P0171

[Ilya]

Don’t know how many of you know anything specific about a 4th generation Maxima but maybe you guys can give me something to try…

So…let’s start off with a bit of history.

In July of 2007…I got SS AutoChrome Headers and Y-Pipe, Magnaflow High-Flow Cat, Budget B-Pipe, and a new OEM 4th Gen. Muffler. I also got an O2 Simulator since I was going from being Cali. Spec. to Fed. Spec.

Soon after it seems, I got a ghost code for being lean on bank 1 (P0171).

In the winter of 07…I switched from the SS AutoChrome Y-Pipe to a stock OEM Fed. Spec. Y-Pipe due to noise. I wanted something quieter. Still, the code was ghost.

About 1 month ago…I installed a Apexi VAFC-II because I was planning to 00VI/MEVI VERY soon. Since then, the P0171 code has been lighting the CEL (no longer ghost). I had the VAFC-II doing NOTHING…so I don’t know why it would all of a sudden trigger that code to become an actual CEL. But anyway…2 weeks later I got an 00VI.

I had some major problems with the 00VI install. I ended up having a cold start (which I have fixed by adjusting the idle). I also had a vacuum leak and a rear valve cover leak. I fixed the rear valve cover friday night with a brand new gasket from Nissan…although with new cover grommets and bolts. I also found the vacuum leak and took care of that.

At the same time that I had the issues above…I also developed a P1105 (MAP/BARO Sensor Fault) code. I fixed that by getting another used “boost sensor” (located on the intake snorkel of a 4th Gen.)

Now…I’ve done a LOAD of searching on this P0171 code. Most links and threads led to it being a MAF problem. Now, I have three MAF’s…one of which throws a MAF Circuit A Failure code. What is the probability of the other two being bad?

Right now I only have a P0171 CEL and a P0171 Pending CEL (running lean bank 1).

Here is what I’ve done (cliff’s notes):

• Tried all three MAF’s
• Replaced RH O2 Sensor (the one located in the back near the IM)
• Replaced Boost Sensor
• Replaced Knock Sensor during 00VI install
• Fixed any leak I could find…spraying the engine bay with TB cleaner trying to find any other possible leaks
• Replaced PCV Vavle
• Replace Rear Valve Cover Gasket (suggested and needed)

I do have an exhaust leak somewhere under the car it sounds like (Y-Pipe flex section perhaps?). Would this cause a lean code CEL? I have the Apexi tuned a little bit…do I need to go get an A/F Dyno and tune it better? The guy who tuned it had the values for a similar setup written down in a notebook.

All of my maintenance is up to par. I’m anal about maintenance.

I NEED HELP. My inspection ends at the end of this month and I’ve spent about $275 and 3 weeks of time trying to combat this myself. I do not want to spend $300 on a new MAF sensor either. Could it be my O2 simulator? I have another new that I never used cause I thought my other one died (light wasn’t blinking but it’s been fine for like 8 months since)…but if the sensors controlled by it were bad…I’d be getting a P0172 (bank 2 lean). Is it a result of my cheap EBay ram air intake? I’m getting a 5th Gen. complete intake that I’ll be installing as soon as I get.

SOMEONE HELP ME. PLEASE!

Here is how the bay looks right now:

[88slowmarro]

honesly in all seriousness bring it to a shop that can diagnose it and not throw parts at it it will save ya time and money in the long run ,now that bein said yes a exh leak can cause a lean code if its before the o2 sens but i see ya did a intake swap on it so it could be a bad intake gasket loose intake bolt pcv valve or a list of other shit along wit o2 sensors …new headers will burn up o2 sensors cause of the oil they ship them with wrecks them …i couls sit here all day tryin to explain it but i cant say anything solid unless i saw it :nod

[Hooked_on_240]

If you have a cone then y is the stock intake thing still there… :confused

[Ilya]

@88slowmarro

honesly in all seriousness bring it to a shop that can diagnose it and not throw parts at it it will save ya time and money in the long run ,now that bein said yes a exh leak can cause a lean code if its before the o2 sens but i see ya did a intake swap on it so it could be a bad intake gasket loose intake bolt pcv valve or a list of other shit along wit o2 sensors …new headers will burn up o2 sensors cause of the oil they ship them with wrecks them …i couls sit here all day tryin to explain it but i cant say anything solid unless i saw it :nod

Headers are old…oil definitely burned off by now.

Exhaust leak after the IM swap was fixed with new bolts, grommets, and gasket. Exhaust leak I believe is right before the cat…after all the sensors.

O2 sensor that I replaced last week was the one that could possibly cause that code (Bank 1 - RH).

