rough idle,hesitant power, not coilpacks.

[VINNYMAN72]

Hello all, could you please help, my car has starting running a bit rough. On start up its always been poor whilst the secondry fan works for about a minute, but now its a lot worse, then it'll warm up and be ok ish, a bit kangarooey sometimes, but the tickover will sometimes become low and judder the engine and the interior of the car, it defo feelslike the electrics ie plugs or coilpack, ive changed all four plugs to bosch super 4's, i bought one coilpack and then went changed through the cylinders hoping for an improvement, cylinder 3 seemed to make a very tiny improvement, the car feels slightly better but its still rough and the fuel economy has become shocking, could it be that all the coilpacks have worn the same and i need to replace the other three. The car has now covered 61k and was running after the initial dodgy 1 min startup absolutely perfectly,you couldnt tell it was running, took it to a garage and im sure the guy who worked on it took it for a good rag about could smell hot brake dust etc i jut knew. Since then its started running like a bag of knackers. The strange thing is that only once whilst i drove the car frm the mechanics has a light come on it was yellow looked like abs but went off too quick to see, but now no lights are on, its a friggin mystery man and its doin my ed in!!!!! Any ideas would be brilliant, L8rs.

[bobjim]

MAP Sensor

[Neo_VR]

I would say temperature sensor, or boost leak..
did the garage not read the error codes off the ECU?

[sabredylan]

Check all hoses for rips, especially under the intake manifold. Try some injector cleaner in your tank. Unplug the maf sensor, if it idles better thats knackered. If it makes no difference give it a clean. Clean the Maf and intake air temp sensor with electical cleaner. Change your water temp sensor if you notice any fluctuation on the temp gauge, they are not expensive. Most important check your timing belt tension, it may be ready for a new one. If the tensioner on the belt is on its way out it will have a dodgy idle, hesitate, be down on power and may lead to big bucks if it fails.

[VINNYMAN72]

Cheers Sab and tothers, sab it does sound like the latter how do i check the cam belt tension, is it simple as feeling for slackness wth your hand???? I guess it should be rock solid? Thanx again for your help.

[fatty5000]

Throttle body may need a clean, if it's minging cleaning it will help with your idle problems.

This will help http://briskoda.net/forums/octavia-i...le-body/78898/


Top tip ......If you don't unplug it when you clean it you don't need to reset it with vag com

[fordfan]

A fault code read would be good, as it does it from cold it could be a lambda probe heater problem. If the probe isn't providing the correct readings it could affect the fuelling.