LS experts... P0171 and P0174

EmersonHart13

Member Selfie
Donating Member
Joined
Jul 18, 2007
Messages
46,947
Reaction score
1,031
I am getting a P1071 and P0174 code on occasion, it goes away after a few starts and then will pop back up again a month or two later. From reading I have gathered that this means that is on the intake side as I am getting both simultaneously. I have already re-tightened the stock intake twice. (I have a Svede to install but I was waiting to try to get this sorted out first) I believe the next place to look is the intake manifold. I tried spraying around the edges to see if I could get an idle change but nothing happened. Is my best bet to re-torque the manifold? I has to be a pretty minor leak I think but my logic could be completely wrong.

Your thoughts please!

Thanks in advance,

John
 

framos242

Drink the shot, pussy....
Joined
Sep 9, 2008
Messages
4,229
Reaction score
4
Re-tighten the manifold. Looks for any leaks in the hoses. Could it also be the MAF??
 

EmersonHart13

Member Selfie
Donating Member
Joined
Jul 18, 2007
Messages
46,947
Reaction score
1,031
I cleaned it while I was checking the intake. I suppose it could be bad. I should probably re-torque the TB too.
 

Stink Star Productions

Don’t Drive Angry!
Joined
Jan 20, 2008
Messages
12,155
Reaction score
42
Location
Big wood cock
check the data at idle for calculated airflow compared to actual airflow, should be very very close. if its not id suspect cracked intake gaskets or carbon buildup on the MAF. sometimes even after you clean it, there is a "crust" that forms on it that needs to be scraped off
 

EmersonHart13

Member Selfie
Donating Member
Joined
Jul 18, 2007
Messages
46,947
Reaction score
1,031
I have always heard, don't touch the MAF. Gentle scrub with a soft brush?

I know the manifold has been off the car so there is always a chance the gasket is worn or the manifold needs to be torqued.
 

Stink Star Productions

Don’t Drive Angry!
Joined
Jan 20, 2008
Messages
12,155
Reaction score
42
Location
Big wood cock
well you aren't supposed to touch it, they expect you to replace it if its bad, but i sometimes take a 90* hook pick and GENTLY scrape back and forth on the sensor wires the entire 360* of their circumference. i only suspect MAF because i assume there is a k&n filter on this car. the intake being off raises an eyebrow for a twisted or pinched gasket of course. even though those gaskets are encased in a plastic frame they can still be crushed past the point of usability or cracked from over torque.
 

EmersonHart13

Member Selfie
Donating Member
Joined
Jul 18, 2007
Messages
46,947
Reaction score
1,031
Right now it is a stock intake. I know it had an aftermarket on there before so it could be it. I had a leaky valve cover gasket that I had to replace because it was pinched so the intake is probably suffering from the same problem. I will check the torque first and then pull it if it shows again.

Thanks!
 

GearsForYourRears

NAPA Know How!
Joined
May 4, 2012
Messages
69
Reaction score
0
Location
Batavia, IL
I know it's not LSx related, but I had the same two codes on my 97 Mustang. I tried all kinds of things to fix it including new (non oiled) air filter, new DPFE sensor, checked everywhere for vacuum leaks, replaced intake manifold and gaskets (upgraded to PI), among other things.

Turns out, when I pulled the engine apart to install new heads, I found a vacuum line going from the intake over to the purge solenoid, that was heated by a previous exhaust leak. The line looked fine, but when I bent it, I found it had thousands of tiny cracks from the heat.

Replaced the hose and no more codes!

Make sure you inspect your vacuum lines extremely well!
 

Create an account or login to comment

You must be a member in order to leave a comment

Create account

Create an account on our community. It's easy!

Log in

Already have an account? Log in here.

Top Bottom