1.2 TSI small dips in power?

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sinny89
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1.2 TSI small dips in power?

Post by sinny89 »

Hi again guys, got my polo up and running the other day after cam chain stretched.
quite a bit of work but managed it myself.

All running fine, nice low idle sounds a lot better than before. Give it a few goes up and down my road i was ecstatic as it ran perfect.

So i decided to give it a good blast up the dual carriageway round the corner, i noticed when giving it a bit it had a couple of small dips in power( really quick small judders). like 3k revs in 3rd and 4th (i didn't want to go into 5th).

I did notice the lights dipped slightly.

polo 1.2 tsi 6R

Any ideas what this could be before it turns into a money pit?
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Jay-Jay
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Re: 1.2 TSI small dips in power?

Post by Jay-Jay »

Check the spark plugs cables, because they tend to oxidate and cause misfires.

How many km have you driven with the spark plugs? Maybe they need to be replaced.
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Re: 1.2 TSI small dips in power?

Post by Ricmondo »

You’ve had it in bits which entailed disconnecting various electrical components.

Well done fixing the main problem, it must be very satisfying.

Your symptoms point towards something on the electrics/electronics side. The fact that the dips coincide with the lights dimming suggests a a loose or incomplete connection or a bad earth.

Check all the cable connections but my first task would be to check the earth connection from engine to chassis, make sure it is undamaged, clean, free of paint or muck and tight.

Hope this helps and good luck .
sinny89
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Re: 1.2 TSI small dips in power?

Post by sinny89 »

Thanks for the replies, so the spark plugs have maybe done 8k, so guna order some, ngk or Bosch?

It has had two coil packs in the past, one on a recall and one under warranty, last one was around 3 years ago.

im guna order a obdeleven so i can see what cylinder is misfiring, if it is a misfire. Then i can swap the lead and see if it follows.

would i get a warning light if it was a misfire? as i have nothing coming up when it judders.

also this only happens once the engine has warmed coz ive been out this morning and it seemed fine then tried again this afternoon and after a few blasts it started again.

as to the electrics i did have a loose earth but i sorted that before this, but you are right with that one as i didn't have a cats bat what was going on when that was loose. (jumps starts, sparks the lot)

its like when you pull off to quick and get that wheel bounce shudder but a bit more subtle and when the car is at speed.

again cheers guys and i hope i can get to the bottom of this without to much expense. still gotta get it through its mot.

and yes very proud, all ive been getting is people saying i hope you know what your doing, and ye mad haha. so i just wanna be able to say see.. i told you it'd be sound
veteran
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Re: 1.2 TSI small dips in power?

Post by veteran »

One thing that I've wondered about, on my own 1.2 TSI, is the silicone paste that the factory stuffs up the sparkplug lead, around the point where the lead clips to the sparkplug. Is this meant to act as a moisture-repellant, ie as an insulator, or is the paste electrically conductive? I always thought that silicone (note the 'e') was an insulator, in which case if you spread it all over the top terminal of each sparkplug, or anywhere near it, you're bound to eventually have running problems. Having inspected one of the sparkplugs on my own Polo, I've realised just how much that paste (greeny-yellow in appearance) inevitably contaminates the entire sparkplug. If alternatively it's meant to aid conduction, then with it unavoidably getting spread down the outside of the sparkplug insulator (especially if you clip/unclip the lead more than once), it would encourage mischanneled spark energy, giving rise to misfiring. After exposing the sparkplug and then removing it, I found that I not only needed to clean off significant traces of the paste from the top and outside of the plug but also I had to carefully clean out this paste from the inside of the sparkplug lead, to avoid this.

Whether or not you've the same paste, or indeed any paste, stuffed up the EHT leads on your vehicle, sinny, I'm not sure; you don't specify the year of your Polo. The factory and workshop practise of using this paste might possibly be relatively recent. But if you do find it upon personal inspection of your plugs, you might want to reflect on my comments. What I appeared to discover was that as long as you don't disturb the factory lead-to-sparkplug connection, this paste doesn't get spread around. However, IMHO it's an impractical use of such paste, as (quite aside from the paste issue itself) in due course the complete set of sparkplugs will of course require changing. It might be that you or your VW workshop has performed a sparkplug inspection or replacement and this paste, if used, has possibly migrated and contaminated a sparkplug connection, causing either intermittent conduction at the lead-to-plug connection, or leaking spark energy down the outside of the sparkplug (depending on whether the formulation is insulating or, alternatively, conducting).

