stockc5Z06

2003 Z06 93,000 miles, installed kooks headers, green catted x-pipe, AFE cai, AEM afr gauge and aeroforce scan gauge, new plugs/wires.
Car has always run a little funny even before everything was installed. Every time I go WOT I get a different reading on afr gauge, it can be anywhere from 12.3-13.4 at power enrichment. This does not seem normal???
No exhaust leaks, afr sensor is good, no cel light, new plugs/wires.
On the aeroforce gauge I pick up an occasional misfire any where between 2-10 misfires. Is this normal? again no cel.

danieloneil01

Stock tune? When I added headers and a cheap filter it was really lean at WOT. Are you getting that lean of an AFR (your highest you posted) at peak tq and hp, ie above 5k rpm?

stockc5Z06

car has been street tuned and dyno tuned. I will give you a scenario.
Each time I go WOT to 6000rpm's, it will hold 13.2-13.4
Stop to get gas or something to eat. Go WOT again it will hold 12.8-13.0
Go home park car, next time I drive go WOT it will hold 12.3-12.5
I hope you kind of understand what I am trying to type and explain. This has me confused on why it would do this.
Also I have cleaned maf, throttle body and checked clamps from airfilter to TB.

danieloneil01

Weather the same? Any codes?

Joshboody

I take it the WB reading is 1 bank? I’d check the narrow band voltages and see if there’s any correlation. Possible the WB’s not consistent, or maybe an injector.

A misfire would show lean AFR… not sure how sensitive misfire detection is on the ls1. Misfire would likely be a coil.

But I have no ls1 experience yet… just purchased my vette.

tblu92

You are experiencing a timing deduct from a heat soaked IAT sensor--When the car is hot and parked or driven in city traffic the IAT can spike to 140*--where the ECM will remove 7-10* of timing--This reading is false--It begins reading a heat soaked underhood temp rather than incoming air temp as designed-- LESS timing would a give you a RICHER mixture at WOT---(due to less timing) when the engine is cold and the IAT hasn't had time to get heat soaked the IAT will read normal and not remove any timimg so your AFR's can be spot on--
That being said if you are using a wideband--13.4 is extremely lean for a non dedicated race car---Best for a DD or weekend racer is an AFR of about 127 to 12.9
13.4 is really leaning on it hard !!
You can eliminate all the false timing deducts with a tune with HP or EFILIVE---I do this instinctively on any car or trk I car stock modified--It make the AFR more consistant as well as having you commanded timing match your "actual timing" and that makes it much easier to sort out and fine tune