samsonite

So my CEL is on... whats new. Im throwing the P0140 code for "Heated O2 sensor rear no activity detected." I am trying to decide whether it's actually the sensor, the circuit, or something else. The problem... when i punch it in 2nd or sometimes 3rd it hit about 4000rpm and all power is lost. The engine just stops at 4G's and I dont' speed up even while im flooring it. BUT, this does not happen every time. Sometime i'll let up for a second and then hit it again and everything is fine. So my first thought is fuel delivery... I can only speculate the O2 sensor is throwing a false rich reading and cutting fuel... maybe? Second thought, VAIS. Well no problem there. BOV? Any othere ideas? Could a rear sensor really be causing this much power loss? I have an autotap and have been looking at the voltages and they look ok so i have a hard time beleiving its the sensor but I am throwing the code. Anyone?

MaxInProgress

iTrader: (2)

Hey man sounds like my problem, my o2 went in the back and the car hesitates and runs rich as a pig. Ima replace my o2 this thurs and let you know what happens. My cell is on also. Are you buckling at all while boosting? And do you have a wideband reader?

jcy98maxse

iTrader: (8)

Your symptoms sounds like mine, except mine runs like crap midrange and kicks in at 5k. AF ratio is fine but I hear my exhaust pop and gurgle like I'm running super rich. At least ur CEL is on and may be able to tell a tale. Me, I'm stuck with no CEL or leaks and I've done most of the small cheap things AND still can't figure out why my car runs like crap. I hope you find your problems soon, keep us updated and good luck.

Nealoc187

iTrader: (23)

I sincerely doubt an O2 sensor could cause that problem. My experience with O2 sensors failing or being non-existent is fairly extensive: My turbo car has NONE, and runs fine, my old 96 NA bolt on max had that same sensor fail, I never bothered to replace it, and that car was (and still is) one of the fastest NA maximas on this board - no power loss there - and my 95 beater has a bad rear O2 sensor and at 185K miles still holds the record for quickest bone stock 4th gen on the forum - no power loss there either. While this doesn't mean that the O2 sensor is not your problem, it is evidence that O2 sensors problems don't necessarily cause problems with the engine running.

What you describe sounds sortof like a coilpack problem, though I've never really heard of those being intermittent. My beater 95 had bad coils when I bought it and it exhibited that type of behavior, but it did it EVERY time, it didn't come and go.

maximamaybe74

Yea ive had the rear 02 sensor heaters fail and my car still ran fine with no loss in power either.

samsonite

Could it be MAF sensor? just a thought...

gb21914

iTrader: (1)

I'm not boosted...but I had a similiar issue with a knock sensor. Might want to look into that too. Sucked all my power under 3000rpm.

jcy98maxse

iTrader: (8)

my maf is bad. My buddy swap in a good one and it drove like its suppose to so now i have to find a new z32 maf.

Turbo95Max

iTrader: (25)

im having a simlar prob with mine, i suspected the Z32 MAF, so i swapped it with another Z32 MAF and it ran normal for like 30 min and now i have the same prob again....cant figure it out...ive sorta given up on it, i juss dont drive the car as much....heeh...sad but true.

jcy98maxse

iTrader: (8)

Man i hope that dont happen to me, I didnt even drive the car when he swapped it in cuz i was at work so it was only in there for like 15mins. I would hate to buy a maf for nothing.

MaxInProgress

iTrader: (2)

Is there a way to test the coilpacks to see if maybe one of them is dead?

jcy98maxse

iTrader: (8)

u test for resistances between terinmal 1 and 2.

Turbo95Max

iTrader: (25)

hahha

well, we were 400 miles from home and i was stressed about not being able to figure out the prob and the hesitation/surging and power loss was SUPER ANNOYING. So we tried another Z32 MAF that my friend said was 100% sure it was working. Swapped it in and my first test drive around the block car ran normal. SICK! so im happy go back clean up and we leave....20-30 min later the prob comes back and now its back to the hesitation power loss thing....ugh.

MaxInProgress

iTrader: (2)

Do you have a wbo2?

jcy98maxse

iTrader: (8)

well we'll see when i make the purchase tomorrow. I can always sell it later i guess but I hope it runs right cuz I'm dynoing tomorrow afternoon. hehe

Turbo95Max

iTrader: (25)

if you wanna sell the Z32 MAF let me kno...i might be interested in trying another one...i dunno...we'll see

jcy98maxse

iTrader: (8)

I will definitely let you know. I hope i dont have to sell it but hey its worth a shot.

samsonite

No i dont' have a wb02....wish i did. Keep me posted on that MAF swap. I keep going in and out of town so its hard to find time to work on my damn car.

Turbo95Max

iTrader: (25)

how much does a Z32 MAF go for nowadays anyways?

jcy98maxse

iTrader: (8)

mine was $100 locally. Havent been able to find anything less, the ones that are less would cost about the same with shipping.

ewuzh

iTrader: (20)

Got mine for 100 shipped w/ pigtail. I've seen prices as high as 130 + shipping...