A few people have told me that I can pass inspection with one light depending on what year my car is. I think I’m just going to go spend $21 and give that a whack.

@Hooked on 240

If you have a cone then y is the stock intake thing still there… :confused

Cone was given to me by the guy who did the swap. I don’t plan on using it permanently. It’s just a hold over until I get the intake from the 2000 Maxima.

That resonator wouldn’t matter anyway…it’s just a box with a couple vacuum lines.

[88slowmarro]

@Ilya

Headers are old…oil definitely burned off by now.

Exhaust leak after the IM swap was fixed with new bolts, grommets, and gasket. Exhaust leak I believe is right before the cat…after all the sensors.

O2 sensor that I replaced last week was the one that could possibly cause that code (Bank 1 - RH).

A few people have told me that I can pass inspection with one light depending on what year my car is. I think I’m just going to go spend $21 and give that a whack.

Cone was given to me by the guy who did the swap. I don’t plan on using it permanently. It’s just a hold over until I get the intake from the 2000 Maxima.

That resonator wouldn’t matter anyway…it’s just a box with a couple vacuum lines.

cant have any codes in comp sorry buddy im a inspector

[Hooked_on_240]

oo… im just picky :tong that shit would have been ripped out asap.

[Ilya]

@88slowmarro

cant have any codes in comp sorry buddy im a inspector

Are you sure? I’ve had three people tell me otherwise…one of which just had his car inspected with the CEL on. I think it depends on the system that fails (such as EVAP, EGR, etc.).

[88slowmarro]

waste your money then pal it wont happen but good luck wit that :idiots dont say i didnt try and help ya

[JiM_P_2001]

could be a shitty connection throwing off the resistance

[Ilya]

@88slowmarro

waste your money then pal it wont happen but good luck wit that :idiots dont say i didnt try and help ya

I’m not saying you’re not right…but he says it’s on the DMV site itself. So I dunno? He’s gonna show me.

[Ilya]

@JiM P 2001

could be a shitty connection throwing off the resistance

I hope not…hard to track down something like that. The wire could be bad anywhere :(.

[03zx2]

88slowmarro is right any car that is obd II and has a check engine light on will fail.Most garages that do inspections will ask you is the cel on before they do the inspection so you are not out 21 bucks.

[Ilya]

@03zx2

88slowmarro is right any car that is obd II and has a check engine light on will fail.Most garages that do inspections will ask you is the cel on before they do the inspection so you are not out 21 bucks.

Incorrect. Up to 2001 model year…a car is allowed to have 2 systems readiness tests not completed (which could result in a CEL). It’ll still pass if that is the case. It’s on DMV’s site.

I’m going to take my chances.

[88slowmarro]

go for it its a eng managment code it wont run the monitors before eng light comes back bud ,oh and monitors and codes are 2 diff things in case ya didnt know ;D

[Ilya]

@88slowmarro

go for it its a eng managment code it wont run the monitors before eng light comes back bud ,oh and monitors and codes are 2 diff things in case ya didnt know ;D

I guess we’ll find out.

If anyone has any other ideas of what to try…please post. Thanks.

[Ilya]

Update as of 11/9/08.

On thursday night, I took off the y-pipe to see if I could track down a leak…thinking that’s what was causing my lean code. Sure enough, the rear gasket between the header and the y-pipe was completely burnt. Luckily, I had two Nissan gaskets for that part of the exhaust. So, I swapped out both front and rear gaskets. Called it a day and started putting it back together.

Long story short, I stripped one of the studs on the rear header/manifold.

Friday and Saturday (4hrs friday and 7hours saturday) I spent taking the radiator, cross member, manifold, and both rear headers off and swapping in the OEM fed. spec set I had along with new OEM Nissan Gaskets for between the block and headers, and headers and y-pipe.

Everything runs fine, car is much quieter, and I can’t really hear any exhaust leaks anymore.

Cleared the code, and after about 25 miles I still have P0171.

My question is…should I get new gaskets for between the headers and y-pipe since the ones I put there (Nissan ring type) were already used once the day before? I’m thinking since they got crushed/smushed during the first install…they aren’t holding as well now…even with special exhaust sealant.

Regardless, my issue is NOT gone and I still have a CEL. Of all the guys who have turbo’ed, sc’ed, and otherwise modded their engines…NO ONE has any idea what is causing this for me?

