Misfire just on gear change

[redscout]

Hi

I kept my 09 octy scout (petrol 1.8) because the wife who is the main driver loves it and the dealer pushed me down the repair route after I identified on here that I needed the stage 2 repair.

I've now got a strange hesitation after gear changes (all gears) which an Indy and a stealer think is a misfire. I've no codes and no engine light. Coils and sparks have been swapped with donors to no avail. The only time I saw a slight improvement was after a fuel filter change (when I put some injector cleaner through as well). Since then I've run bg44k cleaner through and some millers the Indy gave me but no improvement. Stealer thinks it's a head off job to clean valves (they didn't clean them when it had stage 2 repair-CDAA engine) - I've seen the clean via inlet manifold technique and may try that next spring (no decent garage and it's chilly now!). In the meantime, can anyone offer any advice as to any sensors that might be on their way out and causing this?? VAG diagnostics show nothing.

[redscout]

OK. Just updating this thread to keep a track of my progress (or lack of) and to see if anyone can add anything along the way. If I solve it, it may become a useful solution to someone in the future.

 

Yesterday I pulled some sensors. The camshaft position sensor was full of crud on the connector so I gave that a clean up and cleaned the sensor end - the misfire after the 1st to 2nd gear change has disappeared but is still there on 2nd to 3rd etc. I've seen how to check wiring to this sensor but not how to test the sensor itself - is this possible?

 

I've also cleaned the inlet manifold temperature sensor but can potentially rule that out because the misfire was still there after that, though there's no guarantee that it isn't defective (and comparatively cheap to replace).

 

From reading other sources, the MAP sensor might be a culprit but as yet I can't locate it - any tips welcome. Likewise, I'd like to locate the crankshaft position sensor.

 

After servicing the car (and dropping a very heavy Scout undertray on my bonce) I noticed a fair amount of oil down the rear left (looking at it) of the engine (turbo area). This could indicate a turbo leak or be contaminating sensors in that area.

 

I can't find a  picture/diagram of this engine (1.8tsi CDAA) so any pointers or links would be hugely appreciated,

[redscout]

Coil connectors checked - Earth continuity is ok but don't have knowledge to check others, rubber seals replaced, terminal connections are fine

PCV system checked - appears ok but can't get top (circular) cover off to check internal diaphragm - will revisit if can find instruction

High pressure fuel pump cam follower checked - no sign of wear

[Almal]

They suffer carbon build up on the inlet valves and also the flaps inside the inlet manifold can fail. 2 birds with one stone maybe?

[redscout]

They suffer carbon build up on the inlet valves and also the flaps inside the inlet manifold can fail. 2 birds with one stone maybe?

Yeah, thanks. That's a job for spring though. I have very little shelter from the elements and don't want to be stripping it down too far in case I need to get it back together in a hurry...and I'd sooner be working on it without my extremities going numb from the cold!

 

Having said that I've been back under it today to look for the DV. I appear to have the G version and there are signs of leakage around the seal. I do have what sounds like a slight vacuum leak when I lift the throttle so I'm going to replace it anyway - didn't bother to remove it completely to check the rubber diaphragm because it looks like a PITA to get back in so I'll wait until I get the new one - not sure yet whether it needs to be the revision D or C. I'm mindful of throwing parts at the car willy nilly but the G version of the DV appears to have a bad reputation whether there's visibly any damage or not.

[redscout]

Pulled the DV out today and it's fine - no split, tears etc. so that's something else ruled out.

 

I did notice when I fired the car up from cold that the idle dropped within about 30 seconds - is this normal? It is a mild day but I wonder if this point to Idle Control valve or not...clutching at straws perhaps!

 

Would appreciate some help in pinpointing this issue if anyone has any ideas please......

[simion_levi]

If you just mean the ~1200rpm down to ~800rpm then no, it is normal when starting from cold. They have an accelerated heat cycle programmed in, probably to assist initial lubrication/oil pressure.

 

Have you ever changed your fuel filter? Mine was certainly full of crud at around 60K. Skoda have no service interval for it, so it is never changed unless you do it yourself. I wouldn't necessarily hold out hope for a miracle, but then again you think that the cleaners had an effect and hesitation is possible if fuel pressure is not up to spec.

 

About £18 and a very easy job to swap over.

[redscout]

If you just mean the ~1200rpm down to ~800rpm then no, it is normal when starting from cold. They have an accelerated heat cycle programmed in, probably to assist initial lubrication/oil pressure.

 

Have you ever changed your fuel filter? Mine was certainly full of crud at around 60K. Skoda have no service interval for it, so it is never changed unless you do it yourself. I wouldn't necessarily hold out hope for a miracle, but then again you think that the cleaners had an effect and hesitation is possible if fuel pressure is not up to spec.

