Today my truck kept dieing out on me while I was idleing in traffic. At 1st I couldn't pull any codes with my Preditor. Then, after it started back firing a little, I got a check engine light. I had Bank 1 and Bank 2 fuel trim lean codes. I did a real time data check and when it was about to die, I was reading 0 for both bank short term fuel trims.

What could cause this? BTW, I have 135k on the clock...

Thanks,
J.R.

 

Check you Long term trims as they are a better indicator. If they are maxed at 25 you may have a leak after the MAF sucking in a lot of unmetered air.

 

They were at 25. This has happened to me twice before. Everytime it was while idleing in traffic for a while and after driving around for a couple of hours. The 1st two times, all I had to do was let it sit about 20-30 seconds and it was back to normal. This last time took a lot longer.

Today I drove about 30 miles then sprayed carb cleaner all around the intake tube and intake manifold. I didn't notice a change in the idle speed. Of course, it wasn't wanting to die on me at the time so I'm guessing the leak isn't that bad....

The next time it happens, I'll get out and check it then.

 

Mine too are maxed at 25 and I am fettting the same code

 

me too, at idle after the truck warms up my aeroforce guages read both banks 1 and 2 maxed out at 25 and then I get the code. All though part throttle and WOT seem to be ok, right around 13. (guess thats ok) Ive put new header gaskets and my exhaust is leak free and still does it so now im gonna start looking at the intake and fueling.

 

I hadd a huge leak at the throttle body ....fixed it...code's gone now

 

Make sure you dont have any disconnected vaccum lines as well.

 

I have a 2001 5.3 liter. I have the same problem. Got the run around from some places and finally got fed up and went to the dealer. They were very nice, spent about 30 min. on the truck and to me it was a intake gasket leak. Showed me that both banks 1 & 2 are running lean reading 25 @ idle. Then shot some starter fluid on the driver side of the intake....no idle change but the short term & long changed big time. In the process now of trying to find a (How to) replace a intake gasket on this site