Wideband very lean at idle no matter how much fuel I add to ve

[the Dragon]

Starts at 13-15 af at startup and then gradually goes past 17 at a sitting idle. Is it just because the size of the cam and the valve events?

I read a few threads saying that af would be inaccurate at idle depending on how big the cam is.

If this is the case, how in the heck do I know if I have too much or too little fueling at idle?

I have FAST 36lb injectors and a Racetronix fuel pump.

Thanks for any help!

[mr.prick]

If adding fuel does nothing, diagnose the WBO2.
The sensor may need to be calibrated or replaced.

[the Dragon]

Damn. I was worried about that possibility.

It shows the changes in the rest of the VE and at WOT as well. The factory O2's are in line with the 13.0 the Wideband shows too.

Somethings gotta be screwed up because it will read fine for 20 seconds or so and then spike lean.

How do I diagnose the Wideband?

[the Dragon]

I didn't have my PO103 set to B: trips emissions related. Just fixed it. Could that be causing the problem?

Sorry for all the questions but the 18 af at idle concerns me

[WeathermanShawn]

Dragon, also if you are Open-loop SD you are likely to get leaner as your ECT/IAT increases.

You might check into a COS as it has a temperature modifier. Closed-Loop will usually always swing quite nicely around stoich..but what you are describing does not sound that unusual if you are indeed Open-Loop..

[the Dragon]

Dragon, also if you are Open-loop SD you are likely to get leaner as your ECT/IAT increases.

You might check into a COS as it has a temperature modifier. Closed-Loop will usually always swing quite nicely around stoich..but what you are describing does not sound that unusual if you are indeed Open-Loop..

Is a COS always necessary? How does everybody else tune speed density using their factory OS?

And if there's no way to tune SD without using a COS I'll have to figure out how to do a COS lol :(

[WeathermanShawn]

Obviously there are Tuners running SD without a COS. Probably helps to have perfect fueling..but if you 'Google' Speed Density and Heat Soak, you see page after page on the topic..as ECT/IAT climbs the fuel mixture gets leaner and leaner.

Not saying that is your problem. As Mr. Prick said, could be problems with the wideband. A good way to tell is to do a log at Idle and see if the AFR gets leaner as ECT/IAT climbs. Also log IBPW and see if it changes or stays the same.

The COS does address those issues.

Just some ideas to ponder Dragon. Its either the wideband or heat soak IMO..

Edit: Just re-read your comments on P0103. One thing you must be absolutely sure when running SD is that you need to throw a DTC for the MAF. You don't need the MIL, but you do need the DTC. Thats the only other logical explanation..You're hitting the VE Table when inadvertently your MAF was still enabled..

[the Dragon]

Aha! I didn't even realize that I overlooked my mistake about the DTC.

Now that I changed it, if I'm not throwing the DTC how do I get the car "completely" into SD?

It's so weird that I'm only having this issue at idle :(

[WeathermanShawn]

Wow, its been awhile since I have played with SD..C2901 should be 1..C2903 should be 1 (I'm going totally off memory here).

Personally I always turned my P0101-P0103 Engine DTC MIL Enabler to MIL. I always wanted to see the MIL light on when I at least started tuning it in SD. Also, on a regular COS you are running off the Low-Octane Spark..make it different than the High-Octane..even 1 degree less or use decimals. Its a great sanity check to make sure your running off Low-Octane.

Nothing beats that MIL Lamp..Not sure why just at Idle..If you get stuck post up your Tune & Log..

[the Dragon]

Yup. They're both at 1.

I'm at a loss. What parameters would you like me to log? I'll post the log later today and the tune after this post.

Thanks Shawn!