 

About £18 and a very easy job to swap over.

Thanks for this...

 

I changed the fuel filter about 3 months ago and did notice a significant improvement for a couple of weeks but then the problem reappeared (I put cleaner through at the same time). I used a Crossland filter for the replacement - I've used these filters on other cars and never had any issues. You might be right that there's a link here but it shouldn't really be the filter again already should it?

 

My wife took the car out earlier (after my DV check) and said it was playing up. When I took it for a run, the revs seemed to stick at 3k for a short while when I let off the gas - I thought I'd succeeded in making my problems worse but I can't get that particular symptom to happen again!

 

I'll probably try a TB clean next to keep costs down but I'm skeptical of that making a difference.

[trundlenut]

Have you used VCDS to check for faults or something else?

[redscout]

Have you used VCDS to check for faults or something else?

Hi trundlenut...

 

The cars spent months at 2 different Skoda dealerships for the Stage 2 repair, subsequent cam adjuster valve replacement and then to identify the misfire (which started occurring after the cam adjuster failure/repair). They've had it plugged into their system and nothing shows up. I've since taken it to an independent who has plugged it into VAG-COM and the other (VCDS?) neither of which showed anything up.

 

I'm not sure what happened at the dealers but the indy's tests were while the car was stationary. The problem here is that I only get the misfire whilst driving (after gear changes).

 

There is noticeable whine/whistle noise when letting of the gas that I thought might be turbo problem or leak but the dealer assured me that was normal turbo sound. I've tried investigating around the N75 area but I'm not convinced that my symptoms match to a N75 fault because after the initial misfire, acceleration is smooth...and it's very hard to access that area of the engine bay which was also caked in old oil...I mentioned this oil contamination to the dealers but they didn't seem to think it pointed to anything significant.

 

I've just been looking at the VAG-COM leads on ebay but most seem to exclude the Octavia 2 from compatibility listings - and I'm not sure yet whether these would help me (because I'm not familiar with them yet and still struggling a bit to build my understanding of all these valves/sensors etc.) but if they would enable analysis/monitoring whilst driving, that might be a sensible purchase...

[trundlenut]

Hi trundlenut...

The cars spent months at 2 different Skoda dealerships for the Stage 2 repair, subsequent cam adjuster valve replacement and then to identify the misfire (which started occurring after the cam adjuster failure/repair). They've had it plugged into their system and nothing shows up. I've since taken it to an independent who has plugged it into VAG-COM and the other (VCDS?) neither of which showed anything up.

I'm not sure what happened at the dealers but the indy's tests were while the car was stationary. The problem here is that I only get the misfire whilst driving (after gear changes).

There is noticeable whine/whistle noise when letting of the gas that I thought might be turbo problem or leak but the dealer assured me that was normal turbo sound. I've tried investigating around the N75 area but I'm not convinced that my symptoms match to a N75 fault because after the initial misfire, acceleration is smooth...and it's very hard to access that area of the engine bay which was also caked in old oil...I mentioned this oil contamination to the dealers but they didn't seem to think it pointed to anything significant.

I've just been looking at the VAG-COM leads on ebay but most seem to exclude the Octavia 2 from compatibility listings - and I'm not sure yet whether these would help me (because I'm not familiar with them yet and still struggling a bit to build my understanding of all these valves/sensors etc.) but if they would enable analysis/monitoring whilst driving, that might be a sensible purchase...

Ok, just wanted to check that more than a generic OBDII reader had been used.

Has the problem been escalated beyond the dealer to the technical people at Skoda?

As regards VCDS, you need an official lead from a ross tech distributor. The cheap kkl ones on eBay only work with VCDS lite, which doesn't do can bus, so no good for your car. The cheapest option would be a micro can cable at just over £200. Anything claiming to be full vcds on eBay for a lot less will almost certainly be fake.

Sent from my D5803 using Tapatalk

[redscout]

Ok, just wanted to check that more than a generic OBDII reader had been used.

Has the problem been escalated beyond the dealer to the technical people at Skoda?

As regards VCDS, you need an official lead from a ross tech distributor. The cheap kkl ones on eBay only work with VCDS lite, which doesn't do can bus, so no good for your car. The cheapest option would be a micro can cable at just over £200. Anything claiming to be full vcds on eBay for a lot less will almost certainly be fake.

Sent from my D5803 using Tapatalk

Hi trundlenut

 

Thanks for your quick reply...

