Sr20 idling lean... Video inside

[solo_ryder]

https://www.youtube.com/watch?v=345bnPHqYBg&feature=youtu.be

Any ideas guys? Anything relevant is listed in the description of the video...

Sometimes it will idle stoich, other times lean, its not consistent.. Having the AC on seems to help it idle abit richer as the idle is abit higher.. Under WOT the car starts out great but by 6k rpm its at 10:1.. normal?

I dont think I have any vacuum leaks as the vac at idle is good and boost stays steady at 6-8 psi..

[mhubeny180sx]

https://www.youtube.com/watch?v=345bnPHqYBg&feature=youtu.be

Any ideas guys? Anything relevant is listed in the description of the video...

Sometimes it will idle stoich, other times lean, its not consistent.. Having the AC on seems to help it idle abit richer as the idle is abit higher.. Under WOT the car starts out great but by 6k rpm its at 10:1.. normal?

I dont think I have any vacuum leaks as the vac at idle is good and boost stays steady at 6-8 psi..

Take a look at your spark plugs, if not take a look at your o2 sensor make sure nothing is loose too lol. Alot of the time its the most simple thing. In a boost leak situation under boost you will run rich, and lean on idle.

[solo_ryder]

Take a look at your spark plugs, if not take a look at your o2 sensor make sure nothing is loose too lol. Alot of the time its the most simple thing. In a boost leak situation under boost you will run rich, and lean on idle.

I will do that. I will also check my BOV it may be leaking.

[Kingtal0n]

disconnect the o2 sensor

stock turbos still create enough movement at idle to cause a rich condition when the bov leaks. Its not a leaky bov.

[solo_ryder]

disconnect the o2 sensor

stock turbos still create enough movement at idle to cause a rich condition when the bov leaks. Its not a leaky bov.

So disconnect 02? can you explain why I would do this?

[solo_ryder]

Still looking for an answer for this issue

[KoukiMonsta]

AFR reading at idle are worthless. Talk to any reputable tuner about it...

Mine are all over the place at idle, you want consistency cruising/WOT

[cotbu]

AFR reading at idle are worthless. Talk to any reputable tuner about it...

Mine are all over the place at idle, you want consistency cruising/WOT

Not true, you need a tune! Ask a reputable tuner to help you out with that!:cool:

Now if you're tracking the car, hmm you can probably get away with it as long as you don't have to idle anywhere to long or and have the knock sensor disabled along with 02sensor.

So disconnect 02? can you explain why I would do this?
If your 02sensor is failing, this might shed some light, by keeping you close to the values in the fuel map.

Sent from a Highly Tuned Note 4.5!!!

[KoukiMonsta]

Not true, you need a tune! Ask a reputable tuner to help you out with that!:cool:

On my current setup (and two previous ones) I have never seen the idle AFR's dead on consistent. AS in red light to red light they will change..sometimes simply spike to very rich or lean.

All of these builds were tuned by reputable tuner (that everyone on this board is familiar with). His input on this question, which was a concern of mine at one point, was that typically the wide band o2 sensors need more flow past them to see accurate readings.

Believe it or not, I am not trying to argue..I have seen plenty of your posts w/ good info. Hit me with some knowledge!

Another thought, since there is no load on the engine at idle being lean should not produce harmful effect, correct? Thinking about the AFR's some newer 'fuel efficient' vehicles see is part of what I am thinking.

[cotbu]

On my current setup (and two previous ones) I have never seen the idle AFR's dead on consistent. AS in red light to red light they will change..sometimes simply spike to very rich or lean.

All of these builds were tuned by reputable tuner (that everyone on this board is familiar with). His input on this question, which was a concern of mine at one point, was that typically the wide band o2 sensors need more flow past them to see accurate readings.

Believe it or not, I am not trying to argue..I have seen plenty of your posts w/ good info. Hit me with some knowledge!

Another thought, since there is no load on the engine at idle being lean should not produce harmful effect, correct? Thinking about the AFR's some newer 'fuel efficient' vehicles see is part of what I am thinking.

Idling and coming down to an idle should be consistent (repeatable), there are factor that change the AFR at idle. Temperature being one of them.
If your car doesn't perform a normal 1300/1500rpm 13.5afr cold start? I wouldn't consider that a problem unless it's 1500rpm 17afr then leans out to 20afr by 850rpm and 80°c. Maybe its on the richer side, 12.5afr cold, 11.5afr at temp. Worthless info? maybe?

The idle AFR will fluctuate, but it should have consistency to it, 14.2 14.5 15.2 15.0 14.7 being solid 14.7afr, would mean perfect condition for complete combustion is happening. So stop light to stop light and idling should be pretty consistent unless you give a Lil more throttle or happen to blow off this time or do a rolling burn out or ride longer in lower/higher gear whatever. But if you happen to idle for a while all should come back to normal being whatever idle AFR and rpm you have.

I never seen anyone blow and engine at idle, but I've seen damage from engines that idle too rich, (bad rings and cylinders)and too lean (pitting, failing ring lands) deterioration .


So I don't think they're idle air fuel ratios are worthless for a street car anyway.

Sent from a Highly Tuned Note 4.5!!!