Did I read somewhere something about the interior of EHT leads corroding on Polo 6C/Rs? If there was ever any truth in that, then maybe the use of this paste by VW has been a stop-gap measure (sorry about the pun), designed to keep out moisture? If so, it's been a rather 'dirty' solution, since there's no means of controlling where it gets to.
sinny89
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Re: 1.2 TSI small dips in power?

Post by sinny89 »

veteran wrote:One thing that I've wondered about, on my own 1.2 TSI, is the silicone paste that the factory stuffs up the sparkplug lead, around the point where the lead clips to the sparkplug. Is this meant to act as a moisture-repellant, ie as an insulator, or is the paste electrically conductive? I always thought that silicone (note the 'e') was an insulator, in which case if you spread it all over the top terminal of each sparkplug, or anywhere near it, you're bound to eventually have running problems. Having inspected one of the sparkplugs on my own Polo, I've realised just how much that paste (greeny-yellow in appearance) inevitably contaminates the entire sparkplug. If alternatively it's meant to aid conduction, then with it unavoidably getting spread down the outside of the sparkplug insulator (especially if you clip/unclip the lead more than once), it would encourage mischanneled spark energy, giving rise to misfiring. After exposing the sparkplug and then removing it, I found that I not only needed to clean off significant traces of the paste from the top and outside of the plug but also I had to carefully clean out this paste from the inside of the sparkplug lead, to avoid this.

Whether or not you've the same paste, or indeed any paste, stuffed up the EHT leads on your vehicle, sinny, I'm not sure; you don't specify the year of your Polo. The factory and workshop practise of using this paste might possibly be relatively recent. But if you do find it upon personal inspection of your plugs, you might want to reflect on my comments. What I appeared to discover was that as long as you don't disturb the factory lead-to-sparkplug connection, this paste doesn't get spread around. However, IMHO it's an impractical use of such paste, as (quite aside from the paste issue itself) in due course the complete set of sparkplugs will of course require changing. It might be that you or your VW workshop has performed a sparkplug inspection or replacement and this paste, if used, has possibly migrated and contaminated a sparkplug connection, causing either intermittent conduction at the lead-to-plug connection, or leaking spark energy down the outside of the sparkplug (depending on whether the formulation is insulating or, alternatively, conducting).

Did I read somewhere something about the interior of EHT leads corroding on Polo 6C/Rs? If there was ever any truth in that, then maybe the use of this paste by VW has been a stop-gap measure (sorry about the pun), designed to keep out moisture? If so, it's been a rather 'dirty' solution, since there's no means of controlling where it gets to.
Image
Image

So these are from two of my leads. I doubt that it’s the connection but the green dust seems like corrosion or the dielectric paste.

After warming up it is more prevalent and happens on hard acceleration and if I’m labouring it with hard acceleration.

I’m starting to get worried about all sorts of other things it could be I.e crack cylinder head or gasket leak as the engine seems to get quite hot. There was oil in the coolant be that is from when I took the head off and oil spilled down the water jackets of the cylinder.

Don’t know if I’m just being paranoid.


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veteran
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Re: 1.2 TSI small dips in power?

Post by veteran »

Your pics indicate that your Polo's probably older than I thought and doesn't have sparkplugs that sit in sealed-off wells in the cylinder head and which are EHT-fed individually from separate coilstacks, which is what you find now with 2014 - 2017 TSI Polos. There, each coilstack is an 'EHT lead', and it's the top-inside of the coilstack where the silicone paste is found. In your pics there's no sign of anything like that. I'd say that, apart from some very mild signs of mildew, your EHT lead connectors look pretty sound and clean.

How old, including mileage, are your EHT leads? Are they proper multistranded, copper-cored leads? Might be worth trying to find out, and maybe even measure the end-to-end resistance of each, as single-cored ones that had 'graphite string' cores used to break down internally and give rise to misfiring. Not sure if VW has ever used those, though.

