Help with Vag Com data + Graphs

S3 Nattie

S3 Nattie

Quattro ist für sissies
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Ok, well been having a play with Vag Com recently as I feel my car is not performing how it should

Its seems pretty heavy on fuel and performance is a quite off. Boost gauge used to spike to about 14 psi then level of and hold about 11.5 psi (standard). Recently my gauge will not spike and only boosts to about 10 - 9 psi.

Done a bit of logging (new to Vag Com so not sure if logging the correct blocks) and made some graphs from the data, hopefully relevant.

Any help understanding the data would be great thanks Nathan.

http://i601.photobucket.com/albums/tt99/S3-Nattie/Vag Com/015016114.jpg

http://i601.photobucket.com/albums/tt99/S3-Nattie/Vag Com/031032115.jpg

http://i601.photobucket.com/albums/tt99/S3-Nattie/Vag Com/115001114.jpg

http://i601.photobucket.com/albums/tt99/S3-Nattie/Vag Com/115116002.jpg

http://i601.photobucket.com/albums/tt99/S3-Nattie/Vag Com/Block32.jpg

http://i601.photobucket.com/albums/tt99/S3-Nattie/Vag Com/H02SControl.jpg

http://i601.photobucket.com/albums/tt99/S3-Nattie/Vag Com/N75DutyCycle.jpg

http://i601.photobucket.com/albums/tt99/S3-Nattie/Vag Com/RequestedvsActual1.jpg

http://i601.photobucket.com/albums/tt99/S3-Nattie/Vag Com/RequestedvsActual3.jpg

Sorry about the links, I have forgotten how to upload pics on here.
 
Is your car mapped?

Looking at them quickly, max airflow you are seeing from your MAF is 175(ish) g/s which looks std to me... 200g/s and above should be achievable on a mapped car.

max requested boost is around 0.8 bar which also suggests std. Requested v actual boost looks about right to me....

Do some third gear runs using the following blocks 031,115,020 and 031,115,002 and post those...

<tuffty/>
 
Thanks for the reply Paul. Ye my car is standard and im happy with the MAF readings, have logged 180g/s few weeks back.

With the requeted vs actual boost readings I thought there shouldn't be a difference of 100mbar between them both, which mine has near enough all the way through the rev range after 4000rpm. Even though it saying its requesting 0.8 bar, my actual boost pressure is not and my boost gauge doesnt spike or hold the same boost level as before.

In block 001 the H02S control is all negative values. Does that signify my car is running lean through out the rev range.

In block 32 the Part throttle readings are all negative too, unsure what this means. I have logged block 114 twice (N75 duty cycle), and get a reading of 95% ish aat the start of the rev range and slowly decreasing to 65% at the top. Not sure if the readings I got back are any good.

Im trying to understand what the readings in the blocks mean, as im unware exactly.
 
S3 Nattie said:
With the requeted vs actual boost readings I thought there shouldn't be a difference of 100mbar between them both, which mine has near enough all the way through the rev range after 4000rpm. Even though it saying its requesting 0.8 bar, my actual boost pressure is not and my boost gauge doesnt spike or hold the same boost level as before.
Click to expand...

Not an unusual pressure drop and the curve across the rev range looks about right. Might be indicative of the actuator getting a little softer. Boost spike is typical on a small turbo (particularly with a remap). If the actuator is getting softer then the N75 can control it better... I have seen this with my own car as the actuator softens a tad the actual boost drops off.

I would be tempted to check for boost and vacuum leaks before reading too much into this tbh. It would be worth while going round the charge system and checking/tightening/replacing the jubilee clips on all the boost pipes then looking for split pipes etc in the vacuum system...


S3 Nattie said:
In block 001 the H02S control is all negative values. Does that signify my car is running lean through out the rev range.
Click to expand...

the 0.9xx's in block 031 would suggest it is leaner than I know Bill prefers but its in line with whats being requested so doesn't indicate a fuelling issue IMO...

