wideband reading

[mattysr20]

ok I've searched around but haven't found the answer I'm looking for so once again I turn to zilvia....

ok so basically I was just curiouse about my wideband readings its an autometer wideband. The car runs great with no issues but I just wanna make sure there isn't gonna be a issue down the road..

while driving it stays around 15.0-14.9 but after driving a little its drops to like 10.5 the kinda bounces back and forth from around 15-10 but most of the time its is at around 15 wich from what I gather is good. I'm just wondering if it jumping around like that is normal ? is there a way to fix it? or is it no big deal since it doesn't stay rich?
its an s15 Sr it has an aftermarket fpr and the bov is vented to atmosphere wich I was told can cause this.. it also has a Jim wolf ecu for my setup. any insite would be awesome...



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[2.5T_/<ouki]

Your getting rich readings due to the BOV venting to atmosphere. Your AFRs while driving around are good as they are pretty close to stoich (14.7:1). It could also mean your o2 sensor is starting to fail, but more than likely that's not the case and almost certainly it's from being vented to atmosphere.

[mattysr20]

that's what I figured. I was looking under the car and the wire from the o2 was hanging so I'm gonna get that strapped back up and see if that does anything cause it might be coming loose or something


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[2.5T_/<ouki]

What's actually happening is that the MAF & o2 are working in conjunction with each other telling the ECU the amount of air being metered and what the fuel to air ratio looks like. What's happening in your case with the rich AFRs is that the MAF is telling the ECU that there is so much air being metered so it then tells the ECU to administer x amount of fuel for the specific amount of air (it wants to be as close to stoich 14.7:1 as possible). Now, since the ECU has already gotten the signal from the MAF and administered the proper amount of fuel, you are then actually releasing all the air that was metered and supposed to be going into the engine out into the atmosphere; pretty much the raw fuel that was administered is not being burned up, the o2 senses this super rich mixture and now tries to compensate and get back to 14.7:1

[Kingtal0n]

way over complicated.

The maf sends a voltage to the ecu regarding how much MASS of air is entering the engine.

Before injecting fuel based on that voltage, the ecu checks with the O2 sensor and makes small limited adjustments based on what it remembers.

b.
Your problem MIGHT be due to that atmospheric bypass. It could also be due to any number of other things such as a boost leak.

[mattysr20]

I was thinking maybe boost leak but my boost gauge reads fine and it idles perfect so I ruled that out cause I figured it would idle rough if it had a boost leak.


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[Lhimes]

Boost leaks normally don't effect idle, due to it leaks on boost not on idle. Unless you have one major leak. I'm going with bov

[Croustibat]

I was thinking maybe boost leak but my boost gauge reads fine and it idles perfect so I ruled that out cause I figured it would idle rough if it had a boost leak.


Actually a boost leak may not show on a boost gauge. You'd get on boost a little bit later, sometimes it is even not noticeable. If it dips down to 10, you may have a pinched hose somewhere that only leaks when a certain vacuum or boost is achieved. Best way to make sure is to loosen every piping couplers, wedge the hoses a bit so they stop sticking to the piping, and tighten everything back. A big boost leak would cause the engine to stumble, so you are tracking a small one.

This usually solves all boost leak issues, when they are not coming from defective IC core, 1 way valves or badly set beathers.

Boost leaks normally don't effect idle, due to it leaks on boost not on idle. Unless you have one major leak. I'm going with bov

They do, esp. when there is a bov involved. Bov leaks at idle because there is a strong vacuum that pulls the piston. You can go from 15 to 11 / 12 AFR with a leaky bov at idle. Lower readings are usually the result of a bigger leak though.

[mattysr20]

Quote:

Originally Posted by mattysr20

I was thinking maybe boost leak but my boost gauge reads fine and it idles perfect so I ruled that out cause I figured it would idle rough if it had a boost leak.

Actually a boost leak may not show on a boost gauge. You'd get on boost a little bit later, sometimes it is even not noticeable. If it dips down to 10, you may have a pinched hose somewhere that only leaks when a certain vacuum or boost is achieved. Best way to make sure is to loosen every piping couplers, wedge the hoses a bit so they stop sticking to the piping, and tighten everything back. A big boost leak would cause the engine to stumble, so you are tracking a small one.

