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Discussion Starter #1
G'day from Australia,

Apologies for the long-winded post - it's somewhat structured and should give enough background to paint a decent picture of what we're dealing with at the moment. Please ask away and we'll work to reply ASAP. We're GMT+10 here.

We've got a 2013 Skoda Yeti (CDAA motor) - 1.8 litre 4x4 model with the 6-speed manual gearbox. It's in a very "mature" mileage range, at 190,000km (118,000mi), and it's had some rather expensive surgery of late, though she still ain't right.

In 2016, we bought the car second-hand, and have since replaced a bunch of parts:
  • Clutch (original replaced with a Valeo)
  • Master & slave brake/clutch cylinders
  • Water pump (replaced due to a leak)
  • PCV valve (bypass was usable)
    • Thought to relate to #2
  • Radiator (original cracked)
  • Accessory belts, etc
As for regular services, and what's been done in the last 5,000km, we're looking at:
  • Oil filter
  • Fuel filter
  • Engine air filter
  • Cabin/pollen filter
    • Filters all Ryco
  • Spark plugs (NGK)
  • Ignition coils (NGK)
  • Battery (Century)
  • Engine/motor oil
  • Gearbox oil
    • 10k ago
The car has been developing some strange issues of late, and our European specialist mechanic has been struggling to work out what's going on. Looking at the subject/title, the issues are numbered and are then named affectionately.

#1 :: On ignition, as you turn the key to start the motor, there is a single click in the exact same instant that all 12V power disappears. Interior lights go out, gauges go blank, 12V sockets have diminished power (enough to light up a tiny LED, but not enough to power the accessory itself), remotes/keys aren't able to lock/unlock the car, etc. Provided with enough time, the 12V returns after that distinctive post-turn-off "click"/"knock", and a subsequent attempt will either succeed in starting the car (which proceeds to issue #2 if the motor was cold), or has the same fault, after which another attempt or two gets it started.

#2 :: When starting the motor after a cold night (it gets to just above freezing point here at the moment), if issue #1 doesn't prevent it from happening then in the first 20-30 seconds of operation the motor's idle rev varies significantly. 1k RPM is the "average" while cold, then it should settle to around 0.8k RPM. The fluctuations see it vary from 0.6-1.4k RPM, and the drops/peaks can be rapid. The drops can be severe enough that you can see them in the exhaust's output (in that cold phase when the output looks like steam) as small but complete gaps in the exhaust output, with the rev gauge dropping to 0.2-0.4k RPM, even stalling out in worst cases if we don't try to intervene.


Issue #1 (CLICK DEATH) has rapidly been getting worse, and from research online it appears that the #100 relays may need replacing? We rang the local spares distributor for Skoda and they advised that our relays have been replaced with a newer vintage, and advised that to replace the 2 of them we're looking at over $100AUD (about 65 quid). Opinions on that fault have been hard to locate, and include a potential failing starter motor or just the solenoid/switch that could be on the way out. Given the immediate loss of power with an A-OK battery, I would assume that the issue is electrical somehow, though the computer read-out doesn't seem to definitively point a finger, despite the volume of metrics within.

#100 relay: 4H0951253 - Relay. Power - Genuine Volkswagen Part

Issue #2 (COLD GRUMBLE) has been gradually getting worse over the last 1-2 months, and is now consistent. We're avoiding that problem by applying very light throttle to the motor during that susceptible period (raising it by 0.2k RPM) and then removing that power once the revs stabilise (at which point the throttle input is enunciated and the revs climb significantly). I'm assuming that it's at that point when the motor's out of the "stone cold" phase of calculating its needs, as it proceeds in to "normal operation". Maybe it changes from reading one sensor to using another? Or perhaps a sensor with a partial blockage is then a bit warmer and able to move, so stops sending wild values through to the ECU?

Our mechanic was confident that the PCV valve was clogged and in need of replacement to fix the issue - he was able to change the idle noise by (very briefly) blocking the valve's bypass on the side. It was replaced, though the issue remains just as bad. The mechanic is now suspecting that it could relate to carbon build-up on the intake valves, as he thinks that the mileage bracket would align with that - a potentially expensive hunch - they also suspected a stretched timing chain, and then landed on the PCV valve which didn't resolve the problem. This wild goose chase is becoming quite costly.

