Is my o2 sensor dead? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

confuzed240 · 11-05-2009, 04:44 PM

If I let the car warm up from idle to fully warm, once the car is fully warm the idle will start to bounce some and my vacuum will jump around from 17-20. When I go out and drive the car is runs fine and boosts properly. If I stop at a light the idle will not bounce and the vacuum and steady at 20. Its only random when it happens

Another problem is that my narrow band o2 sensor is reading more lean then normal when I am idling and leans out off the chart when I go into boost. I know I am ruining rich, I can smell it and black smoke comes out when I go into boost. I didn't know if this meant the o2 was shot.

I just installed a electronic boost controller but the car ran fine and the o2 sensor read rich after I installed it. The problem came up about a week later. Tell me what you think, thanks!

SoguRacing · 11-05-2009, 05:05 PM

i dont think it's your o2 sensor. try unplugging it. mine didn't make a difference whether i used it or not.

*ManoNegra* · 11-05-2009, 07:07 PM

Only way to know for sure weather an O2 sensor is busted is to check the signal
Cosult or a quality graphing multimeter would be needed to do so
signal should oscillate ~5/second over a 0-1 volt range IIRC
Most SR swaps I've seen tend to run rich which probably is why SoguRacing you didn't notice a difference when you unplugged it

OP: sound to me like you may have a vacuum leak somewhere or your MAF is loose/dirty

SoguRacing · 11-06-2009, 02:04 PM

your o2 sensor reading isn't used when under heavy load. you're in open loop. so the black smoke is a tuning problem or other related issue.

confuzed240 · 11-08-2009, 07:36 PM

So I drove the car today for a while pushing it hard. The a/f gauge starting reading normal again. I know I'm running rich so I guess the o2 sensor got clogged up, I checked my spark plugs they aren't caked up or anything.

Another weird problem is that when I set my adjustable FPR to 3 bar, by the time I'm done driving it will have dropped 5-7psi, any suggestions?

*GSXRJJordan* · 11-08-2009, 08:02 PM

Quote:

Originally Posted by SoguRacing

your o2 sensor reading isn't used when under heavy load. you're in open loop. so the black smoke is a tuning problem or other related issue.

Exactly ~ o2 sensor on these cars is only used for closed-loop fuel control at steady speed/light throttle.

Quote:

Originally Posted by confuzed240

So I drove the car today for a while pushing it hard. The a/f gauge starting reading normal again. I know I'm running rich so I guess the o2 sensor got clogged up, I checked my spark plugs they aren't caked up or anything.

Another weird problem is that when I set my adjustable FPR to 3 bar, by the time I'm done driving it will have dropped 5-7psi, any suggestions?

The FPR is attached to a vacuum line right? Set the base pressure with the line not attached, then check detach the line again when you check. If it's different, your adjustment is moving, if not, it's just the vacuum affecting it.

lazysk8er2 · 11-10-2009, 04:22 PM

im having the exact same problem i from the looks of it the ecu temp sensor is possibly going bad. its like 20 bucks so im gonna do that first maybe you should check it out too

i know my tune is fine cuz ive changed the ecu like 5 times and its the same crap.

only happens after warm up!

p.s. not thread jacking

confuzed240 · 11-10-2009, 06:19 PM

Could that damage anything?

lazysk8er2 · 11-12-2009, 08:32 AM

kinda its just running mad rich after warmup. but its better than running lean!!!

11-05-2009, 04:44 PM	#1
confuzed240 Join Date: May 2009 Location: Raleigh Age: 20 Posts: 29 Trader Rating: (2)	Is my o2 sensor dead? If I let the car warm up from idle to fully warm, once the car is fully warm the idle will start to bounce some and my vacuum will jump around from 17-20. When I go out and drive the car is runs fine and boosts properly. If I stop at a light the idle will not bounce and the vacuum and steady at 20. Its only random when it happens Another problem is that my narrow band o2 sensor is reading more lean then normal when I am idling and leans out off the chart when I go into boost. I know I am ruining rich, I can smell it and black smoke comes out when I go into boost. I didn't know if this meant the o2 was shot. I just installed a electronic boost controller but the car ran fine and the o2 sensor read rich after I installed it. The problem came up about a week later. Tell me what you think, thanks!

11-05-2009, 05:05 PM	#2
SoguRacing Post Whore! Join Date: Nov 2007 Location: (714) Age: 24 Posts: 2,885 Trader Rating: (23) Rides Gallery: SoguRacing	i dont think it's your o2 sensor. try unplugging it. mine didn't make a difference whether i used it or not. __________________ Pre Tune Checkup! Compression,LeakDown,Vacuum Test $80. Cams Install: $180

11-05-2009, 07:07 PM	#3
ManoNegra Premium Member Join Date: Jan 2004 Location: SoCali Posts: 4,712 Trader Rating: (27)	Only way to know for sure weather an O2 sensor is busted is to check the signal Cosult or a quality graphing multimeter would be needed to do so signal should oscillate ~5/second over a 0-1 volt range IIRC Most SR swaps I've seen tend to run rich which probably is why SoguRacing you didn't notice a difference when you unplugged it OP: sound to me like you may have a vacuum leak somewhere or your MAF is loose/dirty __________________ S-Chassis/Z32 Rear Upright Spherical Bearing Group Buy

11-06-2009, 02:04 PM	#4
SoguRacing Post Whore! Join Date: Nov 2007 Location: (714) Age: 24 Posts: 2,885 Trader Rating: (23) Rides Gallery: SoguRacing	your o2 sensor reading isn't used when under heavy load. you're in open loop. so the black smoke is a tuning problem or other related issue. __________________ Pre Tune Checkup! Compression,LeakDown,Vacuum Test $80. Cams Install: $180

11-10-2009, 04:22 PM	#7
lazysk8er2 Zilvia Junkie Join Date: Jul 2008 Location: new york Age: 24 Posts: 520 Trader Rating: (5)	im having the exact same problem i from the looks of it the ecu temp sensor is possibly going bad. its like 20 bucks so im gonna do that first maybe you should check it out too i know my tune is fine cuz ive changed the ecu like 5 times and its the same crap. only happens after warm up! p.s. not thread jacking __________________ Yea sure its a stock turbo...

11-08-2009, 07:36 PM	#5
confuzed240 Join Date: May 2009 Location: Raleigh Age: 20 Posts: 29 Trader Rating: (2)	So I drove the car today for a while pushing it hard. The a/f gauge starting reading normal again. I know I'm running rich so I guess the o2 sensor got clogged up, I checked my spark plugs they aren't caked up or anything. Another weird problem is that when I set my adjustable FPR to 3 bar, by the time I'm done driving it will have dropped 5-7psi, any suggestions?

11-10-2009, 06:19 PM	#8
confuzed240 Join Date: May 2009 Location: Raleigh Age: 20 Posts: 29 Trader Rating: (2)	Could that damage anything?

11-12-2009, 08:32 AM	#9
lazysk8er2 Zilvia Junkie Join Date: Jul 2008 Location: new york Age: 24 Posts: 520 Trader Rating: (5)	kinda its just running mad rich after warmup. but its better than running lean!!! __________________ Yea sure its a stock turbo...

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