Low RPM hesitation (2.4)
 

I inherited my wife's car as my DD about a year ago. It's a 2000 Alero, 2.4L. It seems to hesitate when giving it gas, but it seems to only do it in the low RPMs, regardless of what gear it is in, but more noticeable from a stop. The car has 193,000 miles on the clock, last year we replaced the fuel pump and a PCV hose, plugs about 13,000 miles ago. It feels like it still has plenty of power in the high RPMs.

Prior to replace the PCV hose, it would often die at a stop, so I'm thinking this could be vacuum related. It looks like it might have a small coolant leak from the manifold. I'm also thinking it may be a fuel filter, although the present one is not much older than 4000 miles. Anyone have any ideas?

On another note, I'm thinking of taking this and my 94 S10 (205000 miles) and selling both for something with lower mileage. Should I keep the Alero with the miles and risk it, or sell them both?

it could be fuel or spark related. I would test the injectors and fuel rail pressure. Also maybe plugs or coils.

clean the injectors (via fuel additive) and spark plugs (or replace if needed...) and also make sure the butterfly valve on the throttle body moves easily. Also, make sure you are up to date on fluids maintenance. beyond that, I have no idea.

No coolant in any manifolds on this engine.
Possible; unlikely, based on mileage and symptom.

It is most likely a vacuum leak. Check all vacuum lines that come off the throttle body. Make sure none are off or broken, or with gaping holes like the brake booster line (like mine for some reason had a while back).

I always forget about the vacuum lines. this sounds like it.

my car does the same but only after it has sat for awhile and then after i accelerate for the first time it goes away. i noticed it after i changed my spark plugs but it only does it once then it is fine.

Man, I have the same issue! I'll check my Brake Booster line when I get back from alberta. Anyone got any ideas where i could pick up a replacment for it? I have a feeling mine is shredded. (AKA I know it is :P)

You guys are right on with the brake booster. Before we replaced that pcv hose, it would die when you hit the brakes. It doesn't do that anymore since the hose replacement, but that was just one hose.

Today, it's not hesitating hardly at all since the weather heated up, so I'm thinking that points to vacuum. I need to take a look at everything again.

I think I'm going to hang on to it for as long as I can. I have personally maintained it very well for the last 100k, so I guess I will take my chances for another year. The A/C is still blowing cold. I have a love/hate relationship with this car

Don't rule out a coil cover either! I've seen those cause some hesitation issues even with no evidence of them being bad.

The coil housing cover can leak spark even on a newer car especially noticed when under load say between 1500 and 2500 rpm when you give it some gas. Those were a problem on a lot of the 2.4 2000/2001 aleros while under warranty. If you have over 150,000 km I would say replace plugs, boots, and check the housing and coils.

i had a very similiar problem, turned out my fuel pump was push 25% of the pressure it should have been