Next steps; thoughts; etc

We're able to pick-up the #100 relays from the distributor if it's likely that it'll resolve the strange issue #1 CLICK DEATH, which is becoming frequent to the point that it's unusual if it doesn't occur once or twice before the motor starts. From reading online, relays either work flawlessly, behave really strangely and inconsistently, or are completely broken. If it's the relay/s in this case, then it seems as though we're sitting in that middle state. What could the problem be caused by? Is there something that we could/should check with a multimeter to verify/rule-out a problem?

As for the #2 COLD GRUMBLE, we removed the Mass Air Flow (MAF) sensor and cleaned it with Liqui Moly Air Flow Sensor Cleaner. It was then left out for a few hours to dry in a ventilated spot, then reinstalled with the car left off that evening and through the night. We first thought that the issue was resolved the following morning as the roughness was 90% better, though the following day it was as though that "fluke" had never occurred. Whether that means we didn't clean it enough, or that the temperature that night was higher than others, or whatever else remains unclear.

It was recommended to us that we disassemble the throttle body and clean it out. We purchased some WD-40 Professional throttle body / carby / choke cleaner, however after researching online some people reported that they made their problems worse by attempting to clean the throttle body, so we erred on the side of caution and held off. We can go ahead with that clean, likewise with another clean of the MAF sensor and anything else that could be relevant (O2 sensor?) - at this stage, we're looking to gather other opinions before we invest much more money and time in to the car. Given the "cold start only" nature of the rough/stalling idle, what are the most logical potential causes? Where/what should we be checking to further narrow down the problem?

Issue #1 has worsened very quickly.
Issue #2 has been more gradual.

OBD read-out

We've already dealt with a damaged wire in the driver's side wiring loom, which is common in this car especially at its age. That occurred a couple of years ago, and the suspect wire was replaced. In the last few days we took a full OBD read-out from the car via OBDeleven to try to get a better idea of what could be going wrong with the internals.

It threw a bunch of control unit faults, many relating to the LED globes that we've fitted. Some did appear more interesting though, primarily with regard to the emissions. Since the below was taken, we've cleared the codes but are yet to do a read-out again - that's likely to happen in about a week, after which point we can check again, though the below codes were thrown relatively recently (last 1-2,000km) so I don't believe that they're stale entries by any means.

P0441 - EVAP Emission Contr.Sys.Incorrect Purge Flow
Intermittent (This reads like it could be related to our issue #2 COLD GRUMBLE?)

00470 - Combination comfort databus in single wire Open circuit
Intermittent

02123 - Door warning light / entry light Electrical error in circuit
Intermittent (Suspect this means that more wires in that loom are on the way out)

01316 - Brake control module No signal/communication
Intermittent

Life of the car

We've heard of the CDAA motor (with the manual gearbox) lasting in to the 300,000km (190,000mi) and beyond range with regular love, and if we're able to navigate through these problems then we don't see a problem with continuing the relationship. It's a fabulous car and not one that we'd like to do away with, especially considering the rarity of them these days. The VW dealer themselves saw it and said "you wouldn't trade that in to us if we tried to convince you, would you?"

Any and all help would be very much appreciated. If we're able to do anything at all, please let us know and we'll get straight on to it - with some luck, we'd like to see our plucky Yeti see us through another 100,000km of driving pleasure.

Cheers,
Bastian
 

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I've given your list a quick scan only so far.

Issue #1
You say the battery is ok, so have you checked the earth(ground) points and earth cable between body and engine?
 
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How old is the battery, has it been stress tested in anyway, are you able to "borrow" a replacement battery? Many years ago I had a Ford with nowhere near the electronics but similar starting problems which turned out to be a failing internal battery connection. If you could borrow a battery you could rule that out at nil cost.
 

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#1

Second vote for poor earth or battery connections, given that all the other electrical things seem to die at the same time (Assuming that the battery itself really is OK!).

Without a good solid reference voltage the car can be prone to all sorts of running issues as it is difficult to get stable readings from sensors etc.

Perhaps a simple test would be to put a volt meter onto the battery terminals and have an assistant try to start the engine.

If the battery voltage drops a lot (like from 13.8V to 10V or something), when you just get the 'click' then that suggests a duff battery, but if you get a click with a minimal drop, then that suggests the juice is not really getting to the starter.

