1.4 petrol low compression or dealer fast-one?

Slight typing mistake from my last post. It should have read No.2 injector (towards the cambelt end?), rather than No.2 injector (closest to the cambelt?).
It is most definately No.2 injector that is playing up.
Just waiting for Mr.Ebay to deliver. Thanks again everyone.
 
Hi, here is the latest update. I changed the injector and eventhough it has the same part number as the original part, looks slightly different, with the harness connector slightly higher.
Car still runs roughly with the EML flashing. I did a compression test and funnily enough all the cylinders are spot on with reading from cylinder 1 to 4 as: 210,210,220,195 psi. I don't know how or why the main dealer found
No.2 to be low (error code relates to No.2 cylinder), but he was adamant that the head had to come off, and he was unable to print the compression test results for the previous owner....
I used two Gunsun Colourtune plugs in cylinders 2 and 3 to compare flame colour and No.2 seemed richer (there is only so much you can tell from this test).
Connecting/disconnecting the new injector whilst the engine was running showed that it was working.
Reading the Audi self study program 247 (page 20) pointed out that when defective, the Hall Sender G40 makes the injection run in parallel mode rather than sequential mode and the ECU goes into emergency running mode.
Maybe this is the rough running that I am suffering from.
Connecting/disconnecting the sender changes nothing to the way the engine runs.
When I took it out, it had a build up of oily/magnetic swarf on the tip. Cleaned up and refitted, the rough running is the same.
All fingers crossed, this might be the problem.
Has anyone else experienced the Hall Sender failing, and if so, how did the engine run?
Philippe
 
I changed the Hall sender G40, no change. I noticed that the car would start on four cylinders and then after about 3 1/2 minutes would run on three with No.2 cylinder not firing.
I changed the temp sender incase it was related to the warm up period, still no change.
I have had the ECU checked by a specialist company in the UK and it is fine.
Reading another thread has shown that the 1.4 petrol engined cars can also suffer from injector harness breakage, even though less common than on the TDIs.
I would like to do a resistance check from the injector connector pins back to the ECU, trying to find a cracked wire or bad connection.
I would be most appreciative if someone can tell me the pin order on the ECU, or if someone has a diagram showing the pin layout.
Many thanks, Philippe
 
the diagram will most likely be somewhere in ElsaWin if you haven't got it already. Good luck with the repair!
 
This car is driving (or rather not) me nuts! I replaced the injector connector and dodgy wiring and the car ran really well. The EML light was still on but not flashing, but the engine was pretty smooth. The next morning the car started fine and then went into limp home mode after 5 minutes or so, with the EML now flashing. It sounded and felt like a rough diesel as if the ignition and injection timing were both off. I drove the car for 10 minutes in limp home mode and then left it for an hour. When restarting it, it was back to normal, running pretty smoothly, EML lit but not flashing. The same thing happened this morning. Starts fine, goes into limp home mode and then fine again if turned off for half an hour.
My question is: Can lambda sensors gradually breakdown with fluctuating performance or do they just stop working? I've ordered both sensors and while waiting for them to arrive will clean the EGR and give the car an oil and plug change.
I was recommended to clean the throttle body as well. If I remove the TB, does anything need to be reset afterwards? Many thanks as always, Philippe
 
You need to recalibrate after cleaning out the TB. It's a simple operation if you have VAGcom or VCDS light for example.
I've read somewhere here that one can disconnect the battery for a number of minutes and it should do an automatic reset, but that has never worked for me. So, best bet is to hook up the computer.
 
Update, as it seems that I have been chasing a red herring. I changed both the Lambda sensors, no change. I then changed the crankshaft position sender G28 that works in conjunction with the G40 sender. Still no change. I then changed the MAP sensor, no change. I checked for air leaks and cleaned the TB and EGR valve. The car would start fine on four cylinders and sound ok, but not really super mechanically quiet and after a few minutes, would start to misfire on No.2 with the EML light coming on, before the signal for NO.2 injector would cut out completely. I had presumed it was a signal fault from a sensor telling the ECU to cut No.2, or resistance build up in the engine harness.
Yesterday morning it started as per usual, but the engine was super quiet and smooth with no mechanical noises or misfiring. Again 3 minutes later it started to 'pop' 'pop' 'pop' from the exhaust and the car went onto three.
I had always presumed the roughness and mechanical noise were caused by poor firing or detonation.
I booked the car into my local dealer for a diagnosis yesterday morning. I know the parts guy very well by now, and even though concerned that another local Main dealer had charged 2 hours labour to the previous owner to do a compression test, decided to try my local dealer anyhow.
The workshop manager was not exactly very friendly as I explained what I thought was the problem.
He phoned this morning to say that the car is electrically perfect, but they believe there is a lifter/valve problem on No.2 cylinder.
What I believe has happened is that the lifter is losing its pressure after a few minutes running and the inlet valve is not opening fully, hence the combustion is not complete and the knock sensor or other is picking this up and eventually cutting the injector signal.
I bought an OMD2 wifi sender and use the App REV on my i-phone.
I was picking up high +40% Long Term Fuel Trim, suggesting that the ECU has been trying to compensate for the partial combustion.
I was surprised when the workshop manager said that they did not have to change all the lifters, but only the faulty one.
He was meant to get back to me with a price to do this today.
Can anyone give me an indication please of the number of hours of labour required to change a lifter.
I imagine the procedure is: Cam cover and ancillaries off, cam belt off, cam off revealing the lifters?
I read on another thread about £600 or so for a complete change of all the lifters.
Any guidance most gratefully appreciated.
Cheers, Philippe
 
Philippe Holland said:
Can anyone give me an indication please of the number of hours of labour required to change a lifter.
I imagine the procedure is: Cam cover and ancillaries off, cam belt off, cam off revealing the lifters?
I read on another thread about £600 or so for a complete change of all the lifters.
Any guidance most gratefully appreciated.
Cheers, Philippe
Click to expand...

