Audi RS2 Avant
Engine:
2.2l
Mahle pistons
scat rods
GT3071R turbo (0.63AR)
OEM inlet/exhaust manifold
custom intercooler/downpipe
water-meth injection
70mm catback with x2 200cpi BN pipes catalysts
Stock cyl head with stock ADU cams
Spec 3+ clutch kit for dual mass flywheel
running VEMS with megatune 1.1.27 for 9 months now!!!
Results with Perfomance box: around 410hp with 1.85bar overb. and 1.7-1.8bar steady to redline on 4th gear pulls.
Max torgue reached: 600Nm, but keep it around 580Nm now.
Next year:
Holset super HX40 with 0.70AR
reverse inlet manifold
SQ exhaust manifold
New downpipe
Issues:
Idle control finally solved but always small modifications for fine tuning. I use diode for ISV valve and a combination of ignition based idle and IAC intervention to keep idle steady and allow minimal play when fan kicks in or A/C is working. So far im very pleased with the results
Version 1.1.27 is very stable but would like to switch to 1.1.62 with vemstune.I managed to connect the laptop to ECU on 1.1.27 with vemstune. I will wait for the 1.1.63 version which has the boost control bug fixed, as i use vemstune to control boost with an industrial solenoid valve. Very accurate boost control!!!
15/11/2009
Removing the MAF from the airfilter caused some overboost cut outs for some reason and i had to adjust the boost control figures. Noticed that the offset feature will not accept value 15 on 1.1.27. It will only go from 16 to 14, although when i did save and burn to ECU the value 15, i did notice a change in the highest boost reached.
13/12/2009
After more tests, i had to reduce the boost offset to 12 and redo the boost control vs rpm in order to avoid fuel cuts as it was spiking. But everything seems to be working fine now. I do get a bit of drop in boost on higher revs, but i dont mind. it is minimal,and maybe required as well.
The idle has been altered a bit,but here is a video of how it works now. I am really pleased,and the only thing which has been posted before about A/C control and idle is the one thing that can possibly make it even better.
http://www.youtube.com/watch?v=JR13Wx9h2-0
Marcel has my settings and can work with them or improve them,but the way they are now, it is working quite well.
Car is making about 420hp and 620Nm of torgue.
08/2010
car now has:
SQ exhaust manifold
New downpipe
GT3076R turbo, 0.82AR
reverse Wagner inlet manifold
220psi water injection pump
7A flywheel and southbend clutch kit
Car now produces around 500hp
Im still using 1.1.27version of megatune as Vemstune still gets upgraded every other week and there isnt a version yet that can utilise boost offset feature. Im planning to upgrade to a later version of vemstune as soon as i feel that it is stable and working nicely.
So far im pleased with the results from the car and i drive it everyday!
TODO: cleanup this and add vemslog
Pasting some info from mail from Vasilis:
- I have used now the lower DC as 29% so that it does not allow the IAC to open more as IATs get higher, and that seems to work also.
- I will put a link to a log i have had recently, im not sure that it will show excactly the behaviour though
- it is improved now that i have the TB slightly modified. it is mostly the fact that the idle tends to become higher when IAT gets higher, but i think that has to do with the integral limit decrease.
IDLE: (1.1.81 firmware now).
i used the following method to tune idle speed:
Ignition based idle: DISABLED
integral limits: ZERO
cold start the engine and set idle ref DC
I use for the bosch 2pin IAC valve: 35hz and limits of 0 and 100% DC
I managed to make the ref DC table close to my cold and warm idle speeds using the IAC control alone.
Problem: Once IAT starts to go higher than 25-30C the idle speed goes UP!!!
I have disabled the refpos for MAT slope feature completelly and it still does it!!
with ignition idle settings enabled i end up having something like: 1050-1080rpm idle speed on CLT:83-85.
If IAT is anything between 0-18C --> idle rpm is 940-970 (which is my target rpm)
On the bosch valve and with the above settings, any DC below 28 on the refDC table, makes the idle speed HIGHER!.
So setting the integral limit more than 20 takes the refDC below 28, and the idle speed goes higher!
my refdc table has the number 29 for refDC from CLT of 70 to 90C.
- a vemslog before i did the change to the TB.
In the log in Idle mode the minimum was 839 RPM, can you excactly show your problem?
- Could you post a log file with high and low MAT, so we can investigate why idle speed goes up
Do you use ego-correction? I`ve seen simular problems with ego correction off, and I would have to modify the MAT/TPS table at 0% trottle. That was related to an MAT-sensor heatsoaking issue, causing lambda to go lean and rich after different tempratures. -reidar
--
thanks for the answer, i do use EGO correction and have some heat soak issues for which i used a phenolic spacer which minimised the problem. However according to some tuners, if the IAT goes higher, the idle usually drops, it doesnt go higher, which is why mine does the opposite for some reason.
I have now modified the TB a bit and i get a bit better reaction, so im happy with it.
Tuning cruising lamda and ignition:
may i ask what is the optimal that tuners have used for the areas:
2000-4500rpm
50-120kpa
compression ratio: 9:1 and fuel: 97 octane
what lamda and what timing?
I am struggling to get good fuel economy on my car. I know i should have gone to a dyno and did the proper thing, but id like to know what other people use for the time being.
i can tell you why idle speed goes up when MAT goes up.
integral degrease limit tries to keep idle speed low when the MAT goes up(as idle goes up with it if IAC is off completelly, i dont know why), sometimes its only the IAT sensor heatsoaking probably.
if integral degrease limit takes the IAC DC below 30, then the audi IAC goes into its safe mode which from factory means that it starts to open again instead of keeping shut. For audi IAC, 30% DC is the completelly closed position. So as integral is taking the DC to lower levels (for example 25% or 20%, the idle speed goes high.
Try it in an audi with this mechanic IAC valve and you will see that if you use DC of 20 or less, the idle goes higher. WHich is why i set the lower DC limit to 29 so as the idle to try and stay as stable as possible.
22/9/2011
The engine is rebuilt with new pistons (oem mahle 81.51), ported head with larger valves, higher compression than 9:1(probably closer to 9,3:1), southbend clutch kit full feramic.
I replaced the injectors (siemens deka) with EV14 650cc.
I have the simplified dead time values from the shop:
8volt 2.55ms = 2550us
10volt 1.70ms = 1700us
12volt 1.20ms = 1200us
14volt 0.92ms = 920us
16volt 0.75ms = 750us
Apparently when i use these values i get another validation error from VEMS, although they are the correct spec from the shop they tested them.
Vems help says that i may get very low values on the VE table around idle. Other than that, is there any other reason i would worry about this new validation error, or should i ignore it?
thanks