2001 hyundai elantra starts and idles but has no power. almost feels like a plugged exhaust. or like it is only running on 3 cylenders.

Sounds like you have a plugged converter.

could be a couple of things. if the check engine light is on and flashing you probably have a misfire causing the concern. if the light is just on solid it could be a plugged convertor. if its a plugged convertor it could be covered under warranty still by a dealer. this particular convertor is attached to the manifold and has been known to crack so hyundai extended the coverage.

i also have the same problem and the light is flashing all the time and my car is running rough any ideas

if the light is flashing you have an active misfire that could cause damage to the engine. more then likely if its idling rough its probably plug wires or spark plugs but if these both seem ok it could also be a coil. less likely , but i have seen it is an intake gasket leaking causing too much air in the cylinders acting like a vacuum leak. you can usually hear the air sucking into the intake where the gasket cracks if thats the case. bbut i would check the plug wires first. just spray a light mist of water on the waires and see if it starts running worse. or with the vehicle off visually inspect the wires for arcing.(this will look like little lightning bolts on the wires). also check the inside of the wire where the plug sits visually for arcing

thanks ill give it try cheers ill let you know how i get on

hi james i tried what you said and one lead is arcing the second one from the coil ive swaped the spark plugs and same thing happens so do you think that plug lead is broken

sounds like it.id replace the plug wires. also id check the spark plugs to make sure none of the porcelin on the plugs is carbon tracked

any answers on idle but no power?

did plugs wires new cat

still no power after plug wires and a convertor? have you checked for an intake gasket leak?

just did sprayed brake clean around intake

i tke it its not leaking then, check engine light on? if so any idea what codes there are?

I also am having an issue like this...I took it to Autozone to have the codes read. The light is on and is solid (not flashing) but the code came up as a cylinder 4 misfire. I'm hoping it's not the converter? If its within the cylinder itself, what all could it be? I replaced the spark plug just to be safe, but no difference. It could still be the plug wire, the coil...am I missing anything? Any ideas?

I was at a light and went to take off but there was no power. It idles fine and the engine light is on but when I pin it it wont go hardly at all. No stumbling seems to run fine. What could it be?

My kid has an 03 Elantra and ran rough with poor idle and acceleration. The CEL was on steady. The codes is was throwing indicated multiple misfires on 2 cylinders. Replaced plugs and wires. Ran a bit better but within a few days of light driving the CEL, codes and rough running returned. I removed the intake manifold and found the the intake manifold had in effect, collapsed! The top portion of the gasket had been drawn lower and allowed outside air to be pulled fully into 1 cylinder and partially into a 2nd. I replaced the gasket and used some spray gasket adhesive on both sides of it prior to installing it. That took care of the problem.