Bky engine stalls on idle.. cured if you unplug egr valve

[Damiansheffield]

I have a 1.4 16valve automatic fabia with bky engine. The engine cuts out when idling but i found that if you unplug the egr valve it is fine... so far i have cleaned the tthrottle body., egr pipework, breathers, replaced the fuel tank breather valve and crank case breather valve.. it has also had a new egr valve but nothing has cured it... the local garage had it for 6 weeks and sent it back with the egr valve unplugged and said they couldnt find what was causing it. I have searched all over the net for answers and come up with nothing... im about to just scrap the damn car its been a nightmare since i got it! Anyone know why i might have this issue? 

[Breezy_Pete]

What year is the car?

You could try an experiment that might narrow down the problem. Fuse 7 in the cabin fusebox seems to power the EGR solenoid, and the heater in the PCV system, and nothing else that I can see at a glance*. Remove that and see if the engine behaves itself at idle even with the EGR connection in place. I'm doubtful that it'll make a difference, but it should be a quick and easy thing to try. This will put a fault light on, I expect, but I should think you're seeing that anyway with EGR unplugged? If it does make a difference, it may suggest that the EGR is being opened in an uncontrolled way (e.g. by a wiring fault between it and engine ECU).

On my BBY engine (previous version to BKY) the EGR isn't used below about 1500rpm, or below a certain coolant temperature (50?), but I don't know that the BKY employs the same strategy. Does yours show the problem during warm up, or only at operating temp?

 

* Edit: erm...a better glance suggests it'll stop the power steering working too, so best do this test on the driveway, handbrake on.

Edited 17 December, 2017 by Wino

[Breezy_Pete]

@Damiansheffield, please note the quite important edit to my above post.

[Damiansheffield]

Thanks for the reply... I tried the fuse with the egr connected.. no different... I've noticed on certain pics of the egr online that there is a small pipe at the side of the egr valve, mine is not connected to anything.. any idea what should be on it?

 

[Breezy_Pete]

The little round plastic thing in some pictures is a tiny air filter.

[Breezy_Pete]

Check the brake servo vac hose for leaks at the joints.

[LB123]

I had problems with my daughters 16v BBZ (same engine) with unstable idle and occasional stall. Also had fault code for EGR. First replacement from GSF wouldn't adapt and was faulty. Second one was fine. But you do need to run adaptation with VCDS to set it up. On the basis that the ECU was telling me it was essentialy an unmetered air leak I finally bit the bullet and removed the inlet manifold and all its connected pipes. Replaced the MAP sensor and RTV coated all mating surfaces of pipes/sensors/joints and refitted. Did EGR and Throttlebody adaptations and it idled like silk.

 

I fixed it but I don't know exactly what I fixed.

[LB123]

Here was one of the leaks I did identify. Servo hose.

[kbo21]

Hello guys, sorry to dig up this old thread but I have exactly the same issue with my Polo 9N, which also has the same BKY engine.

 

I've been driving with my egr valve unplugged since I found out that unplugging it cured the unstable idle/stalling (it does stall inevitably).

 

Damiansheffield if you can hear me.. Did you eventually find a solution?

 

Note: I have vcds lite in case anyone else wants to help me out

 

[Breezy_Pete]

Using @Damiansheffield should send a notification that may bring him back to have a look at your post @kbo21.

 

Have you examined the brake servo vacuum pipe for splits at the terminations as photographed above by @LB123?

[kbo21]

Hi Wino, thanks for the tip!

 

I did check the servo hose when this problem started (early 2019...) although not very thoroughly. I can't see how it would lead to such symptoms though. I mean, wouldn't it affect idle even without EGR ?

 

I will check again tonight just to be sure.

 

Also what the OP didn't mention is whether he did the basic settings of the EGR valve and throttle after disconnecting/changing them.

[Breezy_Pete]

19 minutes ago, kbo21 said:

I mean, wouldn't it affect idle even without EGR ?

 

I have a suspicion that the ECU will go into a different operating mode when the EGR is 'undetected', and that mode may be more robust against 'false air' problems.

Just a guess TBH.

[kbo21]

It makes sense...

