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53 plate Octavia - Intermittent lumpy idle, juddering acceleration, smell of fuel,


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Fitting coil packs is a piece of ****. Take engine cover off. If it's one that's under the vacuum box at right hand end take that off (3 allen bolts iirc). Unplug coil pack (use a flathead to gently prise the catch so it clicks), take plug off. Pull coil pack out.I use a beefy flathead and slide it underneath to prise up (as straight and direct as possible), don't go mad just use it to help you pull, it will be stiff but will pop and lift out. New in, push down as far as it goes, plug back on, replace vacuum box.

Skodaparts.com are very good, just a shame you have to pay postage. DONT pay a dealer 140 lol. Was he wearing a mask and riding a black horse?

Good luck with smoke test. I can't remember revised part number though I'm afraid, skodaparts.com should be selling the most current one, all dodgy ones got binned.

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Hello all.

Smoke test carried out today.  No leaks found.  Mechanic said he was very confident with the results - "it was holding pressure well."

 

This is the description of the work carried out:

 

-------

"Carry out smoke test, no evidence of any split breather pipes.

Performed diagnostic check: 2 fault codes in engine management:

 

P1297: Turbocharger (TC)/throttle valve, hose connection - pressure loss

P1128: Long term fuel trim, entire speed/load range, bank 1 system too lean

 

Deleted codes and performed a throttle body basic reset due to this being cleaned in the past."

--------

 

I'm disappointed in some respects as I was hoping that a leak would be found and that would be my answer.  Looking for the positives; I guess it's another thing eliminated.

There was talk of actuators in the turbo which may be sticking (or something like that) but that was just one of many hypotheses he mentioned - I think he was trying to tell me that unless components are taken apart, the fault may not be found.  I asked if he used VAGCom kit and he said it was SnapOn.  Not sure if that makes any difference.

 

Interesting that the P1297 code was thrown again (although I don't understand how the smoke test came back OK when the description for the code says "pressure loss".)

Also interesting is that the P1128 code seems to be (to my inexperienced knowledge, or lack of) the inverse of the "17545 Fuel Trim bank 1 (Add) System too rich P1137 _" code from my first post.  Any explanations welcome.

 

Today's mechanic was adamant that if a coilpack was to blame that it would have thrown a code.  I didn't argue with him.

 

Bearing the above in mind, what do you think next?  Incidentally, the car drove like an absolute dream on the way to the garage despite me ranting the nuts off of it.  Smooth as you like on the return journey too. :@  Typical.

 

Trying to stay positive even when the bank balance is not.

Edited by Troubled
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If this was my car, in view of what you have already had carried out on the car, I would be making a visual check of the coil pack loom by the camcover to make sure you have no brittle insulation on the cables that is going to ground on the engine, Also, check the coil loom earth screw on the cam cover is clean and not heavily corroded which could be why it is so intermittent. Also you could visually check the N249 valve to make sure nothing is hissing near it. I would like to hope that a professional would have already checked these, but you can never tell nowadays.

 

As you are showing a lean condition code, you have a vacuum leak somewhere, and it is highly possible to be one of the small bore lines leading to one of the many solenoid valves that the 1.8T engine possesses  Fuel trim is explained in this Ross Tech video if you want to bring yourself up to speed a bit https://www.youtube.com/watch?v=yM3iarhSP68.

 

You could also double check the wiring connector to the N75, as I have found breaking wires in there that are only holding on by 1 or 2 strands, causing running issues, but not normally a lumpy idle, but it may be shorting out to another part of the loom so you never fully know until you check.

 

I would echo G-slave really and be looking to find a local member with VCDS to log the car before you spend anymore serious money. you can also do output and readiness checks on the majority of solenoids to check them rather than renew them with VCDS which is obviously very cost effective. All the things I mentioned above to check at worst would require either a length of vacuum pipe or a small length of wire and some solder, so not much outlay really. On the coil loom, if it is compromised, you could temporarily wrap the cable with a length of insulation tape and try it for a few days to see if the fault goes away. If it does, fault found, and we can guide you how to effect a more permanent repair.

