PD Hiccup / Hesitation under light pedal

All three of the 4cyl PDs sold here use different intakes and EGR cooler setups.

The BEW is the only one with the twin intake ports, so it is the only one with that vacuum servo.

The BEW and BRM both have EGR cooler changeover flap servos, but the EGR coolers themselves are very different. BEW uses a Modine waffle style cooler, BRM uses a Valeo log style cooler.

BHW uses a log style Valeo EGR cooler, with no changeover flap. The BHW's intake is the simplest and least problematic. It also is the only PD that got a better Garrett turbocharger.

The BRM's EGR coolers fail because they leak at the changeover flap shaft, which is intagral.

The BEW's EGR coolers fail usually from a botched recall job where the bracket and fasteners get left off, which also causes the pipe to crack.

BHW EGR coolers rarely fail, but when they do, they just pump coolant into the intake/exhaust and cause a James Bond smoke screen behind the car.

However, ALL the PDs use an electric actuated EGR valve, and they ALL can suffer from the same hiccup driveability issue if that valve is not working properly. The BHWs actually had an early software update to address this.

oilhammer said:

However, ALL the PDs use an electric actuated EGR valve, and they ALL can suffer from the same hiccup driveability issue if that valve is not working properly. The BHWs actually had an early software update to address this.

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Interesting, guess the valve is the first check whenever a PD hiccup situation is involved.

UPDATE:

Even after the new EGR was installed, It still has a "slight" ever so subtle hesitation when driving...I will check the other things listed but its not too noticeable driving the car this way and my previous EGR was pretty clean honestly!

Don't know if the bew turbo has the same issue as the brm, someone more knowledgeable will chime in. if so, search on the zip tie mod (check myturbodiesel.Com as well.

The problem is it doesnt hesitate when the EGR is unplugged (even with the new EGR valve it hesitates and is very noticeable under load when pulling a trailer)


I would like to at least see what other options it could be; Next up is setting my torsion value as im still getting only about 37mpg...any suggestions?

How about the n18 valve that actuates the EGR valve?

eddieleephd said:

How about the n18 valve that actuates the EGR valve?

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The PD has no such device.

oilhammer said:

The PD has no such device.

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What's the circuit to be checked for this?

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The PDs (all of the three 4 cyl versions sold here) have an electric EGR valve that is controlled by a motor and has its own internal position sensor.

It makes a very noticeable hiccup when pulling my small trailer to the point that it will hiccup like 5 times and once it passes the 2k rpm range its good

This is a brand new EGR valve and if i unplug it, it never hiccups once


Im not around to adjust torsion yet but i will check that next as my mpg is around 35-37mpg

Well after experimenting with torsion from -1.0 to 1.0 to 2.5 the car still hesitates to the point where it makes a sudden stall and its noticeable; im starting to realize after $200+ in the EGR valve that it wasnt that after all; if i leave the EGR disconnected it runs fine no hiccups at all...im stumped on this

Would it be fine to adjust torsion to -2.5 or more and advance it to +3.0 and more? Im determined to see if i can fix this

trying to revive my old thread as the problem has gotten worse. I have a new EGR valve on the car and it hesitates bigtime when its under load. When i unplug the EGR valve its perfect...any ideas?!

Look elsewhere, it's not the EGR. The conditions change with it unplugged, making the issue go away, it's something related to air, could be circuitry related to those devices.. Does the PD have the anti-shudder valve with the EGR like the VE? Consider what else happens when EGR is unplugged. Esoteric, I know.

Checked the output tests and the EGR works as it should; wires seem all intact with no signs of wear but maybe im missing something?

It is so noticeable with the EGR plugged that ive been running the car with it unplugged until i fix it


I wonder if i missed something as i was checking?

Dannyboy said:

Did you check the Anti shutter valve movement with boost hose off?

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I did not check it (do i use VCDS output test for this?)

Seems as though my ASV is working properly so im stumped what else it could be at this point..

I think my Skoda is doing this too. It has a 1.9 PD BLS. It's very faint, I used to think it was doing a regen but now I'm starting to think it's something else. If I drive in 4th gear just below 2000 RPM with very light throttle I can feel it jerking a bit.
I replaced the DMF last year and that made it better so I thought that the flywheel was causing it but I think it was only making it worse because it was so worn and had a lot of play in it.
I haven't checked anything yet but will start with the EGR and gas pedal.

nokivasara said:

I think my Skoda is doing this too. It has a 1.9 PD BLS. It's very faint, I used to think it was doing a regen but now I'm starting to think it's something else. If I drive in 4th gear just below 2000 RPM with very light throttle I can feel it jerking a bit.
I replaced the DMF last year and that made it better so I thought that the flywheel was causing it but I think it was only making it worse because it was so worn and had a lot of play in it.
I haven't checked anything yet but will start with the EGR and gas pedal.

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any luck checking things out on it?

golfere said:

any luck checking things out on it?

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I've read the fault codes but didn't have anything related to this.
I checked the accelerator pedal via OBD2 and it showed very smooth action so I think it's ok.
Will check the EGR, but I saw that you have replaced yours and still have this hiccup so I'm not betting on that improving anything.

The hiccup on mine is very minor so it's not bothering me. Yet.

I wonder if the harmonic balancer (crank pulley) could cause this?

OK so I removed and cleaned the ASV and EGR and after my short test drive it actually seems like the hiccup is gone. We'll see if it was just too short of a drive or if it's fixed!
The EGR was very clean for the 295k km it has, and probably never cleaned.

Fingers crossed!

I noticed that the o-rings (more like x-rings) on the intake tubing looked tired, that's possibly a source for a boost leak.

How hard is it to remove and clean the ASV? Mine is significant and i need to get it fixed ASAP

I

golfere said:

How hard is it to remove and clean the ASV? Mine is significant and i need to get it fixed ASAP

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The ASV is the butterfly valve bolted to the intake. https://www.youtube.com/watch?v=RZRLTO1kx_o
Remove the intake tubing (boost pipes) in one piece between the intake and intercooler, undo the electrical connector on the bottom of the ASV, straight below the intake hose.
Unscew the three screws holding the ASV to the intake manifold and you're done!
There should not be much to clean since the ASV is upstream of the EGR, some oily residue is ok.

I have driven 350km since my EGR clean and the hiccup is gone! But it does regen too often IMHO, more than before (not related to the egr cleaning, just a side note)...

Good to hear! You cleaned the EGR and ASV?

Yes. But your car seems to have a more severe hiccup than mine.

It seems to not be so noticeable anymore! I just pressed the EGR plug harder after cleaning it

Still have the ASV to clean but why would cleaning it help that much?

It was the cleaning of the EGR that made the difference, I just cleaned the ASV since I had it removed for better access to the EGR and to be able to see if the intake was clogged.

The problem has came back again! I am starting to think that cleaning the EGR and the ASV doesnt fix it because once the EGR is unplugged it runs great! Trying to figure this one out and im stumped

Check out the last page of this rather lengthy thread. This guy has similar issues and finally solves it in the next to the last post.


http://forums.tdiclub.com/showthread.php?t=487065