This thing is driving me up a tree 97 eldorado I had it6 monnthsit has 120,000 on it check engine lite is on I purchased a code reader and I am getting a lean burn situation on both banks....I have replaced plugs platinum ones, air cleaner, both oxygen sensors cleaned throttle body, put a tank full of highest octane I could find .I love the car but I like things to be rightanyhelp would be greatly appreciated. Thanks Bill

 

Lean fuel trim on both banks would indicate an air/vacuum leak somewhere on the intake or throttle body.
The other possibility would be a faulty reading from the mass air sensor.
I have seen the leftovers from a bug stuck on the sensor causing false readings.

The freeze data should tell you if the failure is at idle or cruising RPM.
Failure at idle would suspect an air vacuum leak.
Failure at cruise i would look more at the MAS.

 

thanks much I will try both bill

 

I just started same prob(svce eng. soon light on)with my 2001 ETC. A local parts store "tech" hooked up a code reader and got " lean cond. bank 1, bank 2". He pointed to a cylinder shaped casting with one elec. connector, I believe on the throttle body. Is this the MAS(sensor)?. He called it the "idle mixture control valve."

I pulled up on the dash : PCM P0171 CURRENT, PCM P0174 CURRENT, RF U1064 HISTORY.

I sprayed starting fluid after removing the induction cover, and I guess idle may have increased slightly around throttle body hose clamp for a millisecond, but it`s tight as hell.I visually inspected vacuum tubes and all look like new. BUT I swear I hear a vacuum leak, andI don`t remember hearing hissing b4. I`m extremely **** when it comes to my vehicles/mechanics in general.

Conditions are: svce. engine soon light on, after starting and after rev down(stop at red light), idle remains at 1000 to 1200 rpm for 5-10 sec.
P.S. Twice since I owned etc, I had no radio and no "Key in ignition chime" until driving, shutdown, restart a few times. I bought the GM repair manuals for my vehicle. Now I need a manual for the manuals. lol

Any help would be appreciated
Mick