Polo 9N MK4 2007 plate 1.4 TDI BNV - Not firing

[saj121]

Hi all,

After searching around endlessly and having even a mechanic come and look it. I honestly cannot fork out any more on this car so your help would be very much appreciated!

Basically it was bought as spare car, started a few times and died randomly.

No codes on VCDS.

I've changed the starter motor, injector loom, fuel pump relay, crankshaft and coolant temp sensor. After all those, I decided to get a mechanic to look inside of the engine/injectors, he said the injector washers seemed worn so changed those. Fuel pump is working fine as there's fuel going in, he also checked the compression and said that's fine too.

All it does is crank but no fire/spark.

He said for me to hook it up to a diagnostic, turn the car and see if what comes up in the live data (not sure what to look for now).

Can you think of what's left to change? I really wanted to get this back on the road as my commute car!!

Thanks

[grant19841]

It's pd tdi engine, a spark won't happen it has glow plugs.

So did the mech check the only fuel pump ( in the tank)?

Compression is good, air is entering the chambers then so must be fuel related.

Have you changed the fuel filter? May as well do the air filter too.






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[saj121]

yes sorry thats right - pd engine, glow plug lights come on and go off within a second.

he checked the fuel pump the tank one and also the vacuum/tandem pump on the front.

tried some easy start but that didn't work either.

I've changed all the filters inc fuel and air.

thanks

[grant19841]

No codes on vcds,before vcds check have you had the battery out recently?

Mech said fuel is getting to the filter etc?

Egr clean? Maf ok?


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[saj121]

It did have a flat battery at one point and I swapped it for a new one.

Yes mech said fuel is getting to the filter.

Not sure on EGR or MAF - will get back to you tomorrow on this. thanks

[Rob69]

When you say he tried easy start and that didn't work, what do you mean? Did the engine start, run briefly then stop or did it not even fire up with easy start? If it wont fire with a sniff of easy start then there is either no air getting into engine (anti shudder / intake throttle flap stuck shut) or the engine has no pistons or valves ! (ruled out by compression test already done).
The engine needs to reach a minimum cranking speed to admit fuel and fire on diesel, check the cranking speed with vcds, I can't remember the figure, but 280 rpm rings a bell, search forum as that's been discussed

[grant19841]

When you say he tried easy start and that didn't work, what do you mean? Did the engine start, run briefly then stop or did it not even fire up with easy start? If it wont fire with a sniff of easy start then there is either no air getting into engine (anti shudder / intake throttle flap stuck shut) or the engine has no pistons or valves ! (ruled out by compression test already done).
The engine needs to reach a minimum cranking speed to admit fuel and fire on diesel, check the cranking speed with vcds, I can't remember the figure, but 280 rpm rings a bell, search forum as that's been discussed
That thought entered my head too,
The battery swap must of erased old codes.

Asv would not allow car to start if faulty.

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[saj121]

Hi just wanted to say thanks for your help so far.

It did not fire when easy start was applied. It made no difference.

I've just done some searching someone said to check if it hits over 200rpm within a second of starting under group 5 on vcds.

Will report back in a bit!

[saj121]

So based on what I've read about the rpm it looks like mine is too low.

What could be causing this? It's new starter (actually the second new one as I fried it the old one a month ago trying to turn it on so much!)

Pics of vcds reading while cranking

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[Rob69]

That crank speed looks v low, did you give it a while for vcds to get a stable reading, is it a fresh battery and do you have good clean battery and motor terminals and a good earth? Anything getting hot while cranking, cables etc?
I'm surprised you couldn't get it to cough over on easy start as well.

[grant19841]

Very low, check starter connections and battery voltage (even if it's new).

Silly question I'm sure, is it the correct bat for car?

Also turning the Starter for more than 10sec will burn it out.

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[grant19841]

Try a voltage test on the bat and the starter, not cranking and cranking.

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[saj121]

That crank speed looks v low, did you give it a while for vcds to get a stable reading, is it a fresh battery and do you have good clean battery and motor terminals and a good earth? Anything getting hot while cranking, cables etc?
I'm surprised you couldn't get it to cough over on easy start as well.

Yes, I gave it a while but not so long as scared it will burn out. They are good terminals, I saw that the earth cable has corroded previously so I bought a new one but this is also starting to show some heat on the wire (little bubble) but this could be from the previous starter when I was turning a bit too much.


Very low, check starter connections and battery voltage (even if it's new).

Silly question I'm sure, is it the correct bat for car?

Also turning the Starter for more than 10sec will burn it out.

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It's the right battery, got it from eurocarparts along with the starter - the battery has warranty so will go swap it for another one just in case. It's fully charged and i've even tried jumping it with no luck.


Try a voltage test on the bat and the starter, not cranking and cranking.

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Ok i'll try it again in a bit, p*ssing it down outside!

Thanks for your help so far both :)

[Rob69]

Check the earth from car body to engine, may be a braided flat cable, thinking you've a bad connection somewhere.

