Running Rough/Idle issue

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Beddy957
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Posts: 2
Joined: Tue Jul 12, 2022 12:55 pm
Drives: VW Polo Mk5 6N2 1.0L
Location: Mexborough

Running Rough/Idle issue

Post by Beddy957 »

Hello to everyone, this is my first post, a problem one to start off, sorry in advance🤣🤣

Ok the car is a 2001 Polo Mk5 6N2 1.0L Petrol

Before we start the main bit, had a couple of times when the car refused to start and the EPC light came on as well. Plus had the rough idle issue for ages.

So to tell you everything what has happened so far, this is my missus car and about 4 weeks ago she got into it to go to work, car wouldn’t start, (crank but no start). So I did all the checks I could do and nothing, everything worked as should.
Got RAC to come out but they said it was fuel pump, ok. So took it out checked it and it buzzed under power and seemed to work. So put it back in and still nothing. Cranking but not firing.

Did some research and it said it might be ignition coil, so changed that nothing, then changed the Camshaft Position Sensor, and it fired up and worked fine.

So the missus used it for two weeks and then broke down again. RAC came out again. I again checked the fuses and Relay and the relay showing correct volts and resistance. Checked for spark and that was working. RAC man checked everything and pulled the line off the fuel pump and said the fuel pump has gone as it’s not pumping. Stating that when i had moved it about last time, it was like a starter motor and give it some life again, only to die 2 weeks later.

So I have changed the Fuel pump, checked fuel in tank and replaced the fuel filter. Also checked for vacuum leaks and replaced a couple of suspicious pipes and a pipe from the Fuel Pressure Regulator.

Now the car started first time with vigour and ran fine for 30 seconds and now the car wants to stall as it coughs every now and then. Like it has not enough air/fuel or spark to the engine. So I thought I would take it for a spin. Car worked fine, driving around the corners and full or little throttle in a straight line. But when you come to a junction and it’s at low revs and your about to stop at the junction the car would die, but not every junction. Could happen at the third or fourth etc etc. BUT BUT the car hasn’t stalled yet parked on the drive, like I said just drops revs from 800 to around 500 or so and it’s like it remembers it’s supposed to be running and kicks up to 800 revs again. Oh and there is plenty of fresh fuel in the tank.

So

No vacuum Leaks
Fuel pump and Fuel Filter changed
Ignition coil changed
Camshaft position sensor changed
Checked spark plugs and they work fine

Been googling and they say could be the fuel pressure regulator, injectors, some other sensor(air mass flow etc etc) or even the spark plugs.

That’s what I have left to check. But getting a bit fed up of buying parts and the car still wanting to stall.

I haven’t much experience around cars, but what could be causing it to cough on the drive and cut out at certain junctions, but work totally fine in a straight line.

One final weird thing, might not be anything, but before all this started. When the car is stopped with engine running, when you turn the steering wheel, the RPM’s drop say 50-100RPM and then revert back to normal. I thought the fuel system doesn’t intermix with the steering system, or could I be wrong.

Anyway, if you got this far, I can’t thank you enough and we would be very gracious to any of your thoughts.

All the best

Rob
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alexperkins
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Re: Running Rough/Idle issue

Post by alexperkins »

Coolant temp sensor is a prime one for causing starting issues

Another also common issue is the crank position sensor (G28)

have you plugged it in with VCDS to scan for faults?

have you cleaned the throttle body and performed an adaptation cycle on it also?
Beddy957
New
Posts: 2
Joined: Tue Jul 12, 2022 12:55 pm
Drives: VW Polo Mk5 6N2 1.0L
Location: Mexborough

Re: Running Rough/Idle issue

Post by Beddy957 »

I didn’t get to do much more on the car as it annoyed me to the point I was looking at my sledge hammer. So I took it to a garage around the corner, who is very good, and they said, they were getting fault codes for the ECU. They sent it off only £30 to get it tested and … the ECU is toast.
So going for scrap, took everything off to take back like fuel pump etc, and stripped everything off to sell for anyone who needs a cheap starter 2 years old and same for the alternator etc etc.
So thank you for the reply and all the best to everyone.

Rob
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