I’ve replaced:

• O2 Simulator
• Headers (from SS AutoChrome to stock Fed. Spec.)
• Oxygen Sensor located on the left side of the IM near the firewall (rear part of the Y-Pipe)
• Replaced Y-Pipe Gaskets with NEW Nissan OEM
• Replaced Header Gaskets with NEW Nissan OEM
• Replaced rear valve cover gasket with NEW Nissan OEM (had an oil leak there after the 00VI swap)
• Replaced Fuel Filter
• Replaced Knock Sensor
• Checked the injectors for abnormal clicking with this stethoscope device type thing for cars
• Tried three different MAF’s
• Tried different boost sensors (located on intake snorkel - had a different code for it but I thought it would be worth mentioning here)

I have 6 brand new spark plugs that I didn’t install yet…but otherwise I don’t know what else to do or try. I’m at wit’s end.

ANYONE? PLEASE!?

Perhaps I should try this? Anyone with a VAFC-II that knows if this will negate the point of the VAFC-II or not? Will it still be able to do what it has to?

@Member on Maxima.Org

I think I am having the same issue with the op and I will chime in with what has happened with my car and what I have to done to fix it.

Well I used to get a code for running lean as the op did and so I decided I would reset the ecu and it came back so then I bought some bosch oxygen sensors. I replaced bank 1 sensor 1 I believe (the one on the rear header) and that didnt fix that problem so I thought about what could still be wrong. I remebered when I first got my 00VI swap up and running I had a knock sensor check engine light which was because I was told to connect the knock sensor wire to the apexi VAFC-II. So then I thought what if it was the same type of deal with the 02 sensor as it says to connect that upto the apexi as well. So the other day I cut the wire coming from the 02 sensor going to the apexi and that issue was solved. Now I am trying to get my system ready so I can return and get my inspection sticker done without failing…again, so I am trying to do the drive cycle that is supposed to get everything ready. Which it worked partially but I just didnt have enough open road to do soem of the things it says to do. So I then plug in my dads new little toy…a scan tool which does pretty much everything (trouble codes, monitors the systems readiness, dyno, drag, and a bunch of graphs and stuff on pretty much everything you could ever think of). So then after I do the drive cycleI checked to see if my systen is complete and ready to take it in for the sticker and I see that all I have left to get complete is the catalytic converter and the evap system. So then for fun I check to make sure I have no codes just to make sure and I have code P0136 which is 02 sensor malfunction bank 1 sensor 2…the catalytic converter 02 sensor. I have a cattman full exhaust and I tried using the 02 simulator but it didnt work for me at all it made me throw a code so I removed it and I have never had any problems until now. I have kept the 02 sensor plugged in, its just not in the exhaust stream, but until I got it secure and out of the way it dangled a bit and hit the ground maybe it finally realized I need a new one??? But thats as far as I am upto with trouble shooting today…

Maybe there are some similiarites between our problems and if not sorry for hijacking…and if anyone has any answers that would be appreciated.

Thanks and good luck with your problem…

[88slowmarro]

your only gonna get a lean exh code if the leak is before the o2 sensor you have a problem wit either the maf or map sensor could be wiring or the swap ya did or both bad sensors just cause ya changed em dont mean ya fixed it obviously stop throwin parts at it and take it somewhere that can diagnose it right ,the money and time ya spent tryin prolly cost more than what it would be to do it right ,not tryin to be a dick but i see it all the time at the shop

[Ilya]

@88slowmarro

your only gonna get a lean exh code if the leak is before the o2 sensor you have a problem wit either the maf or map sensor could be wiring or the swap ya did or both bad sensors just cause ya changed em dont mean ya fixed it obviously stop throwin parts at it and take it somewhere that can diagnose it right ,the money and time ya spent tryin prolly cost more than what it would be to do it right ,not tryin to be a dick but i see it all the time at the shop

I’ve only spent about $180 (cost of that O2 sensor and Fuel Filter/Gaskets). The knock sensor was done as ‘preventive maintenance’ during the swap.

But yeah…I dunno what else to try.

I’m thinking of going to Nissan and giving them an hour with the car to see if they can diagnose it using CONSULT. Anyone know of any good techs at a Nissan dealership that won’t just screw me over for that 1hr charge? I actually want them to look at it but I have heard crappy stores about dealerships in general.

[88slowmarro]

avoid the dealer first thing they will tell ya is to bring it back to stock then fuck ya harder go to synapse or another shop that are used to swaps and can read flow charts did ya have the code before the swap or no

[Ilya]

@88slowmarro

avoid the dealer first thing they will tell ya is to bring it back to stock then fuck ya harder go to synapse or another shop that are used to swaps and can read flow charts did ya have the code before the swap or no

Okay I will keep that in mind. That’s actually why I asked if anyone knew a Nissan tech personally so I could have him and only him look at the car. I know dealers look down on those of us who mod.

I did have the code before the swap.

Do you think that post about cutting the wire to the VAFC-II and just have the ECU take care of that O2’s instead of having VAFC-II input could help?