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Car: 02 SE 4spd auto trans. 105k miles

Extras: Iceman CAI, MPx TB, OBX header, original cat, Vibrant dual axelback.

Engine maintainence: Mobil 1 synthetic every 5k miles starting at 60k miles, Trans flush at 36k and 100k.

Issue: From 0 to 40ish mph the car feels sluggish, like it's being held back or towing something. More gas doesn't really do anything unless I stomp on it. Once the car gets to 45ish it slingshots up over 60 and goes just fine.

Tried: Replaced TPS. Didn't help, made car idle sh!tty and engine look like it was going to bounce out of the car. Put old TPS back in.
Checked for fluid leaks but nothing.
Checked plugs, looked good.
Checked plug wires, also good.
Checked for exhaust leaks, sounds/looks good.

Considering: Reflash ECU, never had it done and have read/heard that it helps to "remap" the air/fuel mix.

Tried to give as much info as possible but if you need more I'll post it ASAP.
Any "could be this" or "try this" or "don't do that" is appreciated because at this point it just seems haunted!
Thanx in advance.

Ever since my re-flash on my 03, my cars felt slower, even when comparing videos side by side. I wouldn't worry bout it too much since you have an automatic.

clogged cat? i have the same model/year of your car. it's slow as shit too.

:]

Problem: ATX

Solution 1: MTX

Solution 2: 3.94 MTX w/ mag head

Solution 3: SRT swap

Not too sure what you'd expect with that 200LB auto-slush-box strapped to the engine... The gearing in the ATX's is crap. Swap to 5-speed!! night and day difference.

You may want to take a look at your o2 sensor. since i came from philly down here to florida the hotter air has been playing hell with the mixtures in my car and its turbo so definitely more menstral when it comes to mixtures. So if you have checked everything else the o2 would start to be my next guess. because when you mash on the peddle and go WOT the computer ignores the 02 and starts dumping fuel. so yeah o2...it could be that.

and the standard swap response is getting kind of annoying... even though the 4 speed does suck nutz... 3spd rocks.

Good luck
J

I wouldn't think clogged cat. because 45 mph + seems ok. possible tranny / module problem? Has it always been this way or is it something that just started? Uless they seriously changed the 41te for the neons I can't see it being that bad. the one i my sundance duster did ok. Granted it had a V6 in front of it but it also had a heavier car to move, and that 3.0 isn't that much more in output than the 2.0 (9 hp, not sure what the torque difference is). Any way the duster was pretty snappy off the line. Don't know if they changed gearing or not. The internals should be interchangable though. But it will never hold as much power as the 3 speed. The low speed clutches/drum was rated @ over 600ftlbs of torque for some insane overkill reason. the 3 speed was the same for turbo/non-turbo cars.

Thanks to those with a real theory (you know who you are!)

It's a recent thing, more noticeable in past few months.
No cel codes have popped up so I don't think it's anything serious. I think a bad O2 would set off a cel code right?

Since I just did a trans flush at 100k and the shifts and off the line power are still strong I don't think it's that. It just feels like it's lost it's low end power. And the weird part is once it gets over 40ish mph it shoots up to 60 mph and then it's all good. Can transmissions do that?

To me it's got to be some sort of bad sensor/ECU/electronic issue but I'm not a mechanic by any means so...any REAL advice is appreciated.

The rest of you are just a bunch of goofballs!

well mine does the exact same thing your describing, so im gonna have to watch this topic. no codes, can put the pedal to the floor, and its a slow crawl up to 3k feels like im draggin ass, or like driving into heavy wind until it hits 3k
rpm / 35-40mph

3spd 01 w/ 52k on it. stock intake, r/t muffler.

i was thinking cat, but my top end is fine.
was gonna try and replace 02 sensor, but no codes, so i dont think its bad..

also thinking maybe clogged fuel filter


one thing i did notice is on my atx, it didnt like the CAI, or exhaust, lost low end.

Yeah mine does this too, just pretty sure its just the 130 hp strapped to the atx. I mean I have the exact same symptoms down to a t. 60mph+ the car has better throttle response, it also is at a good spot to downshift and take off and has momentum too. 0-3k you dont have much torque down there to move the atx.

Your mods are great and probably help gas mileage however you have to take in consideration that if those mods give you 8hp on a 500 hp engine then on a 89 hp engine its going to give you about .25 hp. Just my thoughts.

Like you said the trans part is just a theory, but if the tcm is not sending the right signals to the trans it may not be shifting when it should or the torque converter may not be giving the engine enough rpm's which will definately kill power. If I recall the tcm and pcm share info from tps and some other sensors. My duster service manual explained it pretty well I think. I'll give it a look tomorrow, If I find anything that may be relevent I'll post it. I had a B&M cooler w/perma-cool t'stat on the duster and it seemed to do alot better with the tc lock/unlock. When your tranny does wear out you'll know it. It will not shift out of 1st or 2nd gear! You will have to pull over and shut off the car and restart it and if your lucky it will work for a while but it will keep doing that until the clutches are replaced. Not that it is your problem I'm just rambling - I'll shut up now!

My car does the same thing and its a mtx. I just figured its the lack of torque. I tried my buddies msd coilpack and that made no difference. Also changed plugs, wires and no difference. I was thinking of the o2 sensor, reflash like you mentioned. How much worse did this get do you think recently?

Hard to say because I've been driving 2 different cars around for the summer but it seems that its reached a pretty consistant point of power loss, 9 times out of 10 it's the same symptoms as described in original post: 0-40ish mph then vroom to 60 mph and smooth normal acceleration after that. Doesn't seem to be getting any better or (thankfully) worse.