jcy98maxse

iTrader: (8)

well like I said I would, I purchased a used z32 maf today. It improved a lot in performance compared to my last maf, I have some mid range back now but still not at full stregth especially at 10psi. Its still running like crap, we did a third gear pull and it was slow *** hell. The spool is there but there seems to be a lack of power or responds to boost.
A couple of observations now after swapping the maf:
1. Car cuts in and out throughout the powerband, its very inconsistent. One it feels better then the next it fells like crap. It feels studdery.
2. Same day my friend swap mafs before I made the purchase, I threw a CEL for cam sensor, 0101. We replaced that but to no affect to this particular problem, it made it back to running like crap from barely running at all.
3. Did a few WB datalogs and was quite puzzle that my old tune which was in the ballpark of 11.2-11.3 has now turned into high 12's and 13. I now only see airflow % of about 57% compared to 65% on my old maf. Voltage-wise, it dropped from as high as 4.86v to now 4.3ishv which I guess makes sense for the lower % airflow?
4. Even tho I have researched many threads regarding the z32/j30 maf, my friend who did the maf swap said that his maf had a white strip containing the part # and was for a 93+ 300zx TT. As far as I know all of the z32 had the same part# and with and orange strip. They all were the same except of a variation of the pigtails. SO now I am curious to find out what the hell kinda of maf he used and if so why would it run better??? I'm almost certain that this new/used maf that I bought is in working condition due to the immediate affect on how my mid range came back from non exsistent to some what exisitent.
4. Car is unsually lope or poppy form the exhaust. I mean its ridiculous how bad it is, the most disturbing thing about it is and idle rev, I get this pop (I wanna say detenation/backfire) in the feedpipe. Sounds like what Subaru does if u ever heard of one. A single pop or two especially around 2800-3000rpm. I also wanna say it may be the cam sensor affecting timming but its also a working sensor so I'm lost there too.

Man this is a mistery that have stump everyone that has touch the car and even people that are on here. I wonder if I can ever get the darn thing running right again.

BTW- Knock sensors has been changed out already, I think its the reason that started this whole mess. The KS fail and opened up a can of worms for the car.

jcy98maxse

iTrader: (8)

We will be swapping out the maf again later today to the one that he put in to make it run "normal". i will look and see if there is anything different about the maf and maybe able to take some pictures for comparision. I really have no more ideas what could make my car act this way, if anyone have anything new to bring to the table please do...

samsonite

well i first said the problem was intermitent... now its gaining in consistency. I can barely use any of the power band above 4000rpm. ALSO, now the car has been dying on me if i push it to the point where i lose all power. VAC leak????? Coils??? This is really pissin me off. Now i have an exhaust leak, an 02 sensor bs headache, and now this crap. I'll keep everyone updated. Please chime in if you got any ideas. thanks

samsonite

could it be my aux fuel pump not kicking in? I guess i could just connect it straight to the battery to find out if its still working? any thoughts.

MaxInProgress

iTrader: (2)

Hey man I started to get that pop also when i would put the car in nuetral going in second gear and it falls between 2.3-2.9k I also hear this pop coming from my exhaust, but im thinking thats from running rich as hell.

jcy98maxse

iTrader: (8)

*Final update* We swap MAFs and its did feel better. It was the same part number but just made by a different company. I believe the orange label MAFs are made by JECs, the other is unknown. I was actually able to break second loose without much effort compare to before.
However, shortly after changing the mafs, the cam sensor situation came back. I continue to trip CEL thru out the day. We replaced it with a new one but in the process of changing it out, the bolt that holds the sensor in place broke due to corrosion so the sensor is loose causing my car to barely run, this is my major problem now. All it does its either trip a CEL and hesitate or no CEL and the car bucks all over the place, I can't even drive it normal at all.

Since I would need to retap the bolt, I've decided to just do a DEK swap. The bolt problem isnt the only reason why I'm doing the swap, I've had a slight main seal leak and coolant leak (not headgasket related) for some time. Also the motor is over 120k miles so it time for a new/lesser milege motor. Doing the DEK would cost just about the same as fixing the current problems that I have now so I just dont see the point of fixing my current motor. I may rebuild it while its out so I would have a spare.

I wish I would of been more help to you guys regarding this thread but I will continue to check on this and maybe we can figure out this thing. Good luck.

MaxInProgress

iTrader: (2)

So your gonna swap a dek into a maxima?

jcy98maxse

iTrader: (8)

Yea, probably ordering the motor sometime this week.

samsonite

PROBLEM SOLVED...
I limped the car into the garage from the street (literally died about 6 times) and pulled the MAF sensor. Noticed the little metal film used to monitor the flow was dirty. Used a q-tip and some isopropal alcohol and cleaned it. Also cleaned the prong type things next to it. Put it back in and ALL power is back. My CEL for the O2 sensor is even gone. So all good right... not so fast. I had knocked out 2 of 3 problems w/ my car. I thought the last was a exhaust manifold stud issue. But, after driving w/ my mechanic neighbor and driving briefly w/ a nissan guy they both said it sounds like transmission. Nissan said it would be around 3000 for a complete overhaul. I thought he was crazy. I still am not 100 percent sure the noise i am hearing is coming from the transaxle. I only hear it when i start to pull in gear. Its expecially pronounced if i am in 1st at high rpm and let off the gas. Sounds like the manifold problem discription of "flipping through cards." I may attempt to rebuild it myself or take it to my a guy I know who owns a couple of amco trans. shops. He'll give me a deal. Just when i thought everything was going so well.... At least i have my power back. But that may have caused the tranny prob. , who knows. Sometimes I think my car is a rolling disaster... then i hit the gas and i like it again.

MaxInProgress

iTrader: (2)

Good quote lol I feel the same, im gonna try and do the same thing with my maf because I started the car today, tried to boost and it just died at 4k rpm, and then 15 min later the problem went away, it would go past 4k if i feather it, but if it starts seeing boost it just felt like it hit a wall.!!!! So im sure my maf is one of the problems im having.

Turbo95Max

iTrader: (25)

wow its like MAF related stuff for everyone

i fixed my prob yesterday too. My MAF ground was bad, fixed it and car runs great again....smooth and has power.