S3 Nattie said:
In block 32 the Part throttle readings are all negative too, unsure what this means.
Click to expand...

That block is the ECU adaption values. I think (I have to ask Bill this all the time as I keep forgetting) a negative value is the ECU pulling fuel out to compensate for a mixture thats too rich.

S3 Nattie said:
I have logged block 114 twice (N75 duty cycle), and get a reading of 95% ish aat the start of the rev range and slowly decreasing to 65% at the top. Not sure if the readings I got back are any good.

Im trying to understand what the readings in the blocks mean, as im unware exactly.
Click to expand...

N75 duty cycle always goes mad initially as it tries to control the sudden onrush of boost, it will then settle after the initial spike... Don't know what is deemed normal off hand but as its consistent and not all over the place I would say its ok

<tuffty/>
 
Thanks for the info. When I get a chance I will check the hoses as I think I may have a split some where after the MAF so its unmetered.

I will try and log the blocks you listed above today and post them up. What will I be able to see if I log the blocks you listed.
 
turbo's a little slower to get going from the logs, but not wow bad..
lambda's removing a few % fuel mid range and adding it higher up
032's are fuel trims and not worth logging during runs, just check em.. first one is short term trims and the other long term (if short term goes significantly +ve then on idles ecu is having to add fuel.. aka there's likely a vac leak somewhere)

you can get the turbo to hold more boost albeit with a little initial spike perhaps by gradually adding some preload to the actuator rod.. as tuffty says, actuators can and do go soft after a while. (shorten the rod a few mm)

airflows are ok.. std on std car

the fueling is leaner than you would want for best power, but being as its std its mapped to meet emissions controls as much as anything. Ideally you would want to see 0.8-0.85 under boost.

nothing i've seen jumps out as wow bad..
What are you looking for?
 
Thanks for the reply. I read somewhere, I think on the 1.8T info sheet (cant find it now because you cant search at the mo) that on block 32, if the value is more than 2% on idle its likely there a vac leak somewhere, mine is on -7 and -4.7 through the range.

I dont know if this is correct but also thought that on block 001, fueling, you didnt want negatives. Thought 0 signified perfect a/f ratio. The main reason for my concern is that my car feels like its being held back and boost gauge shows a drop in pressure, with no spike. I had a lambda fault few weeks back (deleted and hasnt returned), and always thought my car was running rich as mpg is rubbish.

If I log 31 115 20 and 31 115 2 as paul suggested, what will that show.

Thanks again
 
Last edited:
Ye thats the correct link thanks. What you think of the readings, anything not quite right.
 
Nothing leaps out after a cursory look over them tbh... not getting any timing pull, airflow is a little down from the last lot but not enough to make a judgement on... Actual boost is still lower than requested but that may well be normal on a std tune car. I never really logged mine in std tune but Bill should be able to shed more light on this... It could of course indicate a boost leak and its normal for the boost to tail off like that at higher RPM as the K04 has run out of puff by then.

If you feel performance is down then all I can really suggest at this time is to do the checks I already mentioned looking for potential leaks and the like. MAF may be getting tired but other than that, I would just get it mapped and be done with it :)

<tuffty/>
 
Thanks for looking Paul. I do think I have a boost leak somewhere, its just such a pain trying to find it, if there is one. Dont really now what else it could be.

Not sure what is wrong at the mo but its is slightly down perfomance and fuel wise. In this cold dense weather it should really be boosting higher than usual. See if Bill has anything to say about the new logs.

I will try and have a good look over all the vac and boost pipes over the weekend and fit my silicone TIP as it maybe collapsing and could be the reason why my actual boost pressure is off at the top of the rev range.

Thanks

One more question. Just had a look back at some of the requested v actual boost readings. Just wondering why is the requested boost up and down slightly, requesting a certain amount of boost at the start of the range which I would say is to get the turbo going (spike) then lowering it then raising it mid range, then it naturally tails off. Is this normal as I thought it should be consistant as my actual boost is.
 
