hey everyone! ive got an 89 max. And it was running pretty rough. it got so bad that when its hot outside, just from shifting from park to drive, the RPM drops and i stall out. I recently changed new plugs, wires, cap and rotor, and the fuel filter looks clean(oh and the air filter). I notice that when im in park and i rev the engine it only goes up to like 2k or 3k and then starts cutting out and it wont rev higher than that.

Ive got 2 theories. what im leaning toward is the catalytic converter is clogged. is there any way to test that for sure?? im not throwing any engine lights. If so what size diameter replacement would i need??

My other theory (maybe) is that i need a new oxygen sensor. but would that cause me a stalling problem??

im pretty sure its the catalytic. if anyone has other theories, i would glady accept your ideas!! ALso please let me know what size catalytic cause im probably gonna buy a universal. thanx alot to each and everyone on the board!!!

 

i just changed my o2 yesterday because my car was boggin out stalling and idleing rough i changed the o2 and it runs fine id check it out.....

 

I notice that when im in park and i rev the engine it only goes up to like 2k or 3k and then starts cutting out and it wont rev higher than that.




that could be your mass air flow sensor going out

 

well, thanx alot for the advice. but is there anyway to test those things before i started replacing everything. i mean its kinda expensive to start replacing all those things. autozone has the o2 sensor for $75 and i dont think the MAF is going to be cheap.

wouldnt the o2 sensor throw and "check engine" light if that went bad. come to think of it the mass airflow sensor would also send a check engine lgiht wouldnt it?? once agin thanx for the reply

 

they may or may not throw a light
when my MAF went out it didnt throw a light

when my cat got clogged my car had a big power loss but still ran fine

to check for clogged cat just unbolt the cat and separate it from the y pipe and go drive it

could also be your transmission or torque converter

 

o2 doesn't neccessarily throw a check engine light (actually on our cars I don't think it ever does)

 

So if the o2 sensor doesnt throw a check engine light, how are u ever supposed to know if it went bad or not. is there a way to test it? besides plugging in a scanner that i dont have. i mean how would anyone know when it was time to replace it?? alot of people on the board are saying they changed their o2 sensors and then the car ran great, but no one ever said how they knew to change that.

 

it's supposed to be changed every 60k
there is a test procedure that the ECM can do if you know how to do it.

 

does anyone know where i can find the o2 sensors for cheap? so far i only checked autozone and they want $75.

 

Hey, internetautomart, this is where you are supposed to chime in with a lower price...

 

$60 plu S&H

 

i dont think you can test your o2(mkaybe im wrong but ive never heard of how to do it) but i just thought of this after i pmed you i think you can have the MAF tested at a mechanics with a scanner it may tell you your MAF is bad with out to much confusion. if its o2 and it does like mine did it will say EMISSIONS which would narrow it down to egr, o2, etc.... big mess of things. hope this helps

 

ANY sensor on ANY vehicle can be tested.
the only question is if its practical or easy to do.
the o2 does have a procedure for testing in the FSM

 

My MAF was bad and I could drive with no complications one moment, then it would cut out as if my ignition coils lost voltage, however the MAF sent false readings to the ECU which caused the injectors to spray too much fuel. I could smell that there was a bad fuel mixture as well.

I got THE CHEAPEST(+/- $180) remanufactured MAF from Advance auto parts, returned three before getting all my money back, because they were all bad! Not Kidding! The expensive MAF was about 300 bucks and probably would have worked. I Pulled one from a junkyard for 45 bucks, runs perfect since!

 

i know they can be tested i had my max tested but it didnt specifically come up as o2 it was throwing an emissions deal then after having it tested with the new o2 nothing came up i dont know if it was the scanner or the way our cars are set up???? do you know the procedure or have a link to it i am highly interested so i can figure out if i have these probs again to see if it is specifically the o2.

 

I'd tell ya the o2 procedure, but I don't feel like typing it all in.
Just get an FSM and that answer, and many more, will be in there

 

[QUOTE=Ive got 2 theories. what im leaning toward is the catalytic converter is clogged. is there any way to test that for sure?? im not throwing any engine lights. If so what size diameter replacement would i need?? [/QUOTE]


humm....just take it off (if you can) and take a look at its ceramic honeycomb subtrate to see if they're still in tact.

 

humm....just take it off (if you can) and take a look at its ceramic honeycomb subtrate to see if they're still in tact.

 

i explained how to check the cat in my last post and i dont mean to sound like a dik but if you would read the replys you wouldnt still be asking this question

diconect the cat and drive the car. if the problem still exists your cat is not the cause