Blowed&Stroked

If I have a catless x-pipe system, did I lose a oxygen sensor? I replaced the one behind the header but can't find the downstream sensor and I'm thinking it was eliminated with the exhaust system. Are my speculations correct? I have a cobra hood with a custom scoop molded on top of it that has a air passage, well that cutout is directly over the distributor. After being caught in a rain on the way home one day, the car started running funny. after i figured out that the cap had moisture in it, i had fouled the plugs too. After a new cap and plugs, it was still running like crap so my next thought was the o2 sensors. i replaced the one i found its still running like crap. I'm thinking it may possibly be the second o2 sensor, if there is one, or the TPS. If I hold the rpm at 3000 it will hold that for a few seconds then drop to 1000 rpm, then bounce back up to 3000 then drop to another lower rpm range?? And the only way I can keep the car idling is to slightly keep foot on pedal or else it will lope down so far and stall. I'm leaning towards the TPS sensor but it possibly be a mixture of both???
Thnx

Duncan_GT

There's only 2 o2's on a Fox

Bklyn 5.0

Definitely 2 o2 sensors, couldn't say exactly where they are cause I put my pipes (BBK off-road xpipe) on so long ago but i'll be taking it out of the garage Sunday and I'll take a look if you want.

I could be wrong but as far as I know the only result of a bad o2 sensor is very poor gas mileage.

mjr46

as stated, no post cat monitoring on obd 1 foxes

Mike T

Remove and clean your IAC, if you haven't already. It's a common idling problem contributor on the 5.0.

Blowed&Stroked

Thnx guys. I know there's 2 o2 sensors on stock mustangs but I think the catless exhaust system eliminates one. But bad sensors cause rough idle, misfire, and falls on its face during acceleration. All symptoms of my car. My buddy has a diagnostic reader and tell me what's wrong. I'd take it to autozone but I can't make it out the driveway! Mike T thnx for the info, I'm gonna try to do clean the iac valve if I can get out of bed. Think I got walking pneumonia

rmodel65

unplug the MAF sensor and see if it runs better..

mjr46

no the catless exhaust does not eliminate one, listen!! they have 2 and no more and not 1 less......one for each bank end of discussion.......and the code reader won't tell you anything more than a code, it doesn't diagnosis the problem, and 9 times out of ten the vatozone bafoons don't even know how to run a koeo/koer test on a obd 1 stang much less have the tool to do it. A lot of things can cause the prob you have, I doubt it's a o2 sensor issue.

Duncan_GT

An o/r system doesnt eliminate any o2's. You have two regardless