lean idle all of a sudden. Help Please

[SSonic92]

Well i just finished putting my new turbo on, got that all done and drove it that night, everything was fine. Well the next day i get into it and when i come up to the light all of a sudden it idles down and i see my aem wb start heading full lean. I spray carb cleaner all around trying to find leaks, i dont find any. I go through and check all my clamps and make sure they are all good, dont see anything wrong with them. Look all over my intake for anything off and i still cant find anything. I dont know if they has anything to do with it, i can take my hose off the pcv valve and cap the intake line that runs to it and i idle rich around 11 to 12. while cruising the most ill see is around 13.5 that way though, never hits 14 or higher which is what you want for good gas mileage right? i wanna know why it will run like that with the hose off but with it on it runs like s***, I mean it idles where it needs to around 750 to 850 but its all the way lean, and like i said it just happened all of a sudden. I also noticed my vac on my gauge is slightly lower then usual but cant find a leak anywhere, the only time i see it go up to higher then normal is when i cap the line that runs to the pcv valve. Any help with this would be very much appreciated. And yes i have searched through the 250 or so post on here that pertain to lean idle and other websites, still cant find a similar scenario to my situation.

[compactfean]

3 things come to mind. Pcv is open way too much (just buy a new one for good measure), brake booster check valve is bad or brake booster itself has a leak or both, or you have an exhaust leak pre wideband causing a false lean reading, its also possible low fuel pressure.

[SSonic92]

Fuel pressure is good, can check on my aftermarket fpr, checked the break booster checkvalve, it is good, I checked the pcv Valve but I guess I'll have to try a friends to see if that's a prob, tightened my exhaust so that shouldn't be a prob either. I'll check the pcv valve bc that's what I think it is

[SSonic92]

And also if there was a leak before the wideband it might throw The reading off but it wouldn't cause the car to act weird, so it's gotta be one of The other things hopefully.

[Lobo240sx]

Change the PCV valve as stated. The ball is probably stuck.

[SSonic92]

But even if I can blow into it and it holds that still doesn't meant it can flow to much right?

[Lobo240sx]

If you take it off the ball inside it should move free when you shake it. You should be able to blow and suck into it. The ball should move back and forth. With the symptoms you are having I'd start there. 91 Sentra SER part.

[SSonic92]

Well when I took it out I think it did rattle, but when I get off tonght I'm gonna try a friend of mines and see if it fixes it

[SSonic92]

Well checked my pcv and tried my friends and it did the same so its not that, mine rattles just like his also. ordering a new 02 tomorrow and ill see what that does for it.

[compactfean]

Nissan ecus don't read o2 during idle. If its a sensor issue is look into the cts but one never seen a lean condition from one, only rich. Is your setup stock tune/inj/ maf??? Also bad maf can cause lean conditions.

[SSonic92]

Ok well I'll check my maf next and see if that maybe it, how do I test it? I got a friend that has one so I'll try his also

[SSonic92]

And yes maf is sohc maf, stock injectors and stock tune

[compactfean]

Check power at plug for 12v (14 while running) on black wire with white stripe. Check ground wire for good continuity (should be no resistance what so ever) at plug and finally, check maf voltage on signal wire for voltage while running. Should be between 1.6-1.8 with a sohc maf @ around 900 rpm.

[compactfean]

If you have no vacuum leaks on the intake manifold (boost leaks before intake manifold causes rich condition), cts and maf check.out, fuel pressure is within spec than it could also be a clogged injector. If injectors ohm out and are within spec you can soak them in sea foam and then put new o-rings on and reinstall and usually cleans them pretty good.

[SSonic92]

Well just hardwired my pump today so now it's getting 14 volts instead of barely 11, no leaks, I need to check my cts maybe too, I mean all those small sensors are new bc I did a rebuild. Could be injector too but it runs fine driving and in boost but I guess one could still be clogged. Cause I mean driving it shows fine on my wideband but right when I stop and my idle settles to 800 or so it will climb its way to lean.

[SSonic92]

Haven't got a chance to check my maf yet but I did notice something last night. I took my afpr off and put my stock fpr back on to maybe see if it was The prob, it wasn't. And this was before I hardwired my pump. Well now my pump is hardwired and I decided to put back on, well it was adjusted to where it needed to be before I took it off so i slapped it back on. Well after driving I noticed it was a little boggy and rich as hell so I went and looked at the gauge and Thr pressure was around 60 to 70 psi, so I adjusted to where it needed to be stock and drove around. After driving a little I come up to stop and I check it again and I'm around 25psi at idle. Idk maybe if the pump is going out or the fpr is going out. When then pressure was jacked up high it was idling in Thr 13 range.

[compactfean]

Id say fpr is doing some wierd stuff.

[SSonic92]

Well I adjusted it one more time to where it should be and now it's fine, have checked it multiple times after stopping while I was out yesterday. New o2 comes in today so I'll let you know if anything changes, thanks for the help so far.

[rswails]

Sure you don't have any intake hose leaking at all?

[D-UNIT]

This is happening to me right now! My car idles at 15.1: 1 and when I tap the gas it'll go full lean and then back to 15. When driving it will sweep back and forth from 17 to 11 afrs at part throttle! If I stab the throttle in gear it goes straight to 18: 1 and bogs (scary)! I notice that there is no misfire or knocking which is weird. So I decided to bust out the parts gun and fire away. I realized that my 255 walbro is almost 10 years old! Safe bet to change it and my stock fpr. So I bought and installed a Aeromotive 340lph fuel pump and a Tomei fpr. My car started better and ran smoother but guess what? Still super lean , the exact same readings. I was tripping out!

Anyways couple days later I noticed a faint exhaust leak that I couldn't find. After a week the leak got worse and louder. So I looked again and I found a 1/2 inch hole in my manifold to turbo gasket facing backwards! I don't know if that is the cause but I'm going to buy a new one from nissan tommorrow. I'll let you know. It makes sense tho.

[SSonic92]

Yea that's probably your prob. A leak there will cause a problem. I haven't had a problem anymore.

[S14BEAST808]

What was the fix?

[D-UNIT]

Turbo manifold gasket was blown out , so burnt exhaust fumes were being reingested into the intake. I changed the gasket. I also changed the two intercooler couplers. My car idles at 11 afr now. Now what? I swear my iac is not working. I unplug the tps to shoot timing and the revs jump to 1100. Its suppose the to at 750. The idle screw does nothing...

[S14BEAST808]

Hmmm so i sit and idle that rich just fine? Is it not stumbling?