BPC - weird (and scaring!) vibration

and_pir

Aktiv-Mitglied
Hello ppl. Once again I'm here seeking for help. I finnaly bought that t5 for my friend. 2007 2.5tdi bpc manual. Frankly now I regret this… it was my 1st diesel of this type so maybe I'm paying for my inexperience.
I have to be long to describe well what happened.

I had to drive the van for 4000km, and it worked fine, but:
1) the output tube that was opened because the van may have hit on someting in the underbody, so I came back home breathing the eau de toilet du vw PDE, since the smoke entered in the van;
2) an overally weird smell of the smoke, very heavy and irritating for my throat; but at that time I could not know that since this is my 1st experience with modern diesels. At that time I just thought it was because of the diesel gate.
(If I get lungs cancer now I know why)
In short, the lights were all down, no indication of malfunctions, no visible smokes, a great drive thanks to all that torque and an amazing mileage (I have the VR6...)!!! The DPF was fixed recently (I have the bill).

After 1500km I could service it so the output tube was fixed properly, the memory checked and also I got some more controls (injections balancy and more). All ok.
At 2000km, I had an uphill drive in the mountain where I just had a little of fun with the gas pedal to enjoy the bpc. When I got down the van to open the trunk, I remained surprised because the smell of the output gas was different, a lot less stinking, and a way less irritating. I could just not recognize it… and I was happy of that. I could not understand what happened, but since it was an improvement, I just was happy. A super engine and now "clean" as well...

The happyness lasted a little because while comeing back in the down hill, the light of the engine (the one about the antipollution system, that looks like an engine) turned on. I connected that the smoke smell changed with that and brought it to the service. They told me that I got 2 errors, one about the lamba sensor and the other about the device that weights air. They just turned off the light and send me away.
In a little of kms, like 100, the light turned on again. Back on service and this time it was only the lamba sensor. Again they cleaned the memory and sent me away because I needed the van to prepare for my friend and had to drive it for 1500km again. They said to drive it without fear because the lamba is not important for the engine, it's only to keep the smokes clean.
The light turned on almost immediately.
I did what I had to do, and then I handed the van to my friend.

I noticed that he has the tendency to drive it with a long gear with very low rpm, near to overcharge the engine. Especially, he stops or slow down in 3rd and push the clutch the last moment. Actually, the first days, he used to force the engine off by pushng the clutch too late.

The other day he calls me telling me that now the van "vibrates". I drove it and noticed nothing, but he wanted to drive and I saw that SOMETIMES the engine vibrates at the idle or near the idle.
What is curious is that the engine starts to vibrate when he reaches the stop or the traffict light or the roundabout with a long gear, as I said, like 4th or 3rd or even 2nd without pushing the clutch in time.
The engine starts vibrating, the vibration is light, like if it was somehow unbalanced; you can feel it clearly in your lower belly and under your feet. But that phenom happens seldom and last a short of time, like less than 1 minute and if you have the chance to get the green light in like 10 secs and you accelerate a lot, it stops vibrating (you can stop again, in a correct way with the clutch down, and feel the regoular idling). However sometimes it happens again even if my friend drives correcly, like you are driving at 40kmh and you can feel it. But until now, it never happened without that my firend makes his "trick". It's like it works fine until my friend doesn't awake the problem up doing his trick.
The vibration is sporadic and never happens if you are motionless with the engine idling, like when you start the engine and wait immobile (both warm and cold engine). It happens only when my friend drives and does it trick in before; but it's not normal anyway, otherwhise it would not keep vibrating for so many seconds or even starting on vibrating again in a short of time.

Now the idea I have is that this problem could not be due to engine's wear or other mechanical parts problems, because the vibration would always be there. I think it could be connected to the lamba and the air weighter, but I can't know that because the light is on for a while and I don't have the vag com. But since the mechanic is not sure himself, I fear he will change a lot of parts and not resolve the problem. Also I wonder if someone hided the lambda problem by the manipulation of the electronics (creating that nasty smoke).

But what scares me is that, since it is likely realted to an electric problem, it could also be something related to the PDEs, like one of the 5 that is dying…. and this would be a real tragedy. Malfunction of the injectiors create damages to the engine, also when you have to open it, they say it's just better to get an engine swap that means a bill higher than the van's value.

Now I really regret to have offered myself for such a favour.

What do you think could create this vibration? Which part should I make my mechanic check?
Thanks ppl
 
Hi,

Was the Lamda changed with the DPF or is this the old one?

And another wild guess: Check the AGR system (Abgasrückführung. Beats me, what this is in English, sorry).
A cleaning of the valve might be enough, they collect soot over the years and might not work well then.
The vacuum control might also have an issue.

Regards
 
Thx, I told this tipp to the shop guy.
However he said that we can't know nothing for sure before the problem of the lamba gets fixed and that this new problem could be related to that.
The EGR should be killed, in my opinion XD. I'm sure that, when dirty enough, it can mess up other sensors.
The van is parked at the shop's internal lot. As for now, I can only wait and hope for the best… :(
 
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