VRS Tdi PD running issues

[GeorgeL]

Since taking ownership of my VRS I have been very pleased. However, I have be surprised with the variations in performance. On occasions the car can feel very flat and somewhat under powered. On the flip side the engine can feel very strong and pull very well. I have had the engine remapped by P-Torque.

More recently the car has began to judder under acceleration. In the higher gears it feels like the I am coming on and off the pedal. This doesn't happen all the time mind. Today I was cruising on the motorway around 85 with no apparent problems. It wasn't that I noticed anything until the traffic slowed to 55mph and then cleared that I wanted to resume my cruising speed. When I put my foot down the turbo feels like it spools and as it starts to pull all most instantly there is a sensation of throttling back. Its like the turbo almost cuts out.

A bit later on the glow plug light came on, and the other week the DPF light came on for a very short while. My local dealer has checked the ECU and the VAGCOM "apparently" hasn't show any errors, except for a single overboost.

I am a bit lost with this one. Is it down to the remap? Is it the DPF? Was the plug light a red herring? Maybe the acuator or the veins in the turbo are sticking? Or maybe I am nowhere near with any of my hunches?

If anyone could shed any light or suggest anything I might wish to try I would be very grateful. I have till January to before my Manufacturer Warranty expires, obviously I want to resolve it before then. Or at worst I want the car to blow up before then! lol

Cheers in advance.

George

[Nick P]

Hi George.

I have exactly the same problems with mine. I had the DPF removed a year ago, so I can take that out of the equation. The car has always had an intermittent habit of hiccuping when putting your foot down after a long time of cruising at a constant speed, usually accelerating out of one of those average speed camera 50 limits on the motorway. Very recently, the problem has gotten much worse and is happening annoyingly often and can happen at any time I'm at full throttle, not just after a long period of steady cruising. As far as I can make out, the only things that could account for the problem suddently getting worse are:

1. N75 valve sticking

2. Sticky vanes

3. ECU adaptation (reflashed the map just over a 1000 miles ago)

With that in mind, I did some VCDS logging of requested boost, delivered boost and N75 duty cycle...

That graph shows me accelerating hard in 3rd and into 4th. Right after I got back on the power after the gear change there was a big stutter. You can see the boost spikes (although the ecu doesn't give values above 2601mbar to VCDS so we can't see how high it actually spiked). The N75 duty cycle looks very strange to me, but I don't have a healthy PD170 graph to compare it to.

Ben and Mikko at Shark Performance were very helpful and put one of their maps on for me temporarily to see if it was just a mapping issue on the Custom Code map. Mikko kept tweaking the N75 tuning, but we couldn't eliminate the problem. This leads me to think that it has to be a hardware issue.

I took the vacuum line off that goes to the VNT actuator from the N75 and tried sucking on it. The VNT road seemed to move smoothly. I also tried doing the N75 test from VCDS which also appeared to move the VNT rod fine.

It's driving me mad. :S

[GeorgeL]

Hi!

Thanks for the reply. Unfortunately I can't see the graph at work as the image hosting site is blocked. It sounds like you've tried a fair amount of stuff! I'll be going back to the stealer and asking them to look at it again! I'm worried about the turbo tbh. I've had a lot of back look with VAG Tdi units in the past. As I see it if the problem is reported whilst the car is in warranty, even if they can't diagnose it before the warrenty expires the fault is still covered. Is that correct?

On a sperate not my adaptive service light came on after 7k? Now either the system wasn't reset properly or I need to switch to standard service intervals! What should I expect mileage wise between services?

[mark kelsall]

as for the service light, i dont really get it, we have a few octavia's at work, bought at the same time, the 1.9tdi service light came on at 7k, one of the other 2.0tdi pd units came in at 11k, ive got just over 14k on mine and im yet to see the service indicator light come on.

[Nick P]

I've never seen it come on at anything less than 18,600 miles unless the garage reset it to fixed.

Probably best if we keep the focus of the thread on the boost issue, otherwise that'll just get lost in a mountain of variable service chatter.

[GeorgeL]

I've never seen it come on at anything less than 18,600 miles unless the garage reset it to fixed.

Probably best if we keep the focus of the thread on the boost issue, otherwise that'll just get lost in a mountain of variable service chatter.

Yes quite right! I'll take the car do another dealer and see what they have to say. The car actually lost power completely yesterday. It felt like it had gone into limp mode?

Gotta love this...

[Nick P]

Sounds like it could be your N75 aka boost control valve aka pressure converter. But I'm surprised if it's gone that bad that it hasn't lit the workshop light on the dash. Take it to the dealers or get someone with VCDS to scan it.

[GeorgeL]

Sounds like it could be your N75 aka boost control valve aka pressure converter. But I'm surprised if it's gone that bad that it hasn't lit the workshop light on the dash. Take it to the dealers or get someone with VCDS to scan it.

Thanks mate, I'm going too! The only lights to appear, and go off again, are the plug light and what I am assuming is the DPF light?

[Nick P]

IIRC, the glow plug light will flash or stay illuminated (can't remember which) if you drive the car with the N75 electrically disconnected.

[GeorgeL]

IIRC, the glow plug light will flash or stay illuminated (can't remember which) if you drive the car with the N75 electrically disconnected.

Ok, so that would suggest the N75 (Whatever it is) could be faulty.

[Nick P]

It's a likely candidate in my opinion.

[Nick P]

I've ordered an N75 at a cost of £36 inc VAT. Will fit tomorrow. I suspect my £36 outlay will guarantee it's not the N75 at fault and is the MAP sensor or VNT mech or something else, but you've got to start taking things out of the equation somewhere.

[GeorgeL]

You sound about as optimistic as me! Let me know if you get a result or not.

I've still not found the time to get to a main dealer yet.

[Nick P]

N75 didn't fix it

[GeorgeL]

LOL, I feel a little guilty letting you spend your hard earned to solve our joint problem! I'll try and get across to a main dealer next week with my car.

[Nick P]

Yes, get yours fixed please and let me know what it was. I need to know whether I need to put the stock map back on and re-fit the DPF so I can just take it in as a warranty job.

[GeorgeL]

I will do! Work will be alot quieter the week after next so i'll get it across to the dealer then

You are not alone with your running issues by the way. Maybe worth joining SCN and sharing your findings?

DPF Delete Leon FR TDI

[AndrewJB]

Thats my Thread

Yep its a Common PD170 Problem, Mine had never done it until the day i had my DPF Deleted but it seems theres a few Standard ones who also have the problem

[GeorgeL]

Its a flipping ballache. It doesn't look like theres a fix to me either!

[Nick P]

Mine's gotten so bad now, if I hadn't spent money on other areas of the car, I think I'd be looking to trade it in. As it is, I need to get to the bottom of this.

[cheezemonkhai]

Tried the MAF I assume?

I only ask as this might tell the car there isn't enough air and stall the turbo.

[Nick P]

It's not the MAF - the car will still do 140+ mph and boost well as long as you're higher up the rev range.

[Genoa1893]

Just throwing out words: injectors? Are they free flowing?

Air intake: is everything clean?

[Dolla]

Could be map sensor

may be worth having the turbo cleaned

interesting that it showed an overboost

I got the 170 pd engine standard with dpf still fitted it's done 16700 miles,so far not had any problems..

[cheezemonkhai]

It's not the MAF - the car will still do 140+ mph and boost well as long as you're higher up the rev range.

It could still be the MAF as I've had stuttering at certain revs caused by the MAF.

A replace fixed it, I can only imagine that it had an odd output curve (There are some electronics on it to go wrong).

I'm not saying it is this, but a MAF swap would disprove it.