big_g

You know when you hit the power band on a 2-stroke dirt bike? Yeah, my car runs kinda like that. During medium/hard acceleration from low speed it bogs (no stutter or anything, just not as much power as I know there should be) a little until all of a sudden it hits some magical sweet spot and takes off. No codes, gas mileage seems fine, and it otherwise runs great.

Could this be a bad/dying O2 sensor? Most of the threads I searched for on here with bad O2 issues the cars were running way worse than mine is. I would bet that the sensors in my car are probably original... I have 60K miles on the car, but it's now my DD. I just don't want to fix things that ain't broke.

wssix99

iTrader: (5)

Usually, this is due to oiled air filters fouling the MAF sensor. What kind of air filter do you use?

big_g

Just a paper one. One of those FRAM ones.

Could this be a bad CAT? Thought I might have smelled some rotten egg smell the other night.

wssix99

iTrader: (5)

That's good.

A bad cat would give you decreased power all the time. If you just have it for a short time and then the engine kicks in to normal power, then that's a sensor/fuel mix problem. First, check the engine for any codes - even if your Check Engine light isn't on. If there are no codes, you probably just have a sensor or other related part out of whack. You may also try driving the car with the MAF unplugged. This will cause the car to go in to open loop and ignore some sensors. If the car drives better, that would lean back towards a sensor problem. (Beware - this act will cause a code to be thrown.)

From there, I'd check for the following, in this order:

- Dirty MAF
- Clogged/old fuel filter
- Bad/old O2 sensors
- Air leak in the intake system after the MAF

big_g

Ok, will do. Thanks. Is there such a thing as an "old" O2 sensor? I guess I always kind of thought they either worked or they didn't?

wssix99

iTrader: (5)

Yep, they wear out over time. When they get really bad, they will throw a code, but before then they will make your life painful. The bottom of this page describes the mechanism for degredation: http://exhaustworks3.com/what-to-watch-for/

LS6427

iTrader: (2)

Absolutely can be a bad 02 sensor........those damn things can cause all kinds of weird symptoms. They don't just fail, they slowly fail.

Get a scan to see how they are switching at operating temp with the engine running.

Does it happen for the first 5 minutes or so of driving while the engine is still cold?

.

big_g

It does seem to be worse when the engine is cold, but it also happens when warm too.

LS6427

iTrader: (2)

If it happens when the engine is cold....then it may not be the 02 sensors. The 02 sensors do not work until the coolant temp is above 122*F (IIRC).

The MAF does all the work along with the IAT sensor. After the engine is warmed up above 122*F then the 02 sensors come into play along with the MAF.

You could try cleaning the MAF.

If that does nothing.....I would go buy a new cheap MAF at PepBoys and hook it up.....if it doesn't fix the issue....return it. Just tell them its the wrong part and you already found the new one somewhere else and you NEVER installed this one.

Or if you have a friend with a T/A or Camaro.....pop their MAF onto your engine real quick, see if it fixes the issue.

Also, when this loss of power/stuttering happens......is it with the throttle remaining in place during the stuttering and then if you keep the same throttle input (not adding more throttle) it then takes off at some point?
Because if you are gradually adding throttle to it while its stuttering and then it takes off at one point....it could be a worn spot inside the TPS sensor.....where a good contact is not being made in that worn spot. Then as you pass that worn spot it takes off.....

.

big_g

Well, it isn't a stutter, it is just what I perceive as a lack of power. It is like... Vroooom...Baaahhh...Vroooom I think the throttle is constant, but I never put conscious thought into it. I'll check today on the way home from work.

I'll try cleaning the MAF. And the O2's are cheap too (Denso PN's 2344025 and 2344087 is what I found on rock auto for $28), so I may just change them out since I do have 78K miles on 16 year old sensors as it stands now.

I just know that this 2000 T/A does not have nearly the punch as my old 1999 T/A (may she rest in peace) and they were both stock. The 99 was much better maintained and I'm still trying to figure out what was done/not done to my 2000. I bought it from the son of the owner who had passed away a couple years before. When I bought it I know the fuel pump had been replaced (with "some non-ac delco brand"), the plugs were never changed, the guy (supposedly) did all his own maintenance, and it was bone stock.