Hey...Just came of replacing both precats and 2 upstream o2 sensors in my 02 6spd...Car is definitly better now.......But I stil have the feeling of the car is better pulling when it's not fully warmed up.....car has around 120xxx miles...

By the way...It has no SES light
thanks

 

Cause it's cold, tight, enriched a bit to aid in warming up and it's in open loop operation......

 

you shouldn't notice better performance because you shouldn't be beating on your car when its cold

 

My 01 has the symptom of better performance when cold too. And you don't need to beat on it to notice it, it's moreso quicker shifting and MUCH faster throttle response, the car just seems like it wants to race when it's cold, when it's warm it's just slow and sluggish in comparison... I do have an intermittent CEL I forget the code for it, but it's some 'Intake operating pressure level' type code. I need to buy a Scanner again I sold my old one when I had my 97.

 

Heat.

 

Could be something about the whole open loop vs closed loop stuff which I believe relates to knock sensor stuff...

 

its because the car is running rich as hell to try to get warmed up

 

I'm sure my issue is sensor related, but I have no idea what sensor. The car acts that way whether the SES light is on or not (some days it's on, some it's not, it's like it's triggered sometimes at startup)
Anyways I'm not trying to steal from the OP's questions.. but if it's anything like my issue, trust me it's not just due to a closed loop...
My car is like a different car when it's cold... no lag time at all it just does what it's told briskly and beautifully. So I have to suspect that one of the sensors that becomes active in Open loop mode is causing issues when the car warms up... that's just a theory.
The other thing I note is that when it's warm and I go WOT, it still lags, like it's deciding whether to downshift and actually do something, and I thought WOT was supposed to enter Closed loop right away? What could cause this terrible lag?

Eventually I'll look into this further, my fuel mileage has been going downhill too. I will have to take a break from modding to fix the car lol.
Also, I've got the DE-K so obviously not the same as the OP

 

I have the same issue and already got the knock sensor replaced and the car tuned up. I have a code for one of the O2 sensors and my mechanic told me that could mean the cat is clogged or the O2 sensor is bad.

 

 

Every sensor but the O2 sensors......

 

MAF or Water temp sensor is the culprit....

 

Thanks for that imput I suspected MAF. Ill clean it soon to try that, only 90,xxxkm on it (56000mi).