AFR @ Idle

[woode]

On pump gas what is the stock AFR at idle?

I just installed a turbo, its not tuned yet, but its reading 18.9-19.6 at idle.. seems like it shouldn't read this high no matter what? I would think that, even without a tune, as long as its not in boost it really shouldn't idle much different? Or tell me if I am retarded.

When I rev it a touch, it drops to the 14-15 ballpark.

My friend revved it and it it threw a CEL for "running too lean". I didn't pay attention but it sounded like he stepped on it a bit much and I think he spooled the turbo a bit and that caused it - maybe not though.

Before anyone says to get it tuned - yes, I know. I am not driving it around like this. Tuesday is tune day. Just doing a "function check" so to speak to make sure the turbo was spinning, car starts, etc.

Thanks

[Dipstik-sportech]

I'd wait till after the tune before u panic. Check for air leaks, did you change the injectors?

The Frozen North

[woode]

Originally Posted by Dipstik-sportech

I'd wait till after the tune before u panic. Check for air leaks, did you change the injectors?

The Frozen North

No, injectors will be done immediately before tune since I'm sure the car will barely start, if at all, with 700cc injectors and no tune.

Could the crankcase breather affect this at all..? I don't see how it possibly could but I'm stumped. I don't have that going anywhere at the moment.

[lexusb3]

Cold start I'm at like 11-12. Warm idle like 14.0-15 ish

[Ross]

ok breather hose not hooked up what about pcv ? also what is you maf voltages? exhaust leaks? I am surprised you are not getting a lean pop if it is actually that lean. Just read the up pipe thread, fix your waste gate and should come close to in range, as well the maf scaling will be off so your load reading will be off. Do not get into heavy load at all, and definitely no boost.

[woode]

Awesome, appreciate the responses guys. As soon as it warms up to at least above freezing in a couple hours I will go tinker.

[FA20Club.com]

incase you overlooked my response in the other thread you need to put the valve seat inside the wastegate. as long as its not there you are pulling in fresh air in between exhaust pulses into you exhaust stream.

[woode]

Yes, it was the fact that I forgot the valve seat

I didn't realize that would make that much of a difference. Lesson learned.

[woode]

So I think everything is good to go for driving it to get the tune tomorrow.. I drove it around carefully staying far away from boost and my AFR was normal and the car drove fine. But when I let it idle for like 20 minutes it eventually threw a "running too lean" code. Not sure why, because at idle it was sitting steady between 14.7 and 14.85.

Every couple minutes while idling the car would randomly rev up, then drop down to like 500 and level back out, and I am guessing this has something to do with it? I wasn't in the car so didn't peak at the AFR when it did this..

Oh, and FWIW, I have the damned crickets now.

[Sportsguy83]

Originally Posted by woode

So I think everything is good to go for driving it to get the tune tomorrow.. I drove it around carefully staying far away from boost and my AFR was normal and the car drove fine. But when I let it idle for like 20 minutes it eventually threw a "running too lean" code. Not sure why, because at idle it was sitting steady between 14.7 and 14.85.

Every couple minutes while idling the car would randomly rev up, then drop down to like 500 and level back out, and I am guessing this has something to do with it? I wasn't in the car so didn't peak at the AFR when it did this..

Oh, and FWIW, I have the damned crickets now.

The "lean" codes are thrown not because you see swings in AFR, they are because the ECU is needing to compensate more than 10% in fuel to keep it the target 14.7 AFR. That can very well happen on a base tune, or it might be a vacuum leak (unmetered air) post MAF.

[Ross]

Your fuel trims are off, slight larger maf housing does not help the situation. Also is you pcv hooked up to the intake manifold. Were is the fresh air inlet that used to go to the intake pipe hooked up to?

[woode]

Originally Posted by Ross

Your fuel trims are off, slight larger maf housing does not help the situation. Also is you pcv hooked up to the intake manifold. Were is the fresh air inlet that used to go to the intake pipe hooked up to?

The PCV breather has a little mini-filter on it at the moment.

So, if I am understanding this right (I work on airplanes not cars, so the ECU and tuning side of things is something I am still learning a lot about).. the computer is pumping in extra fuel, and it thinks something is wrong because of that.. but as long as my AFR is alright - it's not actually a problem. I can drive it to the tuner like this, right? (obviously staying low in RPM and out of boost)

Thanks again

[Sportsguy83]

Originally Posted by woode

The PCV breather has a little mini-filter on it at the moment.

So, if I am understanding this right (I work on airplanes not cars, so the ECU and tuning side of things is something I am still learning a lot about).. the computer is pumping in extra fuel, and it thinks something is wrong because of that.. but as long as my AFR is alright - it's not actually a problem. I can drive it to the tuner like this, right? (obviously staying low in RPM and out of boost)

Thanks again

Yes, you can cruise it to the tuner and just watch the AFR to be close to stoich. Also, make sure to check there is no leak on the throttle clamp. The tune will take care of it.