Rough Idling 54 plate VW polo twist

[ArchieDog79]

Hi, i’ve been having a problem with the above. about a month ago whilst in stationary traffic the revs became really erratic dropping to about 100 and then rising erratically to the point that it stalled not long after. No problem firing up. I changed the fuel filter by the roadside to no immediate success, returned to it a couple of days later and all seemed fine. across the next couple of weeks i had moments where it would happen again, revs would drop and or become erratic but i was able to keep the revs up and push through. i put a fuel injector cleaner through the tank and assumed it was working as i had 7 good days. Unfortunately it happened again a few days ago whilst out with my daughter, i managed to limp it home, died a couple of times on the way and now it’s sat outside. I’ve checked the air filter and it appears fine, new spark plugs, starts fine but idle us all over the place and certainly not fit to drive. i started to think maybe a vacuum leak, i’ve been losing a fair amount of coolant over the last 18 months, though it’s stayed fairly steady for the last 3 or 4 and when i was checking out the air filter i noticed a cracked and perished hose (pic attached) i hoped this was maybe it so i bound it tight with gaffer tape (just to test the theory and run it on the drive) alas its as bad as ever. Anyone have any suggestions as to things i could try? common problems.

[ArchieDog79]

correction…. no picture cos i can’t work out how to. The hose sits to the right at the back of the engine just below the air filter housing runs to the left and into the body of the car just below the brake fluid.

[Belle427]

If one hose had split its worth checking the others too, the coolant going missing would worry me though.
Any signs of water in the oil?

[ArchieDog79]

no not noticed anything in the oil, it’s very black and could probably do a change. I’ll have a good look over all the hoses. thanks

[E-bmw]

WRT a pic, you could search google images & copy/paste the www address into a post.

What does the hose do?

Intake/water etc.

WRT your symptoms, I would still be thinking inlet air leak.

You need to get everything off the car after the MAF & have a good look at it whilst bending etc.

Prime candidates are usually concertina pipes/hoses, in the bottom of the dips.

[ArchieDog79]

Thanks for the reply. I did as described today and it was the only split hose i could find. After i taped it up sunday i could hear it sucking/blowing periodically, so i removed all the old tape and sealed it up again and the car now seems to be idling fine (though i’ve had this false dawn before) and i’ll now look to replace the hose…. i still couldn’t post an image, i added it to Imgur but as a new member to the forum they won’t allow me to post a link to 14 days. From another source online i’m led to believe it could be a the brake booster hose, it looks to run from the throttle body and directly exits under the break fluid reservoir. Hopefully i can get a new hose and it fixes the problem, though i’ll post an update and an image in 10 days or so if it is resolved.