un-smooth engine, need advice

Xios

Hey guys,
i've a little problem with my car. It's a '99 hyundai accent, 1.3 gls.
So the problem is that while the engine is running the revs keep dipping, as if it's about to cut out, but it doesn't, it just rumbles and climbs up then falls again. Also, at low revs when the engine is cold, it chugs and jumps while moving. It hasn't stopped the car from running, and i think it could be one of three things. A cylinder is misfiring, the fuel pump is failing or theres a problem somewhere along the throttle linkages. Anyone have a similar problem before? I'm fairly broke at the moment so having a mechanic look at it right now ain't an option.
Any advice will be much appreciated

Matt Simis

Sounds like it could be a faulty MAF too. Try unplugging it and seeing if the symptoms improve.
It also sounds like a Vacuum leak, looks for a damaged pipe in the engine bay.

Anan1

Dirty throttle body?

PADRAIC.M

its your idle speed control valve, seen this loads before. sometimes you can get away with cleaning it out but usually have to replace it. they are the old type of basically two pipes on a big valve body with an electrical conection on it.. located just near the intake manifold.. try some carb cleaner.

Muckie

Sounds like the trottle body could do with a clean, 10 years worth of
carbon/dirt build up, that or possibly the MAF sensor.
Is there any fault lights showing on the dash?

cjt156

PADRAIC.M wrote: »

its your idle speed control valve

+1
The fact that its only at idle and cold, low revs. Once warmed up and at speed it's OK? All the other suggestions are good ones, but apart from a dirty throttle body they'd affect higher revs too.

Xios

Thanks for the advice guys, much appreciated, now i just gotta pop the hood and figure out where each part is, should it be in the manual or shall i just google the part and work from there?

shedweller

All that technical stuff won't be in the manual. But you should find something online. In any case, try a can of carb cleaner. Remove the intake pipe from the air filter so you can spray it into the intake directly into the engine. Start the car and let it idle while spraying into the intake. This worked for me with an old civic and it idled fine shortly afterwards. You could also use a bottle of fuel system cleaner in a tank of petrol.
Just be careful of fan belts etc. You don't want this turning into a big job!!

Good luck.