I read another thread on a french forum where the guy tried an interresting experiment after facing a similar issue. So, he first replaced his egr valve while investigating on another problem, then noticed that he had stalling issues at idle when the new valve was plugged. He then tried connecting the old valve (unmounted) while leaving the new valve mounted and disconnected. Well, the issue was the same.

 

So maybe the ECU does use a more robust control alorithm when no valve is found.

[sepulchrave]

This is definitely caused by an air leak somewhere, if you haven't found it then you simply haven't looked hard enough.

 

If you or anyone you know uses a vape then blow a nice fat cloud of vapour down behind the engine while it's running and look to see where it gets sucked in with a torch, it should be pretty obvious.

[kbo21]

Hi guys,

so my situation evolved a little bit. First, I got a DTC while doing some tests with the EGR valve plugged:

17519 - Oxygen (Lambda) Sensor Regulation: Bank 1: System too Lean
P1111 - 35-00 - -

I researched a lot about that and it seemed to confirm the vacuum leak theory. "Unfortunately" I don't smoke and don't have any close friend who smokes either so I couldn't do the test you said @sepulchrave

Anyway, a few days ago, I plugged the EGR valve, performed the EGR basic settings with vcds, then I tried starting the engine but it stalled right away. I tried a second time and gave some gas about 3000rpm and this time the idle went perfectly stable! I then got the following DTC:

16825 - EVAP Emission Control Sys: Incorrect Flow
P0441 - 35-00 - -

 

So now, I think that the vacuum leak must have come through my canister purge valve N80 (for which I had an intermittent defect once before) that must've remained stuck open.

My car has been running fine with the EGR valve plugged since that day. I ordered a replacement valve and it should arrive tomorrow. Hope it will be the end of my problems.

 

I noticed something weird though, here is a photo of the canister purge valve connector on my polo.

I measured the voltage while performing the output test of the valve with vcds, turns out it was -10V between the black/blue and red/purple wires. I thought red was the +12V and blue the GND? The valve is from Bosch, ref. of the valve is 0 218 142 345.

 

 

 

[kbo21]

I forgot: I also tried actuating my valve by applying GND to pin 1 and +12V to pin 2 and I couldn't hear any clicking sound, so that's what made me think the valve is faulty (unless i applied the wrong polarity?)

[Breezy_Pete]

Yep, wrong polarity.

Blue/black on pin 1 is the positive feed from fuse 14 in the cabin, purple/red on pin 2 connects to the engine ECU. This will be pulled to ground in a PWM waveform to actuate the valve, I think.

[kbo21]

Hi!

So, no more problems after replacing the canister purge valve!

I had a hard time passing all the emissions tests (the readiness statuses in vcds). Actually all statuses passed after 1 or 2 drive cycles except the Catalytic converter. After 100km+ and 5+ drive cycles it was still "Failed or incomplete". Eventually had to get its temperature up to 430°C and perform the basic setting to get it "passed".

Anyway thanks for your help @Wino @sepulchrave

 

[kbo21]

By the way @Wino, could you tell me where/how to find this kind of info?

 

On 12/10/2019 at 19:16, Wino said:

Blue/black on pin 1 is the positive feed from fuse 14 in the cabin, purple/red on pin 2 connects to the engine ECU. This will be pulled to ground in a PWM waveform to actuate the valve, I think

 

[Breezy_Pete]

Good news, and thanks for letting us know what solved the problem.

[Breezy_Pete]

Just now, kbo21 said:

By the way @Wino, could you tell me where/how to find this kind of info?

 

 

 

There's a site called erWin Skoda (and another, very similar erWin VW;  best for you) where official workshop information is available, for a small fee. You can download entire pdfs of wiring (and/or workshop/repair manuals, and/ or self study programmes).  The cost for one hour of access is just 7Euros plus tax. Find what you need under the 'Individual Vehicle information' tab. If you browse around ahead of paying your 'flat rate' you can usually get a hell of a good deal in terms of information per Euro. I've always run out of ideas about what to download before the hour is up.

[kbo21]

Wow! Awesome!!! I ran accross this website during my research but I didn't check how it worked. I might give it a try next time!