TitusM

I might have found the issue. I just discovered that the MAF - mas air flow sensor in lupo has a different code than the one in Audi. Also you can find cheaper good quality versions - pierburg - only the sensor without the housing (almost half price). The price today 09-2025 here was 76 euros. The code for the part is: PIERBURG 7.22684.14.0 I did check the graph with vag com AAAAND surprise. The original bosh maf that seems to work does not read the same as the pierburg lupo one. I did replace the bosh with a meat&doria version longer ago but that one was even worse so I got back to the original. The original bosh has a very weird reading -- idle reads ~420. At 1000-1500 rpm reads 313. At 2000-3000 goes around 500 and it does almost reach 600 sometimes when rpm is around 4000+. The new pierburg maf at idle reads a little higher 440. At 1000-1500 rpm reads 480. At 2000-3000 reads almost 550-600. At 4000 reads 750-800. SOOOOO this one might be the headache I was having with bad consumption. It makes sense because the original maf was indeed defective and the replacement one that was not oem was another defective one. I will keep you posted if the consumption is better or not. I hope this will fix a bit part of the consumption Issue. So all of you that said MAF might have been right all along. What I did not really expect is bad maf reading. The car accelerates ok and has no other symptoms than bad consumption. More air would mean less fuel and more power...hopefully. Fingers crossed. The injectors and the cylinder head will be next on the list but that requires a bit more cash.

google translate: Ich würde das Auto so nicht fahren. Versuch lieber, die alten Schrauben zu ersetzen. Du brauchst einen Schraubenzieher – ein Set gibt es bestimmt für 10 Euro. Bevor du den Schraubenzieher ausprobierst, erwärme die alte Schraube. Hier ein Beispiel (es gibt auch Schraubenzieher, die keinen Bohrer benötigen, da sie selbst schon ein Bohrer sind): https://youtu.be/dCqU1LgsJfU Tipp: Bei korrodierten Schrauben gibt es zwei Möglichkeiten: 1) Mit einem kräftigen Hammer daraufschlagen, damit die Korrosion abbricht (funktioniert auch bei Bremsscheibenschrauben). 2) Mit einer Gasflamme (falls die Stelle es erlaubt) oder einem Induktionsofen erhitzen – die Schrauben öffnen sich wie Butter. Da das Aluminiumgehäuse auf alte Schrauben trifft, löst sich die Verbindung. ---------------------------------------------------------------------------------------------------------------------------------- original: I would not drive the car like that. Better try to find a solution to replace the old screws. You need to buy a broken screw remover - you should be able to find a set for 10 euros. Before you try the broken screw remover heat up the old remaining screw. Here is an example (there are removers that do not need a drill because it already is a drill itself): https://youtu.be/dCqU1LgsJfU As a hint - when ever you have some corroded bolts you have 2 options: 1) hammer very hard on it so the corrosion breaks off (works also for brake disks screw) 2) heat it up with a gas flame (if the location allows it) or induction coil - it will open like butter. Because of the aluminum case hitting old screws helps release the bond. Good luck

And what are your stats now after new maf?

Where do you have this consumption? How much does it consume when driving out of the city. In my case I can say that I fixed lots of stuff that were wrong with the car. Unfortunately the consumption is not one of them:)). But I do have much better idle and no more leaks and the car is much more fun to drive. In your case - as far as i know polo is common rail. It is a non PD. Tehnically the next generation after lupo and audi 3l BUT the body is not the same. VW did not invest as much in bodywork anymore. My stats over all are 6.5-7 L/100km city and 4.4l/100Km outside/highway (usually city with the car almost empty and outside with the kids and wife so maybe around 120kg extra). I do own a vcds diagnose - without it is impossible to start somewhere(maybe vacuum leaks and other small checks). In your case I would start with the steps below: Usually with any car I start with (injectors and turbo are the last ones): 1)any visible leaks -- vacuum leaks -- and here I include N75 solenoid that moves the turbo vanes The easiest way to check this is with a hand vacuum pump (i bought a cheap one) with a meter on it. You pump and see the vacuum stays the same and also check each vacuum line - turbo, brakes, egr for leaks. To check the N75 solenoid I used a vacuum meter that I connected to the N75 output and i waw that the vacuum was not stable when idling. After fixing it I got less turbo lag. Lately i got a smoke machine from aliexpress. I fixed quite some issues with it(i did not know i had before it on the air intake side). The intake leaks fixed the lag quite a lot. 2)MAF -- in vcds engine -- see if when the engine runs the readings are moving and are in a reasonable area. This is usually one of the reasons vw's consume a lot. 3)lambda sensor if the engine has it. Euro 4+ usually have it. My 1.2 does not have lambda or nox sensor. You can check this if you look at the exhaust. If there is no sensor on it..than there is no nox/lambda sensor:)). Polo for sure has the sensor (maybe even 2 sensors one before and one after the catalytic converter) 4)check for any fuel leaks / even perforated filter hoses, fuel tank. Usually this type of leaks do not register on the car dash so you would catch those only if you calculate full/full. 5)check for stuck rear brakes but that usually is very easy because the rear rims get very hot if the case. 6)the last checks would be injectors and turbo. (also turbo leaks). In my case the injector deviation was fine until I changed the vacuum/tandem pump. After longer Idle there was "white" smoke. The high pressure pump was inserting oil into the fuel. After changing the tandem pump the car would idle better but when looking with vcds i noticed the injector deviation being greater (maybe the injectors were not as lubed with oil as before:)) ) What you have to take into considerations is that NONE of my cars consume "well". I owned: 1,2 tdi, 1.4 tdi, 1.6 tdi, 2.0 and hybrid gte. Each of them had their own particularities and i learned a lot about what causes consumption. I did not get as far as i got with the 1.2 tdi. This is the one I experienced a lot with and that I invested the most and learned a lot about diy diagnose. They tell me I drive quite aggressively so i assume at least 10 ,20% of consumption is my right foot.

