Doing some wideband tuning the (properly calibrated) LC-1 bounces between 14.2 and 15.5 at idle, though it tends to stay in the mid-to-high 14's. at higher RPM the wideband readings become more stable, then at WOT its very stable. I usually attribute all that to the moderately aggressive motor (see brother's LT4 in signature). Maybe the individual cylinders are running very different at low rpm.

The exhaust still smells pretty nasty at idle and normal driving, even though it barely ever goes below 14.0AFR or above 15.5AFR (no catalytic converter). My Camaro doesn't smell that bad, but I do have turbos if that means anything. Are there any tuning methods to reduce the smell of fuel in the exhaust when the AFRs seem to be on target? without adding a catalyst? idle timing is 20*BTDC?

 

Keep in mind an oxygen sensor only senses the presence or lack of oxygen in the exhaust. A cam with alot of overlap and duration will pull unburned air/fuel mixture into the exhaust and cause the sensor to read leaner than the engine is actually running. This will cause you to add more fuel in to bring the reading back toward 14.7:1. My moderately cammed 350 Vortec likes idling at an indicated 15.5:1 on the wideband. There is no unburned fuel smell and the spark plugs stay super clean.

 

any little bit higher AFR (constant 15's) and the O2 sensor gets overheated. it will throw code 8. Is the exhaust gas temp at idle too high or is this brand new sensor defective. I did just realize that I haven't looked at a spark plug since November.

 

On my LM1 I idle at 14.9/1 commanded in OL to 14.0/1. So as Fast stated I believe overlap plays a part. At idle my ext is clean. Very much so. WB is calibrated every 30 days after not being driven for 2 days.

My cruise A/F is around 14.9 as well commanded to 14.3 CL.

Idle timing is 20 SA.

 

where is the O2 sensor located?? if its on one side of the headers and not on the ending of the y-pipe, it could be missing something happening on the other side. my 454ss truck for instance, was running alright to say the least and it smelt like garbage. but the truck wasnt acting any different. turns out one of the plug wires wasnt even on the plug.. threw it on and it smells alot better and has more zip. so check your plugs. but on another note, my exhaust still smells rich, partly because they run rich to begin with..

 

good point. WB only sees one bank in in a segregated pipe.

I used to run a triple 2 cycle engine with 3 egt probes in triple pipes. Digitron. Would tell me instantly if a cylinder is getting misfire. I miss the smell of 2 cycle in the morning !

 

The wide band is in the passenger collector. I have a stock 4 wire in the driverside and it seems to cross count pretty well. There is definitely no shortage of power, and sounds crisp and clean, but the banks could be running a little different. I plan to check at least one plug tonight.

 

hrmmm, sounds like a damaged sensor.

Idle EGTs are super low, unless you're running very very retarded timing or have some other problems. Like for example, if they're glowing red at idle, you're not running right (but I have seen that!).

The sensor MUST be after the turbo, not sure if that's where you have it.

 

no turbo on this car...long tubes.

I read a lot about possible damaged LC-1 modules (not the sensor) on the innovate forum. I didn't have any error codes on the LC-1 tonight. We checked the #1 plug before tuning and the ground strap was medium tan. I started jacking up the idle timing untill 29*. The LC-1 started to average 15.5 without any VE changes. The smell actually improved a little. By the end of the night the timing ended up at 27* since it idled smoothest. The idle kPa went from between 48-52 down to 45-49. Seems like a step in the right direction.