Sod's law says it will just fire up perfectly for you though ! 😁

Spag
 

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Third vote for the battery to engine block (starter) earth connection not being continuous or only intermittent. So the earthing is otherwise being forced to take a different path, that can’t cope with the starter’s draw. I had similar symptoms to #1 some years ago on a Ford Escort Mk1. That turned out to be the earth cable between body and engine/gearbox broken but still looked OK to the eye. So the earthing was going via the clutch cable! Could also cause some of the other weird “faults”?

I’d check that before splashing out on the relay. Although the relay could still be an issue?

When you fixed the front door wiring, was just a single broken wire replaced? Inside the door to A-pillar trunking. Or the whole door loom replaced? If the former, other wires can fatigue and snap too. Intermittent continuity in the door loom can cause all sorts of seemingly unrelated faults. Similarly was just the driver’s side fixed? Or both front door looms? Both sides are vulnerable. Just the driver’s side usually gets the symptoms first, because that is used more often. Recommended replace the whole loom if there are visible problems with any individual wires.
 

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At least you don't mention the bane of 1.8s, the thirst for oil.
 

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Fourth vote for duff earths or duff battery terminal connections. Absolute classic symptoms. If the latter, it it possible one of the battery terminal connections will feel warm to the touch after repeated attempts to start the car.

And a second vote for Flintstone's suspicions about the front door(s) wiring. Broken door wires have caused all manner of weird and seemingly unrelated faults on older Yetis. Later Yetis have a modified wiring harness.

Oh - and welcome to the Forum! (y)
 

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Discussion Starter #9 (Edited)
G'day all,

Many thanks for your replies about issue #1.

You say the battery is ok, so have you checked the earth(ground) points and earth cable between body and engine?
That's not something that's come up, so to date we haven't checked. Interestingly though, when the issue #1 doesn't occur it sounds as though all starts up as usual. I suspect it could be intermittent though? (the best kind of car trouble)

What's the best method for checking those earth/ground connections? The main one (bolts on to a plate to the right of the battery) has a decently large gauge cable connected to it, which runs straight across to the negative pole of the battery. Aside from that, there's a smaller gauge cable connected to a separate bolt for the UHF radio & LED bar.

How old is the battery, has it been stress tested in anyway, are you able to "borrow" a replacement battery?
Brand new in November 2019, so 10~ months. The current battery: Century DIN53LH (500 CCA)
Reference: Product - Century Batteries

We replaced the original VW/OEM battery with a Century, though the shop assistant provided the wrong size (1.2L) for the 1.8L Yeti. We went back a couple of years later due to the quick death of the battery, and once they realised what they'd done wrong, it was replaced with the correct battery (which fits the holder). Above is what's now installed.

As for stress-testing, it hasn't been properly checked by an auto electrician (ie. with a CCA tester that I'm assuming you're referring to?) since the install, though it's been happily starting the car since install, including during #1 & #2.

There aren't any batteries here that we can swap out for, though we might be able to convince our auto electrician to temporarily swap ours out for a brand new battery to see if it changes the behaviour. Is that worth going ahead with?

Alternatively, we have a CTEK battery charger (12V/5A) that we can hook up if you think the voltage should come up. That's more to do with my reply to spagley below, which shows the resting and failed-start voltages.

Perhaps a simple test would be to put a volt meter onto the battery terminals and have an assistant try to start the engine. If the battery voltage drops a lot (like from 13.8V to 10V or something), when you just get the 'click' then that suggests a duff battery, but if you get a click with a minimal drop, then that suggests the juice is not really getting to the starter.
We've just done this. Resting voltage was 12.8V which would likely align with not being driven much recently due to the issues. This Century battery has an in-built status indicator which reports that the battery is OK. When we attempted to start the car, it produced the #1 "click" fault, dropped to 12.4V and then crept back up to 12.8V. Turning the key to ON (pre-starter) was responsible for about half of that drop, then the start attempt did the other half.

You're suggesting that the minimal drop would indicate that the power isn't reaching the starter - does that point the finger more towards the relays? Or does this strengthen the concerns about a potential earthing fault in the car?

Sod's law says it will just fire up perfectly for you though! 😁
Weirdly enough, not this time around! I guess we should be grateful that issue #1 is worsening? 🤔

Third vote for the battery to engine block (starter) earth connection not being continuous or only intermittent. So the earthing is otherwise being forced to take a different path, that can’t cope with the starter’s draw. I’d check that before splashing out on the relay. Although the relay could still be an issue?
Fascinating - tying back in to my reply to bryetian, what's the best method to check earthing?