Last edited:
S3 Nattie said:
Thanks for looking Paul. I do think I have a boost leak somewhere, its just such a pain trying to find it, if there is one. Dont really now what else it could be.
Click to expand...

What I would do is remove the bumper (not as difficult as it sounds) and replace all the jubilee clips with Forge hi-torque ones. Make sure they are pretty tight but not over tight as you will get the dreaded 'click of doom' and then the clip is essentially wasted. I have done this to a few cars now (including my own) and it will happily hold 2bar (30psi) without leaking.

Its also worthwhile taking the pipes off and giving the inside lip a clean with brake cleaner as over time oil will seep past and that won't help the seal. Clean the mating faces too (intercooler end pipes etc).

To get at the MAP sensor tube and the clip at the bottom of the throttle body hose you will need to remove the battery and tray (again not as bad as it sounds), you 'can' get to it without doing this but past experience says it will save you the time, frustration and swearing :)

Check the pipes under the inlet mani that go to the FPR and the N249 valve, check the DV and N75 pipes off the charge pipe too...



S3 Nattie said:
Not sure what is wrong at the mo but its is slightly down perfomance and fuel wise. In this cold dense weather it should really be boosting higher than usual. See if Bill has anything to say about the new logs.

I will try and have a good look over all the vac and boost pipes over the weekend and fit my silicone TIP as it maybe collapsing and could be the reason why my actual boost pressure is off at the top of the rev range.

Thanks
Click to expand...

Boost pressure is off as the K04 has run out of puff not because of a boost leak mate...

<tuffty/>
 
Ye i will give the above a go at the weekend. Hopefully the weather will be ok lol. Il report back once done and do some logging again.
 
Ok well I been having problems with my MAF recently. Its really strange because I still get good MAF readings but it runs quite alot better without it plugged in.

Done some logging last night to calcualte power. With the MAF plugged in it ran so rubbish than it did when it wasnt plugged in but I get better readings with it plugged in. Really strange.

I know one of the prongs on the MAF has broken off on mine but do you think it could be shot even though its still giving good readings.
 
The question is..... Would you be happier knowing that you have a good MAF?

OK - yours giving good readings, but that doesn't mean it doesn't have problems. My old MAF gave readings, but turned out to be FUBAR and car was much better after a replacement...

Is it worth the money for your piece of mind? Is it worth the money to know it will be good and you won't have to change it again any time soon?

I think the answer to both of those questions is yes.
 
Sorry to bring up this thread again but I have been logging again as I feel my cars still performing pretty poor and massively overfuelling. Had a full car on the weekend and every time I tried to take off the car would stutter really bad and start boosting and dumping randomly traveling like 10 mph.

Anyway, I logged my MAF and that gives a reading of 223bhp (AMK 210) but when I calculate the BHP using VAG COM I get a maximum of 185bhp @ 5200rpm and a torque reading of 208 lbs-ft @ 4100 rpm.

Anyone have any info on this please.

Nathan
 
S3 Nattie said:
Sorry to bring up this thread again but I have been logging again as I feel my cars still performing pretty poor and massively overfuelling. Had a full car on the weekend and every time I tried to take off the car would stutter really bad and start boosting and dumping randomly traveling like 10 mph.

Anyway, I logged my MAF and that gives a reading of 223bhp (AMK 210) but when I calculate the BHP using VAG COM I get a maximum of 185bhp @ 5200rpm and a torque reading of 208 lbs-ft @ 4100 rpm.

Anyone have any info on this please.

Nathan
Click to expand...

what actual airflows do you see peak? 003
what lambdas? 031
what lambda adjust? 001
 
I actually when to Audi yesterday to ask about the MAF connector, but they said its fine. The actual MAF sensor has 5 pins within in it. The connector that goes on top of the MAF sensor only has 4 slots to go on the MAF 5 pins. However the slot that doesnt go onto a pins doesnt have a wire to it (connector has 4 wire even though it has 5 slots). The slot that has broken off on mine doesnt have a wire to it so its not needed, hope thats understandable lol. I checked with Audi and they said its ok and checked a few other VAGS and there the same.

