Crazy High AFR's

[SalemChiro]

Hey guys,

I'm running COBB Stage 1+ Sport on 93 octane and data logged for the first time.

Everything looked good but the AFR shot into the 200's. After pulling codes, the LPFP comes up. Could this be causing the AFR issue? Should I revert back to stock tune for now?

I'm new to data logging and couldn't post the data here....

Thanks for any help.

Sean

[Stohlen]

200's????

[Tee-Dub]

I don't know what "200's" means. Could be an anomaly? Don't think the car would run. Have you sent your logs over to COBB, they're supposed to have excellent support.

[DRedman45]

if the afr was 200:1 the motor would have blown apart, or melted rings from running that lean...put the stock tune on and log the afr...if that situation really occurred it would more likely be a component failure

[SalemChiro]

This is what I could copy and paste.... I'll try to data log again today and see if it was an anomaly. The car feels like it runs fine, no hesitation or sputtering.

Lambda (Bank1) (AFR)
13.96
14.55
16.17
17.35
27.78
38.07
75.41
98.78
220.21
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
200.95
79.53
28.81
24.4
21.46
20.73
21.17
24.11
29.69
35.28
47.48
56.89
79.38
108.63
135.24
181.54
221.24
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
235.2
201.39
62.03
38.81
27.78
22.49
19.55
18.96
18.23
17.93
17.2
16.32
15.58
14.55
14.11
13.82
14.11
14.11
13.67
13.23
13.08

[Stohlen]

Somethings not right, lambda is measured based around 1. Where 1 is stoich.

Originally Posted by DRedman45

if the afr was 200:1 the motor would have blown apart, or melted rings from running that lean..

No at that A/F it would have just shut off...

[SalemChiro]

OK, thanks for the input. I sent the log to Cobb for viewing and I'll record new logs today with stock and stage1+ tune.

[c_ozanich]

Originally Posted by Stohlen

Somethings not right, lambda is measured based around 1. Where 1 is stoich.



No at that A/F it would have just shut off...

that's correct. 14.7:1 is stoich for "perfect a/f ratio"

at 200:1 that's saying there are essentially 200 lbs of air to 1 pound of gas. There wouldn't be any mixture of gas and air to create fuel and it wouldn't ignite strong enough without super high pressure in your cylinders; meaning the engine would think there just isn't any gas at all, and shut off. You would be running ridiculously lean and it wouldn't even give the engine a chance to hurt itself by igniting full combustion.

Originally Posted by SalemChiro

OK, thanks for the input. I sent the log to Cobb for viewing and I'll record new logs today with stock and stage1+ tune.

sounds like a solid plan. keep us posted

[DRedman45]

Originally Posted by Stohlen

No at that A/F it would have just shut off...

I am aware...but the op's car was still running...my point was there is something wrong other than the actual afr from the tune, because its not possible

[c_ozanich]

Originally Posted by DRedman45

I am aware...but the op's car was still running...my point was there is something wrong other than the actual afr from the tune, because its not possible

i wasn't meaning to be insulting in explaining, just making sure OP is on the same page as everyone and knows what he is doing with his car. You are correct that it isn't possible to sustain combustion with the given a/f ratio.

I bet it more has to do with an error in the data logging or in the tune itself provided the car stayed running and didn't fail in that sense.

[Freon]

That is engine decel and nothing to worry about. When you let off the gas and coast with the transmission in gear, the engine turns off the injectors and you go "infinitely lean" because there is zero fuel. Loggers and sensors generally have an upper limit. It seems it is 235.2. Some stop at 22:1. My LM-1 sensor will actually read oxygen % on its display, but my gauge stops at around 22:1 IIRC.

[b1aze]

Log the throttle position and line it up with AFR.