Running too lean?
 

I already have a CAI, test pipes and a true dual catback. That's a lot more flow than OEM, I am also planning on getting some long tube headers sometime soon. My fear is that my engine might start running too lean which from what I read, know isn't good (can cause detonation??).

How lean can I go before I start getting worried? Do I NEED a tune? I'm staying away from that for now as the only solution out there for me to get a tune would be to get chipped or get a standalone (not going to happen anytime soon).

I do plan on getting a few dyno pulls once the headers are in to get exact AF numbers

Your input is muchos appreciated

Cheers,

I know you stated you didn't want to get a tune right now but I think that's your best bet. I know some vendors are having a sale on the Cobb accessport might wanna take a look.

Yes I did state that, and here's why

Cobb APs don't work on non US spec G37s as they don't recognize our ECM numbers or so

one of my friends got the Cobb AP and said it was a PITA and you couldnt even really adjust much.

So I've heard too, AAM seems to think otherwise though. It's not an option I would/can consider anyways

There is only one way to find out. Get the car to a dyno or install a wideband gauge. The G37 uses closed loop lambda feedback, so it will make adjustments to AF ratio at WOT in attempts to maintain a safe AF ratio. That said, if the intake causes a distruption or unusual flow across the MAF sensor, then you may end up running lean or rich regardless.

If you are indeed running lean, then we could send you a custom UpRev e-Tune to correct the condition.

Would your UpRev e-tune work on my Gulf Spec car?

Do you, or someone you know, happen to have a Cipher cable? I need your ECU ROM number to determine if I can flash it for you.

So is running lean something everyone should worry about if they have a cbe and hfcs with or without a cold air intake?

I have a catback and want to add some high flow cats (no intake for now), but I don't need any problems with lean mixtures. I just don't know enough not to worry about it.

Not that I know off, but I am going on a dyno when my headers come in for sure.

What's the most accurate way to measure A/F numbers? Would using sniffers in the tailpipe be enough?

IMO the most accurate way to measure a/f is from a wideband sensor in the test pipe or high flow cat. If putting them in the cat, make sure the sensor is ahead the actual catalyst.

Thing is, my FI test pipes have a J-shaped bung to fool the sensor in some way as to not trip the CEL, so that will require me doing custom work which I don't think would be worth it.. or would it?

Are sniffers completely off? Seen a few local Turbo Z's do it.

Sniffers are set on the tailpipe. How do you place the wideband sensors?

From my experience, tailpipe sniffers seem to be fairly accurate at WOT, when gas velocities are the highest. Trying to tune idle/cruise/light load though, they tend to read a little lean.

I was doing some pulls on a Dynojet last month, and the tailpipe readout on the dyno's software consistently read about 1-1.5 points leaner than my Haltech widebands mounted in the downpipes.

If it's just for a tuning session, we temporarily remove one of the factory o2 sensors and replace it with our calibrated wideband sensor.