightly confused, to me a cold engine needs the same amount of fuel regardless of the time taken to reduce its temp, underwater or not. But the laptop does report running silly rich and it does feel rough (in a rich carb setup kind of way) when the temp drops.

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Easier to just change the WUE ASE settings so 100% only at 30 degrees ?

Get engine running / warmed up then switch maps.

That said having typed this you might need the extra fuelling if it cools the engine

Maybe somewhere in between ?

Nige

Might be worth a punt - Im glad you dont see an instant answer - perhaps this could be a true trial and error one?

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Might be worth a punt - Im glad you dont see an instant answer - perhaps this could be a true trial and error one?

Erm

No

Actaully I have had a though :P:lol:

ASE & WUE are exactlt that, after start and warm up, not sure that if the engine temp drops hugely it goes back to it, ans the engine is warmed up and running (a MS grown up will be needed to confirm this :lol:).

If thats the case then the issue will be EGO as the O2 goes cold, so switch it off :).

I think then doesn't matter what the MAT sensor may read, it will solely run off the VE Map ?

Nige

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There is an easy fix :P

Yes WUE is warmup enrichment, triggered by engine temp, you need it there for good starting from cold but since the thing's underwater the coolant (&sensor) goes cold even though the internals are happily around operating temperature. ECU thinks engine is cold and chucks in more fuel, which can then be tending towards flooding (with fuel, not water :P).

So instead of switching fuel tables, you switch the coolant temp sensor off. If you ground the sensor wire, it will hit the limp-home value of "the engine's probably warm enough":

THERMFACTOR:

; ADC Fahrenheit - Celcius - resistance in ohms

DB 210T; 0 - sensor failure, use limp home value.

Thermfactor.inc for RV8 CTS

You could be really swanky and stick a 330R resistor from the switch to ground, simulating a temperature of about 80C. If you want an adult to solder it up for you I can stick a switch in the post for you :P

How this works (AKA the science bit):

The ECU has an analogue-to-digital converter in it to convert the voltage from the sensor circuit into a number between 0 and 255.

As the sensor is a resistor, it will almost always have a resistance that is inside it's normal range (-94 to +260 degrees :o ).

So - it will never actually hit zero or top resistance unless you move to the moon, which means the sensor circuit will never send exactly 0v or 5v to the ECU.

The Thermfactor file tells the ECU a list of temperatures-vs-ADC counts (0 to 255) for your sensor.

But, since we can assume it's never going to really hit 0 or 255 (or if it does, it's gone way beyond happy-time anyway) we know that if it does, either the sensor has failed short circuit or the wire's shorted to ground (ADC=0) or has shorted to something live / is disconnected (the wire will "float up" to 5v with nothing on the end, giving ADC=255)

In either case, we know the reading of 0 or 255 will likely not be correct, so we use a "limp home" value of 77C which should be roughly OK to use under most conditions.

This means that to disable the sensor, grounding the wire (0v) will make the ECU use the limp-home value of 77C. Everything else will run as normal (there is no actual limp-home mode like some factory ECU's which limit power / speed etc.).

The lambda sensors, even if heated, will probably be struggling to stay anywhere near a useful temperature underwater as they are bolted to a huge heat-sink (your exhaust) immersed in cold water. Widebands will be doubly unhappy as they need to "breathe" outside air to work properly.

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Nige,

What have you done to my engine?....

From the top,

MUCH Smoother idle, tho still occasionally stalls when load applied, ie winch, PS pump Alternator

"I can feel it" tm better acceleration

No nasty popping sounds on the overrun

Feels a lot smoother all round

and the exhaust note is a wonderful burble rather than a shuddering heap.

Thanks

RR

ps Drove 15 miles for the hell of it on special tracks.

O well another fiver gone...

OT why doesn't my avatar appear?

I've uploaded a picture to my profile?

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There is an easy fix :P

Yes WUE is warmup enrichment, triggered by engine temp, you need it there for good starting from cold but since the thing's underwater the coolant (&sensor) goes cold even though the internals are happily around operating temperature. ECU thinks engine is cold and chucks in more fuel, which can then be tending towards flooding (with fuel, not water :P).

So instead of switching fuel tables, you switch the coolant temp sensor off. If you ground the sensor wire, it will hit the limp-home value of "the engine's probably warm enough":

Thermfactor.inc for RV8 CTS

You could be really swanky and stick a 330R resistor from the switch to ground, simulating a temperature of about 80C. If you want an adult to solder it up for you I can stick a switch in the post for you :P

How this works (AKA the science bit):

The ECU has an analogue-to-digital converter in it to convert the voltage from the sensor circuit into a number between 0 and 255.

As the sensor is a resistor, it will almost always have a resistance that is inside it's normal range (-94 to +260 degrees :o ).

So - it will never actually hit zero or top resistance unless you move to the moon, which means the sensor circuit will never send exactly 0v or 5v to the ECU.

The Thermfactor file tells the ECU a list of temperatures-vs-ADC counts (0 to 255) for your sensor.

But, since we can assume it's never going to really hit 0 or 255 (or if it does, it's gone way beyond happy-time anyway) we know that if it does, either the sensor has failed short circuit or the wire's shorted to ground (ADC=0) or has shorted to something live / is disconnected (the wire will "float up" to 5v with nothing on the end, giving ADC=255)

In either case, we know the reading of 0 or 255 will likely not be correct, so we use a "limp home" value of 77C which should be roughly OK to use under most conditions.

