Code 44 Lean Exhaust
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
Code 44 Lean Exhaust
Yesterday i was driving along, everything was fine. Check engine light comes on for about 15 seconds then goes away. Get home, pull codes and its a code 44.
I looked it up in the FSM and it says to run the car until warm so i drove it around for 10 minutes. Then it told me to ground the diagnostic terminal, so i did and it was flashing the check engine light once per minute which indicated that the car was in closed loop mode.
The FSM says that the code is intermittent.
Now my question to you guys is..lately i've been experiencing **** poor mileage. my instant readout at 60 mph is 17 mpg. it used to be up in the high 20's and sometimes even seeing 30.
Is this a bad oxygen sensor?
I looked it up in the FSM and it says to run the car until warm so i drove it around for 10 minutes. Then it told me to ground the diagnostic terminal, so i did and it was flashing the check engine light once per minute which indicated that the car was in closed loop mode.
The FSM says that the code is intermittent.
Now my question to you guys is..lately i've been experiencing **** poor mileage. my instant readout at 60 mph is 17 mpg. it used to be up in the high 20's and sometimes even seeing 30.
Is this a bad oxygen sensor?
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 411
From: WV
About 3 weeks ago I discovered my 89 was running lean,the Block learn was at 146.. Replaced the O2 sensor and all is well, but the only way to know for sure is to hook up to a scanner..If the block learn is higher then 128 the car is running lean, if its lower then 128 its running rich,the ecm can correct for this to a certain degree but the numbers should be somewhere around 128..The integrater should also be around 128, the integrater is your short term fuel/air correction, Block learn is long term.Also don't rule out a vacuam leak for causing a lean condition ..WW
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
7 Bolt-On Upgrades From Extreme Online Store to Level Up Your C6 Corvette
Pouria Savadkouei
How Likely Are These Five 2027 Corvette Rumors to Be True?
Brett Foote
9 Best Corvettes You Can Buy for Half Price (& 1 You Should NEVER Buy!)
Joe Kucinski
8 Very Best Corvettes of Amelia Island 2026
Joe Kucinski
Top 10 WORST Corvette Engineering Failures of All Time!
Joe Kucinski
10 Records the C8 Corvette Generation Has SMASHED (& 1 Glaring Failure)
Joe Kucinski
7 Wildest Corvette Concepts Ever Made
Brett Foote
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
Racer
Joined: Oct 2008
Posts: 299
Likes: 1
From: Ottawa Ontario
Which one did you change? How do you know you changed the right one? It also takes some driving to re-learn. I know when I changed mine it took at least an hour or so of driving for the MPG to get back to it's usual norm.
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
Mine only has one, its on the drivers side in the Y-pipe.
Should I disconnect/reconnect the battery?
I put new plugs in it too, some of them were looking pretty beat up. Cylinder 7 has oil on the threads of the spark plug..what does that mean?
Should I disconnect/reconnect the battery?
I put new plugs in it too, some of them were looking pretty beat up. Cylinder 7 has oil on the threads of the spark plug..what does that mean?
Race Director
Joined: Jun 2004
Posts: 13,895
Likes: 691
From: WI
Probably just from your leaking valve cover gaskets. There's no oil on the ground strap etc right? I remember you posted about having an exhaust manifold gasket leak, is it on the side with the O2? That could throw some codes.
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
Before i put the new runners and stuff on, the mileage was good..it makes me think that its a vacuum issue, or maybe a fuel injector or something.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Even the smallest exhaust leak can cause a lean condition.
I once had a tiny pin-hole leak develop in the #5 TPIS header tube, too small to even see without looking very carefully for it. That caused a lean condition indication.
Jake
West Point ROCKS! Nation's TOP COLLEGE per FORBES Magazine!
I once had a tiny pin-hole leak develop in the #5 TPIS header tube, too small to even see without looking very carefully for it. That caused a lean condition indication.
Jake
West Point ROCKS! Nation's TOP COLLEGE per FORBES Magazine!
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
Even the smallest exhaust leak can cause a lean condition.
I once had a tiny pin-hole leak develop in the #5 TPIS header tube, too small to even see without looking very carefully for it. That caused a lean condition indication.
Jake
West Point ROCKS! Nation's TOP COLLEGE per FORBES Magazine!
I once had a tiny pin-hole leak develop in the #5 TPIS header tube, too small to even see without looking very carefully for it. That caused a lean condition indication.
Jake
West Point ROCKS! Nation's TOP COLLEGE per FORBES Magazine!
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
My dad pointed it out to me, I have no idea how he saw it. It wouldn't be possible for it to reseal itself somehow would it? Could i just start the car and feel for leaks with my hand before it gets hot?
2nd Gear
Joined: Jan 2020
Posts: 3
Likes: 0
Yesterday i was driving along, everything was fine. Check engine light comes on for about 15 seconds then goes away. Get home, pull codes and its a code 44.
I looked it up in the FSM and it says to run the car until warm so i drove it around for 10 minutes. Then it told me to ground the diagnostic terminal, so i did and it was flashing the check engine light once per minute which indicated that the car was in closed loop mode.
The FSM says that the code is intermittent.
Now my question to you guys is..lately i've been experiencing **** poor mileage. my instant readout at 60 mph is 17 mpg. it used to be up in the high 20's and sometimes even seeing 30.
Is this a bad oxygen sensor?
I looked it up in the FSM and it says to run the car until warm so i drove it around for 10 minutes. Then it told me to ground the diagnostic terminal, so i did and it was flashing the check engine light once per minute which indicated that the car was in closed loop mode.
The FSM says that the code is intermittent.
Now my question to you guys is..lately i've been experiencing **** poor mileage. my instant readout at 60 mph is 17 mpg. it used to be up in the high 20's and sometimes even seeing 30.
Is this a bad oxygen sensor?
Here is how it works and why you got the Code 44.
First the EGR open when the EGR Temperature Sensor tells the computer the engine temperature is 175 at the EGR Valve.
The EGR Temperatures Sensor, sends a signal to the ECM,
The ECM sends a signal to the EGR Vacuum Regulator
The EGR Vacuum Solenoid open or closes the EGR Valve so the engine valves can be cooled and the air fuel mix is properly adjusted.
I replaced the EGR after testing when it dropped after a few minutes with a thump, still had 44.
The EGR Vacuum Solenoid worked electrically but the vacuum was leaking and I replaced that, still had 44.
The Code 44 stayed after the EGR and EGR Vacuum Solenoid were replaced as well as the Computer,
After full aggravation I replaced the EGR Temperature Heat Sensor, that was it, no more Code 44.
I recommend if you have a Code 44 get the new Temperature Heat Sensor it is only $76 and solves that problem.
