WB showing way lean @ idle

[Afterhours Performance]

is a 20:1 WB reading normal for a cammed engine at idle? I know with more overlap there is extra air getting to WB but 20:1 seems excessive...thnx for the help

[Black02SS]

No.

[rally1]

Where and how is your WB sampling? If your using a tail pipe type sensor that is sampling close to the exit you can get lean readings from the larger than normal reversion from the cam, you will find if you rev the engine your mixtures will show “normal” mixtures.

[Rusty]

I have been having a similar problem. Large cams may have high MAP KPa during idle. Changing the VE table to correct the AFR seems to result in unrealistic airflow values frim the VE table. You can see this if you disable MAF and force the PCM to use the VE table.

If you only installed a larger cam then the problem may be fairly simple to correct. Most likely a larger cam upgrade will be in combination of other engine component upgrades.

Have you changed injectors? What is your MAF airflow at idle?

Also, since the spark tables use airflow / cylinder to determine spark advance, you may need to increase the spark advance for the airflow range at idle. I found that increasing spark helped smooth idles.

Please post some logs!

[hog]

Widebands dont read well at idle.

peace
Hog

[Afterhours Performance]

MY wideband is in the collector for the headers {hooker long tubes for a 71 chevelle} Engine is 408 {6.0 iron block} with dart pro1 heads,11=1 comp. will take some logs tomorow night!

[swingtan]

Widebands "can" read fine at idle, providing you understand the reading coming from them. I've seen engines idle at 19:1 and they didn't do too bad a job of it. It may just be the air flow tables that need adjusting or it may be something else. While an engine may idle at 20:1 it's certainly not desireable.

For starters, I'd try cross referencing the IPW signals to see how much fuel is actually being pumped into the motor. If you've changed injectors and not set the flow rates right, then this could be the problem.

Another cross reference would be to look at the stock NB O2 voltage to see if they indicate a lean condition as well. when I saw the 19:1 ratio on the last car I tuned, I thought the WB was off, but it was reading correctly.

Simon

[smokeysbandit]

Also double check your AIR pump settings. If that puppy is on you'll never get an accurate read on your WB
-Brandon