Octavia Mk1 - starts/idles OK but now power and black smoke on accelerating

[Wobsta]

As per title, starts and idles fine. No funny noises really at idle, just sounds like the tractor that it is.

 

KI can just about move the car on a flat surface at low speed but as soon as you put the engine under load it will just die. And there will be quite a lot of smoke and it does sound a little odd - almost like listening to the engine as though it's "baffled". I think it's something that's been deteriorating for a while as I had noticed that I had to boot the car a little more than usual up the many hills that there in these parts and thought I had seen some smoke in the rear view, but initially it was that gradual that I sort of doubted myself.

 

I've never really had problems with a turbo, but to me this doesn't make sense that it would be a dead turbo, as I would expect some performance from it in the lower rev ranges before the turbo kicks in?

 

Any ideas?

[KenONeill]

Maybe a popped boost pipe joint. I had this exact issue after a cambelt, when the pipework wasn't reassembled correctly. It's easy to diagnose, and way cheaper and faster than a blown turbo to fix too.

[Wobsta]

Have read of a few similar cases. Having read about how the setup works though, I guess my theory regarding the turbo being OK may be flawed. I guess the ECU could be underfueling (though black smoke implies unburned fuel I think) so maybe not enough air (scratches head). Air filter sure needs changing but I did run it briefly without the air filter on and the same problem was there from memory.

[KenONeill]

Black smoke is definitely over-fuelling, but this engine starts to boost from 1_200rpm, and if you're losing boost and the map doesn't back the injectors off far enough for the reduced air supply you'll be seeing the smoke man.

[Wobsta]

A couple of photos. I'm guessing the oily pipe connected to the air intake hose is for burning crankcase emissions and would likely be unrelated, but the round thing on the right hand side of the block (also oily) has to be a vacuum pump since it's connected to the brake servo. I presume that boost is regulated by vacuum too, so maybe worth checking the vacuum pump. A couple of days before Xmas I did have an intermittent hard pedal. Is that related perhaps?

 

I expect the way to check for a non obvious leak would be to pressure test, which of course I can't do. To be honest I generally leave engines alone other than servicing though I'm quite happy working on the running gear. It does seem to be a lot more complicated than the last diesel I worked on. Only really having a look as the time of year means I can't really get it in to a garage yet.

[KenONeill]

See the blackish rectangular section that runs through between the coolant header and the cam belt cover? I'm thinking you may have popped a joint in that pipe or the one below it (Turbo cold side to intercooler in RHF wheel arch and back to manifold).

[Wobsta]

Can't see anything obviously adrift there, did notice this, don't know if this is of relevance. Photos aren't great but you make out that one of the pipes is damaged, and the electrical connection is almost worn through also. I've removed it just to get a better picture of what it is, but since it;s directly connected  to the valve/gate on the intake (is that the throttle body?) I guess it could be. If that could be a cause, is there a way to test?

[KenONeill]

I'm not sure that's your fault, but it needs replacing anyway.

[Wobsta]

No it wasn't. It was still intact though very weak so I've bodged it for now with some chemical metal.

 

It isn't the turbo though, or it least I very much doubt it is. I popped the top left rubber elbow/boost pipe twixt the inlet manifold and the plastic part and also popped the cold side turbo to intercooler pipe under the car, and I can feel air blowing from the turbo when gunned, also looks nice and clean in there which isn't what I would expect if it had failed. Guess it could just seize though and look clean, but as I say there's a pronounced volume of air coming out the cold exit side and no odd sounds which is a good thing I think. Not very scientific but the best I can do under the circumstances.

 

I did however notice with the top elbow off that I have something (smoke/steam?) coming out of the inlet manifold which seems wrong given that the correct direct is inwards. Makes me think maybe of manifold/head leaks, maybe timing, or an inlet valve not closing sufficienty? I guess any of those would explain the lack of performance. I don't get smoke out of the exhaust either with the two pipes disconnected or not that I noticed. When the performance first dropped off the cliff, there were clouds of black smoke too, but not so much now. It's still not good, but it doesn't kill the local wildlife.

 

Any further thoughts?

 

I'll probably have a look at the timing tomorrow, but I guess it would be a compression test if valves aren't working properly.

