Question Regarding Polo 1.4 9n

**Joe90jr** · 16-07-2015,10:35 PM

Hi there we recently bought a Polo and are having some problems with it I hope you may be able to help with. Its a 1.4 petrol MkIV 2005 9n engine type BKY. When we first got it it started to misfire. I have access to a VCDS reader cable and it duly diagnosed coil pack on no.4 which I replaced.

It now plays up - it never feels like its running right an lacks some power. It has now started to cut out and refuse to turn over at random intervals. I have changed spark plugs, air filter and coolant temp sensor.

Today I ran the engine to see how it did. I noticed that it got hotter but the fan didn't kick in, neither did the temp gauge go above halfway. Worrying about overheating I turned it off and it then beeped and showed the oil light. It then wouldn't turn over at all but beeped each time and flashed the oil light. When it had cooled down a bit it started fine. I checked the rad hoses to see if the thermostat was ok and it did the correct top hose warming before the bottom hose so that seems right too. So it might be the fan switch but why would it stop the car turning over at all ? Battery seems to have decent charge as well. It is not logging any fault codes at all.

Any ideas or pointers greatly appreciated.

Cheers
Craig

**Doctle Odd** · 16-07-2015,10:42 PM

Temp gauge on VAG cars is supposed to only to 90 which is half way. I think you have problems with earthing points on the car

**Joe90jr** · 16-07-2015,10:48 PM

Thanks for such a quick response. The main earth looks ok. Are there any usual suspects or is it a case of going through them all ?

**Doctle Odd** · 16-07-2015,10:55 PM

When she doesn't turn over do the ignition lights come on? Is the wiring to the starter clean and tight. There are a few earth/ground points including the battery I forget where they all are.

**Joe90jr** · 16-07-2015,11:09 PM

No not all the lights seem to. I'll go through them tomorrow. Still confused about the fan but I guess it might be related ?

**niall campbell** · 17-07-2015,08:57 PM

Hmmmmm its not an oil problem and car is seizing ?

When was last time you changed the oil and oil filter ?

I woudnt be bothered about the fan if its not coming on, you may need to drive it around for it to come on; water temp looks okay ....................... unless you want to throw in a new water temp sensor t be on the safe side ............... it doesn't cost much

**Joe90jr** · 25-07-2015,07:25 PM

Update. Thanks for the advice. Since my last post I took out the battery and starter motor and scraped and wire brushed all the main under bonnet earth points and straps. I also tested the starter off the car to make sure that worked. It did. After putting it all back together it started ok and has continued to. So it looks like it was earths. Thanks.
Now back to the original problem of idling rough and stuttering on acceleration. I have read loads on the forums about this issue and have addressed a few things. Here is what I have done so far in order:

Replaced spark plugs
Replaced Air Filter
Cleaned throttle valve and realigned it using vcds.
Replaced coolant temp sensor
Replaced oil and filter
checked vacuum pipe for leaks - seems ok
replaced fuel filter - looked like the original !!
done compression test - seems ok

All the above has made it more driveable but the problem is still there. I haven't done lambda sensor yet because at £160 (cheapest I could find for bky engine type) I cant afford to waste the money. There is no faults logged at all even after repeated reading. Any other thoughts ? Could it still be lambda even though it isn't logging a fault ?
Cheers
Craig

**Doctle Odd** · 25-07-2015,07:27 PM

as you have vcds you might be able to collect some live data

**Joe90jr** · 25-07-2015,07:32 PM

I borrowed the cable from a mate and downloaded the software. I am no expert and am a little worried at cocking things up. I read how to test lambda sensors but got confused between measuring blocks, basic settings, etc. is there an idiots guide for testing o2 sensors on the 1.4 polo ? One of the threads said use group 030 but my car said "error" doesn't exist or something like that. So I stopped.

**Joe90jr** · 26-07-2015,11:45 AM

So I used the really good post on here by crasher and did the basic settings tests on the emissions system. A couple of tests wouldn't work such as knock sensor (gave me an error message) but everything passed and all readiness boxes were showing passed. The only thing that didn't, and it logged a fault code P0420, was cat bank 1 below efficiency. So I am not sure what to try now. I know the exhaust system is a bit blowy and now I know the cat isn't great but I cant believe this would give me such juddery running ? I was just going to try some injector cleaner and take off the inlet manifold gubbins to check for leaks and maybe renew gaskets. Otherwise I am at a bit of a loss.