VersaTune User Forum

Looking for some help with my 2005 MPS6 that I recently purchased. It has a FMIC, BOV, HPFP, cat-back exhaust and supposedly a high-flow turbo (but since I found oil in the intercooler pipes I think the turbo may be on the way out?). That car has a 3" MAF housing but then looks like it flows into the stock intake hose which narrows down to 2.5". The car used to have a custom cobb tune with separate EBC but the PO removed the tune and EBC.

I have installed Versatuner and am currently running the Octane tune. When I tried the OTS tune for the 3” MAF housing it did not run well at all, which I am assuming is because the whole intake pipe is not 3". So the car runs much better on the standard Octane tune.

Was hoping someone could give some advice / insights on the logs I have attached:

1. Octane tune - General low speed driving and one 3rd gear pull.
2. Octane tune - Re-ran the 3rd gear pull to include Accelerator Position for Virtual Dyno.
3. Octane 3 inch / 76mm MAF Housing tune - General low speed driving. Didn’t do the 3rd gear pull as AFRs didn’t look right.

Do the attached logs indicate any problems / areas of concern that I should be looking into? Am I correct that the Octane tune is better for my vehicle or did I miss a step before applying the 3" MAF tune?

The previous owner was getting 203kW and 430Nm but I’m not sure what boost they were running. I am currently getting 158kW and 340Nm at 17psi but want to make sure the car is running well before chasing power. (In case it matters, I currently have the Versatuner Lite license)

There's indeed a fueling issue but at this point I'm not entirely sure if it's all related to the MAF calibration or not.
Not all 3" intakes are the same, but they are within 5 - or say 10%, while at least in closed loop the deviations sometime are much higher than that as if your intake is a lot smaller. All that matters is the MAF housing diameter, the size of the tubing after that is not important. In open loop however the deviations are not that big, ECU manages to correct them somehow.
P.S.: for future logs please change the fuel rail pressure unit from mPa to PSI, this will give a better resolution.

Ok thanks, I understand your comment about the 3" MAF.
So really that's the tune I should be using, regardless what size the rest of the intake pipe is downstream.
I'll change the fuel rail pressure unit and record another run tomorrow using the 3" MAF tune.

What is the manufacturer of the MAF housing you're currently using on your car, btw? Can you post a picture?
The thing is that the AFRs and fuel trims were on the rich side with whatever tune you used. If the tune you used did NOT have the MAF calibration for a 3" intake then most probably your car will not stay on with a 3"MAF cal tune.

Can you please share your current MAF calibration? Or is it the stock MAF calibration?

The MAF housing appears to be custom made. I have attached a few photos. Total width is approx. 2+7/8".

I am using stock calibration but the OTS tune for the 3" MAF housing says that it "includes MAF calibration for 3 inch / 76mm MAF Housing".

OTS tune name = "Base 93US/98EU Octane - 3 inch / 76mm MAF Housing"

93US/98EU + Octane tune for stock or near stock vehicles. Stock DP is required. Provides moderately increased boost, revised fuel and spark, and throttle is opened over an extended range. Includes MAF calibration for 3 inch / 76mm MAF Housing

I recorded a new run using the "Octane 3 inch MAF" OTS tune from cold start. (see attached logs)
3rd gear pull was performed at 647 secs.
Results were underwhelming, as expected. (139kW and 287Nm but it looks like this tune only runs 12psi which tapers down to 10psi so not a fair comparison to Octane tune which held 17psi)

The boost is going to be lower because there is less air entering the engine. The tune is load based, and the load is directly proportional with the amount of air the ECU "thinks" enters the engine. So when the ECU targets AFR of 11 and the actual afr is deep into the 9's the load calculation versus the real load is going to be quite different, and this reflects into the boost as well.

However in the previous logs the AFRs were pretty far off as well, despite the fact that the MAF calibration was less optimistic and probably a lot closer to the calibration that should be into your tune.
The factory MAF housing is 2.65" and that thing you have on your car seems to beat best 3" outside diameter, so the inside diameter is smaller and probably just a bit larger than stock (probably that's a 70mm/2.75" inside diameter pipe). So you're definitely better off with a factory MAF cal at this point.

Ok thanks, so I'll stick to the standard MAF housing tunes then. Appreciate your advice.

Maybe I'll have to try the "Octane High Load" tune now...

Is it just me or is the 158kW I got on Octane tune lower than what I'd expect from a stock MPS6?

A stock 6MPS with the factory tune should put out about 220-230bhp which is 160-170kW. This is basically about 250-255bhp crank. A stock 6MPS with a proper tune can go a bit more depending on the mods list.
However your car is clearly not running properly, so any kind of comparison with a stock cat or otherwise is unfair.