Edited 1 January, 2019 by Wobsta

[KenONeill]

@Wobsta That won't help at all; the fabric hving worn through like that, that pipe will be collapsing internally, so all you've done is waste chemical metal.

[Wobsta]

Yeah I know, but there's not much else I can do today. I figure it's better than nothing. stuff sticks like the proverbial brown stuff and sets nice and hard so it can only improve things I think and I have a massive tin of chem metal . If nothing else the vacuum hose will actually stay in the hose clip now since it's thick enough. It's not a permanent fix.

 

I think it;s just the vacuum to the anti shudder valve in any case.

[Wobsta]

Ah just realised that that part on the inlet manifold includes  the exhaust gas recirculation. Maybe that's what I'm seeing coming from the inlet manifold, some exhaust. It looked exhaustish.

[Wobsta]

So, though I'll not mark as solved yet as it could still be one of two things, I have a functioning car again.

 

Ken, it appears you were correct; I was losing boost, but not through the boost pipes, but rather through the EGR valve it would seem. I put it all back together this morning and for good measure changed out the fuel and air filters (the latter was past its best - I live up an old unmade dusty road, so should probably halve the recommended service intervals). Anyway, I didn't expect that they would, but no difference was noticed.

 

Then I removed the vacuum pipe from the EGR valve - back to full power again. I have to investigate further though as I think it may be the solenoid rather than the valve - perhaps someone can help? Should there be vacuum at the EGR valve at idle? Fro what I've read I think that's a no. If that is the case I believe the solenoid is shot rather than the valve as without vacuum, all is well.

 

In any case I think I'll just delete the EGR going forward, but would like to know what caused the problem. Back on the road in any case. Will update after confirming valve/solenoid options.

 

[bigjohn]

On 03/01/2019 at 19:49, Wobsta said:

 

 

In any case I think I'll just delete the EGR going forward, but would like to know what caused the problem. Back on the road in any case. Will update after confirming valve/solenoid options.

 

 

I wouldn't delete the EGR if you want to pass another MOT. All emission components must be present and working now with no engine management light showing.

 

Sounds like it could be solenoid problem  - usually it's the other way round ie lack of vacuum!

 

[TheSkodaLover]

1 minute ago, bigjohn said:

 

I wouldn't delete the EGR if you want to pass another MOT. All emission components must be present and working now with no engine management light showing.

 

Sounds like it could be solenoid problem  - usually it's the other way round ie lack of vacuum!

 

 

Those VE engines like above don't actually have an EML they just put a flashing glow light on if something is a miss and usually puts it in limp mode having bought and sold recently an Audi A3 with a similar VE engine (a 110 as apose to the 90 above) that has a de cat and egr delete  it passed MOT first time you have to make sure it looks standard because the MOT tester won't know exactly what was fitted to what car in what year. Get it blanked !! itll do the engine a power of good not breathing in its own exhuast

[bigjohn]

9 minutes ago, TheSkodaLover said:

Get it blanked !! itll do the engine a power of good not breathing in its own exhuast

 

My mk I petrol does have an EML and the electric EGR is goosed (engine running just fine) and I've left it that way for some time to stop it breathing in it's own exhaust rubbish especially now the engine is getting rather worn. However, I (well my son now!) may get away with it come MOT as if you clear the code (insufficient flow) it takes a few days before it recurs.  You have to be careful with the new MOT though, lot's of cars now failing that would have passed pre May 2018.

Re Original Post - If there was no EGR valve at all it may get spotted but if still present but blanked off then if there is no EML you will probably get away with it. At least with these older engines it's a very simple valve, with the newer diesels with DPF, SCR the un relaible water cooled EGR is a complex setup and is a real pain to get at.

[TheSkodaLover]

On 06/01/2019 at 10:50, bigjohn said:

 

My mk I petrol does have an EML and the electric EGR is goosed (engine running just fine) and I've left it that way for some time to stop it breathing in it's own exhaust rubbish especially now the engine is getting rather worn. However, I (well my son now!) may get away with it come MOT as if you clear the code (insufficient flow) it takes a few days before it recurs.  You have to be careful with the new MOT though, lot's of cars now failing that would have passed pre May 2018.

Re Original Post - If there was no EGR valve at all it may get spotted but if still present but blanked off then if there is no EML you will probably get away with it. At least with these older engines it's a very simple valve, with the newer diesels with DPF, SCR the un relaible water cooled EGR is a complex setup and is a real pain to get at.