VW aren't very descriptive about what those relays do, but they take enough amperage that I'd imagine they'd "have to" be mission critical to the starting procedure. They're 4-pin, and someone suggested we can test them with a multimeter? If it was them though, it appears that the fault is intermittent so I'm unsure if that'd help. Apparently they can "stick" and behave oddly.

When you fixed the front door wiring, was just a single broken wire replaced? Inside the door to A-pillar trunking. Or the whole door loom replaced? If the former, other wires can fatigue and snap too. Intermittent continuity in the door loom can cause all sorts of seemingly unrelated faults. Similarly was just the driver’s side fixed? Or both front door looms? Both sides are vulnerable.
Our old auto electrician didn't consult us about that, they just went ahead and "patched the broken wires", so either the full lengths of the broken wires were replaced, or the damaged sections were replaced with new pieces of wire. Given the reasons we moved on from that auto electrician, I'm going to assume the latter. Only the driver's side was patched/repaired, so I suspect that both looms are looking to start causing mischief if they aren't already.

When they went, it aligned with suggestions here - all manner of gremlins emerged. Central locking had a meltdown, windows decided to open at bizarre times, and apparently the OBD read-out made for quite a spectacle. Checking on the car in the mornings, it had changed things (locks/windows) from how it was left the previous evening. Through all of that though, the starting process remained OK, though it could be that different wires are now on the way out.

At least you don't mention the bane of 1.8s, the thirst for oil.
Didn't mention it, but definitely suffer from it! Scary how much it chews through across a year - we've brought our oil change interval up from every 10,000km to every 5,000km for a few reasons, that being one of them!

Oh - and welcome to the Forum!
Thank you! I've browsed the forums plenty, but until recently haven't had a need to post.

Appreciate the warm welcome and all of the help thus far! :)

Cheers,
Bastian
 

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Discussion Starter #10
G'day again,

You were all bang on the money! The shop that installed the new battery didn't put the negative/earth connector on the pole properly. Adjusted that so that it's properly installed, and the click'n'die issue is resolved.

Thank you very much to everyone for the assistance, very glad to have that fixed - especially without having to replace the #100 relays. 4 matching opinions were unlikely to be wrong, so thanks for the opinions all!

As for the tricky problem #2, with the rough idle and stalling on a cold start, based on what I've written above, what's likely to be worth investigating there? Is the OBD emissions code related to some degree?

Looking forward to hearing back. Thank you again!

Cheers,
Bastian
 

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Excellent, glad that #1 was such a cheap and simple fix !

Now you have solid power, I'd be inclined to clear any fault codes, then run it for a few days and re assess the codes and symptoms again.

I am not familiar with the P0441 problem, but some info suggests that a faulty purge valve can cause rough idle, which seems fair if it's opening & closing in appropriately. Possibly worth unplugging the valve briefly to see if the idle changes, clean and wiggle it's connector, then see if that changes anything or look at replacing it as it doesn't look to be an expensive part. If you can't find it, I'll have a dig in the manuals and post a pic if I find one !

How much detail does obdeleven give? Is it just a summary or fault codes, or is there a more detailed listing?

Spag.
 

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You were all bang on the money! The shop that installed the new battery didn't put the negative/earth connector on the pole properly. Adjusted that so that it's properly installed, and the click'n'die issue is resolved.
That's a good result where a full description of the symptoms helped a lot to point to the reason for the problems.

On the rough idle issue, I'd second spagley's suggestion of investigating the purge valve. This opens to allow the engine to scavenge fuel vapour collected in the activated charcoal canister. If the valve sticks open, for instance, excess air/fuel vapour will be drawn into the air inlet upstream of the turbo.
 
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Discussion Starter #13
G'day Spag, bryetian & co,

Excellent, glad that #1 was such a cheap and simple fix !
You and me both! Glad we didn't rush off to buy the new relays.

That's a good result where a full description of the symptoms helped a lot to point to the reason for the problems.
Communication both ways has been thorough - I'm in IT, where clear explanations make the world of difference, so I try to convey things clearly where possible. Really appreciate that everyone here has been detailed and clear too.

