UK-POLOS.NET - THE VW Polo Forum

Well, last time, it was someone else asking about it, but I think it's already been covered, just can't find the post.

Engine missing beats intermittently but rhythmically (like, always the same cylinder) on acceleration, particularly full throttle with lower revs after running slow for a short while, and some slight power loss in the midrange when this problem manifests - possibly just the same as at lower revs but with less noticable shake. Worst when "slapping" the throttle down, can almost make it happen on demand, but also sometimes with progressive openings.

Noticable most particularly not long after starting but can happen any time. The power loss noticed when only-just maintaining entry speed of 50 on a hill where normally I would accelerate from 40 towards 60 and onwards in that same gear.
Worst "stutter" coming home from Tesco tonight (it's come on in the last couple weeks - always been a little reticent from cold, but worse recently). Worked gently up to top, doing about 20 (yeah a little slow), decide against my better judgement to bring it up to 30-something, floor it.......... judder judder judder... still accelerates, but not as well, and it's clear i'm running on 3 cylinders, maybe less, until I get to about 35 (held on til it cleared in the name of research). Usually it may complain a little from that speed, make labouring noises, a little more vibration - but that was definately missing beats.

Crapped out spark plug (or lead)? Carbon build ups? Cam/valve? Slight loss of compression in one cylinder (or busted gasket... yet to check for coolant in the oil)? Dirty or blocked up throttle body or injector that may be causing the 'weak'est cylinder out of the quad to not fire properly all the time?
Any clues? This may explain the slightly bad economy of late (besides the regular thrashings) and oil usage. Thinking of which, I need to check that again - topped it off before I went to wales, but test on mates driveway (of dubious levelness) suggested it was low after arriving. Didn't really beleive it as I'd only driven a maximum of 200 miles. Might be a whole lot lower now if that was true....
(bugger, havent checked the dizzy either)

...used an ollllld bottle of Mobil-1 5w50 for the topup (I had nothing else handy!) if that makes a big difference. Fill up on the way back was from Esso I think; and then a top up at tesco.

And for a final variable into the mix - a couple times the battery light has flickered a little when turning on the ignition (before running the starter), even though all other lights are ok.

Silly car!
and silly me, i need to go check all those things before expecting an answer really.

Okay, what you need to do is narrow it down for yourself, as misfires like that are difficult to solve.

Remove your spark plugs and check the colour and the condition of the electordes, clean out your air intake with some carb cleaner, run so injector cleaner through it, do a compression test on all the cylinders (this will tell you a lot aswell such as worn piston rings by adding oil into the cylinder or a blown gasket,) check all you earthing points and battery connections, check the condition of the dizzy, rotor arm and HT leads. Could also be a problem with the fuel pump, so get hat checked out.

This will narrow it down for you, and hopefully isolate the problem.

Think I'll get a new car, easier!

The problem continues so it wasn't just a passing thing, a bit more noticable now too. After running at low speeds and low throttle, progressing to full whether suddenly or gradually runs a good risk of reduced, juddery acceleration and then a sudden transition back to more powerful, smooth 4-cylinder running.

Well i did try popping the HT leads off one at a time and giving a quick rev up, which proved nothing except that a combination of unburnt fuel going through the cat and ungrounded sparks melting insulation makes a worrying smell. Resolutely refused to drop a second cyl while it was running on any set of 3 so can't narrow down which one it is.
The air filter however was disgusting when i checked it (fingers still dirty), but i don't know if i want to get a new one quite yet without first seeing if i can get the worst off this one (last new one wasn't *so* long ago and i dont want to replace it if it's not the cause). Some grit on the "inside" area of the filter housing however so perhaps it's past it (maybe i need to get that broken breather tied off at the housing intake too?)

The other things may take a bit longer. Injector cleaner I haven't put through for a while so may grab some Redex from halfords when I'm out getting CDRs. The carb cleaner stuff is what's used to clear out the throttle body right? Get it from the same place?

Plugs will be a pig because of the air filter housing, but easy enough once that's off (or i make an induction kit!) if i can find what happened to our recently deceased hosepipe. May well be the culprits, can't remember when they were last done (hopefully when it was serviced at MOT time in september... probably quite long enough given the thrashings it's had). Either that or the dizzy again, but it's only been January that I last cleared that out, and that was the first time ever.
But how would I do a compression test - does it require a specialist meter?

Cheers... i suddenly feel so clueless!


PS apart from collecting and burning-off in the catalyser (which is probably done for now anyway - exhaust is getting louder and boomier even though the backbox etc look fine) would the unburnt fuel coming from the missing detonations cause any damage, particularly anything with a lasting effect?

