Hi,

I have a mysterious problem with my Polo 6N2 -2000 with AHW engine (1.4l 16V)
The car wont run properly.. Trying to start it up, it idles with difficulty at around 4-500 rpm.. Trying to give it more gas, and it dies..

Now, what has been done:

- Cambelt is checked, and ok (3 times, one by a VAG shop))

- Comptest is ok

- Camshaft and crankshaft sensor have been replaced with new one

- Engine temp sensor have been replaced

- Engine wire harness has been measured and is ok (by VAG shop)

- ECU has been swapped (by VAG shop)

- Ignition coil have been replaced with new one

- Spark plugs and cables have been measured/replaced

- Throttle body have been checked and re-calibrated

Don´t think i missed anything.. Been a lot of replacing of parts.. :/

 

No errorcodes what so ever.. 

 

I'm running out of options.. Just got the car back from the VAG shop, and they say that it ignites on the exhaust stroke.. I asked how he could measure that, but the answer was that he hears it??

Nobody has been in the gearbox, so it would suprise me if the flywheel just happend to turn itself quarter of a turn...

 

Anybody got any ideas? I'm running out of them...

 

Thanks,

 

Peter

 

Faulty coil pack

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I changed the ignition coil to a brand new one.. If it is this one you mean?

 

First off, I'm not a mechanic so take my advice with a pinch of salt.

 

My 1.0 6N2 started running rough about a year ago. Just general sluggishness, stalling at lights, revs wandering on idle etc.

 

To me, it felt like a fuel blockage. So I brimmed it with good quality fuel (not supermarket) and fed it half a bottle of injector cleaner (Redex?)

 

Result? Well it's been fine ever since! My theory is; my car only does short little journeys around the city so never gets up to temp. Plus I was always filling up with supermarket petrol which somebody told me doesn't contain detergents, so maybe my fuel lines/injectors were clogged with gunk. No idea how much truth there is in this but the results speak for themselves.

My first thought was the fuel, but trying to crank the car basically drowns the spark plugs.. And when you get it to run (or whatvere i should call it ) it smells unburnt gas from the exhaust.. 

Nobody else that have any ideas? 

You need to check the fuel pressure but be careful of what you're nose is telling you. 

 

You can end up with unburnt fuel for 2 reasons, either there's too much or the fuelling is correct and is unburnt because of an electrical fault. 

 

Mechanical pressure gauge on the fuel line would be my next test. 

 

All earths checked and okay?

 

Stick an old school timing light on it and see where it's actually firing on number 1, that'll tell you if there's a misalignment somewhere. 

 

Got access to VCDS to check live outputs from anything?

 

 

 

 

Edited 5 February, 20179 yr by Duffy

20 minutes ago, Duffy said:

You need to check the fuel pressure but be careful of what you're nose is telling you. 

 

You can end up with unburnt fuel for 2 reasons, either there's too much or the fuelling is correct and is unburnt because of an electrical fault. 

 

Mechanical pressure gauge on the fuel line would be my next test. 

 

All earths checked and okay?

 

Stick an old school timing light on it and see where it's actually firing on number 1, that'll tell you if there's a misalignment somewhere. 

 

Got access to VCDS to check live outputs from anything?

 

 

 

 

I´ll try and find a pressure gauge for the fuel line. Earths tested by VAG shop and is ok, according to them.

Yes have VCDS with an Ebay cable.. Don´t know if it supports live data... Otherwise I´ll check with AutoCom..

You'll get a testing kit on fleabay for under £20. 

 

Do do the other stuff first in case it shows an obvious fault and save spending until last! 

I'd give it a go with some premium petrol in it, either Tesco 99 or Shell V-Power.

 

Redex is probably the most popular cleaner out there but I prefer BG 44K... It seems to do a better job.

 

Best of luck!

Ok, got a bit further.. After testing a bunch of things, it seems like the fuel pump only runs when ignition is turned on ( the initial preassure build-up). Measured the amps at fuse 40. and on ignition it comes up at around 4-5A, but then when I try and start it stays at 0 Amps..

 

That leads me to suspect that the fues pump relay is busted..

 

Question is now, when i search for the relays, it is supposed to be relay 410 that is the fuel pump, but here in Sweden, the scrap yards say its relay 100..?

 

Anyone got any ideas on which is which?

Bridge the contacts in the relay box so that the feed to the pump is getting 12v and try and start it

if it runs then the relay is your problem 

Will try that.. Just looking right now how to get better access to the relaybox..

 

Googled  "Access to relays on Polo 6N2" and the answer turned up with "With great difficulty" 

You could just cut out the middle man and put 12v straight to the pump, rear seat is 2 bolts, pop the cover off and there you are! 

11 hours ago, Duffy said:

You could just cut out the middle man and put 12v straight to the pump, rear seat is 2 bolts, pop the cover off and there you are! 

Yeah. that sounds like a plan 

 

Nobody knows what the 410 and 100 relays actually are for?

Ok, back to square one..

Bridged the relay to make pump run, which it did... but the damn car didnt wanna start anyway..

Now, I checked the sparkplug spark again, and it sparks maybe one time out of 10.. 

 

Starting to run out of ideas....

Camshaft position sensor

Already replaced

Checked the spark leads again, tried different leads,  and even tried and checked the spark, grounding it to the battery.. No difference..

If it was me I'd be checking the wiring loom for damage/faults, you also really, really, really need to get a fault tester on it, VCDS or similar.

On 2017-02-17 at 18:18, Duffy said:

If it was me I'd be checking the wiring loom for damage/faults, you also really, really, really need to get a fault tester on it, VCDS or similar.

The VAG shop have measured the whole wiring loom, and they say its ok..

I have both VCDS and AutoCom.. Doesnt help.. :(

Hi

What is the mileage?

Have you looked at the amount of oil in the air filter/housing ?

The single fuel pump relay, should energise when the drivers door is open, to pre-pressurise the fuel system, then it is energised again by the ECU when you go to start, and it also has another input from the airbag ecu, to kill the power in the event of the airbags being deployed. The same relay also provides the power to the injectors and the Lambda sensor heater.

 

You say you've checked with VCDS but have you checked the airbag ecu ?  

The milage is about 190.000km (118.000 miles)

Air filter housing is removed..

I´ve changed the fuel pump relay now (410), also put back the original spark plugs with 2 electrodes (had 1 electrode before)

Fuel pump seems to run ok now, spark is comming as it should (checked with ignition light tester aswell)

No error codes what so ever.. (Checked with Delphi - AutoCom), should'nt Airbag ECU error codes show up here?

The car kinda wanna start when you turn the key now, but gives up after a couple of seconds...

Tried again with starter gas, but no luck...

 

Combustion requires 3 things.. Spark, Fuel and Air..

 

Spark is there

Fuel is there (spark plugs gets wet, and starter gas should  do it if it was a lack of it)

Air is coming (Air filter housing and stuff removed down to the throttle...

 

Could it be that the car is cursed? 

 

Really running out of ideas...?

Edited 21 February, 20179 yr by Eslund

Btw, read somewhere that there is a Base timing that could might be needed to set in the ECU.. Somebody knows if thats true, and how it's done?