This usually solves all boost leak issues, when they are not coming from defective IC core, 1 way valves or badly set beathers.

Quote:

Originally Posted by Lhimes

Boost leaks normally don't effect idle, due to it leaks on boost not on idle. Unless you have one major leak. I'm going with bov

They do, esp. when there is a bov involved. Bov leaks at idle because there is a strong vacuum that pulls the piston. You can go from 15 to 11 / 12 AFR with a leaky bov at idle. Lower readings are usually the result of a bigger leak though.

good to know... ill check everything and make sure its all tight it seems to only jump around when my boost starts going up so a leak seems like the issue


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[mattysr20]

ok so I'm gonna bump this because I'm getting a little worried... I've been reading other threads about what the wideband is supposed to read at different times ( cruse, wot ,ect. ) well mine stays at 14.7-15.1 all the time besides when I'm just driving around normal then it goes rich and bounces around like I said before but when I'm in wot it stays at normal wich isn't right... it should at least move I would think.
It is a s15 Sr with......
tubular mani
tomie rocker arm stoppers
turbo xs bov
z32 maf
aftermarket fpr forget what brand
fmic
Jim wolf tuned ecu
on 10psi
fuel pressure is at 40
car idles fine no smoke
pulls hard boost good
doesn't do anything weird
just the weird wideband readings...



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[2.5T_/<ouki]

So @ WOT its 14.7-15 AFR? Waaaaaaay to lean. I wouldn't even be trying to be in WOT with that AFR. I would contact Jim Wolfe

[cotbu]

Definitely not JWT's fault, although they will help, just like we will. You should do a free air calibration on that wide band or get a second opinion on the AFR reading. There's also a testing procedure that has been known too indicate failing WB sensors

Read the plugs
Or do things that you know would richen up the afr.
just to test out the wide band.
Power balance or create a boost leak, if the afr doesn't change then I'd assume faulty or uncalibrated wide band.
Your tune can't be off if you boosted 10psi and was stoich, I'd think with pump gas you'd be running in the knock map with a 10afr for sure or have fried pistons and or plugs

Comment for the boost leak talk previously:
If your idle is high, it can mask a vacuum/boost leak on your boost gauge!

[mattysr20]

that's what I'm saying but if it is 15 at wot then when I'm cruising it shouldn't be 15 still plus I feel like ide be having other issues if it was that off


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[mattysr20]

ok so I created a boost leak and it still read the same just bounced around from 14.7 down to 10 and everything in between so I dunno what's going on.. would my spark plugs show any signes? white lean black rich right? also my bov was making a squeaking sound so maybe bov?


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[fliprayzin240sx]

How much do you trust the Autometer gauge? I'd check it with another gauge just to make sure the signals you're seeing is accurate.

[mattysr20]

I don't trust it lol but they aren't cheap so ide hate to spend 300 on a new one just to have to go get a 6-700 dollar tune


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[mattysr20]

I don't trust it lol but they aren't cheap so ide hate to spend 300 on a new one just to have to go get a 6-700 dollar tune


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[Croustibat]

300 would get you a complete new system, with a brand new gauge and sensor.

BTW are you sure you have a wideband sensor ? Not just an autometer gauge fitted the standard narrowband sensor ?

[greenwood]

where is the sniffer pickup located? It may be in a wrong spot and have gotten water on it from condensation causing faulty readings. Mine did this.

[mattysr20]

its a wideband and it is right in the bend of the pipe right off the turbo


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[mattysr20]

I just wanna add that over the weekend I checked some things out
first thing the bov was sticking open and making a whistling sound
also where my air filter connects to the maf there is a little gap because the filter has the wrong adaptor so its not flush
are these reasons I could be getting bad readings?


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[Croustibat]

The first one spells "MAJOR BOOST LEAK", which is a cause (if not THE cause) of your problems.

The second one spells "unfiltered air", and will sand down your MAF sensor, your turbo compressor wheel, and your cylinders /pistons in the long run.