Autoquip

So the update…. last night I eventually got round to replacing the crank sensor. I’d like to take this opportunity to thank the team of designers for putting the crankshaft sensor in the most awkward place. however I got it done and will just have to wait and see if it’s a fix or not. I will keep you all informed in the coming days. top tip if anyone is going to try this at home. Don’t mess around trying to unplug the sensor. Take the bolt out (it’s held in the sensor so shouldn’t fall out) then unplug the sensor when you take it out. Fit the new sensor and then plug it in. myself and one of my mechanics both had a go at unplugging it but it’s not easy to get to. Now that I’ve done one I reckon 20 minutes would change it but it’s always easier the second time round.

Hi mate, yeah you’re spot on about the glow plugs playing a bigger part in modern engines and truth be told I haven’t checked them. Might look at them if the fault is still there, cheers for the info 👍 going to post an update in another message.

Just beats me how these cars can have so much fancy electronics in them and this sensor has been playing up for months and yet it has never put on the engine management light or a fault code. I’m just thankful it’s not a customers car because this would have taken hours upon hours of diagnosis and I would have given it back and only charged a couple of hours. Difficult to charge all the hours when you don’t have a solution.

Hi Brian, my car has manual transmission so sort of takes that out of the equation for me. my car varies to be honest sometimes it’s very slight other times it’s quite a jolt. I'm going to try and get it on a ramp this morning, I’ll post later and let you know what I find. cheers

Evening folks, so might have made some progress tonight. On the drive home I was monitoring and recording live data for various sensors. My wife was in charge of pressing the “flag” button if the fault happened. This time it did happen and sure enough poised like coiled spring my wife hit the flag button. When I played the recording back, at the point that was flagged there was a dip in both the cam and the crank sensor readings! So I nudged the readings frame by frame until I got the frame before the hesitation the frame at it and the frame after. Luckily I was also monitoring crankshaft signal status as on the frame before and after the hesitation it’s reading is GAP FOUND but at the point of the hesitation it’s reading is WAITING GAP. I’m not going to get over excited for now. However, at least that gives me a starting point. I’ll remove the sensor and check the ring and flywheel condition as best as I can and then I’ll order a genuine sensor from Audi. I’ll run the car for a week or so and then I’ll come back with an update. I’d say this rules out a fuel issue, if it was lack of fuel I would still expect it to see the gap for the crank sensor. The only other possibility I can think of is that something is switching the ignition off for a split second but how unlucky would I have to be for that? (I do have a lot of bad luck to be fair). My only slight worry is that it’s visible on the graph for the cam, in my head I can make arguments as to why it would and why I don’t think it should be visible on both graphs. But let’s start with the crank sensor and take it from there. very sorry for the extremely long post, I’m not on many forums, I think they are a great source of information and I’m trying to be as informative as possible. wish me luck 🤞 Davie 👍

Nope not yet 😡. To be honest I’ve been busy with other stuff the past few days so haven’t really been in the car. I’ll get the diagnostics back on it probably over the weekend. I’ll keep in touch 👍

Hi toby, thanks for the reply, i certainly will let you know if i find anything. cheers, Davie

Spartacus I had thought about that fuel pump but couldn’t work out why it would cut the fuel for a split second. I think it would have to stop for a period of time before the engine would notice it due to the high pressure pump. However definitely worth checking out.

Hi toby, did you get a solution to your fault? Sorry to dig up an old post

Hi did you resolve your issue? I have the same kind of problem with my 2.0tdi ultra. However I’ve had no dpf light or engine management light and no fault codes either.

Hi thanks for the reply, embarrassing as it is I run my own garage! I understand about the different diagnostic equipment, I am using an up to date Autel maxysis ms909 which I use on a daily basis at my garage. The only other time I have had an issue with no fault codes was a VW Amarok, crank non start with no fault codes and it turned out to be a faulty cam sensor, however I picked that up reasonably quickly as it had no reading on live data when cranking the engine. I am still recording live data whenever I drive it, when I get to the bottom of it I will post here with what I find

Good afternoon, I am new to the forum so apologies if this is posted in the wrong section. I have an A6 avant 2.0tdi ultra with the CNHA engine and manual transmission. I have an intermittent issue which is hard to explain but I will do my best to explain what is happening. On occasion when pulling away from a junction it’s like it cuts the fuel off for a split second and then goes back to normal again, it can do this either pulling away from a junction or driving through the town at 20mph or even cruising at 50mph. It doesn’t seem to have any pattern to it and I can’t “make” it happen. Sometimes it can do it once then be ok for a few days and then do it again, it doesn’t do it every time I drive it. I’d say it seems to be when I am feathering the throttle. I have scanned for codes and there are no trouble codes present, I have tried recording live data for various sensors but I can’t seem to find any discrepancy in the readings. To be honest I wish it would just breakdown at the roadside then it’d be easier to fault find. I have been chasing this fault for about 3 months now and I really am stumped. I don’t want to light the parts cannon as I rather diagnose faults before I replace parts but I am struggling with this one. any help appreciated regards Davie