Initial Mapping Queries

[young_un1]

Hi there,
           Been messing about with the VEMS in my car for a bit and am having some mixed results...

First; I found that TDC on cylinder one corresponded to about 3.5 degrees in "priming,cranking,afterstart - crank advance(deg)"
I then added 10 degrees to that and checked how the engine was running - better but still not great. Kept adjusting and am now at 16.5 deg but obviously this is only really 13 degrees advanced from what is actually tdc. My question is; is there a way to calibrate the vems so that the 3.5 degrees i inserted actually becomes 0 deg? I ask because surely this 3.5 degree anomaly is going to play havoc with the rest of the map that you gave me Rob? Do i just need to move the cam sensor on the front of the engine until the 3.5 degree difference is reduced to 0?

Secondly: my lambda tables are in/around 1 in the region i'm trying to plot just now but I keep getting wildly different readings from my lambda sensor - at first it was showing the minimum reading on the scale of 0.6, it then jumped up to the highest of 2.7 - surely the engine wouldn't even run at this level?! Having done some tests the condition of the spark plugs definitely shows that the engine is running rich. Does this sound like a lambda fault? I've attached some datalogs to see if there's anything awry...

http://www.box.net/shared/xhlyidg08s
http://www.box.net/shared/g0iqmboggw
http://www.box.net/shared/s511xb3kss
http://www.box.net/shared/prsug0xq8o

Finally; hopefully without sounding like a complete idiot, I am very aware that the car is running very "fat and fluffy" at the moment. I have only really played about with the warmup enrichment values - reducing the temps just above 0 degC by around 3% just to experiment and it seemed to be running a bit better but there's still some heavy misfiring. Should I be reducing my injector pulse width to lean out the mixture a bit across the board? I know that you're meant to play about with the target lambda values and spark tables but am just not really sure what stage I need to be at for that or what I'm really trying to achieve meantime... Sorry to be such a dunce but I'm just being cautious at the moment...

[rob@vems.co.uk]

Hi mate,

Firstly you need to set the TDC correctly.  Put the priming cranking and afterstart to 10 (pull the fuel pump fuse out), then adjust the crank angle sensor to give you 10deg when cranking.  That will be your timing locked on nicely.  If you can't get there by adjustment alone then you will need to adjust the TDC after trigger value in Primary trigger - but there shouldnt be any need to do this on the CA18.

Next up the fuel, this is where you'll be tuning the VE table, but first lets consider the lambda table.

The lambda table is the target for the engine, so you'll set idle and light throttle to 1.0 and start to increase the fuel amount (lower the lambda value) as RPM and load increases to around 0.85 at 100kpa.  Once you're under boost, you'll perhaps want to drop the value to around 0.82 to 0.8 as the boost rises.   Using the 3D graph allows you to blend the map to enable a nice smooth transition.#

The values in the lambda table effect the fuelling because they are factored in to the fuel calculation - the calculated Pulse Width is divided by the lambda value.

So if you had a req_fuel of 5ms and a VE of 100 in the map you'd have 4.9 to 5.1ms (depending on temp correction and what have you)
lambda value of 1.00 the PW will stay at 4.9 to 5.1ms
lambda value of 0.90 the PW will become 5.4 to 5.7ms
lambda value of 0.85 the PW will become 5.8 to 6ms

The result of this is a fairly flat fuel map once the engine is off idle.

So, what you need to do is get the engine upto temperature, and go onto the Tuning->VE table screen and start to adjust the fuel in the break points around the area where the yellow ball is dancing around.  You'll hear (and smell) the improvement in the mixture, your plugs will begin to clean up and you'll find that the whole engine becomes more responsive.

That lambda signal does not look very happy to me, most likely to be the sensor with all that rich mixture.  Tune the idle by ear and plug inspection and see if the reading improves.

There are some good tuning guides that Jorgen wrote a while ago:
http://www.vems.hu/wiki/index.php?page=TuningSession%2FClosedloopTuning
http://www.vems.hu/wiki/index.php?page=TuningSession%2FOpenloopTuning
And this one:
http://www.vems.hu/wiki/index.php?page=TuningSession%2FVEtuning

[young_un1]

That's fantastic Rob many thanks, just needed a little prod in the right direction...

Cheers again

[young_un1]

Not good news i'm afraid. After getting the engine running a lot better in low load conditions ie: wheels off ground. I moved onto higher load in an abandoned area. After running for a bit the car started idling badly and eventually cut out. After that it just wouldnt start again, despite cleaning the plugs etc. I have checked and all plugs are sparking. 1 and 4 seem to get wet after a bit of cranking, while 2 and 3 are relatively dry. Could this be an injector problem or could it be that the coil packs on 1 and 4 are on their way out, producing a weak spark and eventually getting too wet to spark at all, whereas the other two are ok and hence dry?! Either way, it doesnt even sound like its wanting to fire at all, even on 2 & 3. I am somewhat concerned that I seem to have two of the three elements of combustion. I will try pressure testing later today. My friend commented that there appeared to be small pops of either yellow flames or sparks from the exhaust - I'm hoping it was the former for obvious reasons. It still smelled like it was running rich as hell and I really havent adjusted the VE table that much, if at all in the higher load regions. Any ideas?WorryWorryWorryWorryWorryWorryWorryWorryWorryWorryWorryWorry......

[rob@vems.co.uk]

Check that things are working correctly electrically - if 2 and three are dry then are you getting any fuel delivery to those cylinders?
The trouble with the setup you have is that there are so many variables - the fuel system, the electrical system and mechanical aspects are all custom built by your own fair hand, so there are more potential issues.

If you're getting spark and compression then the problem does point at fuel, is the pressure regulator in correct working order?

Also make sure your logging things, they can tell you a lot when you're away from the car in a place more suitable for concentration.

Rob