As the title states when I PC log my AFR leans out but on my AEM AFR gauge my meter is saying everything is good. I want to see if anyone knows what the possible discrepancy between the two could possibly be?

My AUX settings look just like:



Here is a video that shows my AFR on the gauge and then on the computer.

View My Video

Here is a partial PC idle log

Time/s Engine Speed Throttle Fuel trim Maf in Maf out UEGO
0 750 0 -27.34375 1.358 1.334 15.5
0.01 750 0 -27.34375 1.358 1.334 15.5
0.02 750 0.1 -27.34375 1.37 1.334 15.3
0.03 750 0.1 -27.34375 1.37 1.334 15.3
0.04 750 0.1 -27.34375 1.37 1.334 15.3
0.05 750 0.1 -27.34375 1.37 1.334 15.3
0.06 750 0.1 -27.34375 1.37 1.334 15.3
0.07 750 0.1 -27.34375 1.381 1.357 15.4
0.08 750 0.1 -27.34375 1.381 1.357 15.4
0.09 750 0.1 -27.34375 1.381 1.357 15.4
0.1 750 0.1 -27.34375 1.381 1.357 15.4
0.11 750 0.1 -27.34375 1.381 1.357 15.4
0.12 750 0 -27.34375 1.375 1.334 15.5
0.13 750 0 -27.34375 1.375 1.334 15.5
0.14 750 0 -27.34375 1.375 1.334 15.5
0.15 750 0 -27.34375 1.375 1.334 15.5
0.16 750 0 -27.34375 1.375 1.334 15.5
0.17 750 0.1 -27.34375 1.375 1.334 15.4
0.18 750 0.1 -27.34375 1.375 1.334 15.4
0.19 750 0.1 -27.34375 1.375 1.334 15.4
0.2 750 0.1 -27.34375 1.375 1.334 15.4
0.21 750 0.1 -27.34375 1.375 1.334 15.4
0.22 747 0 -27.34375 1.358 1.311 15.3

 

hard to read

 

it done this on my emanage as well.......one thing the uego only reads to 18 and i see you have 20 there....not sure if thats it or not.....i know on the emanage i had to play around with the min and max to get the right afr cause they dont have an option for the uego in there.

 

I can't view the video, but I am guessing that it is a few tenths off. Mine does the same. You just have to take some time and adjust the Aux Gauge Setup values a little bit to get it to read dead on.

 

I think its off by more than a few tenths more like 7 to 1.1 tenths. The difference between 14.6 and 15.5 - 15.7.

I know the UEGO gauge is right, it's just getting the computer to see the same thing.

 

Gotcha. Mine is about half a point off. You should be able to get it pretty close by adjusting the voltages in the table though. Before you do that, you might check your grounds. I can't remember which ground it is, either the UEGO or the F/IC ground, but making sure it is a really good ground may help out a little bit.

 

Now you're on to something. I didn't run a ground when I tapped into the UEGO white, analog, to run over to the FIC. Should I also take the ground from the UEGO and make it a chassis ground or the FIC ground and make it a chassis ground or both?

 

I took the (2) pwr grounds on the FIC and the 1 ground on the UEGO and wired them to a common ground. It seems to have stabilized the FIC a little but not completely. I might indeed have to tweak the values in the Aux Gauge Setup to be more correct.

Now instead of reading .7 tenths to 1.1 tenths off it now reads about .5 tenths to .8 tenths off.

 

You should still have them close.. half a point makes a world of difference when it comes to tuning.

My Innovate LC-1 reads the same on gauge and F/IC. The only difference is that it reacts quicker on the F/IC. I would continue playing with your grounds.

 

I've done all I can do with the grounds. The only ground I did not bother was the 'sig ground' which I was unsure could be grounded to the same place as the 'pwr ground'.

 

iv had the same issue but its too close to call for me...

 

That's what it was, it just jogged my memory. I knew I was forgetting something. I think it recommends running the main ground for the UEGO to the same ground as the F/IC.

 

If you guys dont mind me asking, How is the F/IC grounded???

Isn't it just a straight PNP setup???

Where are these ground wires located???

 

It is ground to where the ECU is grounded.. .and I think the ECU is grounded somewhere by the fuse box in the engine compartment. But I'm not exactly sure.

 

F/IC is grounded through the harness, of you have a PNP harness then it is grounded to the same space as the car computer, which I would venture to say is the engine block.

The F/IC uses 3 grounds, from what I can see someone can correct me if i'm wrong, (2) pwr grounds and (1) sig ground. The pwr grounds are your normal grounds, i'm not sure about the sig ground and if it has a floating point ground. I didn't bother to mess with that one or meter it.

You have to remember everyone with the F/IC doesn't have a PNP harness as the F/IC itself doesn't come with a PNP harness, the harness is about $300 alone for a PNP. So sometimes people actually wire it up directly to the ECU.

 

 

yikes..

 

Haha, it looks worse than it is. That is before I tidied everything up. It took me about 4 hours to wire everything up, but that was because I was taking my time and triple checking EVERY connection before I cut/spliced/soldered any wires.

 

 

Ohh ok. Got it