Philippe Holland

Hi Chris, Thank you for your message. My car is now working again. The problem may have been a combination of things, but the part that finally cured the problem for was the ‘knock sensor’ on the back of the engine that detects each explosion in the cylinders. This was the only sensor on the car that I did not change before giving up and handing the car to my local dealer…. Working in conjunction with the cam position sensor and the crankshaft position sensor, the knock sensor allows the ECU to calculate if there is a problem with one particular cylinder due to a bad detonation or if the timing needs to advance or retard. This part has gold plated connectors and needs only to be tightened to 20Nm. If there is a problem such as poor combustion then the ECU cuts the injector signal to that cylinder to avoid unburnt fuel washing the oil off the cylinder wall, or worse unburnt fuel making it to the catalytic convertor and ruining it. Poor combustion can be caused by bad timing of the fuel delivery, bad timing of the ignition or incomplete combustion because the valves are not opening enough to let fuel in, or not enough to let burnt gasses out. I have found researching the Internet that the problem with No.2 cylinder happens often. I changed the camshafts and the cam housing as this was recommended to me to do, due to cam freeze. It did not change the problem, but the car did run a little smoother. The cams are made from heat treated steel and they revolve inside an aluminium housing, without any additional bearings. This is not a great engineering solution and if oil changes have been neglected then the parts can wear quickly. My Audi dealership said they old parts were fine and actually the lobes of the cams that activate the hydraulic cam followers were perfect. However, I had nearly 1mm of vertical play in the journals where the cams turn in the housing and the journals were badly scored. At tick-over, this 1mm of vertical wear may well have caused the valves to open less than they should, hence causing the poor combustion, with the ECU then cutting the signal. At higher engine speeds with a greater centrifugal force acting on the valve mechanism the problem maybe less apparent. The workshop manager did not want to change the knock sensor, because after a year of joint investigation he did not believe it was the problem. I insisted he changed it and at the same time they ran a parallel set or wires from the sensor to the ECU in case there was a broken signal. This cured the problem and the car runs fine now. If I had only changed that last sensor before handing the car over to Audi, then I may have saved myself nearly 4000€…. At least I now know that all the valve gear, cams and associated parts are now new. I just need to keep for car for another 10 years now! Good luck in finding the solution. With kindest regards, Philippe

Hello everyone, We are focusing on air leaks now and the car is being tested as I write. On the inlet manifold there is a round access cover with an inline valve inline with number 2 cylinder. I have no idea what this does. It is part number 036129720. Can anyone tell me what this does please? You can see it here: AUDI A2 2000-2005 1.4 16V AUA AIR INTAKE INLET MANIFOLD P/N 036129711BH (44804A) | eBay I am hoping the leak comes from here and is making the mixture weak and causing the misfire. The misfire starts when the engine and lambda sensors are up to operational temperature and on 'open cycle', rather than on the 'closed loop' fixed map when the lambda sensors are not instructing the ECU to richen or weaken the mixture. We'll see the results tomorrow....(please!)

Hello everyone, Installing new camshafts, housing, hydraulic lifters has improved the smoothness at tick-over and the car runs well, but the fault is still there. If you start the car from cold and left it warm up, it starts fine on four cylinders and then after a few minutes will start to misfire on cylinder 2 before the ECU cuts the signal to the injector when the car will run on three with the EML flashing. Resetting the ECU whilst the engine is running instantly restores the car to four cylinders until it starts to misfire again and then it will cut out back to three. If you start the car and drive it immediately without letting it idle, it drives well. As you will see from previous posts, we have checked and changed everything. I only have two ideas left. I asked the garage to disconnect the knock sender and then start the car from cold. My logic was, if the knock sender was disconnected it would not pick up a misfire and hence the ECU would not cut the signal to cylinder 2. Disconnecting the sender changed nothing. Other thought is that there is an air leak starting in the inlet manifold as the engine warms up causing a weak mixture and misfires. The Audi workshop manager had his head in his hands and we are all looking for a solution. Anymore ideas out there? Many thanks, Philippe

