Running a little learner while coasting/smoke from exhaust

[Rikolas]

Recently I've noticed while I'm coasting in neutral that my wideband has been jumping around from 15 to 16.5. While at idle at a stop it reads around 14.5 to 14.8 or so. Anyone know what causes this?
Also, sometimes I'll get smoke from my exhaust. It doesn't happen all the time, almost random. It happens more around the time if i start it up after about a minute or so of turning it off (noticed this while out looking at garage sales).
Any help will be appreciated. Thank you

edit: title should say leaner, not learning. sorry

 

[talon2gbuyer]

my lc-1 does something similar, during a coast mine will lean out completely up to 21.9 and then once the RPM's settle it will go back to normal of around 13.4-14.8 when sitting at a stop light. I'm curious on this issue as well, mine doesn't smoke or anything, but i'm curious as to what causes the A/F to shift so much.

 

[Rikolas]

Yeah, I'm pretty sure that my two problems aren't linked. My exhaust did this before my afr was bouncing like that. I think that after searching a little bit more that it might be a turbo seal, but I've also heard that you cant rebuild a ball bearing turbo.

 

[talon2gbuyer]

I know absolutely bupkiss about turbo rebuilds, JusMX is the guy you want to talk to about that. He's a pro with rebuilding (currently building my 20g for me ) as for the smoking, can you see what color it is? that's usually a tell-tale sign if its blue smoke then its related to your motor, if its white-ish then its turbo related. I know thats probably not what your looking for, but its a start..

 

[Roberti 2G]

I think that when you let off the gas and coast it normal gives a lean condition, the smoke could be your seals on the turbo to much oil pressure can cause smoke to come out the exhaust from the turbo being over oiled.

 

[talon2gbuyer]

hm.. I'll buy that for a dollar.

 

[And_44]

The lean condition while coasting if your over about 1200 rpm's with the throttle closed the ECU sees this and cuts the fuel injectors to zero. When it hits the 1200 rpm's it will go into an idle loop. There's an article on here about gas mileage and it describes this as a way to save fuel and engine braking.

The smoking on start up could be old valve stem seals. I have same issue only minor though and only on start up. If your exhaust valves are leaking you can usually see signs of it around your exhaust manifold. It appears damp. There's different conditions and signs that tell you whether it's piston rings, valve stem seals, or turbo seals. But from what I gather it only being on start up sounds like the valve stem seals.

 

[Rikolas]

I think its a white color of smoke. And it can also happen while in town driving, it is just more rare to see it. And there mignt be a llittle leak from my exhaust manifold, since I did notice one bolt looking damp. Thank you guys for your help. Ill look into all of the ideas.

 

[schumy]

Are your spark plugs caked with oil ? That takes like 2 seconds happend to me from bad valve seals

 

[Rikolas]

Are your spark plugs caked with oil ? That takes like 2 seconds happend to me from bad valve seals

I'm not sure. I'll be able to check on them tomOrrow when I come home since I'm currently out of town

 

[Rikolas]

Alright so there is another time it smokes. It also does it when I come to a stop if I compression break almost all the way, or if its hard compression breaking.

 

[schumy]

Do u have a good pcv system?

 

[Rikolas]

Do u have a good pcv system?

I don't think there's a place on my intake to have a hose to lead into it.

 

[Rikolas]

Would not having the PCV system properly functioning cause the smoke?