This means that to disable the sensor, grounding the wire (0v) will make the ECU use the limp-home value of 77C. Everything else will run as normal (there is no actual limp-home mode like some factory ECU's which limit power / speed etc.).

The lambda sensors, even if heated, will probably be struggling to stay anywhere near a useful temperature underwater as they are bolted to a huge heat-sink (your exhaust) immersed in cold water. Widebands will be doubly unhappy as they need to "breathe" outside air to work properly.

Smart Arse Good Idea

There is an easy fix :P

You could be really swanky and stick a 330R resistor from the switch to ground, simulating a temperature of about 80C. If you want an adult to solder it up for you I can stick a switch in the post for you :P

Yes please, suitable funding will come in addition to the funds for recently ordered squirting box!

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  • 2 weeks later...
Nige,

What have you done to my engine?....

From the top,

MUCH Smoother idle, tho still occasionally stalls when load applied, ie winch, PS pump Alternator

"I can feel it" tm better acceleration

No nasty popping sounds on the overrun

Feels a lot smoother all round

and the exhaust note is a wonderful burble rather than a shuddering heap.

Thanks

RR

ps Drove 15 miles for the hell of it on special tracks.

O well another fiver gone...

OT why doesn't my avatar appear?

I've uploaded a picture to my profile?

:)

Glad to help,

Seems your chuffed with the "HFH-Phone-Tune" diagnostic service then :lol: ?

Nige

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I guess this is probably to thread in which to talk about air density correction based upon the IAT. ;)

I am currently playing with this to find a solution to the age old problem of sensor heatsoak causing the IAT to rise significantly when stationary, moving slowly, or off road driving.................. once on the open road with some air flow the IAT soon settles down to a sensible number.

For those not familiar with the problem............... the IAT sensor under heatsoak conditions gives rise to IAT's of 30C - 40C . These temperatures are notified to the ECU which in turn correctly leans the mixture. Although the IAT sensor thinks it is reading correctly, it is actually reading the heat that is rising from the hot engine and just being slightly cooled by the incoming air. So ......... after a decent run and then being stationary for 10 minutes, upon a restart the end will struggle to idle correctly as its now running lean ............... the same applies to slow moving in off road situations or traffic chaos on a hot day. Heatsoak is a natural phenomena as all the hot air from a station engine will tend to rise out of the air intake.............. we just need to correct it for the time period that it taskes to clear the hot air and revert back to reading the true incoming air temp. A gander at the MS algorithm that calculates the fueling shows that the IAT has a significant input to the final answer..........

MS does have a facility to correct this ................ 'air density correction based upon IAT' B) (you could also base it upon CLT but that is OK)

Currently I am thinking that maybe something like +15% (VE) correction from idle to 2000 rpm when IAT is at 30C rising to maybe +30% when it gets to 40C.............. I will work on the required curve and report back...........

:)

Ian

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  • 4 weeks later...

Nige,

I should have thanked you ages ago, but didn't I'm sorry.

Just an aside, and reading your answer to another thread,

should I have higher values mimicking the vacuum advance in the mid range of my map?

Please bear in mind that I have 12 degrees of advance before I start!

post-6579-1213196199_thumb.png

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Nige,

I should have thanked you ages ago, but didn't I'm sorry.

Just an aside, and reading your answer to another thread,

should I have higher values mimicking the vacuum advance in the mid range of my map?

Please bear in mind that I have 12 degrees of advance before I start!

I assume that you have 12 degrees advance + the table .............why ? :unsure:

If that is the case then your map looks Ok ish ..................... but it would be better to set up the timing to give you TDC static and then use the table to its full advantage.

:)

Ian

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Cos I'm a numpty and didn't get the sensor in the right place!

I have bought a new bracket, but dont want to to take the pulley off again, yet.

Got a competition this weekend.

It's eating fuel (what v8 doesn't) :ph34r:

I was thinking about the vac advance bit, that the mid table value on the right, should be higher than the WOT value of advance.

This is on a 3.9 with lucarse ecu.

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OK

Table look OK ish

Real prob is your table is back-2-front for us with MAP :lol: Having got my brain around that couple of comments :

Your 4500 and 5000+ table colums are exactly the same, as such there it a column 100% wasted, so re jig and use it.

Your running at WOT 19+12=31 degrees, can't rememebr your engine, so look back in this thread for what the Most advance you can have at WOT per Engine CC is ??

that may give you your last column chnages :)

Your 600 column is all zeros (12) thats not too clever - and a tad high as well ??, and the other columns IMHO similarly have not much variances, have a look at the other MAP tables here on this thread for spark and see how the numbers move within the columns - this is prob why the huge Fuel consumption

I will have a closer look prob next week when back at work :lol:

Nige

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I am running MAP!

Maybe it's my understanding of it that's flawed here.

Basically the top right of the map is closed throttle high rpm

bottom right WOT high rpm.?

So maybe I did have extra values of advance in at small throttle openings and higher rpm?

oh, and 12 degrees of advance, cos I cant get any less..........

Bloomin 3d maps... :rolleyes:

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