Car guys please help :)

[Captain Tom]

Hoping someone has some ideas on this issue with my car.

I have a 2003 Polo 9N with a bit of an odd problem:

Sometimes one of my cylinders cuts out completely. This only ever happens while I am idling, I can avoid it happening if while I am idling I keep the revs over 1000. My initial thoughts were fuel pump or fuel injectors. But here's the kicker... Once this has happened the only way to get all cylinders working again is... To open the hood and shake the engine around a bit.

Spark plugs are fine, ignition coils look fine. I did have a mechanic look at it and he said "Probably the fuel pump or fuel injectors" so he had the same thought as me but that doesn't really explain that the only way to fix it is to shake the engine. I really don't want to spend the money replacing these parts if they aren't actually the issue.

Apart from this happening the performance is 100%. I have run some fuel injector cleaner through the system, no luck so far.



My car knowledge is subpar so any advice would be greatly appreciated

 

[eyetac]

Sounds like a loose wire on the coil.. when you shake the motor, it makes connection again.. and when driving, the car is moving enough to keep connection.

Could also be a block in the fuel rail going to that cylinder.. just enough that when idling, it's starved of fuel.

 

[TheJudge]

Do you mean like the pistons struggle to overcome friction at low RPM?

 

[Captain Tom]

Sounds like a loose wire on the coil.. when you shake the motor, it makes connection again.. and when driving, the car is moving enough to keep connection.

Could also be a block in the fuel rail going to that cylinder.. just enough that when idling, it's starved of fuel.

Thanks I'll check these out after work

 

[Captain Tom]

Do you mean like the pistons struggle to overcome friction at low RPM?

I don't think this is the case, the 1 cylinder completely stops firing, I think if this were the case then restarting the car would have enough umph to move the stuck piston. But again, I have very little car knowledge

 

[Xander8807]

yeah sounds like a coil wire that is loose TBH...trace the Cyl1 coil cable see for any breaks (from sparkplug to Coil) might be some wear and tear on the wire and the plastic is a bit hard/cracked causing it to maybe short out on the head/block/or anything metal

 

[dhirennaidoo]

But here's the kicker... Once this has happened the only way to get all cylinders working again is... To open the hood and shake the engine around a bit.

So...how did you figure this out?

+1 on checking the ignition coils.

You should also get the car scanned by someone with VCDS (diagnostic cable). Sometimes the codes can help you narrow stuff down.

 

[wes1987]

I agree about loose connections possibly in the coil pack.

if the engine is idling normally, and you wiggle the plugs on the coil packs, does that trigger the same behavior?
older engines those plugs can become brittle because of the heat. and terminals get corroded.

 

[Captain Tom]

I've checked out the wiring from the ignition coils, all looks good to be in good condition and well insulated although I will check it again. I am leaning towards it being a non-electrical problem.


@dhirennaidoo I only found this fix because the first couple of times this happened I thought it might be the wires on the ignition coils, and to check those I have to take the engine cover off and taking it off shakes things a bit...

Difficult to replicate too, sometimes I can drive for an hour without it happening.

 

[Captain Tom]

I agree about loose connections possibly in the coil pack.

if the engine is idling normally, and you wiggle the plugs on the coil packs, does that trigger the same behavior?
older engines those plugs can become brittle because of the heat. and terminals get corroded.

Shot for the response I've done this test a few times, start the engine and wriggle basically every wire/connection/anything I can wriggle really and I can't get the cylinder to cut out.

 

[Confucius]

Where about are you based. Find someone with a vagcom cable that will be able to check for fault codes. you can also buy fake cables for a couple hundred bucks.

If it’s only 1 cylinder and gets fixed by “shaking the engine “ then it’s unlikely it’s the fuel pump and a faulty injector doesn’t get fixed by slaking it.

Sounds more like an electrical issue.

 

[TechFreak]

Check the fuses on the battery. Not sure if it could be related but worth a check. They sometimes break

 

[Skalabala]

Have a look for carbon tracing on the spark plugs and coils.(best to google what this is) <---- This is important.
Use OBD diagnostic in live data and look at lambda reading when miss fire accurse, then you will know if its a lean miss fire (fuel related problem) If it is a rich miss fire then it is a spark problem.
Why do you say it is cylinder Nr1?
And when a fuel pump is failing the symptoms are not what you are describing.

 

[Nerd101]

Had a similar issue - Ended up booking the car with Audi because I just could not get it fixed. The day before taking the car in - I realised the connector on my HPFP was not making good contact (the female side of the connector on the pump was broken off) . I am leaning towards it being it lose connector/wiring - maybe not just on the coil but maybe on the pump as well.
One other thing I would check is the LPFP (unless Im mistaken - at low rives like on idle, the LPFP is what keeps the car running). However - if it was the pump - you would probably struggle to start it up in the mornings.
Did you isolate this issue to cyclinder 1? I am assuming you scanned codes? If so - what codes come up exactly?

 

[Captain Tom]

Thanks for the responses lads! I've had a whole bunch of other stuff come up this month so fixing my car has taken a bit of a back seat. Stoked I have this list of stuff to check when I get the time though! I took it to a mechanic and he said there were no issues when he ran the diagnostics (I don't have the cable) but he was also unable to replicate the issue as it happens quite randomly.
I've never managed to actually have it in my garage when it happens.
I will definitely up date you all when I make some progress or get stuck

 

[Captain Tom]

I haven't isolated it to one cylinder, it's just that the power lose and shakiness is on par with one cylinder dropping. Cold start is never a problem

 

[Skalabala]

I haven't isolated it to one cylinder, it's just that the power lose and shakiness is on par with one cylinder dropping. Cold start is never a problem

If you swap that coil with another cylinder does the miss stay on the original cylinder?