I think you should remove your airbox and airfilter and firstly replace the air filter. These are really cheap anyway, so nothing to worry about there. Make sure your airbox is free from any dirt etc aswell. Then, while the airbox is off, give the air intake a thorough blasting with carb cleaner (yes, same stuff as throttle body cleaner and available from Halfords etc.) Open the throttle and spray behing the butterfly aswell. Even the slightest bit of dirt in my intake (usually oil vapour over time) caused my car to judder and cut out, so this is well worth doing.

Also, while the airbox is off, you can have a quick look at your plugs and give em a quick clean with a wire brush. While these are out, a compression test would be a good idea. You need to get you hands on a compression meter. It simply screws into the spark plug thread of that cylinder and has a pressure meter attached to it. All you do is disconnect the coil so the engine doesn't fire up, and remove one spark plug at a time. Get someone to turn the engine over with the starter, while you watch the compression meter. It should reach full pressure in two stages. If not, there is a problem and there are ways of working out what the problem is, such as adding a teaspoon of oil into the combusion chamer.

Unburnt fuel will go into the cat and cause it to overheat, which can cause long term damage.

Try my suggestions and let me know how you've got on.

K.... what i've done so far.

Taken dizzy off and had a go at giving it a quick clean out. It was pretty skanky inside after even just a short time, lots of carbon dust - in fact i'm wondering whether i need to replace the cap as the electrodes look quite worn (not that i have anything to compare with, though!).

Tried popping leads off and revving again now that the problem has become quickly more pronounced (sort of like, any engine speed below ~4000rpm combined with more than 50-60% throttle setting - so it'll still go fast, but low end and mid range torque maximum has been massacred, deadly on a 1-litre! more like a 750cc with a turbo that has *massive* lag).... still didnt find anything out. It's like "removing" a cylinder's spark temporarily fixes the problem. Theoretically removing the lead from the problem cyl should show "no difference", and removing it from any of the others should have it run "normal" on 3 cyls, but revving it should knock it back to 2... no dice!

Got some Red-X. Mixed it into a full tank at slightly more than stated strength. Driving around for a while like that showed little improvement (well, it should take a whole tank after all). Tried their method for "carb" and I assume injector throttle body cleanout. I don't now think it's the filter as it still stuttered some with the housing lid off.
((i.e. - first, removed the lid and tugged the cable some to open the valve to a "quick tickover" and squirted a fair bit in around below the injector. Put it all back together and went for a gentle 15 minute drive keeping the revs around 2500rpm. Stopped, killed engine, opened up again, tugged valve fully open and squirted it all around again including getting a good flow down both sides of the valve, reassembled and went for an all-out blast on the same route*))

Doesn't seem to have helped any...! And as for the injector it seemed to be spraying a very healthy amount of fuel at the valve even at idle.
I'll give it another day to soak thru..

Next I will have a look at the plugs... Won't be able to get a guage til after the bank holiday but this is getting worse fast enough that i think it's worth my while deplugging and referring to the haynes spark plug piccies at least. Found a wire brush in the garage last week

Gurrr...

Just hope it isnt whatever outright killed my mates' panda - the symptoms are starting to sound eerily similar. It started chowing oil at an accelerated rate much like the polo seems to be doing (looks like it's got through almost a full litre in a little over 300 miles )

(( oh yes, and i will be repairing the warm intake pipe, and reattaching the silencer/restrictor "trumpet" to the cold intake, just in case either of those have some kind of small but significant impact ))

Aint nothing like losing 25-30% of your power to make you really appreciate the raging fury that is a 1043cc powerplant in full, healthy flow.


* A38 where it crisscrosses the M6 Toll, at 5.45am on a Sunday. Doing 45mph back and forth between the two biiig islands and across the large one in the middle, then 85+, bare seeing another soul, not overtaking anyone and only being passed twice. Apocalyptic!

Right, iam pretty sure you were describing the same problem I had with my car not so long ago. Change the leads. Thats all i did, oh and the spark plugs. Runs much better now, it did seem much worse at the time, it got progressively worse until i broke down 4 times on the way to college. The idle was poor, and it was very difficult to drive. Stuttering and shuddering. Especially when i put my foot down. But like you said, it is almost "on demand". It may be ok for a few minutes, then it would start up again. Sometimes really violent shuddering, as if I was pulling away in 4th/5th! The exhaust sounded like heavy artillery fire, like it was running on two/three cylinders, with a distinct lack of power.

Firstly i changed the spark plugs. Then flushed the injector with redex/carbcleaner. Then flushed the spark plug holes. Nothing.

