Hi everybody. I have a 1997 Club wagon with the 5.4L engine. When I start it in the morning (40 F Degrees) the RPMs drop and it just about stalls (real rough). When it warms up, it runs fine. I took it to the mechanic and the analyser said that it is running lean at idle (both O2 sensors). The computer is making it as lean as it can. Is there a common problem with this year and engine. Thanks, Bill

 

Hi bill5.4l and welcome to FTE

A couple things come to mind here. The rpm drop could be caused by a faulty IAC. It is quite common.
The lean code for both banks could be due to a dirty MAF sensor, or possibly a vacuum leak.
If you hit the search button near the top of the page and search for those things you'll find some info on them.
Let us know how it goes.

 

Hi Racerguy,

I cleaned the MAF sensor, injectors, changed the fuel filter, but cannot find a vacuum leak. The long term fuel trim is still showing +25% at idle after resetting the ECU. I still need to clean the IAC for the idle problem. Can this make the long term fuel trim read a high percentage?

Thanks,

Bill5.4l

 

No the IAC shouldn't affect your LFC.
Did he look at the MAF voltage when he checked things?
Did you check your fuel pressure? It can really mess things up if it isnt where it should be.
Any trouble codes?
If it looks ok and you cant find a vacuum leak I'd be inclined to suspect the O2s.

 

Looks like we're back to normal! It turned out to be one of the hoses between the MAF and the throttle body was not connected correctly. Thanks for all the help.

Bill5.4l

 

Thanks for letting us know what you found