I've been having a issue lately with my 2000 Toyota Corolla. I turn on the car, then I drive down my driveway. Now, there is a small uphill when I turn out of my driveway, and when I give it some gas, nothing happens. I even floored the pedal, and nothing happened. I released it and pressed it again and again. Every time, it gave a squirt of gas, then nothing. I barely manage to get up the hill, and it's a pretty small hill. I also notice after I get over the hill, acceleration is not smooth. I mean, I feel the engine slowly rev up, then rev down as if I'm not giving it any gas, then continue revving up, and down a little more, then up again. I've noticed this behaviour only happens when the engine is cold; after I drive along for like 5 minutes, the problem goes away. And this is with a full tank of gas, there shouldn't be any shortage of it.

So my question is: has anyone had similar issues with older cars? My car has 200,000 km on it. What could the problem be? Fuel pump? Or filter problems? My dad says it could be that the cap on the gas tank may not be allowing air to go through like it used to, meaning there is slightly less air pressure in the gas tank, which could cause gas to stay in the tank instead of going to the engine. Could this be it?

Something to do with the fuel system, I think. Might also be the fuel pressure regulator. Could be a sticky or dirty throttle body. Does the check engine light come on?

it could be a lots of things,prolly u will have to go to a shop and check with computer

theres 100s's of possibility's of what Could be wrong but id say just take it to a garage and get there say on what the problem is.. thought its most likly somethings after comming slightly loose and is lowwing the cars proformance

Does the engine sound like it's running normally, assuming it's unrelated to your throttle pedal? I don't know whether a 2000 Corolla will be on a conventional throttle cable, if flooring the throttle doesn't actually change anything and it just behaves like it's on tick over it could be more likely you've got a problem with the throttle bodies not opening, either because there's some slack or something somewhere in the cable that is only sometimes causing an issue or more likely if they're electronically controlled (which I doubt they are) you probably have the more plausible fault somewhere in the cold running cycle, the Focus I drive has some kind of fault in its cold running cycle that results in it suddenly deciding to idle at 2000rpm, quite exciting when your not expecting it pulling out the drive.

I suppose you could also have an issue with the injectors, or more likely the ECU controlling them, although if you're on a conventional throttle I'd expected you'd hear the change of the butterflies opening and it would result in very lean running.

Quote from theirishnoob :

thought its most likly somethings after comming slightly loose and is lowwing the cars proformance

Loving the spelling Seriously I doubt it is likely to be something loose other than maybe the throttle cable (but I very much doubt it if it clears), something wrong with the butterflies or injectors (likewise) or possibly the airflow sensor in the throttle body, but if it clears I reckon it's more likely to be caused by a fault in the cold running ECU cycle or a sensor which is used in the cold cycle only.

I'm having the same issues on my Golf MKII.. yesterday was really bad. It's only like this when the engine is cold, but sometimes i don't have the time to wait for it to warm up...
This problem was "suppose" to be fixed a month ago, but aparently it wasn't..
It's a very unpleasant feeling... like i don't have the control of the throttle at all..

agreed with ajp there probably something wrong with the ecu controlling the injection on cold running (or one of the sensors attached to it)

does it doe anything unusual on idle as well ?

Quote from Boris Lozac :

It's a very unpleasant feeling... like i don't have the control of the throttle at all..

As in the throttle is opened when you aren't pressing the pedal? That's probably caused by the throttle body being opened too far by an electric motor (fitted on non-drive by wire cars as well) which controls the idle, therefore increasing the idle speed and resulting in the bizarre sensation of lifting off doing nothing, this is what I think happens on the Focus, why is a bit harder issue to solve but if this is the issue then unfortunately it is likely to be some kind of computer fault somewhere.

The car is idling very normally, even when cold. I've never noticed anything different there. And, yes, the check engine light comes on when I accelerate hard. It didn't use to do this in the past. And the throttle is connected by wire to the engine, and it's not loose or anything, it's the same as it always was.

Quote from shiny_red_cobra :

My dad says it could be that the cap on the gas tank may not be allowing air to go through like it used to, meaning there is slightly less air pressure in the gas tank, which could cause gas to stay in the tank instead of going to the engine. Could this be it?

Surely this would cause a constant loss of performance? I don't see how a blockage in your tank vent could fix itself once your engine has warmed up. In any case, modern cars usually have some sort of fuel tank breather connected to the engine air intake.

If the engine warning light is illuminated then the loss in performance might be a 'limp-home' mode which engines use to allow the driver to get to a garage for repair. There could be any number of reasons for this...it's probably best to take it to a garage so they can interrogate the ECU.

Quote from ajp71 :

As in the throttle is opened when you aren't pressing the pedal?

It's not like it goes full throttle when i am not pressing it, but it revs it on it's own, till about 2000 rpms...when i'm at idle...
I had this "fixed" not long ago, it was some monopoint rubber holder, whatever, before that, the throttle was going mad, it revved on it's own to 3000 rpms, it didn't matter if the engine was cold or not, it was like that all the time.. And the engine was shutting down when going full stop in neutral, like on the traffic lights, and the battery and oil lamps went on..
So about a month ago, that rubber monopoint holder was replaced and everything was fine until recently.. It started again but not as bad as before, and now it only happens when engine is not warmed up..

I have what sounds like a somewhat similar problem with my bike, although it's probably because it's carbureted, not fuel injected. My starting procedure is as follows:

Pull the choke out to full
Turn the key on
Thumb the starter button
Immediately push the choke in a bit after it starts, followed by gradually pushing it in over the course of the first 30-60 seconds, after which I push it all the way back in
Let it warm up for 5-10 minutes

If I try to rev the engine at all during that first 5 minutes it just bogs and stalls, sometimes with a loud crack as the piston stops suddenly. Likewise, even after I let it warm up and try to ride it, I can't open the throttle too much or it bogs. It's only after I've ridden it for about a minute or 2 that it gets properly warmed up and makes any power.

Specs:
2002 Kawasaki Super Sherpa (aka KL250, not to be confused with the KLR250)
250cc single cylinder, DOHC, air-cooled
34mm carb