Audi A3 2.0 PD hiccup, hesitate, jumping, jerking

Hello everyone,
I'm a completley new member here.
I serached every single thing about my cars problem here and still didn't find any solution. I'm desparate!


I own a Audi A3 SB 2.0 TDI (140hp, Bmm engine code) with a DSG trans (6 speed) from year 2006.

After a complete engine rebuild and cleaning ( all new gaskets even the one for the tandem pump, seal, injector seals, hidraulic lifters and other inside parts, new EGR , timing belts and so on...) the car hiccups, hesitates, I don't now how to call it (like cuting off power or boost for a second... stoping for a second) around 1900-2500rpm on light throtle.
Also there is a lot of black smoke ONLY on heavy accel (over 3000rpm) driving on highway, but seems to be gone.
For Example:
when driving 140kmh on the highway in 6th gear there are very 'litlle' constant hiccups/jumps almost unoticable.

City driving in 2nd or 3rd gear when pressing the gas pedal litlle harder the hiccup/jump becomes more noticable (it throws me slightly forward like I hit a wall for a sec) a litlle more gas and it drives fine....

There are NO error codes at all, everything was checked and seems to bee tight and in its place and my mechanic just can't find what's causing this. Soo pleasee help if anyone knows what coudl it bee.
As I said every single moving part inside and outside the engine was changed with a new one and the car still does this...


The engine is like new and instead of going like a dream it goes worse than ever (((

Check the actuator on the turbo and the vacuum lines you are losing boost and the engine falls on its face and blows a big puff of black smoke. This same thing once happened to me.

Thanks a lot Nevada TDI for your answer and advice, I'll give an update after I check it. Just like u described its like the engine is stumbling...

Another thing after the rebuild my car can't go over 180km/h on the highway and before it could easily reach 195-210km/h.

Sometimes when this hiccup/jumping happnes there is a sound just in front of me ""like there is some flap closing and opening"" for several times during this hiccup/jumping.

Which version crank sensor does that engine use? The one in the block or the one in the rear seal flange?

oilhammer said:

Which version crank sensor does that engine use? The one in the block or the one in the rear seal flange?

Click to expand...

Hmm sadly I don't now, maybe someone else does...

Medzid22 said:

Hmm sadly I don't now, maybe someone else does...

Click to expand...

Perhaps ask the guy that is "stumped" that you mentioned as your mechanic. He or she would certainly know if that is who rebuilt the engine.

We do not get that engine/car here, which is why I am asking. And both have a different diagnostic strategy to check for a possible solution to your problem.

Update:

I looked at the engine litlle myself and there are two very litlle hoses(vacuum lines I asume) that are wet like something is leaking from them. One of that litlle hoses is going directly on the turbo actuator. Some black fluid is that coming from these two litlle hoses or??
Could that be my problem?

Hope you'll be able to open the images...
https://ibb.co/jZRqHJ
https://ibb.co/b7Zo4y

NOTE: The white stuff on this plastic hose is super glue, its fine...

Oh yeah, vacuum hose should be dry. And holes are bad.

Just got from my mechanic and turns out the vacuum lines are fine. Still no Error codes, car still hiccups/jumps and can't go over 180km/h
(only about 175km/h)

Also there is a sound when this is happening, like some flap colsing/opening for several times (during the hiccup) not a hiss sound...


My mech advise "drive it until something brokes, I don't now what is causing it".................

Yea, good mechanics are hard to find. Look at your vacuum tubes, if they're original I would just replace them all.
Interweb guessing; Note: "some flap closing/opening" many of these are vacuum controlled.

Sad story but true.... The mech will check all the boost/vacuum hoses this week.
Don't want to be a pesimist but seem like I'll have to go in a VW or Audi authorized service to fix this issue....
https://ibb.co/nAkkKy
https://ibb.co/f7z1sJ


The worst thing is that there are no error codes.... damnn

Just woundering could this sound I hear maybee come from the EGR cooler actuator and can it cause my hiccup??

oilhammer said:

Which version crank sensor does that engine use? The one in the block or the one in the rear seal flange?

Click to expand...

Hmmmm.... ignoring this then I guess....

On Monday the engine will get apart again to see if everything is ok, alo I'm going to test the car with the 'EGR software remove' to see what will happen...

Eitherway I will post for sure what happed after that, did I solve my issue or not...

Cheers everyone for your replies and sugestions ����

oilhammer said:

Hmmmm.... ignoring this then I guess....

Click to expand...

Noo my friend I will check this with my mech.... this Monday he will take the whole engine apart again to see if something is broken or not good

Please let us know what fixes it, i have the similar hiccup at similar rpm 1975 to 2375 at light throttle and its quite abrupt back and forth in seat, been that way since i bought it, its a 2.0 bkd, and you can accelerate out of it, and i also get a little more black smoke upon heavy acceleration than it should, no hiccups at anything over 130km/hr ...so it will be interesting what you find.....did your hiccup clear up on its own while still under light throttle


My 2.0 bkd has it in rearseal not sure on the bmm

PROBLEM SOLVED!!

Bad EGR even if it was NEW.

The car just ''don't like'' it. I dissconected it and the accel is smooth as Bethowens simphony, no hiccups, hesitate nothing it drives like a dream ) It's easy to test just unplug the el. jack from the EGR and take a spin. Will try a complete new EGR again, if it happens again then I will remove it completley (softwer delete).

