Definitive Answer ?

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PeterAbbott
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Definitive Answer ?

Post by PeterAbbott » Thu Oct 03, 2019 12:38 pm

Hello all,
The faults I am having seem to be quite a common one without a definitive answer to it. Sorry about the repost would would be very grateful if someone could throw a bit of light on it.

Hello All,
Really am stuck now. 1.4 Auto 6N2 AUA 2001. The little dear has only covered 60.000mls. Bit sentimental as it was my grandaughters. Now the fault is that it starts, no problem BUT as soon as the engine gets up to normal running temperature it just cuts out............no warning lamps up ! Wait a few minutes and she will start and run just for a couple of mins (upto temperature again)and cuts out. Diag has given all sorts of red herring codes and I have changed Temperature Sensor, Crank Sensor and MAP sensor. This only leaves the CAM position sensor. I have had the cluster out and resoldered joints. No stored alarms with the diagnostic at all now but this same fault still exists.
Now, this has to be something that is affected by temperature but what could it be ? Any ideas would be welcomed please.
Thanks ( before someone says "take it to Dealer" I would just like to add that I own a T3 camper and a 2000 1.6 Bora and believe me on a pension at 67 the T3 / T25 camper is a money pit so money resources are tight.........bloody Brexit ! )
Thanks again
Pete Abbott
IPSWICH

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937carrera
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Re: Definitive Answer ?

Post by 937carrera » Fri Oct 04, 2019 7:27 pm

T3's aren't that expensive unless you have tinworm and buy the right parts as replacements.....I have 'em too.

On the Polo.

It is going to be tricky to diagnose this, especially remotely, my first instinct is that it is a break in a wire that makes when cold, but breaks due to high resistance when it gets hot.Some questions:

Now the wire could be getting hot through engine temperature, or by current flowing through it. So there's one fork in the road for you.

Is it fuel or an ignition problem ? When it cuts out what does it do

Does it restart immediately, or does it need a period of time to "cool"

What voltage do you see across the battery when the engine is running

PeterAbbott
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Re: Definitive Answer ?

Post by PeterAbbott » Sat Oct 05, 2019 8:42 pm

Thanks for that. When it cuts out it is though you have just switched the ignition off but all the system check lamps stay off until I remove and replace key. New battery so 13.8v to 14v when running. Will not start until 5 minutes after. Changed the fuel pump relay today and previously changed fuel filter. I have Vagcom and still no fault codes ! Going to get "a man" to visit with full cvds and see what that shows. Very strange. I even had the relay board out (not easy) to check for dry joints but nothing found.
Thanks for the response
Pete

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937carrera
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Re: Definitive Answer ?

Post by 937carrera » Sat Oct 05, 2019 8:51 pm

PeterAbbott wrote:
Sat Oct 05, 2019 8:42 pm
When it cuts out it is though you have just switched the ignition off but all the system check lamps stay off until I remove and replace key.
That indicates that it is something fairly fundamental in the supply to the engine / dash panel. No dashlights = engine running fine, ignition in off position or battery dead.

Does the handbrake light stay illuminated (leave it on, this will help diagnosis)

Are the battery terminals secure and the main earths clean / well made ?

PeterAbbott
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Re: Definitive Answer ?

Post by PeterAbbott » Sun Oct 06, 2019 12:57 pm

I meant no dash warning lamps as if the engine was still running and yes handbrake lamp remains on. Battery terminals and earth's all clean and tight. Could it be the camshaft sensor do you think, the only sensor I have not replaced ? Very strange fault isn't it. Really appreciate your interest and help. I hope you are one of the nice people I wave at when put and about in my camper.

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937carrera
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Re: Definitive Answer ?

Post by 937carrera » Sun Oct 06, 2019 3:31 pm

OK, so the handbrake warning light stays illuminated, so the dash has power

Does the oil pressure light come on ?

Alternator warning lamp ?

My reading of your earlier comment was that neither of these came on unless you switched off and back on again, just want to be sure

I tend to focus on the diagnostics rather than the Kwik Fit school of engineering, so I wouldn't spend money on a cam sensor unless I was sure. You would also expect an OBD code to be stored if there was a cam sensor issue. I assume that no new codes are being generated. I have seen false cam sensor errors too, so more likely to be a false positive than a false negative

PeterAbbott
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Re: Definitive Answer ?

Post by PeterAbbott » Mon Oct 07, 2019 11:42 am

Just going to wait for a friend of a friend to arrive with his full VW diag gear because apart from renewing the wiper blades I am really at my wit's end Only a DIY mechanic but been at it myself all my working life and never been stumped as I am now. Very strange fault isn't it.
Will keep you updated and really appreciate your input.

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Re: Definitive Answer ?

Post by PeterAbbott » Wed Oct 09, 2019 4:07 pm

IMG_20191009_130955.jpg
Coil pack
Looks like this could be my problem ? What do you think 937carrera ? Had CVDS scan and nothing found ! I know the connections look bad but the large crack looks worse.

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937carrera
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Re: Definitive Answer ?

Post by 937carrera » Wed Oct 09, 2019 6:33 pm

Hmm, I'm trying to think of the fault mode.

Cracked casing allows moisture in and corrosion occurs.

Coil pack gets used, works at first,but as current flows across a poor connection it gets hot and the increased resistance makes it go effectively open circuit and the car stops.

So, yes, definitely worth trying another one, though the lack of VCDS codes is a bit unusual

Even stranger is the dash lamps - can you confirm what is happening with the oil pressure /alternator lamps?

PeterAbbott
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Re: Definitive Answer ?

Post by PeterAbbott » Wed Oct 09, 2019 8:23 pm

Yes, to be clear. When she cuts out the hand brake and battery symbol is all that is illuminated. Turn key off then on again and all is as expected when restart. Sometimes it will start straight away and other times not until it cools, probably just a few minutes. I stood over it today while it was running and "tweaked" at the wiring and when I touched the coil plug it cut out. Cleaned the connector and started straight away until I again pressed the connector and she cut out. Removed the coil pack and that's what I found. As you say, this would account for the temperature related fault, hopefully. No misfire at all though. Exactly the same symptom as though you had switched off with the key so perhaps why no fault codes ?

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937carrera
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Re: Definitive Answer ?

Post by 937carrera » Wed Oct 09, 2019 9:57 pm

Ah,so the battery light is also coming on, so situation normal (though you should also get oil pressure warning)

The movement of the cables seem to confirm that's where your problem is so inspect the HT leads and if they are ok get another coilpack

PeterAbbott
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Re: Definitive Answer ?

Post by PeterAbbott » Thu Oct 10, 2019 12:17 pm

Yes you are perfectly correct. When it cuts out battery and handbrake are on, then after a while the oil warning comes on. Polo has to wait for a bit, T3 needs a bit of work for MOT, rear brakes including backplates, love working on my van......no electronics ! Take care mate.

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937carrera
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Re: Definitive Answer ?

Post by 937carrera » Thu Oct 10, 2019 2:26 pm

Brickwerks then

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