Just installed my ProSport Premium Boost, and Digital Wideband AFR gauges.

NOOB Question here: More than occasionally, when driving and when I get off the accellerator, like slowing down for an intersection, my AFR gauge will mometarily peak (few seocnds) and display 20.0 or greater (Lean). My Boost gauge at the time is indicating -20psi or less, no boost or load condition. Is this normal???

The AFR reading will normalize and go back to 12.5 - 14.0 when I stop at idle or again begin accellerating.

Thanks

 

Yeah I think you are fine. I have a FJO wideband in another car, and when I get off the gas, the AFR's flatline meaning it goes leaner than 20.0 I would mainly be concerned with the AFR's under boost.

 

Same thing for me with the AEM. It's normal.

 

My AEM goes off the chart on the lean side when coasting a lot of the time. I think its pretty normal, I bounce between and 14 and 15s on light acceleration. Moderate to heavy is when you need to pay more attention. I think you are good running a little lean in spool but under full boost you should be below 12s.

 

Thanks guys, learning more and more from this forum...

 

Sorry for digging this out, but nobody explained yet WHY it goes lean, it's very simple:

When you get off the gas, there is ZERO fuel being injected, so the engine is nothing more than a giant air-pump being moved by the car's inertia...
Therefore there is no exhaust gas in your pipes, just fresh air, so that's where the 22+ reading comes from...

If you want to try it:
Find as long and steep a hill as you can and just coast down the hill...

 

Perfectly normal. The AFR gauge will hit max when you're completely off the accelerator. My Innovate does this.

What's NOT normal is when it gets stuck at minimum halfway through driving. >: ( I think I have to recheck my wiring.

 

^what he said.. I'm not sure about the "zero" fuel being injected, but it's probably a minimal amount & that is why you lean out.

Normal

 

I was told zero fuel. It freaked me out the first time I saw it too until I learned it was the car. So really you can save a little gas coasting in a lower gear than to downshift.

 

I coast all the time.. I just have a hard time believing it is zero fuel while you are in gear, doesn't mean it's not true, I'd just like an explanation how there is zero additional fuel being added - that would mean that combustion completely stops when you let off the accelerator? ..anyway, this is getting a little OT, so I'll stop haha

 

Try logging injector pulse width and you can watch it go to 0.

 

its normal. but the 12.5 at idle is not

 

Get a Zeitronix and call it a day. You won't have any problems, i promise!

 

okay let me clear this up for some of you guys, i work on dynomometers for GM and i calibrate engines all the time. At idle the A/F is alway between 14-15, and depending on the weather it might go as low as 13. The car leans( its technically at stoich) out because at idle there is not much air getting in. In gasoline cars u as a driver control the air coming in the engine, so at idle the butterfly plate is open enough that so much air can get it and when mixing with a given amount of fuel (which is controlled by the ecu) you will get stoich reading of 14-15. I hope this makes sense, i can go more into details but i hate typing

 

it seems normal