o2 sensor question

[navysnail]

when i check the resistance of the body of the o2 sensor to ground, its 340 ohms. could this create the rich condition i have now, and if so, what can i do about it?

Thanks in advance

[NISTECH]

what are you using for the ground? test the resistance from the O2 to the manifold if its better you likely have a disconnected ground to the engine from the body. or to the exhuast. you can also add a ground from the intake manifold to the exhuast maniold to suuply a better ground to the exhuast .

[navysnail]

im using the battery terminal and intake manifold as grounds they are the same number as a result. the ground thats suposed to connect to the cat, it is completely gone. everything is all rusty on my exhaust manifold so i dont know how good of a connection it will even get. when i rev the engine up and let go of throttle, some black smoke comes out of my exhaust, this is the real problem i am trying to solve but my o2 sensor is the only thing that is in question now, everything else is within specs

thanks mike

[s13sr20chris]

i think i will be beating the maf horse a lot. nissan has a real prob with grounds(shhh its a secret). as i always say .5 voltage drop on the maf ground will fog up the whole place with smoke(rich). try grounding your maf housing to see if that helps.

[s13sr20chris]

by the way, o2 sensor should not make too much of a difference in a/f, but then those obd 1 cars did give the o2 more control then the newer ones.

[navysnail]

alright, maf has a .0 voltage drop, the exhaut manifold is very rusty and rust is not a good conductor of electricity so i was wondering if this coulc cause this problem.

its not that rich, it just puffs a little black smoke when i rev it up, then take my foot off of the gas.

thanks for all the help so far guys

[NISTECH]

coolant temp sensor? Run an alternative ground to the exhuast manifold. under one of the sheild bolts if it dont break off in the manifold. other wise use one of the manifold to head bolts.

[s13sr20chris]

do you drive it hard? if not the ecm may have trouble enriching fuel at wot accurately. glad to hear you dont have ground issues with maf. they are easy to fix but the last thing to check for most folks. a dead spot in your tps would cause a momentary rich condition on throttle snap. ect connectors are known to rot. if rotten then engine torque may cause a brief open circuit. that will make all kinds of temporary richness. how is your cat? a poor flowing cat(like a melted one) can cut the air volume ingested under load. if fuel is not compensated then you end up rich.

[navysnail]

i had my exhaust out the other day and the cat LOOKED fine, passed emmisions with no trouble. there is just a little puff of black smoke when i rev my engine and let the gas go. my friends 92 240 looks the same, im gona do a little tinkering today and check all of the stuff you guys said again

thanks for the help

[s13sr20chris]

no prob. keep us updated.