I got the garage to do a compression test, (Due to recent head gasket change by me & my bro), & check the ignition timing. In the end all it was were the leads.

Steve

Aw man, I've already changed the damn things once since I've had it, which cured a different type of misfire problem I was having... Seeing as it appears to only be the one cylinder playing up, can you buy leads singly anywhere rather than the full set?

Mind you i'd be prepared to try that as its worked before and i'm in an airbox-removing kind of mood after this evening's little fiasco. Plus its cheap (ish)

Shouldn't ignition leads last a little longer than 18 months? Never remember seeing their replacement on the "every 12 months / 10,000 miles" schedule!

OK I'll have some photos to put up tomorrow, but right now i'm just going to scrawl a little before sleep.

Got myself a new filter (and, at the same time, some new hot air ducting - bling bling silver pipework ) from Halfords, a proper champion job rather than their nasty generic thing. Less little flakey bits of metal on the inside for one thing (which I found hanging off the old one). Side to side really showed up how skankalicious the old filter had become in less than six months!

This however failed to make much improvement. Wrote it up to maintenance rather than fixing...

So I had a go at tackling the spark plugs. Got the air cleaner housing off easier than expected, pulled the leads off (numbering them with tippex on the metal sheathes as i went), cleaned all around with a brush, and settled in for the piggin job of removing them. (Had to return to halfords again in the end, cadging a lift - none of our hundred-odd random socket set parts dating mostly to the 70s would work)
Much swearing and grunting with an odd little overpriced tool later and i had one off. Looked......... odd. Referring to the back of haynes it was kind of between Overfuelling and Overheating - which is a killer, because one was caused by too rich a mixture, the other, too lean! (It certainly wasn't "normal" though). The only comfort I could draw was that there was a chance it was caused by the dirty filter.
Did the "loose fitting old hosepipe" trick to get it back in (....eventually) and got the others out in turn, all of them looking much the same. Found a wire brush to clean the other 3 with. Should have got the first one out and done similar but was impatient. Dunno if i did much other than moving the dirt around though!

With deposits "removed", plugs back firmly in place and leads tightly attached, plus all sundry bits (ie air cleaner ), started it up to try again. Again no improvement

On a whim pulled the dizzy off for a better look again. This time noticed - the graphite thingamy in the middle which effectively connects the coil to the rotor was utterly shagged - there must have been a spark gap connecting the two rather than actual contact. The graphite had all turned to flaky carbon, and the spring that tensions it against the rotor had disintegrated totally. Amazed the car still ran as there was a good 5mm air gap!
So, chugged back to halfords for a third time, got a new dizzy cap and installed it. Not much immediate difference (again prepared to write it up to 'essential' rather than curative maintenance) but progressing through the ride home the car seemed to be getting "better". The misfire effect seemed to be petering out lower and lower through the rev range, and happening less often.
Indeed, on the drive to work, it hardly happened at all after the first half mile, and I thought the car was effectively cured.

Nope, it started doing it more often and sustainedly again on the way back. Git. But, it's back to not occuring above ~3500rpm now, whereas before the 'wasted' bank holiday it was taking effect all the way through to ~5500.. So some improvement but no cure.

Also i've noticed, this time, if i floor it either side of a gearchange, it's present in the first of the gears (ie, second coming off a slow roundabout), but disappears almost completely after changing up (eg third, top). Theorised that it might be the oh-so-brief closing of the throttle, and a test with the same pedal movements but (first) no gearchange (and then, no clutch either) proved this. A quick close of the throttle after it starts to play up "cancels" the misfire and full throttle and power can be used.

Now....... what in the world?

I'm going to give it a couple more days to settle down and maybe play nice with the new components, maybe clean the sparkers more professionally, but after that.. back to halfords to breathe deep and buy either a compression tester (£18), plugs (£20) or new leads (£30), maybe all three, none of which may make any difference or tell me anything. Money pit....!

Oh yeah... the brake warning light's started to come on faintly, constantly, only noticed when it got dark. It's been flickering on a little of late because the handbrake sensor seems to be a little ill adjusted (push handle to carpet, light goes out for a while) but I couldn't get this dim glow to disappear. Mate has told me that one of my brake lights is bust - is this the cause? Going through a couple of deep puddles on the way home? Losing brake fluid (or it wearing out - looks a bit dark!) Or simply worn pads / shoes?

