Mapping the fuel / Initial tunning

[Agriv8]

As much as I would like a weekend in the garrage I am going to have to spend the weekend at the outlaws 150 miles away.

I am at the stage where I can get the car to fire up under vems control - but not tick over ( spark is still done by Dizzie at the moment ). Megasqurt/ Term emulator are talking happily to the vems unit

I am after some reading to take with me on how to start the 'Mapping Process' i.e. a step by step gide ( a bit like bobs wireing setup document). I understand that in its simplest for it a case of adding fuel to air in the right quantaties. I would like to get a base map set up so it will run.

how do you go about getting this base map what to do first what to check.

Sugestions and pointer Welcolm

Regards

Agriv8

[dnb]

What size engine? I have some 5 litre RV8 stuff you can use as a guide.

Do you have wideband lambda installed yet?  Without it you have little chance of achieving what you want in a reasonable time frame.  With it, you can get a good attempt at a complete fuel map in a couple of hours.

What I did was calibrate the wideband and turn on VE learning from Megatune.  (The learning parameters are open to some discussion, but I will look out mine for you as  I found these worked with a RV8 quite well) 

I then held the engine in some load cells around idle for a few seconds until it settled down and the lambda adjustment got to within target.  (ie the base map had been suitably modified)   

Once the low load and low(ish) RPM areas were OK, I turned off the learning in these areas (by changing where in the map the lambda control was active) and went for a short drive on my "test track" to set the mid load and mid RPM areas, working up slowly to the higher RPM & load areas.  Again, the idea is to hold the car at a constant RPM and load for a few seconds (5 to 10 should do) until the lambda correction settles to the target.  Best time of day is obviously when the roads are empty. 

You don't need to do every load cell in this way, but you do need to log the data so you know which load cells HAVE been altered by the VE tune.  You can then interpolate the rest of the map by hand or with excel, Matlab etc... 

Note that lambda adjustment level on the LCD is in 1/256 steps, not a percentage!

Hope this is of some use.

Dave

[Agriv8]

Thanks Dave,

only a tidy 4.2 installed

No I know I have to bottom the WBO2 -  its a To Do before mapping commences. unit is apart as I need to fit a cap ( c69 )  and ressistor ( R142 )  so I can run trigger off correct pin 

Ahh didnt know that there was a Learning mode. So thats some reading up I need to do - So you give the Unit some parameters ( targets ) so it can build its own tables ( or parts of its own tables ) you can then smoth the table out / fill the gaps .

Yes if you could send me the VE learn Parameters /  details that would be Excelent 

So Reading so far

Trigger wheel checking ( not done yet Ooops )
VE learn

Anything else ?

regards

Agriv8

 

[dnb]

4.2 is probably close enough for my maps to work, although it'll be a little rich!  I presume you have standard injectors at the moment?   

The learning mode uses the lambda target map in a similar way to how closed loop lambda control uses it.  The big difference is that learning mode adjusts the base map based on filtering the corrections the ECU is applying in closed loop mode.  The parameters control this how this filtering (basically averaging) process works. 

You do need to have entered some sensible data in the VE map (you can treat this basically as the fuel map) to start with, but this can be done with an automated process (I forget where the link to this is).  You provide it with peak torque, peak power and the RPM they occur at plus the engine capacity and it'll generate you a table.  This may be built in to Megatune now - I haven't done this for a year!

Checks I would look to do:

Trigger
WBO2 calibration
Temperature sensor calibration (IAT & CLT)
MAP calibration - this is almost as important as trigger!  (I used an accurate boost gauge and a foot pump!)
Double check of earth connections (believe me, yu can't be too careful with these)
Check idle stepper operation (if you use it)  This can be very frustrating when it does silly things without you knowing...

[rob@vems.co.uk]

If the car barks to life after cranking, then you have to start looking at the priming cranking and afterstart settings.
(MegaTune: Settings->Priming, cranking & Afterstart)

Your prime pulse squirts a bit of fuel down the ports when the engine is switched on - the same as when you press the pedal on a carb'ed engine to squirt some fuel from the accelerator pump.  This helps initially but I find many people prefer to turn it off once the crank and afterstart settings are all sorted.

Cranking, this is the amount of fuel spat into the engine when on the starter motor, check how it compares to your calculated Req_fuel setting. But if your engine is coming to life then its probably pretty much there.