 

I've spent a lot of time on the phone to Skoda UK customer services, explaining the problem and telling them that before the car went to them, there was no misfire. They arranged for the car to go back in for checks and I was told that they'd gone back over their work and could find no problems with that aspect. At this time, I spoke with the service manager who told me they'd investigate fully and sort it out. The car was in for 3 weeks during which time they said they'd referred it to 'technical' who advised the next step was to manually clean the valves because they'd had the inlet manifold off and seen that they were dirty/carbonised, potentially an after effect of the excessive oil consumption. However, they wanted circa £1k to perform this and offered no guarantee that it'd cure the misfire (they also originally told me they wanted £350 just to put it back together without a clean...or I could tow it away - you can imagine my reaction to that suggestion). So, Skoda UK customer services have effectively now washed their hands of the issue, as have the dealership, as have the muppets I bought the car from in the first place.

 

Thanks for the advice on VCDS - I'm just not convinced in my own ability to get anything meaningful from it!

[PerformanceDiesel]

Oil down back of engine the plugs arent being contaminated from oil from leaking valve cover seal? Not usually a problem but if excess pressure in top of engine from failing pcv it blows out through valve cover seal. Have you checked pcv valve with engine running? Try lift oil cap if you can lift and little change to engine running pcv on way out. It should make engine run really rough. Pcv can also cause misfires and hesitation. The coking issue shouldnt be a problem depends on mileage how its been run. DV should be kept to rev G, rev D ones imho are useless and piston always lets by when it should be closed. It also wouldnt cause misfires just general flat running as boost is escaping. The N80 valve on evap system may also be worth a look for correct operation.

[redscout]

Oil down back of engine the plugs arent being contaminated from oil from leaking valve cover seal? Not usually a problem but if excess pressure in top of engine from failing pcv it blows out through valve cover seal. Have you checked pcv valve with engine running? Try lift oil cap if you can lift and little change to engine running pcv on way out. It should make engine run really rough. Pcv can also cause misfires and hesitation. The coking issue shouldnt be a problem depends on mileage how its been run. DV should be kept to rev G, rev D ones imho are useless and piston always lets by when it should be closed. It also wouldnt cause misfires just general flat running as boost is escaping. The N80 valve on evap system may also be worth a look for correct operation.

Thanks PerformanceDiesel

 

I don't think the valve cover is the source but it's hard to tell. I had some fresh oil on the metal pipe that runs down near the DV and ends in a J (like a U-bend) but I wasn't sure what that pipe was (had a braided metallic protective cover) and that oil could have got onto it anywhere along its travel. There was a lot of old oil right around where the air pipe that runs round the back of the engine links to another section as it drops to the turbo; sitting all around the joint. but to be fair the whole area was covered...I've cleaned it all off so will monitor if it reappears.

 

I've removed the dipstick with engine running and it did negatively affect tickover. I also had the entire PCV off to check the spring which seemed ok, and the diaphragm which I couldn't get at (not sure if there's a special tool for the top circular cover, or if it's even supposed to come off)

 

The N80 did cross my mind - when touched I can feel it clicking but I was under the impression they made an audible clicking/tapping if they were failed. At least it's easy to get to so I'll have a search for how to check operation - I seem to recall something about testing whether they hold vacuum but I don't have the means for that.

 

Skoda reckoned that the severe oil burning (up to a litre every 250 miles by the time it was diagnosed) could have dramatically increased the rate of carbonisation but I did wonder whether they were just looking for some money for their 'efforts'....in any case, that job's a last resort really, and I'd clean the injectors while I'm in there. My other half drives it a lot more tamely than I do but it doesn't feel to me like carbonisation is likely to be the problem or it should misfire at other times....instincts are telling me it's a problem specific to the sudden and opposite change in pressure and load when put in a new gear and throttled...(which is why I considered the N75, because I could be leaking pressure to the wastegate between changes - but I may be completely wrong...it wouldn't be the first wrong tree I've barked up!..

[bigjohn]

The oil burning can dramatically increase the carboning up of the valves& inlet manifold due to oil being fed back into the inlet side of things. Get an independent garage to investigate/check - can be done with an inspection camera

[redscout]

The oil burning can dramatically increase the carboning up of the valves& inlet manifold due to oil being fed back into the inlet side of things. Get an independent garage to investigate/check - can be done with an inspection camera

Hi Bigjohn

 

I understand that the carbonisation will have been increased but I would expect that, if that were the cause of the misfire, it would misfire all the time, rather than only after gear changes. The valve/manifold clean is on my to-do list though.

[brad1.8T]

From reading other sources, the MAP sensor might be a culprit but as yet I can't locate it - any tips welcome. Likewise, I'd like to locate the crankshaft position sensor.