Again thanks everyone for your time, advacies and sugestions. Cheeers ))

Race777 my hiccups were on a light throtle (city driving when I need to drive litlle faster, highway when I drive on a constant speed and give the car a litlle push) and very litlle black smoke on really heavy accel.
I have written what was the problem (post before).
I 've put a complete new EGR ventile the day I first got the hiccups. My old egr had some error and the hiccups were terible, almost unable to drive. After that I placed a new egr and they happend not so usual as before but still they were there. No error codes, all was clean, all hoses were tight and in their place, everything was perfect but the car still used to hiccup,hesitate, jump on accel. Today I just unpluged the EGR (two lights came up on the board because of that, nothing serious) and took a spin. The engine was "fluid as milk".... no hiccups, no smoke. It drives like a dream. So my conclusion is that the EGR is a litlle ***** witch I will remove completley if the second new EGR makes the same things again.

You can test it also by unplugin it and taking a spin. After that you can connect it again and you will need just someone with a diagnostic device to delete the errors( if they don't delete themselfs)...

I will still test the car for 2-3days by driving with the EGR unpluged then I'll try another new EGR if it happens again then "hello software remove"

Another update... So my problem is 1000% with the EGR valve, as soon as I plug it on the car hiccups/hesitates. When I unplug it the car drives like a dream. Soo I will perform a complete EGR software remove. Hope my problem wich I solved will help someone else too

Removed and plugged the vacuum line to egr valve and no more hiccups, pulled over and plugged it back in and hiccups came back , so thanks for the help diagnosing.

race777 said:

Removed and plugged the vacuum line to egr valve and no more hiccups, pulled over and plugged it back in and hiccups came back , so thanks for the help diagnosing.

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You are welcome, glad I was able to help you
I will perform an EGR sofwtare delete on mine. I tried a second new EGR (under waranty) and had the same hiccups again. No EGR - no problem!
Cheers bro ����

Your problem lies elsewhere, the EGR being operational is just pushing it over the edge.

oilhammer said:

Your problem lies elsewhere, the EGR being operational is just pushing it over the edge.

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Maybe an ECU remap would fix it, beacuse the ecu is controling when the egr will open and close... But for now unplugin it is the easiest way...
Car runs fine like butter without it )

I do not think you are understanding. The fact that the engine "runs fine" without the EGR plugged in, doesn't necessarily mean the EGR valve is the problem. And the fact that you tried yet another new EGR valve and it still does the same thing kind of confirms that.

It is more likely that something like the MAF is sending an incorrect value, and since the ECU uses that as its primary means of working the EGR valve.... it won't be able to properly work the EGR valve... which means the engine can run poorly. And even tuning the EGR out of the ECU's operational strategy may not actually do justice if it is still using the incorrect MAF data.

It is like saying "my engine has low power, so I am going to put a bigger turbo on it" when the reason the engine had low power in the first place is because there is low compression in two of four cylinders. A bigger turbo may make a sick engine make more power, but it is still a sick engine.

This is why the tuners get so frustrated, because they by proxy get drug into chasing some driveability problem that was there before OR suddenly showed up after the fact that the tune only made worse. I get a half dozen or more sick TDIs in here a year with owners asking for "chips, remaps, tunes" etc. and I always, ALWAYS, evaluate the health of their engine BEFOREHAND before doing anything like that. If you are not starting with 100%, you cannot expect more than 100%.

Now I admit, I am not familiar with your particular engine, as VAG never sold such an animal here, nor anything like it, I can only relate some general basic method of operation as applied to VAG diesels. However, the common sense rule always holds true, and trying to go about it some back door way is not really the best way to address a driveability issue.

I totally agrre about everything you said and understand that. And the two sensors were the first things I've checked after the hiccup started. But my MAF and MAP sensors are clean and healthy. Also the injectors are showing good on the vcds
( if its not lying). As soon as I unpluged it I've got my old car back (before the rebuild) powerfull, smooth, without any hesitate or smoke. My problem wasn't so much about power. The hiccups were the problem when driving, overtaking or trying to get in the traffic. The only thing the EGR valve, as far I'm familiar with it, is to recilculate the exhaust gases back again instead of letting them go dircetly to the exhaust (at least on diesel engines) . For me it's like eating something, throw out and eat it again... You can't feel good at all after that. Same as the engine, instead of getting cold and fresh air in it gets warm and crapy air again wich had already been in the engine.
It can be fixed by driving the car while its plugged in on the diagnostic so the specialized mechanic can edit the opening and closing but it takes a lot of time, money and uneccesary waste of fuel...

So I've decided to remove it (only softwer delte) because even if I fixed it I wonder how much would it take until the same hiccups came back.
I appreciate your respond .

EGR actually lowers combustion temps, just FYI. That is its sole purpose. Displaces oxygen. Under high load demand, it is off anyway. I suspect something is causing a higher-than-normal duty cycle in your engine, causing the issue you are having.

Not saying to delete it or not, just saying I would want to be sure of everything else first.

oilhammer said:

EGR actually lowers combustion temps, just FYI. That is its sole purpose. Displaces oxygen. Under high load demand, it is off anyway. I suspect something is causing a higher-than-normal duty cycle in your engine, causing the issue you are having.

Not saying to delete it or not, just saying I would want to be sure of everything else first.

Click to expand...

Can you expand on what you mean by a higher than normal duty cycle?