my 1994 lexus es3oo hasn't ran correct since i bought it. it used to stall out at idle.have gotten that problem solved. i have seen no check engine light or heard misfiring since i got it. as of now i can start and drive away fine but once she warms up it will sound like the engine is boging down causing it to not shift properly. i know it has a leak between manifold and rest of exhaust but once i emptied the clogged cat. conv. the loudness of the leak moved toward between the cat and the resignator. could a clogged regignator cause the issue i am facing? or should i focus on any other issues ex. sensors? any ideas would be greatly appreciated. any info about car should follow. 1994 lexus es300 3.0 230,000miles (new fuel pump fuel filter mAF sensor air filter)

 

If your exhaust system is clogged, than it will stay clogged whether the car is cold or warm, since it's driving ok while cold, than your problem is elsewhere.

Phil

 

Regardless of the light being off have your had the car connected to computer to check for codes? Swing by an Autozone and have them run it. It's free.

It starts getting expensive swaping parts from a guess.

From your description it "seems" sensor related. If your not experiencing the syptoms cold it sems very odd. Unless for some reason the heat is causing expansion of whatever you have in the cat somehow causing more blockage, but not likely like PGB suggested.

 

i thought that only worked if check engine light was on. and i completly emptied the catalytic converter (first time not dealing with titanium ***** within). i did bang around the resignator with a hammer which seemed to help a little and same with the muffler. it used to be real loud where the manifold and exhaust meet and once i cleared out the cat it moved to where the cat meets the exh. downstream which is why i was thinking the resignator or muffler were clogged. maybe i should drive it to Az but has to be when i have someone to follow me because no plates on car untill i get it running right. then i will register it. will update after Az visit and stop in often to see if updates are any

 

I would check if the oxygen sensor is switching if its doing its job. Fix that exhaust leak or you will lose power.

 

Gotcha on the registration. U can always buy your own OBD2 reader too.

You may have the dash light out for the service light

 

which 1? there is 4 total and only 1 is 4 wire the others are 2. the 4 wire is downstream after cat. (was missing when i bought the car so i wired my own in.)

 

Check both of course. You would need a lab scope to do this accurately though

 

well i have a dvom and an ohmeter but the dvom is on loan and im not sure which setting to use and i heard if its connected to the pcm it wil damage it and im not sure which is connected to the pcm.so if you know which is connected to the pcm and can pinpoint it 4 me i will test the others. i also am unsure on the downstream one after the cat (4 wire) there is a black a gray and 2 white as is there on the actual o2 sensor i wired in but im unsure if it matters which white goes to which white.

 

You cannot check the waveform of the oxygen sensor with a DVOM. First it's not graphing, second, the sampling rate is not fast enough. The oxygen sensors that should be tested are the ones before the cat.

 

then i am at a standstill 4 now...