 

After servicing the car (and dropping a very heavy Scout undertray on my bonce) I noticed a fair amount of oil down the rear left (looking at it) of the engine (turbo area). This could indicate a turbo leak or be contaminating sensors in that area.

 

I can't find a  picture/diagram of this engine (1.8tsi CDAA) so any pointers or links would be hugely appreciated,

The MAP sensor is in the inlet tube just after the airfilter. There's an electrical connector attached to it. You remove a couple of security torx screws (I used pliers) and clean with contact cleaner.

The oil leak is possibly the O-ring for the VVT actuator. It's on the side of the head just near where you add windscreen washer fluid. The partno for the 52mm x 3mm O-Ring is WHT-007-212.

You'll find diagrams at partsbase.org

edit: read more of the thread about the inlet carbon issues.

I can't for the life of me understand why they wouldn't clean the valves if they have the inlet manifold off - the bulk of the work is done at that point.

VW claim that a large percentage of the inlet gunk will burn off (the valves get a lot of heat into them) if you do a 20 minute drive at a minimum of 4000rpm. I tried it a few months back (40km along the motorway in 3rd gear... or maybe it was 2nd - either way it felt odd) and while I didn't do before & after borescopes the engine definitely used less fuel afterwards. Give it a try - the worst that can happen is you will use a big chunk of fuel for 20 minutes.

Edited 21 December, 2015 by brad1.8T

[redscout]

 now that's my kind of solution...no messing about, just a good old fashioned Italian tune-up!

 

I think what you've described is the MAF sensor isn't it? It's the Manifold Absolute Pressure sensor I was after locating.

 

The end of the head looks clean enough - it's just the back corner that was oily - I'm half suspecting the rear PCV pipe connection where it connects to the air pipe.

 

They wouldn't clean the head while they had the manifold off because they don't quite want to put the customer first before hard cash. Because the car's out of warranty they won't accept any liability, whether or not it was their fault for making the pistons out of cheesecake in the first place, or whether or not the car was misfiring before they touched it...what that says about Skoda's ethics, I'll let you decide.

[brad1.8T]

Yes, I am talking about the MAF. I didn't realise there was a MAP.

I had oil dribbling down the rear of the head & it came from that side sensor. The PCV makes sense as well.

Yes, Skoda/VW are an odd lot. They have a lot to learn about customer service, especially since they decided they wanted to rule the (automotive) world. Down here in Aussie there sales have increased dramatically but there are so many first time buyers that are saying "never again" due to poor after-sales experiences.

[bigjohn]

Hi Bigjohn

 

I understand that the carbonisation will have been increased but I would expect that, if that were the cause of the misfire, it would misfire all the time, rather than only after gear changes. The valve/manifold clean is on my to-do list though.

 

Depends on how bad it is. I've had a car in the past in the past that was down on compression due to a burnt valve that misfired on tick-over (3 cylinders) but was OK under load (2.0 Capri as it happens)

 

Have you done a compression test yet?

Edited 22 December, 2015 by bigjohn

[Ootohere]

Sorry not read all posts as on a phone and missing some lines in posts,

but has the engine had nice new quality Spark Plugs fitted recently and set at the correct gap?

Or at least the Plugs and gap checked?

Edited 22 December, 2015 by GoneOffskiroottoot

[redscout]

Sorry not read all posts as on a phone and missing some lines in posts,

but has the engine had nice new quality Spark Plugs fitted recently and set at the correct gap?

Or at least the Plugs and gap checked?

These were supposed to have been checked during the cars 3 week stay with Skoda. They said they'd borrowed plugs and coils from a donor car that was running fine but mine still misfired. I've had the plugs out and they looked healthy...and I've checked the wiring harness which visually seems fine.

[redscout]

Depends on how bad it is. I've had a car in the past in the past that was down on compression due to a burnt valve that misfired on tick-over (3 cylinders) but was OK under load (2.0 Capri as it happens)

 

Have you done a compression test yet?

No, and don't have the means but would have thought this would have been on Skoda's diagnostic check.

 

I'm intending checking the N80 as suggested above by PerformanceDiesel as a further cheap check because I don't want to be throwing money at the car. However, I'm now feeling torn between throwing money at replacement  parts and throwing money at diagnostic tools!

[PerformanceDiesel]

Get Bluetooth dongle and carista app to check for codes. Will show up most things. Ive been very impressed with it. Bluetooth obd reader and carista app can be had for about £20

[J306TD]

Get Bluetooth dongle and carista app to check for codes. Will show up most things. Ive been very impressed with it. Bluetooth obd reader and carista app can be had for about £20

Good tip. Carista is worth its weight in gold. So much you can do with it

Sent from my Galaxy S5