 

[Scrooloose]

I don't recall 100%, but I think these cars have stick coils. To me, it sounds like one of those are damaged. The shake most likely brings the stick coil back into contact with the spark lead, making it work again for a time period.

I replaced the coil pack on my friend's polo back in the mid 2000's, picked it up from Goldwagen for much less than what VW wanted for it.

 

[Captain Tom]

I don't recall 100%, but I think these cars have stick coils. To me, it sounds like one of those are damaged. The shake most likely brings the stick coil back into contact with the spark lead, making it work again for a time period.

I replaced the coil pack on my friend's polo back in the mid 2000's, picked it up from Goldwagen for much less than what VW wanted for it.

Thanks! I am still feeling like it is a fuel issue but have zero cash to look into getting it fixed at the moment

The latest development in this is that when the cylinder drops I have found that I don't need to shake the engine, I can stay inside the car and just rock the car side to side a bit and start it back up and it's fine. (Only works with turning the car off first)

Feel like there is something stuck inside the fuel rail or inside the fuel tank and it like gets sucked up to the pump and then shaking the car shakes it loose, but really I have no idea

 

[Remium]

So I am a bit of a car guy, but don't have a lot of knowledge when it comes to VW's

SO here goes, When was the last time you Did a Timing chain service?
What is the KM of the Vehicle in question?
Do you have any mods (cone filter free flow, etc.)
Lastly, where do you put in fuel?

Also how long has this issue been persistent, and when did it start (has it had a service?)

what do you mean by shake engine around, (engine should be secure in the bay?)

 

[Scrooloose]

Thanks! I am still feeling like it is a fuel issue but have zero cash to look into getting it fixed at the moment

The latest development in this is that when the cylinder drops I have found that I don't need to shake the engine, I can stay inside the car and just rock the car side to side a bit and start it back up and it's fine. (Only works with turning the car off first)

Feel like there is something stuck inside the fuel rail or inside the fuel tank and it like gets sucked up to the pump and then shaking the car shakes it loose, but really I have no idea

If there is something in the fuel line, the most obvious place to start would be at the tank itself. The fuel filter and fuel pump are all located in the back, and some even have the filter attached to the pump.

High mileage vehicles do suffer from fuel pump failures, but the symptom would rather be a hesitation from the engine to pick up speed at low revs rather than the sensation of a car running on one fewer cylinders.

Fouled up injectors would cause misfires too, and while the symptom you describe doesn't quite match it, it is a possibility. They're very easy to clean, using a medical syringe and some carburetor cleaner. I've helped out with a 2010 1.4 Polo with dirty injectors, less than 30 minutes work to sort out the misfires. You also don't need a whole lot by way of tools for this task.

Here's a vid that shows you how to do it.

 

[Captain Tom]

@Remium

Timing chain service - I believe the previous owner had this done about 4 years ago - car is not driven a lot though
KM - Big old 400k!
Nah no mods
"Where do you put in fuel" I don't know what this question is... Shell?

Issue has been going on for over a year.

Engine is secured in the bay but all engines have a bit of suspension so can be wriggled, but you can ignore that like I said in the previous message I can actually just shake the car.

Car was serviced 1 year ago, the problem started before then

@Scrooloose shot, I have been meaning to try something like that for a little while

 

[Nosh]

Hoping someone has some ideas on this issue with my car.

I have a 2003 Polo 9N with a bit of an odd problem:

Sometimes one of my cylinders cuts out completely. This only ever happens while I am idling, I can avoid it happening if while I am idling I keep the revs over 1000. My initial thoughts were fuel pump or fuel injectors. But here's the kicker... Once this has happened the only way to get all cylinders working again is... To open the hood and shake the engine around a bit.

Spark plugs are fine, ignition coils look fine. I did have a mechanic look at it and he said "Probably the fuel pump or fuel injectors" so he had the same thought as me but that doesn't really explain that the only way to fix it is to shake the engine. I really don't want to spend the money replacing these parts if they aren't actually the issue.

Apart from this happening the performance is 100%. I have run some fuel injector cleaner through the system, no luck so far.



My car knowledge is subpar so any advice would be greatly appreciated

Sounds like your spark plug cords are faulty

 

[Spiritzz]

It's hard to just know if your cords are broken btw. They're insulated and sometimes can half break inside the cord. IF that is the problem and you go to a shitty mechanic you might get charged an arm and a leg just for them to eventually figure out it's just the cable, hehe.

But maybe you buy new cables just to find that was never the problem

 

[Legion]

Sounds like the coil pack approx R650

 

[Remium]

@Captain Tom

Thanks for the info,

Ok so if they did not pick it up during a service, Its most likely not a timing issue, - 1st suspect (however 4 years on a timing belt is a bit eish... I do recommend changing that next service, especially on the High KM the car has.)

My suggestion would also be electrical in this sense, Coil pack and plug leads, even MAF sensor (sounds weird but ive seen strange stuff happen when MAF's Fail. - this does not always trigger THE CEL (check engine light))

(when you start up the car does it hunt for revs at idle?)



The reason i asked where you put in fuel, I used to put in Agri -Mark fuel and had endless issues with misfires as the octane amount is somewhat low.

Shell has good octane levels and not that much additives. - So you should be golden there