cyc5181

iTrader: (12)

I've installed the PPE LTH and got an Osiris tune after the installation. The car runs great (@wot & cruise), except during idle, the AFR would fluctuates between 12-16 from both bank 1 & 2. They kinda oscillate between the 2, if bank 1 reads 12, then bank 2 reads 16 from the log and vice versa. And the idle rpm fluctuates between 650-800rpm. The tune was done by an experienced tuner here on the forum.

So far here's what I've done to try to remedy to problem:

1. I've checked everywhere for vacuum leaks, exhaust leaks
2. Cleaned MAF with MAF cleaner
3. replaced passenger O2 sensor (more on that)
4. checked for loose connections

So far I've come up empty and I'm not sure what else I can do. I replaced the passenger O2 (bank 2) because a CEL came on with 2 codes, P2A03, and P0137.02. I read my log and saw that O2 went as low as 0.5xV and thought it was a bad sensor. But still after replacing it, it didn't help. The P0137 code I found that a lot of people have that when they replace the cat with TP so i didn't think it would be a unique situation for me.

Can someone help me identify the potential cause for this? Maybe there's a not so obvious spot to check for vacuum that I might've missed? the only tiny exhaust leak that I know of is between the XYZ pipe and the mid-pipe, but thats really far downstream of the system that I don't think it's the root cause. I've also checked on the bolts on the manifold/header and from what I could reached they all seem tight. I did not removed any coolant pipes/intakes to do a complete inspection.....

Prior to the PPE and Osiris tune, the car idles perfectly normal and the power mods I have was motordyne shockwave v1 exhaust and MREV2/spacer with a K&N drop-in.

This is on an 06 enthusiast.

Thanks for your help!

secwind

iTrader: (8)

I don't know the my exact afr but after I installed my ppe header I had idle problem as well.

The new upstream o2 sensor location is causing this. My tuner raised my idle rpm a bit and everything smoothed out for the most part.

travlee

iTrader: (8)

you could try anti fowlers... space out the sensor some and decrease the size of the of the hole going to it.... but the tuner should be able to deactivate the sensors......

cyc5181

iTrader: (12)

I don't think you would want to use anti-fowlers on the front wide-band O2 sensors. As far as the rear ones for the code, PPE already comes with a bung where you install the rear O2 at.

When you say everything smoothed out, do you mean the idle rpm or the AFR? Did you do a log to see?

Thanks for the input so far guys....... still hoping I can get to the bottom of this!

PeterPotatoes

Sounds like your "iacv" is out of wack. Since the 350z doesn't physically use a valve I used quotes. Its more a combo of your maf, throttle body and ecm. I would try a maf cleaner and reset your idle air control. If you don't know anyone with a scanner there is a way of doing yourself... I have a scanner so I don't know the procedure. You could also unplug you batt for a day or so to do a crude relearn... I think (never tried it on our cars.)

secwind

iTrader: (8)

My car idled like I had cam lope lol. I'm not sure about the AFR since I don't own a cable to log it.

By relocating your upstream o2 sensor further down, the afr reading are delayed. The car tries to over compensate at idle.

cyc5181

iTrader: (12)

If that were the case, then everyone with a PPE LTH should have this fluctuation of AFR @idle, but I haven't seen anyone say anything about this yet. I certainly am not the first one to install the headers and got a tune, so if it's really because of the location of the O2 and the readings are delayed, I would think someone would have already mentioned it.

I emailed PPE about this, Paul from PPE replied saying that they have installed several times and they didn't have this problem. Nor did they receive an email regarding this issue from the 40 or so headers they sold last year.

The idle rpm being jumpy is not a real concern, it's the AFR fluctuation that has me worry. The car is not a DD, I only drive it when I go autox or DE. I want to be confident that the car runs good before I go to these events.

Thanks.

QTB

iTrader: (9)

I don't remember how the EGR and other emissions controls work on the VQ but you may want to look and see what it's doing at idle. Sometime if you have a code they may do odd things at idle to try and continuously compensate. This is just a guess but it's worth a look and it's usually easy to do with your tuning software. They may also be your source problem if they have developed a leak or other issue.

travlee

iTrader: (8)

if he is tuned, he cant reset the ecu......at least on mine i cant. it was dyno tuned and the make the maps for what it is seeing then, so it wont relearn

i would see what codes it is throwing, i had a buddy who had the "lope" like secwind described and he ended up having a bad cam shaft sensor...