VEMS for my (R)S2 with GT3071

[mastermind]

Hi Guys

I am about to order my VEMS. I would like to tune for closed loop at WOT without MAF...Can this be done with Wideband Lambda, EGT, IAT and Knock of course loop back to the VEMS ECU?

Can you give me advice on what to order from VEMS and if there is anything else I should change to ensure I can remove the MAF and narrowband lambda(btw is this a good idea)

Here is what I have in my cart.
1 x VEMS motronic55 with Wideband LSU4
1 x Bosch knock sensor
1 x MAT sensor
1 x red LCD cased
1 x EGT sensor (K-type)

Rgds

[A80Avant]

Hi,

you dont need a knock sensor, as the s2 has them already and VEMS utilises them instead.

it is not advisable to tune for closed loop even with VEMS and wideband,as the wideband is not as fast to control the mixture. Most tuners and users leave that on boost area to work only with fuel map and it works much better. You can tune the cruise with wideband and IAT without problems and that will give you a good map. MAF is not required with VEMS.

are you planning to tune the car on your own?

I would recommend to buy the unit from one of the providers as it will come with a base map to start with and you can order special features on the unit. Im perfectly happy with Marc (EFIEXPRESS) and recently ordered a second unit for a friend.Great guy and lots of info and help after sales. There are others in the forum as well.

I have also posted my config on firmware 1.1.27 on a similar setup with yours, so it might help you

[mastermind]

Hi,

you dont need a knock sensor, as the s2 has them already and VEMS utilises them instead.

are you planning to tune the car on your own?

I would recommend to buy the unit from one of the providers as it will come with a base map to start with and you can order special features on the unit. Im perfectly happy with Marc (EFIEXPRESS) and recently ordered a second unit for a friend.Great guy and lots of info and help after sales. There are others in the forum as well.

Thnx for the advice.
I ordered the knock sensor to replace my 15 year old one. Is it a straight swap or should I rather order this from 034 or Audi Stealer?

I do have a choice of tuners in SA. But if VEMS is not fast enough for closed loop at WOT then will use MAP. Couple of guys I know are using closed loop but they are using Motec M800.

I will look into ordering from others as well.

[A80Avant]

i think most tuners tune with fuel map only on boost. Not worth going closed loop, as if the wideband malfunctions it can damage the engine beyond repair

[Billman]

Thnx for the advice.
I ordered the knock sensor to replace my 15 year old one. Is it a straight swap or should I rather order this from 034 or Audi Stealer?

I do have a choice of tuners in SA. But if VEMS is not fast enough for closed loop at WOT then will use MAP. Couple of guys I know are using closed loop but they are using Motec M800.

I will look into ordering from others as well.

Closed loop works very nice and you can leave it running all the time like this to compensate for altitude and barometric, also for minor alternations on the engine that happen with time as fuel filter clogging up, fuel pump wear etc. You should only see that your VE map rus good w/o ego correction and then enable it as an extra with a narrow margin so if something happens to the lambda nothing will harm the engine.

[Jamo]

Closed loop works very nice and you can leave it running all the time like this to compensate for altitude and barometric, also for minor alternations on the engine that happen with time as fuel filter clogging up, fuel pump wear etc. You should only see that your VE map rus good w/o ego correction and then enable it as an extra with a narrow margin so if something happens to the lambda nothing will harm the engine.

Thats not right you shouldn't run closed loop at WOT or high map, not even the stock ECU does it, as ego correction is not fast enough to in relation to rpm

[Billman]

The stock ecu can't do this because of the narrow band lambda. If you set it with close margins then I think it is a nice feature.

[Jamo]

After reading the tuning methodologies and also more importantly the advice of the vems tuners on the vemsforum and also vems hq, they same only go to 4000 rpm, and around 80-100 map for ego correction.

Ego is for cruise conditions, if your using it at high map values then it means your VE table is badly formed

[Billman]

That doesn't answer the question. Let's say you tune your VE to the poi t that the ego correction is at 98% and you set also your correction to close margins how can it negatively affect the run characteristics and endanger your engine?

The positives are already pointed out.

Note I am not talking about bad VE and have the ego correct, I am talking about a good table having the ego correction for perfection.

[A80Avant]

for some reason, when i had my VE originally done and checked out, once i had EGO on all the time, the car was leaning out on high rpm and EGTs were going higher. Once i started using VE only, it didnt do that at all. It was fine. Now, whether this was something to do with the software of megatune or something else, i dont know. But personally i never had an issue using VE table alone above 120kpa(which is what i do now) and i was noticing that lamda was kept much more stable just with the VE table

[Billman]

maybe the VE table was not in par with the lambda table. If you dont tune VE on the dyno so you can stay longer on a specific load site then the actual reading can fool you because other factors may be present like acc enrichment from time to time because of small throttle imbalances ect so that you run overall a bit richer and because of that seeing lower EGT.
With my old engine i dint have any issues with this and i had the car running almost 3 years with VEMS.

However lets return to topic as it seems that we dont have the same opinion on this one :-)

[prj]

To chime in - newer motronics, that have wideband, use it all the time afaik.
I might be wrong though, but what Billman says makes sense.

[mastermind]

Ok thnx for the info guys.
I think we need to start a thread on closed loop vs open loop tuning using VEMS.

I have ordered:
1 x EGT sensor (K-type)
1 x red LCD cased
1 x MAT sensor
1 x VEMS motronic55
1 x Display-only round


Once the unit arrives I will need your adcvice on setting up. Looking fwd to it now.

If there is anything you feel I should change/upgrade or replace like the knock sensors, crank position sensor, etc. I would appreciate the input.

I dont want to tune using the old sensors which may have taken some wear over the years.


Rgds

[Billman]

Note that VEMS dont read the knock sensors good (at least i dint managed to use them with VEMS) in order to detect knock so i use them to pick up the sound of them and listen manually to the engine.

[mastermind]

Note that VEMS dont read the knock sensors good (at least i dint managed to use them with VEMS) in order to detect knock so i use them to pick up the sound of them and listen manually to the engine.

ok..now that is worrying... I'm going to do alot of logging to check.