Hi, Mine is euro3 so it does not have it. I checked. For now I believe the issue is one of the injectors (it was not visible until I changed the tandem/vacuum pump). The deviation is ~0.7 on one injector compared to the others. I read somewhere that on 1.2 the deviation is much smaller and 0.3 deviation might be an issue already. Since mine is 0.5 from 0 and 0.7 from the other injectors i declare it ...an issue:)). I will keep you posted. In September i will take the care to an expert shop for the gearbox and i will ask them to send the injectors and turbo for revision. I tested 2 other maf sensors - one pierburg and another miele and both of them give bad readings and even worse mileage. For now the original bosh maf seems to be the best (even on vcds the other ones give higher number when idle ~10% but when accelerating it drops very much compared to bosh).

yes:))) in the city.... And I am starting to believe that my driving style and the geography has a lot to do with it. When i get home i have to go uphill for 9KM. It is a demanding hill that asks a lot from the car (I drive usually full power). Outside the city the best I got so far is 4.4 l/100km.

Update: After fixing the air leaks the car runs better BUT 2 months into it and the consumption is again around 6.5l/100KM. I changed the tandem pump (high pressure/vacuum pump) since i suspected it for being a bit old. Replaced it with a pierburg one because i like the design better. The car idles much better now. It is not so rattly when idle. BUT...the consumption is the same. What I noticed is that in VCDS the injectors deviation is different now. One of the injectors is +0.5 and the others -0.2. I guess the problem might have been a bad injector all along but the old tandem pump hid this very well. What is next: I found a guy in my country that does all the gearbox -- bearings replaced, all pump o-rings replaced, hydraulic actuator upgrade. I will take the car there and ask them to take out the injectors and turbo and send it to testing. The turbo seems to have a little play so maybe there is some lack of power there too although it does not show on VCDS.

Sory I tought I answered your question. The total contact on the road is the same as for ecopias (because of the way the threads are built). Maybe ecopias have bigger contact surface (if we take into consideration what off-road drivers say). After a while i am back to same consumption of 6.5l/100. So tires have veeery little influence in my case. The tires i use now are falcon sincera ecorun. If you look at the threads you will understand what i mean -- much bigger distance between longitudinal threads.

6E0601025F They are...quite hard to find. Lupo 1.6 FSI had this model. It is 2cm wider than the classic 3l version but still very light. I did not compare rim to rim weight only complete wheels. About the tires I do have to make a comparison with the ecopias and those. I have a pair of rims with very old ecopias (scarry to drive them on wet surface). I believe that there is not a big difference (I would say 0.2-0.3 maximum on external) because I have eco version on the new tires and if I add up the contact area is the same as the ecopias only 10% weight added. The ride is far more comfortable with the 165 version...no doubt about it. Anyways...the 145 are nowhere to be found anymore. I wanted to buy a new set and no luck. Not even the winter continentals are not available anymore.

not even for the cleaning purposes? only water maybe?

Did you test water methanol injection in this engine? by any chance?

True. As I say power does not come only from air:)) you need to burn something in order to get extra horses. As lupo_3l said he used stock parts to go up to 125 and turbo was not yet at limit. It is good to hear from someone who tested stock parts to limits:). As for tire size...i am not sure that 145 makes a bit difference compared to 165 width. So far i like the ride better with the 165 and the contact surface is almost the same because of the way the tires are build. I bougth B/B markings and they seem to be much better than ecopias in terms of comfort and traction (but i still need to register the new tires and that will be a pain)

Awesome. So you are running manual gearbox? everyone says that 200nm is the limit and that is reached around 100hp if i remember correctly. It is nice to hear from someone who actually tested this things.

Thanks Manni. Yes I aim towards lower consumption but since I suspect turbo for wear I need to choose between upgrading to a more efficient turbo or repairing the old one. Maybe you are familiar with: https://forums.tdiclub.com/index.php?threads/1-2-tdi-tuning-info.390974/ I looked at what he did with his 1.2 lupo. He till has insane fuel consumption but he also done 100 other things to the car. I will not be able to go that drastic but i can implement part of modifications.

Are you sure? As far as I know Tuneko Ltd the one that tuned the 1.2 lupo a lot got 90hp from this engine with stock stuff therefore i believe the turbo is somewhat limited. The turbo on 1.4 tdi 90 is not the same with the one on 1.2 tdi. That's why I believe the 1.2 turbo is not as potent. I agree a bigger turbo has bigger lag but since only the pallets/wheels (going billet) are different I expect an improvement in efficiency for the same garret housing. I expect it to make better use of same flow since the billet wheels are lighter and have better airflow. In fact I expect lower lag because of better use of flow and decrease in spinning mass. Do you think I am looking at this wrong?