lt1 both banks lean
Thread Starter
4th Gear
Joined: Jul 2012
Posts: 4
Likes: 0
From: devlin ontario
lt1 both banks lean
I have 93 lt1 six speed, the ses light comes on and leaves a code for both o2 sensors running lean, doesn't seem right that both sensor would go at the same time. Other than the light the runs and idles just fine. was wondering if anyone else had run into this.
Pro
Joined: Mar 2013
Posts: 628
Likes: 13
From: Indiana
I had this same problem for years and finally found the answer. The rubber 90 degree connector for my PCV valve was pinched shut and cracked. Got a new 90 at AdvanceAuto for $3.00 and the car now runs great no codes. I replaced all four O2 sensors and a few other things first as I went down the list in the FSM. The PCV was way down the list, but when I got to it I found the leak. It is most likely a vacuum leak somewhere on your engine. It also caused my Oil Dipstick to keep popping out. This was also listed in the FSM. Here is a pic of the connector.
Melting Slicks
Joined: Jul 2003
Posts: 3,227
Likes: 50
From: Pomfret, CT
Finalist 2020 C4 of the Year - Unmodified
I had this same problem for years and finally found the answer. The rubber 90 degree connector for my PCV valve was pinched shut and cracked. Got a new 90 at AdvanceAuto for $3.00 and the car now runs great no codes. I replaced all four O2 sensors and a few other things first as I went down the list in the FSM. The PCV was way down the list, but when I got to it I found the leak. It is most likely a vacuum leak somewhere on your engine. It also caused my Oil Dipstick to keep popping out. This was also listed in the FSM. Here is a pic of the connector.
Pro
Joined: Mar 2013
Posts: 628
Likes: 13
From: Indiana
What was kind of lame was the 90 was just a bent piece of hose. It will soften and pinch shut sooner or later because of the gas and oil fumes pulled thru it. The new 90 was cast rubber in the correct shape and should last the life of the car. I don't know what GM was thinking when they engineered this one but everyone should check theirs and replace it with the cast one and a new PCV valve. You will be surprised at the improvement that a new functioning PCV valve makes on the LT1's. I thought mine was running ok even when the codes popped up, but man what a difference having the system not run lean made. Everything is based on the engine having the correct vacuum levels and it is one of the major players in your vacuum control. For $2.50 it is one of those things that should be checked and changed often
Last edited by Klyde; Jul 4, 2013 at 08:14 AM.
