LS1 P0171 code issue
Thread Starter
Teching In
Joined: Aug 2018
Posts: 23
Likes: 1
LS1 P0171 code issue New intake manifold, plugs, injectors , coil packs, map sensor, MAF sensor, vacuum hoses, compression bank 1 all @170 and still P0171 and lack of power. What gives ? Any idea what to do next ??
I’d investigate the intake sealing properly, perhaps torqued incorrectly, or a torn intake o-ring. Maybe check the MAP sensor sealing up also. Does the car idle different now than before?
Lack of power and lean codes.. I would check the fuel pump.
With a vacuum leak.. it "goes away" at wide open throttle since there is essentially little to no vacuum in the intake at wide open so you will still make full power.
However I would think you would also have a p0174 for lean bank 2 with a bad pump. So it could be just the B1 02 sensor.
I would still test fuel pressure and volume.
With a vacuum leak.. it "goes away" at wide open throttle since there is essentially little to no vacuum in the intake at wide open so you will still make full power.
However I would think you would also have a p0174 for lean bank 2 with a bad pump. So it could be just the B1 02 sensor.
I would still test fuel pressure and volume.
You can make pressure and have low flow due to a pump crapping out or clogged filter. Fuel volume needs to be checked.
Or try the fuel filter first and see how it goes then check volume. Easy check is to let it run with fuel pressure gauge on it and hit the bypass on the fuel pressure tester and make sure a good amount of fuel comes out and the engine keeps running. If it dies or fuel just dribbles out you have a fuel volume issue.
Trending Topics
Should affect both banks if it's a central source like fuel pump or vacuum leak from a hose etc. Could be intake gaskets on one side only.. who knows. Weird **** happens so it's always good to check all base items when you have an issue.
I've had a lot of problems with replacement MAF sensors if they aren't high end sensors. What brand maf did you use?
You can try running it with the MAF unplugged and see if you still get a lean issue or just a MAF code and that may help determine if it's the MAF
Do you have a scanner with data capability? If so if you give me some info from it I may be able to help you there.
I've had a lot of problems with replacement MAF sensors if they aren't high end sensors. What brand maf did you use?
You can try running it with the MAF unplugged and see if you still get a lean issue or just a MAF code and that may help determine if it's the MAF
Do you have a scanner with data capability? If so if you give me some info from it I may be able to help you there.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Thread Starter
Teching In
Joined: Aug 2018
Posts: 23
Likes: 1
MAF is Spectrum. Tried another new one, nothing changed. Unplugging idle goes down, then BK to normal on replug.
Wierd thing now is my scanner gets no ltf or stf trims. No changing at high idle either.
Regapped plugs today, unplugged each coil pack and idle went down on each one, so plugs, coil packs good.
Today tech looked at it and had me reroute pcv and bank 1 vacuum Lines into tee connector and plug into side of new intake down stream of throttle body. All other ports on top are blocked off except for side port for HVAC and rear port for map sensor.
Only data reporting is O2 sensor BK 1 (0.935), O2 sensor bk2 (0.810), map sensor (5.25 psi) and MA1 sensor (4.56 g/s) at idle operating temp.
Wierd thing now is my scanner gets no ltf or stf trims. No changing at high idle either.
Regapped plugs today, unplugged each coil pack and idle went down on each one, so plugs, coil packs good.
Today tech looked at it and had me reroute pcv and bank 1 vacuum Lines into tee connector and plug into side of new intake down stream of throttle body. All other ports on top are blocked off except for side port for HVAC and rear port for map sensor.
Only data reporting is O2 sensor BK 1 (0.935), O2 sensor bk2 (0.810), map sensor (5.25 psi) and MA1 sensor (4.56 g/s) at idle operating temp.
Thread Starter
Teching In
Joined: Aug 2018
Posts: 23
Likes: 1
Engine is from 2004 Tahoe 45k miles. Ran it for 10 yrs stock with cold air intake only upgrade. Fee weeks ago got P0171 code and after diagnosis replaced intake manifold with aftermarket type. Ran great for few days and here we are today. 😂👎
If you're gonna unplug the maf you need to monitor things before and after. Not just unplug and replug. To see if the MAF makes a difference you'll need to watch and record LTFT and STFT at hot idle vs plugged in at hot idle. And you want to turn the engine off and back on between each plug and unplug since unplugging it and plugging it while running usually wigs it out a bit.
What size engine is it? Where does it idle hot? All that matters a ton on MAF readings.
However you mentioned the PCV routing... That is critical also.