Now you have solid power, I'd be inclined to clear any fault codes, then run it for a few days and re assess the codes and symptoms again.
That's a wise move - thank you. I'll export the OBD status quo then clear the codes this evening, then will run the car through to this weekend, at which point we'll take another read-out. In the few days between now and then, I'll play around with the purge valve (as below) noting the mileage when we do it to see if it correlates to the subsequent read-out this weekend.

I am not familiar with the P0441 problem, but some info suggests that a faulty purge valve can cause rough idle, which seems fair if it's opening & closing in appropriately. Possibly worth unplugging the valve briefly to see if the idle changes, clean and wiggle it's connector, then see if that changes anything or look at replacing it as it doesn't look to be an expensive part.
Looking around online and through the engine bay, I've located and marked the charcoal canister and purge valve. I'll unplug the purge valve to see if it alters the engine idle at all, and will let you know. About to head on a journey, so will hold off until tomorrow. Keen to hear other thoughts/ramblings on issue #2 for the time being! :)

If you can't find it, I'll have a dig in the manuals and post a pic if I find one !
Do you have the service manual for the 2013 Yeti per chance? We were able to download ELSAWIN however are yet to install the monster that it is. It'd be great to have the service manual on-file as we do for the motorcycle if you had it and were kind enough to share it! We've got a server at home, so may end up sacrificing some space for an ELSAWIN virtual machine (VM).

How much detail does obdeleven give? Is it just a summary or fault codes, or is there a more detailed listing?
It gives a standard read-out, outlining each system (inc. IDs, serials, sub-systems, coding, etc) and any fault codes under each of those. In addition, it provides access to metrics and graphs (ie. catalytic converter temperature, throttle position, angles within the motor and such). Beyond that, there is a crowd-sourced method to research fault codes from within the app - I think it'd glean similar info to Googling the daylights out of codes.

Further, it allows you to apply custom coding to the ECU, enable/disable control units and after-market fittings (ie. TPMS if you fit the sensors post-purchase) and so on. An example of a control unit read-out in full is below for context, though it doesn't have any sub-systems under it.

01 Engine

Software number: 5L0907115C
Software version: 0040
Hardware number: 1Z0907115F
Long coding: 0203000C180F0160

Trouble codes:
P0441 - EVAP Emission Contr.Sys.Incorrect Purge Flow
Intermittent
Priority: 0
Frequency counter: 1
Driving cycle: 255

Mileage: 188886 km

The Google Play Store listing has some decent screenshots which give you an idea of its interface and abilities, which are prettier than the above output (which is an excerpt of a "data export" that it lets you email yourself, but doesn't show you within the app itself). My father-in-law bought it for his 2015 Audi A3 after a bunch of research as to the best way to avoid a $400 service interval reset fee at the dealership (to DIY it, after the capped-price servicing ended). Unlike the Ross-Tech enthusiast options, OBDeleven isn't VIN-limited.

On the rough idle issue, I'd second spagley's suggestion of investigating the purge valve. This opens to allow the engine to scavenge fuel vapour collected in the activated charcoal canister. If the valve sticks open, for instance, excess air/fuel vapour will be drawn into the air inlet upstream of the turbo.
I'm learning about a bunch of components that I'd previously only stared at and gone "I wonder what that does" - glad to hear that the OBD code to do with the purge valve is potentially related to issue #2. Would that sort of valve sticking issue be susceptible to faulting on a cold start, then releasing / resolving itself as the motor warms up? Most people we've spoken to give up with helping as soon as we mention the roughness being in the first minute of operation only.

Cheers,
Bastian
 

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Cool, that's great that obdeleven gives good diagnostic details, it looks similar to the output from VCDS, so the count and mileage are great to pinpoint what occurs during testing.

On a bored afternoon I subscribed to erWin Online | Škoda Auto | for an hour and scooped a big bundle of Yeti PDFs, so have those for reference.

While publishing or sharing those in full seems to be a bit iffy in terms of copyright etc, it seems fair use to post the occasional snippet from time to time to promote understanding of the products :)


It's possible that the valve is sticky, so perhaps the ECU runs through a few 'turn it on and off again' cycles over a period of time before it finally operates as expected?
Maybe temperature does have an effect and it begins to operate when it's innards are warm and happy, or it could be a cable/contact issue which presses together better when warm allowing it to operate.

After a good run - so all is warm, if you stop the engine, wait for a couple of mins then restart, do you get the rough idle again to start with? That would give a yes/no to effect of temperature on device and general mixture control as you should avoid any 'cold start' enrichments and cold components.