Afterstart enrichment is well discussed on this thread:
http://www.vems.co.uk/forum/index.php?topic=36.0

Essentially VEMS richens the mixture derived from the VE map for the number of engine cycles specified in the Afterstart duration, number of engine cycles box.

So how does all this help?

Well first off start up the engine with MegaTune showing Tuning->VE Table and , watch the pulse width gauge at the bottom left section of the screen, the pulse width will start high as the engine cranks then then drop down to the point that the engine stalls, watch the 'flying blob' as it heads off the table.  Go to where the 'flying blob' was sitting and increase the VE amount there, go to the parts of the table where the flying blob passed as the engine was stalling, and increase the fuel by about 10-15%, this will help keep the engine running so that you can fine tune the idle - as the speed drops the engine will get a big slug of fuel which will start it up again.
Once you've got the thing idling you're going to need to have a working wideband to move any further forward.

[Agriv8]

4.2 is probably close enough for my maps to work, although it'll be a little rich!  I presume you have standard injectors at the moment?   

       Its worth a shot nothing to loose - yes standard injector on batch fire ( odds and Evens )

The learning mode uses the lambda target map in a similar way to how closed loop lambda control uses it.  The big difference is that learning mode adjusts the base map based on filtering the corrections the ECU is applying in closed loop mode.  The parameters control this how this filtering (basically averaging) process works. 

You do need to have entered some sensible data in the VE map (you can treat this basically as the fuel map) to start with, but this can be done with an automated process (I forget where the link to this is).  You provide it with peak torque, peak power and the RPM they occur at plus the engine capacity and it'll generate you a table.  This may be built in to Megatune now - I haven't done this for a year!

Checks I would look to do:

Trigger
WBO2 calibration
Temperature sensor calibration (IAT & CLT)
      Done  ( Confused my tropical fish and the missus was not happy me dunking stuff in the kettle / oven )
MAP calibration - this is almost as important as trigger!  (I used an accurate boost gauge and a foot pump!)
      More reading to be done on that

Double check of earth connections (believe me, yu can't be too careful with these)
      Understood
Check idle stepper operation (if you use it)  This can be very frustrating when it does silly things without you knowing...
      Left off or now Can fit later if required

Many thanks

[Agriv8]

Right getting somewhere here comes the the BUT, ( there is always a but ).

i am getting the MAP down to 30 - 40 at tickover 800 to 1200 RPM so I assume that I need to calibrate the MAT any instructions anywhere. The butterfly is set quite wide.

I car get the ingine to tickover roughly 800 to 1200 but not long enough for the lamba to come in.

So where do I go next

PS still running very rich ( making my eye sting !!! ) even though I have dropped the injections opening time down considerably

Many thanks

Agriv8

[dnb]

What's your reqfuel set to?

What is in your VE map?

MAP of 30 to 40kPa is OK.  From memory mine was around this value.  You can ignore MAT calibration (but not MAP calibration!) for the moment as it only performs a correction to the fuelling that is going to be a lot smaller than the "error" you currently have.

If you have a 4.2l engine & standard injectors then reqfuel should be around 16 and the VE table at idle around 30 to 40%.  Don't worry about the batch fire, as VEMS will sort this out for you.

[Agriv8]

Thanks yet again ,

Will give that a go tonight.

Can reqfuel be set in megatune or is it Term entry only if so which one ?

Will lower the VE table .

Agriv8

[dnb]

Reqfuel can be set in megatune.  It's the first item in "basic settings"

[rob@vems.co.uk]

When I calibrate the MAP value I ensure that the values in Settings->Basic Settings are set as follows:
MAP Sensor range (kPa) to the value of your MAP sensor, which IIRC in your case is: 250

The next bit to set is the MAP Sensor offset (kPa), I get this value by finding the local air pressure and adjusting from zero so that the MAP gauge reads the current air pressure. So yesterday the air pressure at APT was 997mb, adjusting the offset gave me a reading of 99.7 flickering occasionally to 99.8kPa. I usually use the BBC's weather site which gives the air pressure for the local weather station in my area.

[Agriv8]

Wey-Hey.

Well thats got it a damn sight closser fires up and ticks over and revs up clear as a bell ( not under load / driven yet )

Still quite rich but not fully up to temp yet so warmup enrichment is probably comming into play.

Got a log can someone take a look at it bit I have no where to post it any pointers where.

but  here is a screen print






So what next ? got my wiring to tidy up Will post up my wiring diagrame but its on my works PC might see if I can VPN in and extract it.

Regards

Agriv8