Yesterday I seen a peak of 176.97 g/s. I always get around about that figure.

Im not 100% whats the best way how to log block 31 and 001. I have always logged it as I log everything else (3rd gear 2000 - redline) but always get the same, near enough 1.000 for block 31 and always -ve numbers for block 001.

Would it be best if I logged the above altogether or do I look at the values after I have done a run.
 
log blocks 001,031,115 doing a run in full throttle from 2krpm to 6krpm in 3rd and 4th gears so get meaningfull logs

001 is short term lambda adjust
031 is request and actual fueling
115 is request and actual boost

logging all these together yes

176g/s is for your std engine yea? not mapped.
 
OK so logged the above blocks mentioned. Logged 001,031,115 - 002,031,115 and 001,031,002 in 4th gear to show MAF values, which are a bit lower than the values I got the other day in 3rd, anyway these are the results.

001031115.jpg



002031115.jpg



0010311152.jpg


My block 001's are always negative which I thought closest to 0 is best as it shows the ECU is taking fuel out and when I let off the throttle my lambda values goes higher, not to sure what that means (correct me if im wrong).

Still not sure why my engine is only producing 185bhp according to vag com but MAF shows more and really heavy on fuel.

Yes my car is standard bar a 007p, silicone TIP and a Jetex which I actually bought from you Bill.

Any helps would be great thanks Nathan
 
Last edited:
S3 Nattie said:
Still not sure why my engine is only producing 185bhp according to vag com but MAF shows more and really heavy on fuel.
Click to expand...

How did you work that out mate?

185 BHP?

From your airflow in the logs above ^^ I've seen a MAF reading of max 167.75 - which to me says 209.68 BHP.

Which, correct me if I'm wrong, is **** on. :icon_thumright:
 
Yes exactly, and I usually always get above 170 g/s when I log in 3rd gear.

I used the equation on VAG COM, block 120 to get the torque output then worked out the power which equals 185 bhp and 208 lbs-ft of torque.

Something aint right so not sure which reading is correct but from the feeling of the car its definately not as quick and loves petrol way to much recently.
 
167g/s to me is low even for a std k04'd motor.
lambda actual sits at a fixed 0.953 number very consistently, which seems too consistent to be true to me.

unplug maf and what does it go like? better or worse?

block 001 adjust seems ok.. +/- 5% either side is acceptable to me

what is currently showing in blokc 032? fuel trims
 
Ye 167 g/s is lower than I usaully get but still reads 209 bhp which is quite a bit more the what VAG COM says. I always get more when I log in 3rd gear, dont know why.

Should the lambda value increase as the engine speed increases, not sure why its so consistent.

Before when I unplugged the MAF it used to run better and give better mpg so bought a new Bosch one from Euro parts and done a couple of miles with it and it ran exactly the same as the old one when it was plugged in so to it straight back. They said it was brand new so took it as its not the MAF if it runs the same as my old MAF.

In block 032 I gets a consistent 0.4 in the first block and get -ve 4.7 to 7 in the second block. Not to sure what these blocks show.
 
any logs done on new maf befre you returned it I guess, so not facts as such

usual check for airleaks, any oily residue on pipes under the inlet manifold area etc, fresh plugs, good known healthy coi lpacks (they can degrade their coil energy), knownworking lambda proibe..
 
No logs done on the new MAF, just when by the feel which was the same as the old one.

I had a quick look yesterday for oil residue under the inlet manifold and did find some so will have a look properly on the weekend.

My plugs are less thans 1000 miles old but unsure of the coil packs. Around xmas time I did have a fault code for the first lambda, however I deleted it and its never come back. My stat was stuck wide open one time and the engine was running cold and the EML came on and the lambda code come up.

I had some bad stuttering and surging when I had a full car other day so think I give all the hoses a good look over and see how I get on.
 
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