Extremely rich idle after a long drive

[lowgman]

My 20V 4AGE has been running very well for the past several months, I had it dyno tuned and have been driving it daily. However, after a long drive today, my car couldn't idle properly because it was running extremely rich. The PW seems to have jumped up and my WB sensor gauge showed 10.x at idle.

I logged about 20 seconds of the horrible idle before I turned off the engine, but couldn't figure out why the PW jumped up so high. It is the hottest day of the year where I am, and the longest drive since I had it dyno tuned. Any ideas?

Does it have something to do with MAT/CLT correction or MAT density tables? I haven't really touched those curves at all.

[Matt Cramer]

Can you post a log of it idling normally, too?

[lowgman]

Sorry! Didn't get to it log a good idle until this weekend. Any ideas?

The injector PW seems smaller on the good idle, not sure what is making the idle AFR inconsistent.

The engine is running open air ITB, I have the AIT sensor right infront of the intake stream. I was thinking it's the AIT sensor getting heat soak, but won't that cause a lean condition instead of rich?

Thanks!

[lowgman]

Sorry! Didn't get to it log a good idle until this weekend. Any ideas?

The injector PW seems smaller on the good idle, not sure what is making the idle AFR inconsistent.

The engine is running open air ITB, I have the AIT sensor right infront of the intake stream. I was thinking it's the AIT sensor getting heat soak, but won't that cause a lean condition instead of rich?

Thanks!

[Matt Cramer]

The IAT readings are about the same, but MAP is different. And so is the spark advance. I would flatten the spark table below 1000 RPM and adjust the VE table a bit.

[pkm123]

I think your linkage is heat soaking and so are your injectors. Had the same problem with my ITB setup. Reduce the injector deadtime to 0.6 or 0.4 and re-tune the ve map in the lower left. The correct deadtime for 630 cc injectors is 0.6, but 0.4 is a safety margin. Make sure the ITB butterflies are against the throttle stop at idle and that there is play in the linkage. Check the TPS calibration when the engine is hot and see if it has moved. Check the voltage at idle vs at speed. If the voltage is lower, your deadtime is increasing. You might read my post in the Success Stories. (452 cu. in. FE) If the problem persists, you can lower the AFR Correction from 1200 rpm to the idle rpm.
Good Luck