Another thought, you could just try pinching the hose to the valve, both during rough idle and normal idle to see if that is the same as with the connector removed from the valve.

Not sure exactly what results we are after, but it's a good data gather!





4313


4314


Spag
(Software development chap for systems occasionally critical to loss of life. Work motto :- "You don't test things until they work, you test them until they don't fail any more".)
 

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So how long is it since #1 was fixed, has there been enough time/usage to establish that it has not cured both problems now there is a consistent contact?
Is #2 worse when the temperature is below freezing, have you checked all the obvious things such as when was the fuel filter last changed, could it be a build up of moisture in the fuel system? I had a Volvo that accumulated so much water in the fuel filter the engine started cutting out at junctions, a bottle of dry fuel is quick and cheap.

After #2 is dealt with even, if it is not part of the problem it would be worth giving some thought to the egr, all that oil being burnt will bung things up. Fuel additives are burnt before they reach the egr so they have little effect.
 

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Discussion Starter #16
G'day Spag & Hood,

obdeleven gives good diagnostic details, it looks similar to the output from VCDS, so the count and mileage are great to pinpoint what occurs during testing.
It's quick too, makes it easy when you can Bluetooth to it rather than have to set a laptop up!

Didn't get a chance (data centre visit for RAID card troubles) to reset the fault codes, but I'll do that this weekend.

On a bored afternoon I subscribed to erWin Online | Škoda Auto | for an hour and scooped a big bundle of Yeti PDFs, so have those for reference.
7EUR for an hour is beyond tempting, I just need to find the hour to download as much as possible. Or does it make more sense to get a day (25EUR) and spend half of it coding up a scraper? It doesn't look like there's too much volume provided it's just one model you're after.

It's possible that the valve is sticky, so perhaps the ECU runs through a few 'turn it on and off again' cycles over a period of time before it finally operates as expected?
That's similar to what we were suspecting - perhaps it does take that short period to kick it enough that it starts to cooperate.

After a good run - so all is warm, if you stop the engine, wait for a couple of mins then restart, do you get the rough idle again to start with? That would give a yes/no to effect of temperature on device and general mixture control as you should avoid any 'cold start' enrichments and cold components.
Is #2 worse when the temperature is below freezing, have you checked all the obvious things such as when was the fuel filter last changed, could it be a build up of moisture in the fuel system?
We don't get the problem if we've been using the car during the day, even after an hour or two since it's been driven last. Very much only first thing in a day.

The roughness is only first thing in the morning when it's been cold overnight, but it doesn't need to reaching freezing point to exhibit the symptom.

Fuel filter wasn't changed too long ago, swapped out for a Ryco just due to the interval, no roughness at that point. We run only 98PULP fuel.

Another thought, you could just try pinching the hose to the valve, both during rough idle and normal idle to see if that is the same as with the connector removed from the valve.

Not sure exactly what results we are after, but it's a good data gather!
That's an interesting one, we'll give it a go provided there's no likelihood to do any damage! From what I can make-out it shouldn't be dangerous, but I'm no mechanic.

So how long is it since #1 was fixed, has there been enough time/usage to establish that it has not cured both problems now there is a consistent contact?
Last night was warmer than expected, and the night before I got back late at night. It does seem like the issue may be improved with issue #1's fix.

I'll check properly tomorrow morning after tonight's colder forecast to see if it's better, and by how much if it is. :)

After #2 is dealt with even, if it is not part of the problem it would be worth giving some thought to the egr, all that oil being burnt will bung things up. Fuel additives are burnt before they reach the egr so they have little effect.
The internet seems to point towards diesels for the EGR valves being blocked up - are they universal across petrol and diesel motors, or is it more like a DPF in being specific?

(Software development chap for systems occasionally critical to loss of life. Work motto :- "You don't test things until they work, you test them until they don't fail any more".)
More like beat the living daylights out of! Some systems these days leave a lot to be desired.

Thanks for sharing the snippets about the canister and valve!

Cheers,
Bastian

(SysOps for a hosting/cloud provider)
 

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The internet seems to point towards diesels for the EGR valves being blocked up - are they universal across petrol and diesel motors, or is it more like a DPF in being specific?

(SysOps for a hosting/cloud provider)
G/day Bastian,

Glad to read we were on the money for #1.