I'm not suprised the engine is worn being a 1.4 in an octavia how many miles has it done ? bet its not the quickest !!

[bigjohn]

2 hours ago, TheSkodaLover said:

I'm not suprised the engine is worn being a 1.4 in an octavia how many miles has it done ? bet its not the quickest !!

 

It has done nearly 130,000 miles now and will be 18 years old in March (my son now has it). Still drives well and doesn't burn much oil except during a brief period at about 80k when the crankcase ventilation pipe contained within the airfilter blocked with oil mayo - crankcase pressure blew oil past valve seals - easy fix though.

 

Except during the first 4000 miles from new it's been nippier than you'd expect for something with 75ps. Probably to do with the gearing and the way the engine is set up. Despite being a small 16v NA engine it's red line is low (about 5500rpm) and it's set up to pull well 2500-4500rpm. Holds its own on a Motorway even today (my son does lots of motorway driving in it now) and it has toured Europe many times in the past (at much higher speeds!). It still does over 40mpg but does rather like higher Octane fuel (has from new).

 

Not sure how long it's got left with the new tough MOT though although the body is more or less rust free and it's been meticulously maintained from new including a recent clutch, cam belt/water pump, radiator and full rear brake replacement (inc back plates)

 

 

 

 

Edited 20 January, 2019 by bigjohn

[KenONeill]

12 hours ago, bigjohn said:

it's been nippier than you'd expect for something with 75ps

Well, that's still more power than an SDi has.

[Wobsta]

So to update and mark (fingers crossed) as solved, I finally got bored of driving around with the EGR vacuum unconnected and investigated further today.

 

For ****s and giggles, I reconnected the vacuum pipe half expecting to be back to the original state of affairs described in the first post, but no, car was exactly as without it connected. Now I know the problem can't be lack of vacuum since brakes, turbo etc still work OK, so still points to a goosed EGR valve or the controlling N18 solenoid,

 

So I put a vacuum gauge on the EGR vacuum pipe, started it up, and gunned it from idle a few times to about 3-3.5k revs. At this stage, I can't say that I knew what I should be seeing but I what I did see was clearly wrong. The gauge sat at around 2 inches and gunning made the needle shake, but it stayed at around the same. Clearly there should be some change there as the alternative is that the solenoid does nothing (clearly not the case). To be sure, I checked the vacuum in, and sure enough I was showing around 27inches there, so all good to the inlet of the solenoid.

 

So, whipped the solenoid off to investigate. I applied 12v to the terminals, and not a thing. Should at least fee a click or hear something, I thought, but no.

 

The N18 I have looks like this (not mine, didn't take photos but looks the same)

 

 

So, to investigate further, I took a junior hacksaw to the metal band at the tap and released it. The top part then separates from the bottom part. The top part didn't appear to be blocked at all. The bottom half has a plunger the full depth of the bottom half with a red diaphragm at the top where the two parts join (so roughly where that metal band sits). Knowing how a solenoid works, the plunger obviously should move freely. Well, it didn't. So I removed the rubber diaphragm to avoid damaging it, and using some mole grips I removed the plunger. It was very tight, and gunked in there.

 

I cleaned the plunger with some sandpaper and the internal bore on the body with sandpaper wrapped around a screwdriver. Then flushed it with some brake cleaner, dried it, applied some light machine oil, reassembled, put the metal ring back and secured it with a zip tie. Tested it on the bench, got a click.

 

Put it back in the car, connected the vacuum gauge to the EGR pipe, and repeated the gun to 3k from idle, and lo and behold we now have over 15inches at idle and zero with some hefty throttle. So some significant differences in comparison to the previous state of affairs. I cleared the error code, and so far so good. Previously the error would com back within a mile or two, but so far no repeat. If truth be told I'd had an EML light for some time but put it down to the MAF sensor. Clearly I got that wrong. But for the first time in a while I have no EML showing.

 

My guess is that the initial state of affairs I described was caused by the solenoid sticking in the open "idle" position, so that all the boost was dumped out through the open EGR. All seems to be OK for now. I guess it will need changing at some point in the future, but who knows, but might run for 2-3 years yet by which time the car will likely be deceased.

 

Thanks everyone for their help.

Edited 22 March, 2019 by Wobsta