Lean at idle

[BlackSS/SC]

Hey guys, just need a little advise. I tuned a cammed LS1 and it seems to be running lean at idle. It happened once the car is totally warmed up. I've seen the gauge in the 18s for AFR. Sometimes it causes the car to stall.

I've set the airflow table accordingly to the cam and everything else is working great.

Sorry I don't have a log handy.

His mods are:
Vig 3200 stall | PnP T/B | SLP Flowpac | TR224 Cam 112LSA | Pacesetter LT headers | ORY | PnP "906" heads

Could this be caused the the long tube headers and the o2 sensors beeing too far down the exhaust? I had to disabe some o2 codes that come with the long tube headers. They are switching fine though.

Any advice would be appriciated!

[WS6FirebirdTA00]

What codes are disabled? Even running lean it should not want to stall (unless it was almost like a fuel cut). What is the IAT doing? A heat soaked IAT may do this. Does it do it from a cold start once it gets warm?

To me it just sounds like the MAF/VE tables are not dialed in, that is if it is not a heat soak issue.

[BlackSS/SC]

What codes are disabled? Even running lean it should not want to stall (unless it was almost like a fuel cut). What is the IAT doing? A heat soaked IAT may do this. Does it do it from a cold start once it gets warm?

To me it just sounds like the MAF/VE tables are not dialed in, that is if it is not a heat soak issue.

I'm going to go dial in the maf and ve again, eventhough the fuel trims are in check.

It seems to be more of a heat soak thing I would say. It's been a while since I've played with this car so I'll have to check it out agian.

So if it's a heat soaked iat, what can we do to fix it?

[WS6FirebirdTA00]

if it is heat soaked, you may be able to adjust the bias if it is an 01+

[BlackSS/SC]

Here's what he wrote in an email:

When its at normal operating temp it reads 17-18 at idle.

When I get home from work it'll be 16.0 or something like that, then I park and if I watch it for a minute, it'll creep upto 18 and bounce around in 17.8-18.5 and sometimes it'll flicker into low 19's.

I'm at work so I can't view the calibration right now, but where is this table located?

[BlackSS/SC]

Oh yeah, O2 codes that are disabled:
-P0137
-P0138
-P0140
-p0141
-P0157
-P0158
-P0160
-P0161

-P1133
-P1134
-P1153
-P1153

I supose all of those codes shouldn't be disabled though?

[WS6FirebirdTA00]

yeah, sounds like he could have bad o2 sensors.

[BlackSS/SC]

I will check that out. He did have a back one a last month. It was funny because it worked perfect for about 15 minutes of driving, it would switch just fine and then it would flat line. The car would believe it and one bank went way lean, lean enough to back fire constantly.

Last time I scanned his car the O2s were working perfectly except one would act funny once in a while. It got lazy and the graph was smooth instead of quick rich/lean. Then it would be fine again.

I'll check it out, thanks.

[BlackSS/SC]

Here's some more of what he said.

I watched a/f today when leaving the house...
Looks like just the a/f starts climbing after the cold start mode is finished and a/f starts at 14.3 and slowly climbs. After idling for about a minutes, I backed out of the driveway and went slow and easy to the stopsign by the baptist church. Sitting at the stop sign a/f went from 16.2 to 18.5. When I goto to the cover of 104ave and 92 (by the condo's) I was @ 17 a/f with my foot on the brake at idle. When I put the car in nuetral it creeps to 18 again.

Weird thing is that after a run down the track it was 15-16 till I shut my car off and it wasn't climbing... yet in town its high.
Even with the cruise set on the hi-way its 17 and I'm getting a we bit of surging after a few min on cruise.