help: running rough

[joshyd-mk2gti]

hey,

my car had been sitting in the garage for about a month. i came back the other day and it started first go, i was surprised the battery wasn't dead. drove around on the weekend, did about 100km and it was fine. sunday night i was driving back on the highway and it started surging evey now and then. it was doing it in any gear and at any rpm. it was doing it in town and on the highway, seemed to do it more when going up hill.

the next day i started it up and it started fine. it idled perfectly for about 20 seconds then started going rough, it idled like a tractor. i let it sit there idling for a while but it didnt get any better. drove around the block and it ran like poo. it was going chug chug chug and there was no power.

spark plugs, leads, transfer pump, timing belt are all around 20k kms old. i havnt changed the fuel filter yet thou, could that cause this?


does anyone know whats wrong with my car???? what would cause it to idle fine for 20 seconds then run like poo?? :confused:

thanks in advance..

[BlackVr6ix]

crap fuel, get a bottle of nulon octane boost and a bottle of injector cleaner and that should sort you out.

[joshyd-mk2gti]

na pretty sure its not the fuel. been on the same tank all weekend, and it was fine for the most part.

any other ideas?

[h100vw]

lambda probe problem?? 20 seconds would be a bit quick for it to warm up but it might be the problem.

[joshyd-mk2gti]

oxygen sensor? hmm. i think the one in it is pretty old and crappy, needs replacing, but i dont think its causing the problem. i started the car with it unplugged and the problem was still there.

it only idles good for around 20 seconds after its been sitting there for a while. if i turned it off then straight back on, it will be rough straight away.

[benissatan]

you sure its not the battery? check the cables and wires surrounding it. thats what happend to my audi. it was creating power surges and it also sounded like a truck in idle.

[joshyd-mk2gti]

good thinking. i think the problem has something to do with the battery/wiring. the other night when i was on the highway, the surging seemed to go away when i turned the heater off. i might try a battery from another car and see how it goes. ill check all the grounds too. cheers.

[benissatan]

yeah, all my wiring had erroded for some reason i dont know how..

its just a simple and easy problem to fix new battery and a general clean up around the battery.

[joshyd-mk2gti]

the problem is still there, i havnt had a chance to try fix it (car is back home parked in the garage, and im only there a couple times a month). i think the alternator is causing the problem, think the pulley has had it. does anyone know how to test the voltage its putting out? if so, could you please explain it thoroughly.

i read that a way to see if your alternator is working is to start the car then remove one of the battery terminals. if the car stalls then the alt isnt working well enough. is this safe to do? as a simple test, should i try it?

cheers

[syncro]

i read that a way to see if your alternator is working is to start the car then remove one of the battery terminals. if the car stalls then the alt isnt working well enough. is this safe to do? as a simple test, should i try it?

cheers

Don't do that. Could fry a few things.

You will need a meter.

[Jmac]

Dont try the battery trick that will fry the ecu. Check your charging rate mate should be around 13.9 volts at 2500rpm. Check your earths on your cylinder head on the right above your gearbox. I just done one here and i rewired the ECU earth and it cured it. Let me know how you go. If you want to run a new earth let me know and ill guide you. Also could be coolant temp sensor, that directs the ecu to alter injection time. Also how is your fuel filter???
Cheers and by the way is it a Digifant motor???? if it is the above applies mate

[joshyd-mk2gti]

hey, yeh all aus delivered mk2s are digi2. im going back home next weekend so ill test the voltage. test it at the battery terminals? i put in a new blue coolant temp sensor last year, is that the one that goes to the ecu? i think the fuel filter is old, so thats probably not helping the cause. ill try get it booked into the mechanic this week. are fuel filters universal, or will they have to order one in?

[Jmac]

Hi mate , yes you will have to order one not universal. Can be a real bummer to change on them. Its at the back right. I know back home the pipes used to rust something terrible and the rubber mounts used to break. Anyway the answer to your question about the temp sensor is yes it is the one for the ecu. By the way also check them earths they are really bad for that especially the one for the ecu.
Good luck mate

[joshyd-mk2gti]

cheers jmac. yeh i cleaned a few grounds around the battery, but didnt get to the one on the head unfortunately. ill have a better look thou.
ive seen where the fuel filter is, and decided its a job for the pro's.

[Lukev85]

Dont know too much bout the mk golf's, is it a carby engine?

If it is, it could be the fact that when a carby engined car isnt started for a while, dirt and grime builds up in the carby itself. This causes the engine not to idel property. Its happened to me many times with past Beetles.

Try pulling the carby apart and cleaning it out. It may work, has for me in the past.

[Jmac]

Mate they dont fit carbies to GTi hence the I part of GTI

[joshyd-mk2gti]

so its in at the mechanics now. he did a compression test and it showed #4 was low. he took the head off and said there was a bit of metal floating around that was holding the valve open. :/

[Jmac]

????????????? piece of metal thats strange,very strange where was the metal sitting and did he show you? carbon was bad for holding valves open but a spray of the subaru decoke spray always done the trick.:rolleyes:

[joshyd-mk2gti]

na i didnt go down and see it. should get it back next week, so hopefully its running properly. the thing is, after it had been sitting for a while, it would idle perfectly for around 30 seconds, then run rough. if the valve wasnt working properly, wouldnt it run like ass all the time?

is that subaru decoke spray the same thing as Seafoam? the yanks love that stuff. they suck it into the engine, it cleans off all the carbon and makes a ****e load of smoke, then it runs sweet.

[Jmac]

Similar mate and yes you are right it would run **** all the time mate