[Kingtal0n]

On my current setup (and two previous ones) I have never seen the idle AFR's dead on consistent. AS in red light to red light they will change..sometimes simply spike to very rich or lean.


not good. most likely due to the maf being too close to the compressor, and combined with your lack of a push-type(similar to OEM) bypass on the hot side.



All of these builds were tuned by reputable tuner (that everyone on this board is familiar with). His input on this question, which was a concern of mine at one point, was that typically the wide band o2 sensors need more flow past them to see accurate readings.
nonsense



Idling and coming down to an idle should be consistent (repeatable), there are factor that change the AFR at idle. Temperature being one of them.

correct



AFR reading at idle are worthless. Talk to any reputable tuner about it...
nonsense

So disconnect 02? can you explain why I would do this?
disconnect the narrowband O2 sensor because you are unable to tell if it is working properly. Or are you? My first instinct would be to Test the sensor's signal wire for the 0.002volt -> 1.002volt signal as it swings through stoichiometry to test it like a real service mechanic if you are able.

[KoukiMonsta]

your lack of a push-type(similar to OEM) bypass on the hot side.

Huh? you talking bypass valve vs atmospheric BOV?

[Kingtal0n]

Huh? you talking bypass valve vs atmospheric BOV?

I dislike to use the term "blow off valve" and I feel like a ricer if I type bov.

Keep a bypass on the hot side as close to the compressor as possible, recirculated back to the inlet pre-turbo, and make sure it hangs open at idle, use the softest setting possible. A greddy type-S or HKS "Race" bypass are ideal and open easily at idle (just like OEM). This will prevent the compressor from buffeting the maf hot-wire around idle, and prevents the wandering A/F ratio that it causes. It also has other benefits, such as improved turbo "spool" (basically the compressor wheel starts off at a higher initial speed). Many turbos are now incorporating bypass valves directly ON the compressor, I can only guess it is because the manufacturers, knowing how important it is to have on so close to the compressor, after seeing many of their units fail because of improperly installed bypass valves (and the wrong type of bypass i.e. HKS SSQV which does NOT operate effectively near idle speeds) finally decided to just give the correct unit, in the correct place (on the hot-side as close to the compressor as possible) directly to the customer, with the turbo.

[KoukiMonsta]

I dislike to use the term "blow off valve" and I feel like a ricer if I type bov.

Keep a bypass on the hot side as close to the compressor as possible, recirculated back to the inlet pre-turbo,

Many turbos are now incorporating bypass valves directly ON the compressor

I can agree with the terminology.

Without trying to stoke this fire too much and completely derail thread..

I am aware of manufacturers w/ bypass systems incorporated into the turbo itself. But, does the SR20DET in stock form have it on the cold side?(then across VC to pre-turbo intake?) Typically I will do my best to follow OEM Nissan engineering.

Yes internal pressure will equalize very rapidly..blah blah physics..maybe placement inst extremely critical. But venting(Bypassing) near the TB seems to make sense since when you close the TB the air will 'bounce' off it and cause 'surge'

well, it's a theory at least.

[Driftwire]

On my current setup (and two previous ones) I have never seen the idle AFR's dead on consistent. AS in red light to red light they will change..sometimes simply spike to very rich or lean.

All of these builds were tuned by reputable tuner (that everyone on this board is familiar with). His input on this question, which was a concern of mine at one point, was that typically the wide band o2 sensors need more flow past them to see accurate readings.

Believe it or not, I am not trying to argue..I have seen plenty of your posts w/ good info. Hit me with some knowledge!

Another thought, since there is no load on the engine at idle being lean should not produce harmful effect, correct? Thinking about the AFR's some newer 'fuel efficient' vehicles see is part of what I am thinking.


Im sorry but my KA24DE-T setup is properly tuned and at idle i have a consistent 14.6-14.7 Idle depending on temperature and conditions. Its true that a properly dialed in car will have a consistant AFR idle. I also agree that a little bit of flux +/- .4 from where your target is also happens in some setups. But anything over that and theres probably a failing or non efficient ignition or fueling issue or a small leak of some sort.

[Ra64mike]

I had the same problem and it was a vacuum leak.

[solo_ryder]

My AF is definitely not consistent at idle. It varies between between 15-17 as you can see in the video at all times.

When the car is warming up however the AFs are good, cold startup is in the 13s as described.

I will check for vacuum leaks.

Will a leaking BOV cause this? I am going to attempt to switch over to a BPV and see what happens.

[Kingtal0n]

I can agree with the terminology.

I am aware of manufacturers w/ bypass systems incorporated into the turbo itself. But, does the SR20DET in stock form have it on the cold side?(then across VC to pre-turbo intake?) Typically I will do my best to follow OEM Nissan engineering.


Older sr20 engines have it on the hot-side
newer (s15 engine) have it on the cold-side,

however, both of these are using SIDE MOUNT systems, which minimizes plumbing volume (the bypass is able to rapidly lower the pressure in the intercooler because it is so tiny). Once you add an large intercooler or larger pipes to the system, you can not longer keep the bypass on the cold side due to higher volume, i.e. the turbo will surge while it waits for your bypass to empty the huge intercooler.