Hi Philippe,

I’d suggest 5 hours labour to strip and rebuild to replace a lifter.
As you imagine, it’s cambelt’s off, remove the cam carrier, remove and replace the lifter and rebuild.
The above said, for the cost of the lifters I’d be replacing the full set of 16, as at approx. £8 each it’s not worth only doing 1.
The difference in time for replacing 1 or all 16 lifters is an extra 5 minutes.

But again, the symptoms that have now been diagnosed could also point to the initially identified cause of a bent valve sticking in the guide.

I’m not sure how you test the integrity of a hydraulic lifter out of the engine, but maybe someone else can advise if it’s possible or not?

It’s a brave man to risk the tear-down and rebuild of the valve-train when another 2 hours labour has the head off to examine the valve seats and guides.

Good luck with whatever way you choose.

Cheers

Jeff
 
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
 
7 months at the dealers?!?!

Just read this thread for the first time. Really expected, given the time frame, this to have been resolved.

Your wallet and patience have trully been tested. I really feel for you and hope the matter is resolved ASAP
 
Ref the knock sensor question, I think they can pick up individual cylinders. There will be a combustion knock each time a cylinder is on the firing stroke and the sensor will pick up the 4 individual 'spikes' which the ECU can correlate to the firing order. The ignition timing of individual cylinders can then be retarded to prevent pre-ignition - another name for pinking or knocking. If the timing change does not have the required effect then I guess its possible for the fuelling to be trimmed to prevent damage to the offending cylinder.
It's rare to find these days but some garages use an oscilloscope to check sensor, ignition and injector fuelling outputs to troubleshoot this type of problem.

Cheers Spike
 
Spike's post got me thinking... The service manager is now so fed up with the car, that I can walk straight into the workshop and talk with the technicians. We brainstormed together this afternoon and I think that I (the customer) have found the problem....
When the car goes onto three cylinders, my cheap and cheerful injector tester (a LED bulb tool made by Draper) would no longer light up and the injector would not work.
However, when the Audi technician used his oscilloscope he was still getting a reading off the injector when the car was running on three.
He overlapped this 'bad' cylinder with another one and got exactly the same curve.
My thinking is as follows: An oscilloscope requires very little electrical impulse to make it work, whereas my cheap and cheerful tester as well a the injector itself probably needs more current.
So, looking at the problem backwards, the injector is receiving the signal, but it is not strong enough to activate it.
The ECU commands the earth signal, not the positive. So, if there was a bad earth between the ECU and the battery minus and this built up a resistance after a few minutes running, to the point where the injector would no longer work, then this could be the problem...
When the dealer ran a two parallel wires from the ECU to the injector, it made no difference. In reality, what I believe is needed is a better/cleaner earth on the other side of the ECU, to allow the negative return to have no resistance.
What confuses me still is why the car behaves like this only at tickover? With the engine running faster, does the alternator charge the battery better and thus the electrical circuits are "stronger"?
I hope that my logic is not utter rubbish!
Cheers Spike for getting me thinking out of the box.
P
 
The G61 doesn't detect which cylinder is knocking only the existence of knock. The ECU calculates it by working in combination with the G40 hall sender and the engine speed sensor to determine which cylinder was firing at the time of the knock.

Could the G61 knock sensor itself be faulty? I note you say it's almost the only thing on the engine that hasn't been replaced?
 
I live in a seaside town and every year when the fat Parisians come on holiday here, they leave their cars for repair as the labour rate is so much cheaper than Paris....they also get free parking at the dealership. It causes mayhem for the dealers.
So my little A2 was pushed so far down the priority list, that it got forgotten for the best part of four months. Every time I went to the dealership, I would get the promise that they would start on it that day....bla...bla...bla.
It seems that the headwork will be covered under warranty. Lets just hope they have a training budget for the rest! If the customer finds the solution when all along they had an oscilloscope reading saying there was a signal, then why did they not fathom out the possible lack of earth themselves?
We are not out of the woods yet, but I have a good feeling about this latest clue.
 
Hey Philippe ...
Now I've Read your posts on This matter... Did i Solve your issue?
I've Got an 2000 ibiza with the same 1,4 16vaua engine and it's Also cutting cyl nr 2.... Despite head removal, new ecu, etc.. Etc..
I'm currently looking out for A wiring loom, because everything Else works...
Vcds ( vw scanner) sets no faults...
Best Chris
 
The German thread probably has more information; I'm pretty sure there was a camshaft change involved. And the last information was that no, it wasn't solved...

More info and lots of links here: http://www.a2-freun.de/forum/showthread.php?t=48156

Could this be a frost issue? Short trips, cold weather means condensation in the system, it freezes and then causes oil starvation. Hence bent cams and the UK guys have never heard of this because it's not cold enough for long enough there. And a 2000 model would be in exactly the right place for the issue...

- Bret

- Bret
 
Solved!

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!
Hope this helps someone else.
With kindest regards,
Philippe
 
Very happy for you Philippe.

I'm glad it sorted, pity it took so long and cost so much.

Thanks for updating the thread, and in such detail.

John.
 
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