Octy VRS Mk1 intermitting turbo??

[DeanMcA]

Hi guys

 

recently purchased a 2005 Mk1 Octavia VRS estate off my grandad (believe it or not) 

A car I loved for 10 years and now I finally have my hands on it! 

 

One issue tho. When I got it the engine management light was on, plugged my fault reader into it and put me to a vacuum leak. 

After finding this forum I released it could (and was) a split hose. I changed the hose and light went out. 

 

But now I have an issue with the turbo. 

When accelerating the turbo will kick in but then cut out for a second or two and kick back again. It happens in every gear and at every point of accelerating. 

 

So my head went back under the bonnet and found another split hose. Changed it but yet the problem persists. 

 

I have checked the MAF and sensor. The ignition coils. Spark plugs and all remaining hoses! 

 

Looking to see see if anyone else has had or knows what the issue could be! 

 

Cant wait to hear your replies!!

 

[kentphil1]

Welcome to Briskoda,

 

What code did the reader show?, sounds like a connection issue to the n75, but without knowing the code we really are just guessing really. Have you rechecked for new codes at all?.

Edited 15 February, 2019 by kentphil1

[DeanMcA]

Hi, thanks for the speedy reply! 

The fault code was 16555 from memory. And after a bit of searching I figured the ‘y’ pipe was a good place to start and low and behold it was. 

 

I had checked the codes before fixing the second split pipe and it gave me 5 faults saying idle to high, running lean and that it was misfiring on 3 cyclinders. This only happened once and it definitely wasn’t misfiring on 3 cyclinders and the idle wasn’t high either. 

 

Is the n75 something I can unplugged to see if the issue is it or is it a case of buying a new one to try? 

[mac11irl]

The n75 is the boost actuator, so unplugging it would probably throw a limp mode failure and no boost,not tell you anything. 

How did you check the MAF? And us ut a genuine Bosch one, or a pattern part?

[DeanMcA]

Bugger! Might be worth buying a n75 then! 

 

I checked all hoses, connections and I had seen on here someone had said about unplugging the sensor and see if it resolved the issue but it didn’t. I also cleaned the connections with contact cleaner and double checked all hoses and clips. 

 

Its a factory part 

[mac11irl]

Well, the MAF test is - is the idle worse with it unplugged? If it stays bad/hunting without a maf then the maf is goosed. If the idle gets bad with it unplugged, look elsewhere, its doing its job. Or if it "seems" to run better on the move without the maf connected its likely goosed, as it will (on the move) run a default assumed air flow rate - fueling (lean or rich) and power might be off but smoother running.

 

But if it seems to be...

Cruising..... foot down... power loss or lumpy.... lift off.... cruise... all ok.

Then id be looking at n75 or divertor valve possibly?

[kentphil1]

At this stage I would hold off on getting another N75 as that code relates to general fuel trim.

 

When you checked all your pipes, did you check the breather pipes under the manifold or the vacuum pipes to the solenoid under the plate by the inlet manifold?, if not, I would start there.

 

More info on your code - http://wiki.ross-tech.com/wiki/index.php/16555/P0171/000369

[DeanMcA]

Driving with the MAF unplugged was no different to driving with it plugged in apart from a light on the dash relating to it. 

 

The second hose I changed was a breather pipe under the manifold. All the hoses around the manifold and the ‘y’ pipe have been checked and no leaks. 

 

I will I’ll have a closer look at the n75 today and take it for a longer drive with MAF sensor unplugged to see if the driving condition changes! 

 

I’ll keep you guys posted on the updates!! 

 

Thanks!! 

[naneek91]

Any more news on this? Sounds similar to a problem I am having. The turbo doesnt fully spool, I get a few small boosts while accelerating, feels almost like taking my foot of the accelerator every few seconds.