 

Hope this helps

Edited by kentphil1
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If this was my car, in view of what you have already had carried out on the car, I would be making a visual check of the coil pack loom by the camcover to make sure you have no brittle insulation on the cables that is going to ground on the engine, Also, check the coil loom earth screw on the cam cover is clean and not heavily corroded which could be why it is so intermittent. Also you could visually check the N249 valve to make sure nothing is hissing near it. I would like to hope that a professional would have already checked these, but you can never tell nowadays.

 

As you are showing a lean condition code, you have a vacuum leak somewhere, and it is highly possible to be one of the small bore lines leading to one of the many solenoid valve that the 1.8T engine possesses  Fuel trim is explained in this Ross Tech video if you want to bring yourself up to speed a bit https://www.youtube.com/watch?v=yM3iarhSP68.

 

You could also double check the wiring connector to the N75, as I have found breaking wires in there that are only holding on by 1 or 2 strands, causing running issues, but not normally a lumpy idle, but it may be shorting out to another part of the loom so you never fully know until you check.

 

I would echo G-slave really and be looking to find a local member with VCDS to log the car before you spend anymore serious money. you can also do output and readiness checks on the majority of solenoids to check them rather than renew them with VCDS which is obviously very cost effective. All the things I mentioned above to check at worst would require either a length of vacuum pipe or a small length of wire and some solder, so not much outlay really. On the coil loom, if it is compromised, you could temporarily wrap the cable with a length of insulation tape and try it for a few days to see if the fault goes away. If it does, fault found, and we can guide you how to effect a more permanent repair.

 

Hope this helps

Many thanks for your response.  I won't pretend to understand all of it but it's given me some further things to research.

That first video is a fantastic intro to understanding fuel trim. Thanks for sharing. I now see the need to get some live logging done by someone who has the kit.  As I've had both codes; running too rich and too lean, is it likely that it's the whatever is being temperamental is responsible for that?, or isn't it worth trying to guess without the using a VCDS on it?  I'm asking out of interest rather than diagnostics btw.  I'd like to be able to do the activities you've described in your post but I have a LONG way to go in knowing where to begin.

You say I have a vacuum leak somewhere - would this have not been picked up by the smoke test?

I'll have a further scour/give a shout out on the regional forums for someone with the kit who might be local.

Again, thanks for your help.

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The fuel trim condition is more of a response than a symptom if you see what I mean, and yes, without logging and tests, you really are just guessing in a very educated fashion, you may get lucky, but you probably wont. If you can spare the time, this vid goes into greater depth - https://www.youtube.com/watch?v=oRX2V6_a3dc, but it may give you a headache. :giggle:

 

The smoke test should pick it up if it is in piping between the engine and the solenoid, but it may miss it if the particular solenoid is deployed and diverting vacuum from that particular pipe or is leaking in the solenoid valve itself. A lot of these valves involve diaphragms in them, which may hold vacuum in a rest position and leak when operated. This is why you need to do the tests while logging to see what is actually happening if anything at all.

 

Most of these long term faults usually eventually come down to a perished pipe, a poor connection or just plain wear and tear, so check the simple stuff first as it is real easy to get moved off track by trying to get too clever too quickly. You may have to still get technical eventually but rule wear/corrosion in stuff out first - it really is easier on the credit card that way.

Edited by kentphil1
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For the coil pack wiring, this how to - http://www.briskoda.net/forums/topic/312558-how-to-install-a-coilpack-loom-cable-guide/ from Bowders has really good photos in it of what to look for, especially piccie number 6. Just ignore the bit about fitting the actual shroud, as you don't have it as it is a mod, and Bowders takes some real good quality pictures to show what to look at.

 

If you look at the black wire on the right of the picture, just below his finger you will see the copper wiring showing where the insulation has split open. It is all just a matter of taking a good close look really.

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I think this may well end up being one of those "spoke to soon" posts but I'm gonna do it anyway!

 

I CANNOT get my car to misbehave at high revs and the idle seems to be a lot smoother.   I've driven it the hardest I ever have and still can't get it to display the symptoms I had before the smoke test and throttle body reset.

The only thing that's concerning me right now is a slight bounce/dip of the revs occasionally when I slow down to approach a junction or stop at a red traffic light.  Confused much?! (Not that it takes much.)

 

I'm still going to check the coil pack loom, replace the coil pack and continue to follow up on all the wonderful advice given here, however it will need to wait until payday at the earliest.

