polo intermittent starting

[bridge9]

hi every one , great forum. i found it by chance while looking for help with my problem. some amazing cars on here too!!!

anyway if anyone can help......i have 2000 polo 1ltr petrol.  it's been giving me trouble for about 6 months now.  the car will not start first time but this only happens some times.. i have been keeping an eye to see if it's at any certain time, like only when cold or hot ect ect. but this doesn't seem to be the case.  it will start one morning and not the next, it will start when hot but sometimes not.   it always starts in the end but some times it seem like this time it wont. oh and some times after a few tries at starting i get a beep like a bell? when you turn off the key and try again the sound is gone.
also the problem comes and goes, as in i can get a few weeks free from starting probs.

any way had it to 4 mechanics (even a VW one), all plugged the car in and found nothing? there's no codes or warning lights
going by all the advice and guesses from the mechanics i have so far replaced 

the plugs and leads
the cam sensor
the temp sensor
the crank sensor
 the last thing i replaced was the crank sensor and the car seemed fine for a week but then it wouldn't start for a while yesterday morning   but it's been starting fine since!!
any help would be great 
thanks noel

 

[bridge9]

the latest news on this, took out a plug yesterday morning to see if there was a spark, the plug sparked first time and the car started. it was a mild dry morning. this morning it was damp and wet so i did the same thing and the plug didn't spark and the car didn't start. it took 7 or 8 tries before the plug sparked and the car started. so has to be dampness? i checked the coil and it looks ok but it has a few tiny hair line cracks in the plastic, if this was getting damp and shorting i taught the car would run badly? mine runs fine once started. the only other thing i can think of is the ECU getting damp or wet?? will check it tomorrow to see if there is any thing obvious?? like i said no warning lights on dash. some one said could be fuel filter but i don't think so as it's a non spark. but i did change the filter first time i got the problem. also the pump primes every time too.....anyway i'll keep at it and keep posting just in case someone else is having same problem.....

[ettorebugatti]

Thought about the immobilizer?

[baggabones]

Try putting a new dizzy cap on her, cheap enough...I had similar on an old veedub and the dizzy cap was letting in condensation on damp/rainy days...new cap=sorted

[ejenner]

I'd say unlikely to be the dissy cap as that usually manifests as misfiring, nearly starting, lumpy running. This problem sounds more like 'nothing' until it actually starts and then it runs fine.

[cobblers]

Oct 15, 2014 21:07:00 GMT ettorebugatti said:

Thought about the immobilizer?

Stock immo on that vw would allow it to start for a couple of seconds, then cut out.

Is it heavy on fuel? these regularly need coolant temp sensors, and will flood the plugs and not start because they think it's freezing cold, and it's not. If you can get it on VAG COM or something check that the coolant temp seems reasonable. The sensor is only about a fiver though.

[ejenner]

I never thought compensation sensors would stop a car starting though.

If the coil pack hasn't been changed then that'd be a good shout if you're into swapping random bits.

[bortaf]

Check you have a live at the coil, the usuall suspect on VW's of the 90's is the ign switch, if it has a CPS it will be coil pack so there's no dizzy cap to change

[bridge9]

G thanks everyone for feed back.....had the immobilizer checked. it's not heavy on fuel and the first sensor i changed was the temp one. there's no dizzy its a coil. gona change that next i think, €60. i spent about 200 now on bits and bobs...all a waste of money so far. whats the best way bortaf to check for live at the coil?? thanks

[bridge9]

oh another quick question at bortaf... i was looking at the ignition switch problems on the web just now, most of the VW's that have switch probs seem to have lights flicker, and radios die ect ect and moving the key around in the ignition highlight theses effects, i'm guessing because it's loose and dodgy and the contact is being lost and gained when the key is jiggled? do these symptoms have to be present when it's an ignition switch prob?? because mine doesn't do any thing like that, it just doesn't start?? thanks again.

[bortaf]

Oct 17, 2014 14:39:08 GMT bridge9 said:

oh another quick question at bortaf... i was looking at the ignition switch problems on the web just now, most of the VW's that have switch probs seem to have lights flicker, and radios die ect ect and moving the key around in the ignition highlight theses effects, i'm guessing because it's loose and dodgy and the contact is being lost and gained when the key is jiggled? do these symptoms have to be present when it's an ignition switch prob?? because mine doesn't do any thing like that, it just doesn't start?? thanks again.

