1.4 TDi hesitation at 1800rpm

Steve Gom

Member
Hi folks,

I'm looking for some advice on something which has just started to happen with my 2001 A2 1.4 TDI. Car is standard, 128K miles, engine service with new belt and tensioner done by Wayne at Autotech NE in April 2021 at 126K. MOT passed Sept 30/9/21. I did use a bottle of Redex in the fuel up before the MOT after a good thrash, but with no signs of the problems Im about to describe.

On the commute to work this morning on the busy A1 I noticed a pronounced step in the power delivery from 1800rpm to 2K rpm, accompanied by some sooty smoke from the exhaust. Once over the 2K rpm the car pulls well until the next gear change. However, when coasting and the revs drop below 2Krpm the car wont' pick up cleanly and only slowly builds up rpms to the 2K mark before revving up as it used to.

Can anyone direct me to a decent indy garage in the North East (Newcastle or Morpeth would be ideal) so I can get the fault diagnosed and potentially addressed.
Whilst 'Alan' is just our station/dog car I'd really like to get it running properly again, unless things turn out to too expensive to remedy.

Wayne has just returned to work having injured his hand and ribs and has no free appointments until 2nd week in Dec and I'm keen to get this sorted asap.

Any input would be greatly received on the potential issue/s and where best to take it for some advice.

Many thanks,

Steve
 
VCDS scan is needed to see what the car has diagnosed. Dirty fuel filter or water contamination could cause this. A failing tandem pump, injector issues either injectors or loom, pressure air leaking from the N75 system and not controlling the turbo correctly, boost air leak, intercooler leaking ( cracks now turning into split ), EGR valve issues, .... and this is not even a finite list.
 
Assuming filters all up to date my guess would be the injector wiring harness, you can test the resistance quite easily.

Mine did a similar thing, fault was injector one. Removed harness and tightened terminals, refitted and touch would all ok
 
Thanks for you suggestion Howey ? - I have the car booked in for some diagnostic work at Swift Motor Engineers, Westerhope on 16/11 so back on the VFR for the commute to work until then.
 
Thanks for you suggestion Howey ? - I have the car booked in for some diagnostic work at Swift Motor Engineers, Westerhope on 16/11 so back on the VFR for the commute to work until then.
Are you aware that there is a list of members that are offering free scan to other members ?
If not, take a look at the this link and see if there are some nearby you :)

I hope this can be useful for you
Cheers
dieselfan
 
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On my last car, a TDI 75, I had the problem you describe which was fixed by replacing the MAF sensor. I think it can be cleaned but I didn't know that at the time. I had just bought it and spookily it was on 128 000 miles!
 
Thanks Diesel fan - I'll try Ozzie for a scan (and get me spare key re-programmed at the same time maybe:)) If it's straight forward I'll get it sorted, if not I'll see how much Swift want to do it.

Providence - I'd happily replace the MAF sensor if that's the problem.

Cheers
Steve,
 
On a famous auction site a MAF sensor is £20 and quite easy to change yourself. That's why I mentioned it. The (non-Audi) garage I was using at the time were looking at codes and couldn't decide what to do until I came on here (in 2012) and saw that it had worked for another member.
 
Just an update. Nothing obvious from the VCDS scan performed by Autotech but whilst having 2 new lowers arms and set of Brembo discs and pads fitted I got the Fuel filter changed along with a perished rubber vacuum pipe, but still have the hesitation on a light throttle accompanied by a puff of smoke until the revs start to spin up.
It's OK driving the car with a heavy right boot, which makes me think this is not the turbo, but going to get a 2nd opinion. Will let you know how I get on.

Cheers,
Steve
 
Be ideal to have someone sit in it while you drive aadn they can watch VCDS live data on turbo and injectors? May show something. What about throttle position sensor and the ASV valve teeth? Could they be a thing to disrupt the smoothness?? Just ideas.
 
Thanks for the further suggestions folks. The problem seems to be beyond me, but I'm no mechanic hence the imminent trip to Swift Motor Engineers, VW Audi specialists. Just hope it's something cheap. My spend on car will be approaching what i paid for it soon :-o
 
A faulty Air mass meter rarely shows up as a fault in a code scan, try driving the car with it disconnected and see if that makes a difference, if you decide to buy a replacement, don't go buying a cheap one, pay the extra for a quality one my preference would be Pierburg.
Another possibility could be that your EGR valve it not closing fully
 
A faulty Air mass meter rarely shows up as a fault in a code scan, try driving the car with it disconnected and see if that makes a difference, if you decide to buy a replacement, don't go buying a cheap one, pay the extra for a quality one my preference would be Pierburg.
Another possibility could be that your EGR valve it not closing fully
More stuff to try, good advice ?
 
Pulled the MAF connector and drove the car. Much smoother than before with no hesitation, especially at lower revs after changing gear under 30 mph.

Car pulls well in 2nd and 3rd gear upto 4K rpm but seems a little flat in 4th and 5th. Its as though the last 10% of shove at the top end and 4K revs is missing.

Going to try a new MAF sensor but which 1.4tdi engine do i have, AMF or BHC? Car is a 2001 model with the smaller 35L fuel tank.

Cheers Steve


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Pulled the MAF connector and drove the car. Much smoother than before with no hesitation, especially at lower revs after changing gear under 30 mph.

Car pulls well in 2nd and 3rd gear upto 4K rpm but seems a little flat in 4th and 5th. Its as though the last 10% of shove at the top end and 4K revs is missing.

Going to try a new MAF sensor but which 1.4tdi engine do i have, AMF or BHC? Car is a 2001 model with the smaller 35L fuel tank.

Cheers Steve


Sent from my MAR-LX1B using Tapatalk
2001 will be an AMF ?
 
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