Hello, Yesterday morning I delivered two new camshafts to my Audi dealer, who was very impressed by the savings I had made and very curious to know the source I got them from! Although not wrapped in "VW" paper, they appear to be genuine parts from an original OEM supplier. Each camshaft cost me 125€ instead of 287€ + 20% tax from Audi, a saving of 440€. I could not find a new 'old stock' housing, so will be getting one through Audi. I ordered the camshafts by phone and got the UPS confirmation that they had been sent before I got the bill from the company. That level of service and trust would never exist here in France. So, hopefully today, we shall see if all this work will result in the car being fixed. A car designer by profession, I had always loved the A2 concept. So far I have driven the car 50kms and it has spent the rest of the time at the dealer. Let's hope that this is it. The link DerWeßA2 posted was word for word the same scenario as my car, so I am being optimistic that we have found the solution. My A2 is also white... Many thanks for all the support. Without you guys, I would be still turning in circles. I will post the results shortly. Philippe

I have found this ebay seller who assures me the parts are genuine VW. 125€ compared to 287€ +20% tax from my dealer. Here is the link. Nockenwelle Auslassnockenwelle Seat VW 1.4 16V 036109101DE AKQ AUA APE AXP BBY | eBay

Can anyone recommend a good source of VW/Audi engine parts at good prices? My dealer in France wants 1300€ for 2x Nockenwelle and a Zylinderkopfhaube. Many thanks, Philippe

Thank you DerWeßA2 for the link. Very interesting that all the cars in that thread were 2002 models. The problems experienced by the other owners and garages are identical to my car. I am seeing my dealer this morning and will give him a copy (thank you Google translate!) My car has had three new cylinder heads, but I cannot see any bill for camshafts , housing or hydraulic lifters. The oil was very black when I got the car. I wonder if the long oil change procedure was such a good thing in hindsight. I will post progress. Thank you everyone

I would most appreciate some more explanation please about the camshaft and its storage. The cylinder head+camshaft+lifters are all new. The dealer has just removed, checked and refitted the head finding nothing wrong with it. Many thanks, Philippe

Yes the car is a AUA with central ignition module, which has been checked, changed and checked again. I now believe that the problem is a bad earth between the ECU and the car. The injector cuts out after a few minutes when ticking over. My cheap LED injector signal tester does not light up giving the impression that the signal has been lost, BUT when an oscilloscope is connected the signal is still there, but obviously not strong enough to power the injector or my tester. I presume that an oscilloscope requires very little power to be able to take a reading.

Dear German A2 friends, This is my first posting here, as Bret recommended I ask your advice. I have a long ongoing problem with my A2 1.4 petrol. I would be most grateful if you could give me some advice. Below is my last post on the A2OC website on the subject: My Audi A2 has now been with my local Audi dealer for 7 months and they cannot find the problem. They are honestly trying their best. Each time I visit them I am now hoping to hear that the car has fallen off the ramp and is destroyed or it has caught on fire... Just to recap very briefly the problem. Car starts fine....if left ticking over, after about 3 minutes....a slight misfire starts on No.2 cylinder (it is always No.2) 30 seconds later, the EML comes on and there is no more injection signal and the car runs on three cylinders. Clearing the fault code whilst the engine is running restores it to four cylinders again until the misfire starts again and the ECU cuts the signal to the injector. If you start the car and drive immediately away, it will mostly run fine, until you come to a set of lights and again after a few moments at tick-over, it will revert to three cylinders. Turning off the engine, waiting half an hour will make it run on four again. I have and the dealer have done the following: - Replaced both lambda sensors, all the engine sensors bar the knock sensor. - Cleaned the Air flow meter and the EGR valve - Had tested and then checked with another ECU, the ECU - Ran a parallel set of wires from the ECU to No.2 injector - Replaced the injector - Replaced all plugs, wires and the ignition module - Removed the head, checked all valves and cam gear (head has done 5000kms) This car is now on it's third head and tracing the history shows that it has been having problems since 2008 at 70,000kms. We are trying another ignition module as we think that a poor spark on number two cylinder is making the ecu cut the signal. We are all at our wits end. I bought the car for my wife who...let's just say, is less than impressed.... Can anyone tell me if the knock sensor can pick up a misfire on a single cylinder and instruct the ECU to cut the signal to that cylinder? I can imagine the injector signal being cut to avoid bore wash if something else was playing up. As a reminder, the car is a bog standard, nice and simple 1.4 petrol with the AUA engine. My only other thought is a resistance building up in the harness from the ECU to the ignition module on number 2 cylinder causing a poor or delayed spark, thus effecting the combustion, thus causing the ECU to cut the injector signal. Truly gutted by this car. Any pointers more than gratefully appreciated. Philippe The first post can be found here: 1.4 petrol low compression or dealer fast-one? Thank you everyone for your help and apologies for making you read this in English