NefMoto

Hello to all,
i have problem with my Audi TT 1.8T APX, rebuilded with all forged, turbo GTX3076R, TIAL BOV and WG. With previous turbo GT2871R was all good too.

All was good (480HP and 530Nm) and at one ride suddenly power loss and bad A/F ratio - about 9-9.9:1 and very unstable idle.

I have issue now with idling and revs falling at idle - when i have maf connected will stall and without maf seems much better but not good - all was ok but at one ride suddenly power loss and very bad fuel ratio. After long tests we hoped that is alternator. Today changed and same state.

Have anybody any idea what can be wrong?

Thanks all for anything.

Really without any logs , nobody can help you....

Great answer mate, logs on idle, all seems good (MAF, injection time, temperatures, ..) this would be some hidden crap ... with diagnosis we spend much time ;)
We are not newbies but in this case we dont see anything and anybody who solved same issue is needed ...

Above idle all works good and still have 480HP and 530Nm on dyno ... ONLY AT IDLE I HAVE ISSUE ...

So you didn't post logs because you couldn't find anything wrong with them... but you want help figuring out why your idle is bad?

I'm very confused :/

No, i trying find somebody who had the same issue ... before about month i made several logs for many peoples and nobody found something - therefore i wrote for what logs, did you understand me?
Can make new logs of course, so what do you want logs exactly? Cold and hot or some special? I using ME7 logger.

Thank you.

Any help appreciated.

i had similar problem today with AUDI S3 model 2002 BAM engine(wideband) with similar specs like yours(GT3076R, 660cc injectors,etc...)and the problem solved after lambda sensor replacement(the first one, in front of catalyst)

 ??? ??? Logs on idle can be very useful..I don`t know why you are being sarcastic. Anyway it can be lot`s of things BUT you have to log.
With O2 voltage for example you may figure out if something is wrong with your λ sensors

I wrote why i am sarcastic, maybe much, sorry.
Today tried second lambda, injectors, maf, now we will change both water temp sensors and tomorrow will make some logs.

One thing is that o2 control is still inactive.

What happens after you reset the ECU's adaption values?

Nothing - absolutely nothing :( Before when reset was made causes change of sound and made adaptations.

I have every important parts twice - ecu, o2, injectors, intake manifold flap, ..

Mechanicaly all is good, timing correct, no air leak.

Log attached - first part with disconnected MAF.

All day with OLS300 and online testing ... nothing, still same state without any good change :(

Almost every variable tested with bad result but not better.

Somebody can help me?

Why is that csv semicolon separated?

Maybe corrupted by excel - correct is here.

Something very screwy with MAF.. maybe bad harness/connector? You said you replaced it?

maybe a vac leak still somewhere?

Yes, changed and still same :( I have ordered one more, do you think is MAF issue?

Here is nowhere can be leak, we tried bypass N75 and N249, brake booster, fpr, press gauge, no other is here.

New MAF - genuine Bosch - third and still same - when i will connect MAF i get error torque monitoring. When is disconnected idle is good.

Lambda control still not active - this can be source of issue but why is still not active?

Any ideas please?

If you have the same results with a 3rd new Maf you are going to search for wiring/Maf plug problems. Before you do that I would recommend flashing a basicaly stock file (Injector`s offset etc only ) leave the MAF table alone and see if there are the same results with a basically stock file.

Tried with stock injectors, stock file and same results. Wiring is ok. One idea is BOV - open type TIAL. I have open type over year and never been any problem.

Today test result:

idle (with gas pedal playing to stabilize) - MAF reading about 3-5g/s -> engine revs up to about 3000 rpm and leave go back to idle (MAF reading good while) -> at about 1200 will open BOV (open type TIAL) -> MAF reading is about 22g/s -> engine stops much rich

I cant set bov that will not open, anybody knows what to correctly set? N249 valve is good.

Thanks all

Ditch the BOV already. Whether or not it "used" to work, ME7 is not designed to lose air post MAF. Period.

Thank you for answer.

Understand but i have many engines with open loop BOV without issues but ME7.5 with wb lambdas.
This engine ran good last 2 years with open type BOV but now is problem with same setup - this is strange. Wrong is only that is not any reaction for lambda - disconnected, connected - no lambda corrections, no adaptations.

Got it. Agree that with WB a lot of the issues with MAF readings being inaccurate go away.


Sorry, i can't think of anything else to try.

Maybe heads? leakdown?

Head and crankcase is vented to air from begin.
No leak, one result is opened bov - when bov will be closed, engine will not stops - is not needed to have bov opened.

Anybody have tested some solution for bov closing? Tried some with emulator but result still same, bov is opened above idle.

CAN PAY if anybody knows how to fix ... will be a little something ...

And new dtc from now with third MAF now 17743 - Torque monitoring ...

Torque monitoring without MAF/leak problems ? Something is wrong either with your new maf or with the wiring/plug have you ever checked you electric wirings ? Also , take another ME7.5 Ecu and check again . I can`t think of anything else you say you changed everything twice ,did a leak test ,coolant sensor (Important! ) ? ,checked the wiring (?!?) etc. Either you missed something or you didn`t check them well  ???

Strange ... with previous MAF isn't this dtc. I have second ecu - tested.
Coolant sensor changed - both are new.

Will check wiring again

I hate old ME7.5 512kB :(

Solved with new N249 connected in plug and BOV connected directly to intake. Sometimes will stall but usable.

Thanks all for suggestions.

Tomorrow will buy and install race engine ecu and haldex racing controller. Spend much money to have half working car :(

I find it hard to believe that your AFR was so much affected by a faulty N249...  I would check again for leaks.
Also you didn`t mention any N249 related DTC`s , is it coded out completely  or just the dtc ? if yes remove it completely...

BOV will stay opened and MAF counting with this air so much rich :(
I dont know how to set that i want bov closed as soon as possible.
No dtc coded out. Maybe much vacuum - i have 10psi spring in bov and in manifold is about -0,7-1b ...

This is why BOVs are stupid.

Yes, but TIAL dont offer any stronger spring :(

But still strange why was all good before about month and at once is crazy ...

hmm ok I forgot about the BOV part , I never never never recommend them , glad you sorted it out anyway  :D

Not so easy - at idle is about -0.6b, in deceleration or from higher revs is -1b and this is problem - bov is opened and when i put pedal engine run rich due MAF reading vented air.

Will be solution stronger spring or closed bov? Dont know why is too much vacuum at once. Other aspect is when will bov open when will be spring for -1b and is -1b in deceleration ...

Or will be solution opening throttle plate for lowering vacuum?

The solution is to let the ECU control a recirculating bypass valve.

Yes, i have connected valve to N249 but without success ...

Any solution ?

finally your o2 sensor control active cames "1" or not?Did it had any activity?I have similar problem.i upgrade 180Q(ajq with 8n0906018b ecu) with 225 parts(flash my ecu with 8n09906018f stock file)but i don't put secondary air pump.My MAF reading right,but on my lambda sensor status only sensor heater and sensor ready values change,the control active value stays always "0".Any solution?