Recently I've noticed a strange power loss after about an hour of city driving. Is this caused by warm air in the air box or what? My car stops pulling as hard as it usually does, the engine growl becomes deeper. So now I have to depress the gas pedal pretty hard to gain some speed. Anyone knows what I'm talking about? It seems like there is something restricting the engine. I dunno, it just bothers me. Any suggestions?
Thanks.

 

just a chance but have you checked your cataletic converter

 

same thing happened to a van I had. If I eased off the gas it cruised fine but when I tried to pass or speed up it slowed down. Always started fine and idled good. Just the acceleration was like I was pulling a trailer. I had my wife rev the motor while I listened to the exhaust. It sounded like a lot of air being pushed out. Got a new cat and it felt like I just put on a turbo.

 

Definately sounds like it's not breathing right. Could very well be the cat. I would also check the air filter and the muffler.

 

could be a leak somewhere in the exhaust.once I purposely unbolted the cat just a bit to leave a crack open and drove around for awhile. drove fine until after around 45mph it started to loose power. when I floored it, it caused the rmps to go way high but I was still around 35 mph.

 

Man, that's exactly what happens with me. I step on gas and the RPMs jump upto 6K, I still gain speed but very slow.
Thanks for all your replies guys, I'm gonna get the exhaust checked as soon as possible.
This is very strange, i still can't understand why this happens only after I drive my car for some time. In the morning it pulls just as hard as it used to, but after being driven for about an hour there is this strange loss of power.

 

This ...

... and this ...

... both sound like clutch or transmission trouble, unrelated to the exhaust system.

 

I'm sure it's not my tranny, i got it inspected not too long ago.
Just called the dealership, made an appointment for next thursday, we'll see what happens.

 

is more and likely 100% correct in his reply. For the symptoms you all are saying that is EXACTLY how I noticed the clutch on my 85 Celica went out. Did it every single time. If the rpm,s are rising and you are getting nowhere, that,s where I would start.

 

Well, see, the RPMs won't just rise if i step on gas as I usually do. In fact rpms stay low, 2K or lower. This is what confusing. Say I go 35mph and want to go faster. In the mornings when my car drives fine i give it a little more gas and the car pulls. The same situation BUT after being in heavy traffic, i give it more gas but the speed increase is much slower and the rpms won't even go high. I give it more gas, rpms go just a little higher and the car starts pulling but still not as hard, seems like something is holding it, like someone here said "it's not breathing right". If i floor it, the rpms go very high and then car starts to pull. But with all this I also noticed the difference in engine growl, it became much deeper.
The delaer said it might be an air flow sensor, so I'll have to wait till next thursday to find out what's wrong.

 

I,m assuming you have an automatic so the possibilities could be that either the fluid level is incorrect or that it does fine cold...warms up and starts messing up which sounds like something worse could be wrong. And just for sheets and grins, check your air filter for cleanliness and your throttle body also. It may even sound like it is starving for fuel which could be the fuel filter. How,s the gas mileage? Getting worse? Starving for air.....possibly.

 

Yes my max is auto.
The mileage is fine, just as it used to be, and I replaced the air filter less than a month ago. Not sure about the throttle body, gotta check that.

 

I,m not sure if this holds true but I know for some transmissions if the filter gets dirty it won,t shift properly. I thought I read a post that states the filter/pickup screen does not normally get replaced but maybe (a long shot) it is somewhat dirty/clogged which would restrict fluid flow. This is basically a guess on my part. Perhaps Dan B. Max could shed some light.

 

The 4Gen Maxima automatic transmission doesn't have a true filter. It has a screen which never needs cleaning or replacement. I've never heard of this screen becoming clogged.

 

could be the alternator on it's way out