I know it could be completely different to my problem, but everything you describe happened to me. Even down to the colour of my spark plugs! The dizzy looked a bit shagged on mine too. (still haven't replaced it yet - oops!) Ive now got an induction kit from a mk3 golf with K&N etc, but I did effectively change the air filter. It didn't do much. The change in HT leads cured it. Honestly, it doesn't sound much, and it could be a completely different problem, but it was as simple as the new leads.

Steve

im just reluctant to change something minor and expensive which i already did once not too long ago, but i might go back to the chav-infested orange and black store and see if they'll let me take the new set back if they are "not required" (which i saw several times on a mate's returns receipt for several service items he bought then didn't want). That is, buy em, swap em over in the car park, go round twice, up the road a mile and back, and see how it goes... shouldnt be too dirty to return by that point.

Right. what I would do for starters is stop buying s**t from halfords. Get ur ass to gsf or euro car parts. You can get a proper set of leads for £20 for a polo and a set of plugs for less than a tenner. As for your misfire, have you even identified which cylinder its on? You can do this by removing each ht lead in turn and see how it runs without it.

The dim glow you refer to used to happen to me after I'd steam cleaned my engine. Moisture got in to the contacts on the brake fluid level sensor and took a few days to dissapear.
Whilst you've been fiddling with the air filter housing, have you reconnected all the small bore vacuum hoses? With these missing or even perished, the idle becomes unstable(non existant in the worst cases) and sometimes causes the lag you describe...Just a thought...
Oh, and yes...stop buying **** from Halfrauds!!!

Gaz i dunno if i already said in the thread (pretty sure I did) but I already tried diagnosing which cylinder it was. No joy - soon as i popped a lead off, it ran sweetly on 3 pots (well, as sweetly as a 4 pot car can on 3), rather than dropping to 2 at any point.

As for buying stuff from halfords.... well blow me down i didn't know anywhere else around me to get it from But I guess I do now.

Plus i'm an impatient MFer, and wanted to stop it wasting fuel/knackering the cat ASAP without me having to drive like it's a milk float, there's two halfords right by me, one 4 minutes away, the other about 9 - how long does shipping take from German/Swedish or ECP? (regardless of the £7 saving which I could really do with, however long they'd take to arrive)

The glow disappeared today. I think I know what it is, now you've described it like that - I happened to encounter a puddle that was bigger than it looked on the way home from work I rode the brakes for a few seconds afterwards to squeegee them off (and again after i noticed it) so I was worried it was an actual fault!
My level sensor could do with a wash anyway - it's a bit sticky

And yep.... i put all the hoses back. Though the one going to the hot/cold doofer isn't totally necessary is it? Seeing as my hot hose was non-existant for a while anyway... (I've put both the hose and the vacuum line back on now - they didn't seem to make any diff)

Got some replacement leads from Halfies... looks like their idea of how physically big a 1-litre Polo engine is and the shape of the dizzy is STILL all to cock. I'm not sure they'll fit properly if at all....... let's try it.

Well don't I just feel like the biggest nob in nobland.

From now on my philosphy on misfires may well become "check the bloody leads FIRST". I managed to only fit the coil cable, number one spark lead and squeeze number two on, but it was enough. Instant difference in running - much smoother idle, no missing at all on revving up, pulling smoothly and strongly (even trying to get a quick start in 3rd - a useful diagnostic tool the old guy in halfords taught at me*), and cruising like silk.

Putting the old ones back on one at a time (so the non-fitting things can go back) and starting/revving in between revealed.... it was number 2. Immediately that I put the old cable on and fired it up, hit the throttle - the smoothness was gone and it stuttered. Replacing again with the new cable, it was sweet again. Good job that it was just big enough to fit!
My original cable looks to have some insulation damage. Kind of mystified as to how that might have occured, unless these crappy halfords cables can't cope with heat above 90 celcius... (well, damn, it's still better than the HotWires I had originally) --- but even if that's the case, the coil cable had a habit of coming to rest against the main coolant pipe, so that should have been the one to suffer damage.

Might see if there's some way I can get a single suitable cable from the big orange and black one. If not, well, i'm returning them for being the wrong size anyway, may as well see what kind of speed delivery the specialists can do for me.

Cheers for all the help guys!


(and hey - i might have spent money on things I technically "didn't need" to rectify this problem, but the filter WAS disgusting, and the distributor cap WAS knackered beyond belief... so I'm non too bothered )

* sort of like, people can talk to you, or talk at you? this guy taught at you. no mercy!

GSF and ECP have shops. You just need to find the closest one to you by going on their website's store finder. Prob further away than halfrauds tho. Good news for me is theyre both about 5 mins from where I work in trafford park!

http://www.gsfcarparts.com
http://www.eurocarparts.co.uk