EGR was originally invented for petrol engines in the 1970s to cut the California smog emitted by gas guzzlers. Used to be fitted to plenty, before Diesel engines started to become popular for passenger cars due to their inherently lower CO2 and fuel figures. Since fuel injection transferred to petrol cars and inefficient carburettors disappeared, enabling tech like fuel cut off during closed throttle running for example. Then EGR deployment on petrol engines also seems to have declined. It’s main impact is to reduce combustion temperatures during periods when max power is not required, by starving the engine of oxygen. There by reducing NOX as a consequence.

I think it’s far less common now on petrol engines. Much more popular on diesels. Hence in the modern internet era references you mention will generally be all about EGR in diesel scenarios.

Not at all sure if the VW 1.8 petrol engine had EGR? As that was quite an old engine design already when the Yeti was introduced. Also dropped from the line up fairly soon in the Yeti’s lifetime (at least in the UK market), as it didn’t sell well due to thirst for fuel and oil. Plus emissions put it in a seriously higher tax bracket than any of the diesels. I suspect not, but someone will know?

As for DPFs, yes, there’s a clue in the name. Although there was talk around 10 years ago of PPFs being introduced for EU spec cars. Before the VW “dieselgate” drew legislators attention away from petrol engine emissions.

Good luck with #2, etc.

When I was writing software and few years ago, then later creating test specs and data scenarios to test other people’s software (that made me rather unpopular in some quarters). There was an adage that “users get the software they deserve”. That meant that if you want it delivered to an impossibly tight time schedule and you want it cheap, but you can’t bothered to specify how you want it to work in sufficient detail, then what you get will be riddled with bugs. I always found it a very accurate and apt concept.
 

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The internet seems to point towards diesels for the EGR valves being blocked up - are they universal across petrol and diesel motors, or is it more like a DPF in being specific?
They do get fitted to petrol engines, SWMBO Fix Or Repair Daily has one that was problematic. Burning oil will not do an egr any good if one is fitted.
 

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Although there was talk around 10 years ago of PPFs being introduced for EU spec cars. Before the VW “dieselgate” drew legislators attention away from petrol engine emissions.
They were introduced around September 2018 to allow cars to meet EU6c emissions limits. Even VW is fitting them! They work more like a conventional catalytic converter, burning off the particulate as it flows through rather than collecting it and having an internal bonfire every so often.
 
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Discussion Starter #20
G'day all,

Many thanks for the additional insights in to EGRs.

On a bored afternoon I subscribed to erWin Online | Škoda Auto | for an hour and scooped a big bundle of Yeti PDFs, so have those for reference.
7EUR for an hour is beyond tempting, I just need to find the hour
I did an hour of access yesterday and managed to get a fair bit downloaded, see below for the haul. They're to-the-minute on closing you out, I was hoping to play with ELSA online, but it threw errors moments after my time was up. Many thanks for reminding me of ERWIN!
  • Everything (workshop manual, repair manuals and circuit diagrams) for the Yeti
    (There's a bunch of commonality across the different model-agnostic engines)
  • Workshop manual and circuit diagrams for every model available via the system
  • Pretty much every training manual, of the missing 10%~ I only wish I'd got 89 & 91
    (They're the only ones that matter - electrical systems, ie. not "how to present a Fabia")
It does seem like the issue may be improved with issue #1's fix. I'll check properly tomorrow morning after tonight's colder forecast to see if it's better, and by how much if it is.
Just tried this, and the issue is better but not resolved. Quite an unusual change to be honest, probably makes sense that it ties in to reliable power though - I'd say that the issue is almost as bad in terms of how it feels and sounds, but in terms of what's reflected by the rev gauge, since the resolution of issue #1 I'd say that the rev gauge is shielding/hiding the problem better.

As in, whereas before what I could hear and feel looked to be instantaneously reflected by the rev gauge, now only the larger variations and rev changes that sound to be engine controlled are visible on the rev gauge, while the smaller fluctuations can only be heard and felt. Perhaps that means that the engine/computer has a better handle on avoiding a stall occurring due to the issue/s?

I'd say that the underlying second problem remains almost just as bad, though it sounds more managed. Will clear/check the codes and try the valve troubleshooting before jumping to any conclusions - though I'm not sure if the above update may help with a diagnosis?

I always found it a very accurate and apt concept.
Exact same story with web development and IT project management - you can have any two of these three factors in your project: quick, cheap, good. You decide!

Cheers,
Bastian
 
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