Rolling Road Results today AMD Essex

[S2central.net]

Actually Andy makes a good point - wonder is it running too lean... Leaner makes more power until you run into knock problems or EGTs get too high for safety. Trying to think thru the logic here... I'd expect a VR6 MAF to have less dynamic range than the S2 one...

Lets say for sake of argument on the S2 that 3V means 20lbs/min of air and that 15lbs/min on the VR6 MAF produces 3V...

So when the engine is sucking in 20lbs/min then it gets more than 3V from the VR6 MAF and tells the ECU to work from a higher load point - as more air is being ingested -this could be OK as it could use fuel & timing values from 'higher' points on the map for that engine speed than normal...

This seems OK until I think what happens when the VR6 MAF maxes out at 5V at say (I dunno) 25lbs whilst the S2 one scales up to 30lbs... This means the ECU would not be able to measure air intake (and therefore load) above 25lbs/min and so accordingly there would be less fuel (and more advance) used for the selected load point.... Therefore indeed the engine could be running leaner than you'd like or have higher EGTs... Now it can't be that bad if the engine is booking 290bhp on a daily basis - but definitely get the AFR measure.... If its leaner than about 12:1 on WOT then you could be storing up problems for the future with overheated valves or heatstroked turbos....

Interesting though intitt ?

[avants2turbo]

That is mad now... Makes me wanna dig up an old idea about getting some MAFs characterised on a big flow bench...

Did you do anything else when you changed to this MAF ?

On a quick look - that torque line is about right... What boost levels are you seeing at the peak then down to redline ?

Nope, just swapped the maf, well i did take that tube thing outa the front of the airbox, im seeing 1.4bar peak and about .8 redline

Its definately just got the mtm remap, ive got the origional receipt, and kim collins at QST confirmed it as just that. Its got a standard k24 7000 turbo

Cant wait to find a rs2 em, can get my new k24 7200 on and new intercooler and 3" exhaust..

[S2central.net]

Seriously - get an AFR meter on it before you go any further...

It might be OK - the advantage might be more from the airbox mod... I know I definitely felt an improvement when I went to RS2 airbox without changing the MAF...

See if you can get a borrow of the upper airbox section and MAF from another S2 - easier than swapping MAF by itself.

For all we know the VR6 MAF has near identical voltage profile than the S2 one. But until you get AFR readings we'll never know !

[avants2turbo]

Seriously - get an AFR meter on it before you go any further...

It might be OK - the advantage might be more from the airbox mod... I know I definitely felt an improvement when I went to RS2 airbox without changing the MAF...

See if you can get a borrow of the upper airbox section and MAF from another S2 - easier than swapping MAF by itself.

For all we know the VR6 MAF has near identical voltage profile than the S2 one. But until you get AFR readings we'll never know !

Where do i wire in a afr meter? Is it something i can easily do myself, also any reccomendations which afr meter i should buy?

[S2central.net]

Its driven by a wideband version of your lambda probe... The good AFR meter kits include a probe that also emulates the normal response of Bosch lambda probe so that the ECU stays happy...

Essentially the lambda probe (once warm) generates a voltage in around 1V depending on how lean/rich the mixture is. A 'wideband' probe is one that responds more quickly than a typical factory item.

Have a look for Zeitronix and other AFR meter vendors on Google - there's a good few - some gauges with dual purpose as well, say Boost+FPR or EGT+FPR... You need another probe for EGT of course, but AFR is enough info here.

An AFR of 14.7:1 is the ideal mixture when cruising - the ECU adapts fuelling to hit this as much as possible, but when you go full throttle you want a richer burn for more power, increased knock resilience and some other secondary effects.

An AFR below 14.7 is rich whilst higher than 14.7 is lean. We can call 14.7 as the point when 'lambda' = 1 by normalisation.

Homefries run to about 12:1 at WOT - thats a good reference point - could probably go a tad leaner but not with all fuel types and some headroom is needed for things like aging of fuel components... Remember at WOT the ECU doesn't make any adjustments for mixture - it runs right off whats in the fuel maps.

[Rusty]

To get 15bhp off a MAF is a large gain! I think a cautionary attitude is good, the rolling road should have shoved a probe up the exhaust and checked the AFR or lambda. As previously discussed, the logical explanation for this is a change in output voltage compared to the S2 MAF. Did your boost increase when you fitted the MAF? Boost figures match up with the power and torque and I too have a modified airbox and believe it makes a good difference. What other mods do you have? Exhaust? Samcos?

I know URS4boy has done some work on the S2 MAF, Perhaps he's looked at others too.

[EspenW]

How much power and torque did you pull at the wheels?
If they had for example standard 1.8T's get factory claimed numbers, the numbers were too low, as these engines usually produce more than claimed flywheel power at the wheels/hubs. This goes for pretty much all forced induction VAG engines, while the naturally aspirated ones often seem overrated..

[avants2turbo]

Right, im a little confused, the AFR meter works off a wideband Lambda sensor right?

do I have to replace my origional Lambda sensor thats on the downpipe with the one that comes with the kit, and if so where what happens with the wiring thats currently plugged into it? or do the kits come with a wiring harness to incorporate the origional connector and the connector off to the meter?

or

do i need to leave the origional lambda sensor where it is, and fit an additional sensor to the exhaust somewhere else?

sorry for my ignorance...

[Jamo]

You need to fit it in addition to the current sensor unless the sensor can do a dual narrow and wideband output

[avants2turbo]

does this mean i have to have a hole drilled in the system and a mounting boss welded in? or is there a blank somewhere for another lambda in the system?

if i have to have another boss fitted wheres best to have it?

[Rusty]

Running the WB02 in addition would be a good plan, yes, have another boxx welded into the DP near to teh other one but not too close otherwise you'll not get a spanner in there to tighten up the WB02!

[urquattro-island]

does this mean i have to have a hole drilled in the system and a mounting boss welded in? or is there a blank somewhere for another lambda in the system?

if i have to have another boss fitted wheres best to have it?

you can get a holder for the wideband sensor so, you can just have it in the tailpipe. You can find it a 034M i think or if its bosh. Dont remember, works fine.
Unless you want to drill a whole in your system..

[EspenW]

you can get a holder for the wideband sensor so, you can just have it in the tailpipe. You can find it a 034M i think or if its bosh. Dont remember, works fine.
Unless you want to drill a whole in your system..

Tailpipe mount works if there is no CAT. However, having the wideband permanently installed is a very good idea.
I mounted the bung for the wideband at the CAT inlet. Works great.

[Jamo]

If you've got an OEM dp there should be a thread already tapped right next to the turbo output flange IIRC

If your getting an after market DP then have it after the oem position or just before the cat

[urquattro-island]

i

have the original and the wideband fitted, was better i think, then you can always keep an eye on the afr...