Car-1993 Lexus SC400

So I've been searching on CL for awhile about the problems I'm having and I've noticed that this might be a common problem for SC's as well. So hopefully for those guys that are having this problem, maybe we can work together and find a way to fix this.

Problem/Symptoms:
-Gassy smell when I start up the car(smell is strong on the outside)
-Exhaust sounds different(Louder than it should be, sometimes)
-Engine is more rough and louder than it was before
-On idle car makes a weird sound(stalling, misfire?, stuttering) and feels like it's going to shut off/vibrates(sound comes and goes) but when in motion the car runs fine
-When I turn the ac on high, a lot of water? started coming out under the car and the engine seems to feel somewhat more rough??
-On idle when I rev the car up to like 3k or 4k and let the gas go, i hear a rattling sound coming from under the car i think?exhaust?

Probable Cause:
-spark plugs,wires,hose,oils,etc.
-exhaust leak
-iacv
-MAF and throttle body
-Catalytic Converter
-Intake Leak
-Fuel Pump
-Fuel Injections
-ECU
-??? any more suggestions of what can be the cause

So do you guys think it's a compression, ignition, or air/fuel ratio problem?(Based on the symptoms above)
Does anyone know what might cause the gassy smell? besides the exhaust leak what can cause it specifically?(hose, gaskets,etc???) Can a leak cause the other symptoms I have above?
If you guys can give me some suggestions of what can be the cause of the problems I'm having please list it. I'll try to narrow down every probable cause to fix my problem.

So please CL members I ask for your help once again. LOL ALOHA!!!

 

Have you checked all the basic stuff such as spark plugs, wires, oil, etc..
Is it an sc300 or sc400 and what year/mileage?

 

Exhaust Leak.....

 

didn't check it yet will do today. it's a sc400 with 128xxx miles.

 

okay i've searched online and I'm thinking that it's most likely what you stated. "exhaust leak".
so how do i check if it's leaking? is there an area where exhaust leaks usually occur? how much would it cost me to fix it? and how much does it cost for a new exhaust?
btw i noticed when i turned on my ac water started dripping under the car. like kinda a lot. is it normal?

and what exactly does misfiring means? i think my car might be misfiring. not sure though.
and what is the symptoms of a car misfiring? could it be caused from the exhaust leak?

you guys think it could be a clogged cat? idk because would a clogged cat cause a gassy smell? what else could be the cause to making the engine heat up faster than it normally does? only a clogged cat right?

 

any help? maybe know ones looking at this thread because of the title? lol

 

sounds like a bad ecu. I had one SC400 do the same thing, the cats even started glowing red. After everything said and done, it was the ecu that was bad

 

I take it you are not getting any codes?

 

when you say codes, do you mean when the lights pop up? if so no lights are showing.

 

can a ecu cause a gassy smell? i heard of a leaky ecu but would that leak have a gassy smell? btw i just noticed today that my car idles at 750(when warm) or 500(when cold) rpm.

 

It looks like your obviously new to the cars scene you should probably take it to a mechanic and have they diagnose it. The a/c only worsens the condition cause it bumps the rpms up so the car doesn't die. The water is what you seeing coming out of the bottom of the car it must have been a matter of occurrence.

Probable Cause:
-spark plugs,wires
-exhaust leak
-iacv
-MAF
-TPS sensor
-Catalytic Converter clogged
-Intake vacuum leak
-Fuel Pump ECU
-ECU

All of the shaking and stuff you mentioned and there is no check engine light? That is just odd and could be a possible computer issue ,but that might not be the case. Have someone else check it out if you don't want to waste money your not sure of.

 

yes. this is my first car. check engine light only comes on in the morning but after the car warms up it goes away. isn't that normal? that's what the previous owner said unless he's lying.

EDIT: on idle when i rev the car up to like 3k or 4k and slowly let the gas go i would hear this squeaking/rattling nose sounds like it's coming from underneath the car, maybe the exhaust. doesn't sound like it's coming from the engine. will test it out again and try to better describe the sound.

 

squeaking and rattling noise are two different noises-

Check engine light should NOT come on until the car warms up -

The gasy smell may be because the AFM is disconnected and the car is running rich - or the ECU is bad

The shaking and dying feeling at idle could be caused by the need for a tune up or the idling system may beaffected

mainly, go with what SHOLEXMAN said - Take it to a mech for a diagnostic, don't waste your money guessing

 

so obviously the owner who had it before me, bs'd about it being normal. since the check engine light goes off after the car warms up what do you guys think could be causing it? must be something to do with the car warming up since at normal temperature the check engine light goes away. but everytime at startups, usually in the morning, the check engine light is there.??? idk

 

If the CEL comes on you should still be able to pull some stored codes.
http://www.troublecodes.net/Lexus/