car idels rough. sounds like a disel on cold days. no cels or anything wrong when its warm out. no signs of loss of power. what could cause this?

 

When the temperature gets colder parts contract and the oil is thicker. After the engine warms up does the rough idle go away?

 

when was the last time the ox sensor was replaced? That is where I would start.

 

well no 02s are out otherwise id throw a code. and ya goes away when its warm. i understand the oil thing but holy **** its only 30 out theres gotta be something more at work. i still have 10w30 in it 400 till change. its so bad when its really cold that if i rev it even up to 2k itll try and stall out when it comes back down

 

I say to much fuel. Bad o2 sensor.

 

if it was bad wouldnt i see a cel? it did it again today. it sounds like a stroked dohc with some big *** cranes cams in it. lol. sounds good but i really need to figure this out. so how would i decide if its a 02? just thow money at it and replace em? is there not a better way?

 

1) check for vacuum leaks first. All over. EGR, Charcoal canister, etc. etc. Sometimes, a small vacuum leak will even out once the system develops enough to overcome the problem, and return once the car is shut off long enough.

2) Clean the TB, TPS, EGR, MAP/MAF, and IAC. Can't hurt and is free.

3) Sadly, O2 sensors CAN start to go bad without throwing error codes because 1) the error has to re-occur often enough within the defined time frame for the specific error to actually trigger the CEL. and 2) if it does record one or more "errors" but goes away quickly enough once warmed up, you again may not trigger the CEL.

If you do end up replacing any O2 sensors, try the upstream one first. O2 sensors are really only designed to last about 75K, so once they go beyond that threshold, it may indeed be time to replace them.

 

occasionally my egr will throw a cel but it goes away everytime after a few days. is would this be a poss cause? i know my egr and downstream have 140k miles on them. upstream was replaed last year. the trottle body has a 2 month old gasket from when i swapped out to the automatic tb and i cleaned heck out of it before i finished the install. and if it is the egr does anyone know where you can get one for 96 sohc mtx? the dealer quoted me 212 for one as the mtx are diff from auto according to them, is that true?

 

1. Take the TB back off, scrape off the old gasket JIC you have a small air leak, and in its place, buy a small tube of silicon gasket sealer and use it. Put a thin layer on the TB and the intake base to insure a good seal.

2. Try cleaning the EGR. Yes the mtx vs. atx is different. Why one is more expensive then the other is probably due supply and demand. Take the egr off , soak it and the pipe to the intake in some clean kerosene overnight to loosen the crud. then take various bottle brushes, pipe cleaners, etc to really dig out the crap.

3. When you cleaned the TB, did you clean the IAC and TPS? If not, when you have it off, do it then.

4. If none of this helps, get a vacuum checker and begin looking for small leaks.

 

yes cleaned both while it was off with the electronic sensor cleaner