S4 MAF reading?

[OllyS4]

I hope to get a remap in the next few months so would like to do my own health check before hand.
I've got two new fordge DV's the car has been seviced, i've run VAG-COM and there are no engine codes.
So i just want to check my maf, it is only a year old but just want to be sure.

What should the reading be on a standard S4?
Also in what gear and at what RPM should i be checking it?
Also what block number in vag-com should i be looking at?

 

[Matt82]

hi mate

from what ive read on here a stock s4 should show about 220g/s. the search doesnt work at the mo, but this link confirms me
http://s4wiki.com/wiki/Mass_air_flow

gear/mph does not dictate the airflow through the maf, rpm does

you want to use the whole rev range. you could use 2nd, that would take you to 65mph or whatever but could be difficult for your passenger to read as the figures will flash up fast.

you could use 3rd but then youre looking at 90mph or whatever, so you decide the risk you want

with vagcom also check youre getting plausible figures on the measuring blocks (ie coolant temp or throttle position)

as for health check. check wiring, hose connections (dead f hose is an easy one to spot, itll blow oil everywhere)

then off you go

do you own gtech by any chance?

 

[Blue_Thunder]

Block 003 will show Throttle Angle and MAF reading.

Block 115 show's Requested/Actual boost which can highlight any problems maintaining boost.

Block 032 can be checked to see what the long term fuel trims are. If these are more than =/- 5% out, this could indicate a problem.

Also worth calculating your FATS time (time taken to go from 4200-6500rpms in 3rd gear) by using the results from Block 003. This can be compared to other stock S4 figures to see how yours is performing.

 

[Blue_Thunder]

Also see you're on the lookout for some S4 side skirts. There's a bloke over on AudiSRS selling a pair for £80 delivered.

 

[OllyS4]

Thanks guys thats all good stuff.
I'll go have a look on audi SRS
No i don't own gteck, why do you ask?

 

[OllyS4]

I did some logs today, i got 220.78g/s @ 6160rpm to 6560rpm so that looks good, i have also loged blocks 3, 32 and 115 but dont know how to post them up on here as there in excel form, any ideas?

 

[aragorn]

You could take a screenshot of the excel output and post the resulting image?

Press the "Print Screen" key on your keyboard, then open up your favourite image editing package (MS Paint will do though), and select paste (or ctrl-v), crop it to size,

Then save as a jpeg and upload/post the image as normal

 

[OllyS4]

hope thisworks

 

[aragorn]

It works, and oddly your car does the same weirdness as craigs does....

Were you flat out from 60 to 70secs?

Craigs does this weirdness where you floor it, and it initially goes to full throttle, ie 100%, then after it comes on boost it drops back to around 50% and stays there, which is what your car seems to have done too on the second run, first run you get 100% right to the redline though.

 

[OllyS4]

yeah i think so.
So what are FATS and do mine work out ok?

 

[aragorn]

You need a third gear pull from around 3.5k to the red line, then use this:

http://ctny.audiworld.com/mark/s4/ecux/fats/

 

[aragorn]

Also If your wanting to do fats time, then only log channel 003 as it improves the update speed.

 

[OllyS4]

4320 at 0.82
6840 at 9.29
That was in another run in 3rd

I'll have to do full 3rd gear run then

 

[OllyS4]

Ok i've worked out my FAT time and the answer is 7.60 seconds
Is this go, ok or bad for a standard S4?

 

[Matt82]

No i don't own gteck, why do you ask?

its a cracking little gizmo, effectively timing gear for your car, it does its calculations based on the g forces it records. can show you acceleration times, but also visual representations of acceleration, torque plots etc vs time and revs

 

[Blue_Thunder]

Your FATS times seem very slow, at least 1 second off the mark. See MRC's database for a comparison - http://www.mrctuning.com/fatsview.php?carselect=B5%20S4

Aragorn has posted up a FATS calculator for people using ECUX (popular with the yanks), not Vagcom. Not sure if it calculates your FATS differently. The MRC site has a calculator on there for Vagcom readings.

 

[Blue_Thunder]

Also looking at your logs, it does appear to be overboosting ever so slightly, although i'm not sure if that's outside of the accepted tolerances for the ECU.

Definately something not right with the throttle angle being limited. Are there no fault codes brought up in Vagcom?

Out of interest, what fuel are you using?

 

[aragorn]

As i say, Craigs ECU does exactly the same throttle cut, and the only thing we got when trying to diagnose it was "take it to MRC", along with some vague handwaving that it might be a boost leak. No fault codes stored and everything else looks normal.

Unfortunately Craigs ECU is older, and doesnt have boost logging available. The fact that the MRC guy entered the thread and pointed out the fact that it was an old ECU and didnt support boost logging, but offered no help or assistance for the actual problem really ****** me off tbh. I realise they're a business, but saying "We've seen that before and its almost certainly a boost leak" for example would ensure that when the time comes for a remap, they'll most certainly be getting the business. Now i wouldnt want to give them a penny.

I think a slight overshoot is normal with an N75 valve, as the valve cant act instantly. And the throttle cut doesnt seem to go away once the boost is back inline.

Also the calculator i posted does both ECUX and VCDS....

 

[Blue_Thunder]

I don't think Olly has a boost leak, otherwise I would expect to see the specified/actual boost values being a lot different and a higher MAF reading.

 

[aragorn]

Yep. Craigs MAF reading is low too, cant remember exactly but it was around 205 rather than the usual 210-215

These arent full pulls, we were struggling to find enough road, but it shows the same thing:

Fields are Time, RPM, MAF, Throttle Angle.