Usually they have most of those problems yes but i have had them where they will only bump start, try and key it over and the ign live dissapears, really had me that one, if you turned the ign on (posII) there was a coil live but turn the key to the start pos (posIII) and the coil live dissapeared and reappeared as soon as the key flicked back to posII, no flickering lights nothing out of the ordenary at all.
Mind you that one also had the RAC and a local indipendant stumped, i had it in for a few weeks as a hospital job (long stay @ cheap rates as i work on them when/if i can) and as you do you try the obv first then get desperate and try the illogical and "crazy" ideas later on
I've golfs where the ign live simply dissapeard for an hour or so after trying to start the car but that was easyer to find as all ign lives dropped out and stayed out, the above one that only dissapeared during cranking was harder to spot but then all intermitant problems are harder to find.

On the coil pack plug there will be 1 live and 2 trigger wires, a coil pack is basicly 2 twin lead coils so plugs 1 and 4 will fire at the same time and 2 and 3, hense the 2 trigger wires and only 1 live, check that live is there and stays there whilst cranking, for an intermitant no start i wouldn't be changing the coil pack yet, unless there is a confirmed missfire it's the last thing to change "unless" you have a known spare handy (cost mainly!), coil packs tend to misfire intermitantly not compleatly fail intermitantly due to the fact there is 2 of them to fail not just the one (if that makes sense ?).

[bridge9]

thanks bortaf, the car hasn't done it for a few days now( weather has been mild again) but i have checked the live at the coil....i pulled the block connector that goes into the coil and tested the wires....there was a brown, black and 2 green i think....i taught i'd get live at the brown but i get live at the black when i turn the key....12.6 v when i crank the key i get from 6.6. to 11
the brown wire gives no volts
the greens give from 0.3 to 0.9 on one and the other gives 0.2 to 0.5 ?
does this sound right???
i pull a plug each time i test it, i'm hoping to see if i get power going into the coil and no spark coming out.. this should tell if the coil is at fault right? but as i said it has been starting the last few days..........
think my head is going to melt!
have not go to the ign switch yet..

[bortaf]

Sounds like you have a right PITA there, i really do hate these intermittant faults! they really do your head in black would be the ign live so that's correct, the greens are from the CPS to trigger the coils and they will have a small voltage on cranking so you know the CPS is working (at that particular time).
TBH as there are 2 coils in 1 in the coil pack they rarely both fail, you normaly get a misfire on 1 or 2 cylinders, normaly a total no start is the CPS BUT as you are finding out an intermitant no start can be a lot of things
keep at it chap, you'll get there

[bridge9]

Thanks bortaf don't want to wreck your head but I have a bit more info.....car wouldn't start this morn. I had the spark plug out and the multi meter connected to the black wire going into the coil....when the key was turned I got 12 or so from the the black, when the key was cranked I got no spark from the spark plug but was getting power between 5 and 9 from the black wire. Any ideas? Thanks!

[bridge9]

right, for anyone who was following this or who is having the same type of problem....i think i have fixed it!!!!!!! because it's intermittent it will take a few weeks to know for sure.... anyway turns out to be the coil!!!!! like i said before it was looking like it happened more so when cold or wet/damp out. i was told by a few mechanics that a coil wouldn't give this type of problem,,,and i taught that myself but still suspected the coil because i was getting power going into the coil but no spark at plug when the car was giving trouble....so the last thing i tried was to heat the coil with a hair dryer in the morning before starting, when i did this it started every time!!! i was talking to another mechanic about this and the first thing he said was, what year is your polo? i said 2000, he said that year had a coil that could give this starting problem and he said he had a spare coil i could have for free!!! once i fitted this coil (which by the way looked a bit more shabby than my one) the car started first go and has been doing so for the past week in very cold damp weather!!!! so fingers crossed this was my problem. my advice to anyone having this problem is 1. get a multi meter and check the power going into the coil while cranking the engine over and at the same time pull out a plug and see if it's sparking. 2. then try the hair dryer trick but this will only work if your car is giving this trouble in cold wet weather!!!

thanks every one for help and advice with this.