onecrazyfoo4u

I was looking under my 01 tib the other day and saw the black wire was totally frayed/chaffed through (appeared to be at least) on my downstream O2 sensor (on the exhaust, not the header). Is there a way to test the sensor to see if it's still good? My engine is running kind of rough at times. When coming to a stop or back down to an idle, the engine will idle really rough and act like it's almost going to die. Then I get on the gas and it goes away. Are those signs of a bad O2 sensor? It only happens after I've been driving for awhile and the engine's really hot.

i8acobra

The downstream sensor is only there to tell your ECU tat the cat is working. Doesn't affect performance. If the sensor is bad, you could get an erroneous p0420 code though.

Tak82

could be an unrelated engine problem..is your car throwing DTCs?





i have a constant p0422 because i have a denso sensor 1 and a bosch sensor 2,

onecrazyfoo4u

Oh okay, I won't worry about the O2 sensor since it won't affect engine performance. What about the O2 sensor in the header, would that affect performance if that one was bad?



No codes at all, I have a scanner. So I don't even know where to start for the rough idle when hot. I'm thinking maybe check spark plugs first?

Tak82

for start..inspect the IAC valve behind the intake manifold, it's attached to 2 thick rubber hoses and a connector..may be dirty and need cleaning..IAC valve should say BOSCH if it's the oem component.



IAC..idle air control valve.

Stocker

If it has never been cleaned, the IAC as well as the throttle body will be full of gunk. Clean them first (it's relatively easy) and see if it helps.



Manual or automatic transaxle? How low does the engine speed dip? Does it actually die when it sounds/feels bad, or does it just shake your dental fillings loose?

onecrazyfoo4u

I just cleaned the IACV like 6 months ago. Soaked it pretty good in carb cleaner and let it dry out. I'm thinking it may be going bad...but not sure how to test it. Throttle body has wasn't gjnked last time I checked a few months back.



Its a manual. It hasn't died when the idle dips. It just keeps chugging real low rpm until I blip the throttle then it goes back to normal idle. This only happens maybe 1/10 times when coming to a stop. I just don't want something to crap out and be stranded.

Stocker

If you never have trouble with it starting, just bite your knuckle and see if it dies; I give it better than even odds that it stays lit. You might try just cruising around your neighborhood and stopping on the side of the road to give it a chance to act up. Pay close attention to how slowly the engine turns, and resist the urge to blip the throttle. See what happens.

Tak82

after doing that..



then check the vacuum hoses for cracks or leaks, spray soapy water around them all, also check your canister purge valve that should be located close to your brake master cylinder, let the engine run and hear for clicking of the solenoid working, put your finger on it and feel for the clicking..if nothing, then remove it and run a 9volt battery with a "pigtail" through the terminals and see if it opens or closes..also, do you hear a pressure burp coming from the gas tank filler door?