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View Full Version : SR: Super Lean 16.9+/- at idle all of a sudden?

MrFairlady
03-02-2010, 07:37 PM
Been driving my car a tad more lately after it sitting for the better part of the winter.

All of a Sudden the car has been running SUPER lean 16.9 at idle only- from a Perfect 14.1-14.3 a few days ago and last few weeks when I would drive it on Short Trips.
Mods:
SR20,d/w 550cc,Sard FPR,Z32 maf,Enth Tune ECU *15psi* 93oct,GT2860BB,Walbro, Exhaust,etc - pretty basic.have AEM UEG,STRI water temp w/ adaptor in upper coolant hose.
Running 40psi base fuel pressure as per [email protected] Enthalpy

Car has Been Driving perfect Still and Boosts great (in the 11's-12) at Boost.Does not stumble or anything.
the idle worries me as its a Chip tune and nothing i can Adjust manually to Compensate.
turns out car was running REALLY hot the other day and I was actually low on coolant somehow.Never let it really overheat but did get close trying to limp it home.Put water in and filled,etc - ALL IS fine Temp wise after that.

Thats the only thing that I can say might have happened diff,and now noticing the Lean Idle.

What could it be? what should I check - Fuel Pump 1st?
fuel pressure at idle is where it should be set.Nothing changed there.
fliprayzin240sx
03-02-2010, 07:49 PM
Bad o2 sensor? Specially since its at idle/closed loop.
greenman100
03-02-2010, 08:22 PM
Exhaust leak.
MrFairlady
03-03-2010, 01:04 PM
Well,..lets see
No exhaust leak as on stumbling or any un-usual behavior other than Lean AFR's.

Factory o2 sensor use to work (have a brand new Harness) using Nissan Datascan (Consult readings) it was working after I ran my own wires to the ecu (stock brand new harness seemed to not work at 1st)....has Stopped working for a while but up untill now has the lean idle started - so it Def could be that.

Would have thought it would have been doing this since its been running.
MrFairlady
03-03-2010, 07:55 PM
Ok - Found my the damn 'T" off the valve cover had popped out of the damn thing.hoses still connected but the "T" was Seperated.

Wonder if that would cause a lean idle??.
So basically my catch can routing from the intake to the "T" - to the block (PCV exhaust Side) was off.

trying to Register my old Datascan software to see if the o2 is working again but from what I'm told this freakin car dosen't even need an o2 sensor.
MANOlOS14
03-03-2010, 08:17 PM
Hey off topic question here: Besides an ECU is there any other way to remove the speed limiter on the ka24de? I have a '95 240sx(s14) I found this Removing Top Speed Limiter (http://www.240sx.org/faq/articles/spdgov.htm) but idk, well it work? has anyone tried it? Also im probably dumb but from what i understood, i wont have a speedometer????? Im a little desperate cuz stupid jack ass integra took me the other day and as u all know, 240s have speed limiter so while he kept goin i stayed, plz help! its degrading to lose to a honda lol!
reccakun08
03-03-2010, 08:45 PM
Hey off topic question here: Besides an ECU is there any other way to remove the speed limiter on the ka24de? I have a '95 240sx(s14) I found this Removing Top Speed Limiter (http://www.240sx.org/faq/articles/spdgov.htm) but idk, well it work? has anyone tried it? Also im probably dumb but from what i understood, i wont have a speedometer????? Im a little desperate cuz stupid jack ass integra took me the other day and as u all know, 240s have speed limiter so while he kept goin i stayed, plz help! its degrading to lose to a honda lol!

Dude dont trash the OP's thread for your random off topic question that nobody cares about
MANOlOS14
03-03-2010, 08:51 PM
ok with out being a jack ass do u mind telling me how u start new threads, im new to forums thing.
reccakun08
03-03-2010, 08:58 PM
go to forums. pick the right category for the new topic/thread. click forum tool on the right side and click new thread.
MANOlOS14
03-03-2010, 09:14 PM
k cool, thanks dude!
steve shadows
03-03-2010, 09:30 PM
Ok - Found my the damn 'T" off the valve cover had popped out of the damn thing.hoses still connected but the "T" was Seperated.

Wonder if that would cause a lean idle??.
So basically my catch can routing from the intake to the "T" - to the block (PCV exhaust Side) was off.

trying to Register my old Datascan software to see if the o2 is working again but from what I'm told this freakin car dosen't even need an o2 sensor.


Sounds like a vacuum leak from the OP

I bet you fixed it now, check for other vacuum leaks.

If your 02 is working right then that is definitely what is causing it.

Think about it...something at low / light load is allowing extra air into your combustion chamber which is elevating your AFRs...

or your fpr is failing and you are losing fuel pressure in low load regions but this is much less likely