[saj121]

This is what it looks like. It was a new cable a few weeks ago!

http://uploads.tapatalk-cdn.com/20160326/c759397a203785b680cef1b56e30c9ed.jpg

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[saj121]

12.8 volts and it dropped to about 10 when cranked

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[grant19841]

It should raise to about 14v,

You must have a short circuit

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[grant19841]

Recheck all earth's again mate,


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[saj121]

I see. I thought it goes up when it's powered by alternator.

Any diagram or lists of where all the earth points are

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[niall campbell]

I have your car and same engine code

What starter did you fit & what battery ?

[grant19841]

Yes sorry wrong thread mate thread mate I answer too many at once and loose track.

Yes a battery drop to around 10v when cranking is normal, your starter will be draining most of that current trying to start it .

Your bat doesn't go drain current as it's reads fully charged at 12.8v.

Have you tested the *starter* current? Maybe the leads are corroded etc

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[Rob69]

Is that the new earth lead you mentioned? The single screw connection onto the battery post clamp doesn't look great and you can see it's been overheated. Was it a genuine vw or generic earth cable? Is there an earth strap from body to engine?
If you have a multi meter I'd take some resistance readings between battery neg and body, and battery neg to starter, you should be seeing low resistance, say less than 5 Ohms.
If you connect your voltmeter across the starter pos and car neg I bet you'll see a lot lower voltage than the 10V you measured across the battery posts while cranking over, due to V=IxR. Be carefull there's some high currents wizzing about though.

Ps I'm not an electrician, so wiser heads may have better ideas!

[saj121]

Is that the new earth lead you mentioned? The single screw connection onto the battery post clamp doesn't look great and you can see it's been overheated. Was it a genuine vw or generic earth cable? Is there an earth strap from body to engine?
If you have a multi meter I'd take some resistance readings between battery neg and body, and battery neg to starter, you should be seeing low resistance, say less than 5 Ohms.
If you connect your voltmeter across the starter pos and car neg I bet you'll see a lot lower voltage than the 10V you measured across the battery posts while cranking over, due to V=IxR. Be carefull there's some high currents wizzing about though.

Ps I'm not an electrician, so wiser heads may have better ideas!
It wasn't a genuine one. From eBay but will report back tomo with readings

Been down with the norovirus so totally wrecked at the moment!!

Thanks for the help guys

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[saj121]

It read 6 ohms

I wasn't able to crank and check.

Also in regards to battery I've got a Lion 100 70AH and I bought another starter from ebay (breaker) so it's the standard for the car.

[saj121]

I have your car and same engine code

What starter did you fit & what battery ?

I've got a Lion 100 70AH and I bought another starter from ebay (breaker) so it's the standard for the car.


Is that the new earth lead you mentioned? The single screw connection onto the battery post clamp doesn't look great and you can see it's been overheated. Was it a genuine vw or generic earth cable? Is there an earth strap from body to engine?
If you have a multi meter I'd take some resistance readings between battery neg and body, and battery neg to starter, you should be seeing low resistance, say less than 5 Ohms.
If you connect your voltmeter across the starter pos and car neg I bet you'll see a lot lower voltage than the 10V you measured across the battery posts while cranking over, due to V=IxR. Be carefull there's some high currents wizzing about though.

Ps I'm not an electrician, so wiser heads may have better ideas!

It read 6 ohms

I wasn't able to crank and check.

Thanks both

[niall campbell]

firstly go to garage and check new battery, ask them to check for dud cell(s) , even though its new, this should be free

secondly, the 2nd hand starter. Do yourself a favour and fit a new one. You don't know if the ebay one is working well enough to get enough speed up to start the car

thirdly or indeed firstly, check the earth from the starter

[saj121]

firstly go to garage and check new battery, ask them to check for dud cell(s) , even though its new, this should be free

secondly, the 2nd hand starter. Do yourself a favour and fit a new one. You don't know if the ebay one is working well enough to get enough speed up to start the car

thirdly or indeed firstly, check the earth from the starter

Hi niall,

battery checked fine, it's holding charge and tested good.

Also managed to exchanged my starter so got a new one, RPM is still low though!

I'm going to buy a new earth cable but surely it can't just be that, I've used a jumper cable and grounded it to a point on the car and still no luck..

Tearing my hair out with this!!

[grant19841]

Petrol and match comes to mind

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[niall campbell]

the Boss has taken her car to work, so cant tell how fast the car turns over to start using Live Data

[tony-1977]

If it's not cranking over fast enough, just a thought but have you tried tow-starting it?


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[Rob69]

Just re reading this rhread. So you have a new starter and battery, but still low crank speed, low resistance between battery negative and body or battery neg and starter? Did you check the positive terminal to starter as well? When you connected the jump lead was that onto the car body or the engine / starter to eliminate the body to engine connection. Could you do the same for the battery + to starter + terminal to eliminate the positive lead (carefully).
I'm still not sure why it wouldn't cough over on easy start, is the asv flap opening?
When the guy had the injectors out to change the seals and check compression what was his take on things? Was it at a garage but then brought back home for you to sort out?

[saj121]

I've had it towed to the garage, only so much a man can do outside a house!

Written what's been done and hopefully hear back on this week! will keep you guys posted...