If you are using the valve covers that have 2 nipples on the passenger side and one nipple on the driver side
You should have a hose on the driver side valve cover nipple coming over to the driver side behind the intake then T into passenger valve cover then into a PCV valve then into the intake. All one deal t'd together to end at a PCV valve at the intake nipple behind the throttle body.
Then there should be a fresh air hose from your intake tube behind the MAF going into the other nipple on the passenger valve cover.
If you have the LS6 style valley cover you run a hose off the nipple on it into the intake, and a fresh air hose from your intake tube to the valve cover
What size engine is it? Where does it idle hot? All that matters a ton on MAF readings.
However you mentioned the PCV routing... That is critical also.
If you are using the valve covers that have 2 nipples on the passenger side and one nipple on the driver side
You should have a hose on the driver side valve cover nipple coming over to the driver side behind the intake then T into passenger valve cover then into a PCV valve then into the intake. All one deal t'd together to end at a PCV valve at the intake nipple behind the throttle body.
Then there should be a fresh air hose from your intake tube behind the MAF going into the other nipple on the passenger valve cover.
If you have the LS6 style valley cover you run a hose off the nipple on it into the intake, and a fresh air hose from your intake tube to the valve cover
Last edited by 00pooterSS; Aug 1, 2019 at 05:50 PM.
If only two on the valve covers run the one on the drivers rear corner to the intake behind the throttle body and the other port on the passenger front into the intake tube behind the MAF. The MAF has to see the air flow through the PCV system since that flow is factored into the flow rate the MAF sees.
There has to be airflow through the engine starting at the intake tube behind the MAF and in front of the throttle blade to a valve cover. Then an hose from another point on the valve cover or the valley cover to the intake manifold behind the throttle body. This hose needs to have a PCV in it.
No valley cover port or port on cold air intake tube behind MAF sensor. Setup now has drivers side pcv port connected to tee with passenger side port then to intake behind Throttle body.
Well then that is not a PCV system. The V is missing in your setup. It's supposed to be a ventilation setup and the air flow from the PCV system is taken into consideration for the fueling and is seen by the MAF sensor. That could be part of your issue. I have had many fords come in with lean codes that had clogged up PCV valves. Sounds weird, but it's a thing.
Just hooking your valve cover to your intake is not the right way to do it. There has to be air flow through the system.
Also sounds like you're missing the PCV valve, unless you are using the newer covers with the PCV valve in the valve cover. If so you have one cover with a PCV going to the intake like it should and the other cover with just a breather tube also connected to the intake, and that one should be going to the intake tube to get filtered air and also give the MAF an airflow signal. Which will raise the airflow it sees and also richen up the mixture.
If you're using the LS1 covers route like the LS1 came and put a PCV valve. If you're running truck covers route it like the truck did. If you have someone around you with a truck like your motor came out of you can pop the hood and see how it's ran and see what I'm saying above.
Oh and if you're running the LS1 throttle body you can hook the one valve cover to the tube on the throttle body like the LS1 comes from the factory. The fresh air on the LS1 is on the throttle body. On the trucks it's on the intake tube.
The pcv valve or pcv valve cover hooks to the intake manifold
If you don't have the LS1 throttle body with the port on it for the hose yes then tap the tube.
The valve cover with the oil fill cap goes to the fresh air pipe on the throttle body (LS1) or the intake tube on truck style.
The valve cover without the oil fill goes to the intake manifold. Just make sure you either have a PCV in that valve cover or add a PCV inline in the hose you run from that cover to the intake manifold.
The pcv valve or pcv valve cover hooks to the intake manifold
If you don't have the LS1 throttle body with the port on it for the hose yes then tap the tube.
The valve cover with the oil fill cap goes to the fresh air pipe on the throttle body (LS1) or the intake tube on truck style.
The valve cover without the oil fill goes to the intake manifold. Just make sure you either have a PCV in that valve cover or add a PCV inline in the hose you run from that cover to the intake manifold.
It depends on what valve cover setup you are running. And what valley cover you have. If your valley cover doesn't have a port on it then forget about the valley cover and focus on the valve covers.
What exact valve covers are you using. If it is the truck ones with the PCV in the driver side cover then you run the driver side cover to the intake manifold and the passenger cover to the throttle body or intake tube.
For me to tell you what to do I need to know what valve covers you are using and which throttle body you are using. Does your throttle body have a pipe on it that is routed in front of the blade?
What exact valve covers are you using. If it is the truck ones with the PCV in the driver side cover then you run the driver side cover to the intake manifold and the passenger cover to the throttle body or intake tube.
For me to tell you what to do I need to know what valve covers you are using and which throttle body you are using. Does your throttle body have a pipe on it that is routed in front of the blade?