If you've been suspecting just one 'pot', have you taken out the sparkplug of that one and inspected the sparkplug? It might have a minute crack in the ceramic insulator of its outside. Whenever you inspect/change a sparkplug it's all too easy, when undoing it or tightening it up, to exert a little bit of side pressure and so damage it, even using a rubber bung in the process. The damage may be only slight and go unnoticed, but could affect the firing.
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Jay-Jay
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Re: 1.2 TSI small dips in power?

Post by Jay-Jay »

Checking the spark plugs cables was the first thing I suggested, since it's a known defect on the 1.2 TSI EA111 engine.
Even if they don't show oxidation on the contacts, they could be internally damaged due to usage and heat. Check the resistance of the cables using a multimeter: it should be around 6kOhm. If it's higher (~8-9kOhm) you need to replace the cables.
Also check the coil's resistance (it should be around 3,9~4,2kOhm) and eventually replace it.
Beru, Bremi, NGK are good manufacturers for aftermarket replacements.
It's important to replace the cables with the newer version, which has a plastic protection.
I recently replaced cables and coil on my Polo 1.2 TSI with NGK cables and Beru coil:
Image
Image
RUM4MO
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Re: 1.2 TSI small dips in power?

Post by RUM4MO »

Good advice there from Jay-Jay, if I had one of these engines with these known issues, I would use these brands of replacement parts, I like NGK spark plugs as well!

Graphite dusted rayon cord leads, yes some of us are old enough to remember that nonsense! Back then, the plan was to measure the lead resistance, then "whack" the removed lead quite firmly in a bid to encourage the graphite dust to spread back along the length of the lead and so improve its conductivity, this was followed by taking another resistance measurement to confirm that that action had worked - for a few more miles! A friend of mine who's van I eventually bought as a first car, who should have known better, improved the radio reception in that van by cutting the "graphite dusted cord" type HT leads and inserting suppressors in line! For him that worked very well, a few months later, after I bought it, it started dropping masses of power (it was a 1200 LC Ford OHV engine so not much power prior to this!) at about 23:00 on a dark night in the middle of no where, in desperation I opened the bonnet, not my wife to rev the engine - and stood there enjoying the resulting light show!! Luckily I had a roll of insulating tape to keep the parts together - and that got us home! The next weekend's job was to check out some scrap yards for "new" leads - as you did when young and foolish?
sinny89
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Re: 1.2 TSI small dips in power?

Post by sinny89 »

So its just passed it’s mot today so I can give a bigger run on the moto. When I get it home I’ll pull the multi meter out of the shed n see but I may not find anything cos it’s only once the engine is warm, either way I’ve ordered NGK leads and plugs so should solve the problem. If not is guna be a sensor or the coil pack. They are from auto doc so may take a while coz it’s a bit hit and miss on delivery speed, also waiting on this obdeleven but Until then it’s just a guessing game. I’m thinkin it is isolated to cylinder 3 or 4 as this side of the engine gets hotter, maybe due to misfiring or just the fact the turbo is on that side. I will be sure to post back with the answers for anyone who my get in the same predicament in the future.

Cheers to everyone for the input and I hope this can help out another brother in the future.
sinny89
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Re: 1.2 TSI small dips in power?

Post by sinny89 »

Little update, all parts arrived today and my obd. Replaced them even tho the weather was a nightmare ❄️❄️ And bobs your uncle car is running perfect.

Faults on the engine where: cylinder 3 misfire, intermittent.
Camshaft sensor intermittent
Cylinder 3 shutdown intermittent

So on this and inspecting the plugs I think it was due to the lead as it runs right above the turbo exhaust side, it my have broken down to excessive heat. I’m pretty sure it was the same lead last time it happend also.

These ngk leads seem a lot better quality but had to remove the corrigated plastic tubing because it would not fit. Also I made sure the lead was not in contact with the metal coolant hose by give it a slight twist to keep it from touching.

Hope this can help anyone in the future 👍🏽
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Jay-Jay
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Re: 1.2 TSI small dips in power?

Post by Jay-Jay »

Good to hear you fixed the problem.
But you shouldn't have removed the corrugated plastic form the cables. It's needed for heat protection.
I have installed the same NGK cables and I had no problems fitting them correctly.
Here is a picture of my engine:
Image
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