 

Presumably the dip in revs mentioned earlier could still be a symptom of the underlying fault(s) which I haven't found yet?

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@kentphil1
 
(I think!) this is the coil pack loom.  Does this look standard to you?  Looks like it's wound in electrical tape to my untrained eye. It's not how I imagined it would look; Regardless, I'm not confident enough to mess about with anything here.  I had enough trouble putting the engine cover back on! 

 
https://www.flickr.com/photos/spleencheesemonkey/27738885882/in/dateposted/
https://www.flickr.com/photos/spleencheesemonkey/27562360090/in/dateposted/
https://www.flickr.com/photos/spleencheesemonkey/27840295425/in/dateposted/ (you can see coil pack 3 that they wouldn't replace under warranty here)
https://www.flickr.com/photos/spleencheesemonkey/27764255001/in/dateposted/
 
As a side note, I found a cable that isn't connected to anything.  Out of interest, does anyone know what it might be?  It comes from underneath the "box" on the near side front and goes nowhere.  (Gotta love my technical descriptions eh?):

 

https://www.flickr.com/photos/spleencheesemonkey/27764256501/in/datetaken/

 

This is the "box" the cable appears from underneath:

https://www.flickr.com/photos/spleencheesemonkey/27562361990/in/dateposted/

 

Sorry for my ongoing questions.  As ever, grateful for all of your responses.  

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The Box is where the battery lives, there a couple of lugs, one each side that you depress, and the main outer cover pulls and slides upwards leaving the rectangular fuse box in the middle - see another one of Bowders brilliant threads here - http://www.briskoda.net/forums/topic/220346-battery-issues-fuse-box-melting/ picture 5. Not sure what that cable is, it may be a power point attached to the battery for some reason for an extra piece of kit by a previous owner. I initially wondered if it was the outside air temp sensor until I saw the cover on the end of the lead. I will have a better screen tomorrow so will have a better look then.

 

The coil looms are basic aren't they, its quite a shock if your not ready for such austerity :giggle: , Is the tape round yours shiny plastic, or matt cloth type?, My screen resolution is playing up tonight so can't see for sure, but it does look like someone has been in there having a tidy up with the tape. Not a bad thing if it has been done right, they just need to have checked for split wires at the same time.

 

I will say that the main earth point terminal to the cambox in picture 1 looks really crusty and could do with a clean up real bad, that looks like rust on it, it should be bright, shiny and tight.

Edited by kentphil1
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Thanks for not taking the p*ss out of me on the battery front! :D I'll investigate where the cable goes to/comes from, but just out of curiosity.

I'll have another look to confirm the tape in the loom but from memory, it really did look like shiny electric rather than Matt fabric.

I'll clean up the earth point too - it is rusty, but securely fastened.

Interestingly I checked the dipstick during the day and it wasn't fully pushed home by a click. "That's it!" I thought. Pushed it in and..... dipping of revs still happened twice on the way home :(

However!....it's still behaving comparatively well on the whole.

Thanks again for taking the time to reply.

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To do the coil earth properly, you really need to remove the bolt, and clean the tag with some medium wire wool, once the rust is gone and it is reasonably shiny, clean the bolt the same way, then refit it nice and snug, once it is tight, a little smear of vaseline to cover the head and tag, job done. Don't put the vaseline on before you tighten the bolt as you will corrupt the earth.

 

If the tape is shiny, it probably is the best efforts of somebody else, if it is fairly sound and tidy, I would let sleeping dogs lie there.

Edited by kentphil1
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  • 2 weeks later...

No news is good news, right?;  Car still running very well apart from the odd bounce in revs when slowing down.  Still yet to find the money for coil pack replacement but will do the coil earth shortly.  Thinking of closing this thread down.  Many thanks again for your all your help.

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You will probably find your short and long term fuel trims have re-calibrated themselves over the last week or so, and have settled to a level that is within spec now.

 

Hopefully, all is good for you now.

 

I know we don't like stuff like this when it happens, but there is nothing like this sort of fault to increase your working knowledge of how the car works.

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  • 3 years later...

So.... long time no post. Had a smoke test done today. Bloody great split in a breather pipe below the manifold (whatever that is). New parts ordered. Hopefully fit on Monday. Wahooo!

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