P0171 & P0174
Thread Starter
|
New User
Joined: Mar 2003
Posts: 5
Likes: 0
P0171 & P0174
I have a 97 ranger with 95000 miles on it and am getting fault code P0171 lean on bank 1 and P0174 lean on bank 2. My check engine light is on constantly. I am burning alot of fuel, get about 250 miles on a tank of gas (4.0L V6). Car Quest replaced my intake manifold gasket thinking that would fix the problem but it didn't. Still get the same fault codes. Vehicle seems to run fine, good power and acceleration, doesn't seem to be misfiring. I wouldn't even know there was a problem if the check engine light wasn't on. Anybody ever seen this problem, if so any suggestions. Thanks
Thread Starter
|
New User
Joined: Mar 2003
Posts: 5
Likes: 0
P0171 & P0174
Yes they cleared the codes when they replaced the intake manifold gasket but the codes came back about 2 days later. Where exactly are these O-ring gaskets? Are there any web sites that might show me? Maybe I need to buy a chiltons book.
Post Fiend
Joined: Jan 2003
Posts: 9,748
Likes: 16
From: Connecticut
P0171 & P0174
Hello BobbyP and Welcome to Ford Truck Enthusiasts!!
I've seen those codes discussed before in this forum and some other forums. You might try doing a search using the keywords "P0171" or "P0174".
In the meantime here is a link to a thread that may give you some more ideas about the causes of your problem:
https://www.ford-trucks.com/forums/s...ighlight=P0174
I've seen those codes discussed before in this forum and some other forums. You might try doing a search using the keywords "P0171" or "P0174".
In the meantime here is a link to a thread that may give you some more ideas about the causes of your problem:
https://www.ford-trucks.com/forums/s...ighlight=P0174
Posting Guru
Joined: Feb 2002
Posts: 1,534
Likes: 2
From: Warren, MI
P0171 & P0174
I had the same codes on my 97 Ranger 4.0L and it was the gasket under the fuel rail but I replaced the "O" rings also. There are three of them in the bottom of the upper intake(big black plastic piece).
It's not an easy job! I'd make sure it's leaking there first. Get some "Quick Start" spray and squirt it around the base of the upper intake. If it's leaking, your idle will increase. If not, you may still have a vacuum leak somewhere else! It could also be low fuel pressure, bad MAF, bad PCM, etc. The list is long for those codes.
Another long shot too! The upper intake is supposed to be retorqued after assembly when the engine warms up. I forget the specs for that.
It's not an easy job! I'd make sure it's leaking there first. Get some "Quick Start" spray and squirt it around the base of the upper intake. If it's leaking, your idle will increase. If not, you may still have a vacuum leak somewhere else! It could also be low fuel pressure, bad MAF, bad PCM, etc. The list is long for those codes.
Another long shot too! The upper intake is supposed to be retorqued after assembly when the engine warms up. I forget the specs for that.
Posting Guru
Joined: Feb 2002
Posts: 1,534
Likes: 2
From: Warren, MI
P0171 & P0174
Wondering why you stated that you were using lots of gas because your getting a lean code which means you should be using less gas!
Trending Topics
Thread Starter
|
New User
Joined: Mar 2003
Posts: 5
Likes: 0
P0171 & P0174
It was explained to me by the mechanic that I had working on it that when the "system too lean" code came up, the vehicle was sucking too much air so the computer would try to compensate by sending in more gas to equal out the mixture therefore burning more gas. Would you agree with this, or is it the other way around?
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
Posting Guru
Joined: Feb 2002
Posts: 1,534
Likes: 2
From: Warren, MI
P0171 & P0174
Originally posted by Bobbyp
It was explained to me by the mechanic that I had working on it that when the "system too lean" code came up, the vehicle was sucking too much air so the computer would try to compensate by sending in more gas to equal out the mixture therefore burning more gas. Would you agree with this, or is it the other way around?
It was explained to me by the mechanic that I had working on it that when the "system too lean" code came up, the vehicle was sucking too much air so the computer would try to compensate by sending in more gas to equal out the mixture therefore burning more gas. Would you agree with this, or is it the other way around?
Can't speak about your engine but mine while cruising along with a scanner connected show no signs of a lean engine. Short Term Fuel Trims were near perfect. Only as decel started did STFT move towards rich, trying to compensate for the extra air. A couple of traffic lights and I'd pop the codes!
If you were using lots of gas and what they said holds true, you don't drive much highway, lots of stop/go.
Thread Starter
|
New User
Joined: Mar 2003
Posts: 5
Likes: 0
P0171 & P0174
I went and bought a can of quick start last night and tried what you mentioned earlier. I sprayed it all around the intake manifold and the idle didn't change. The idle did go up slightly, maybe 100 rpm's (barely noticable) when I sprayed it around the pipe that goes from the EGR valve to the intake manifold. I may have a small leak there. The Haynes book showed me that my EGR valve is supposed to be mounted directly to the intake manifold but mine isn't. I had my EGR valve replaced about a year ago. I had to have the shop do it because the bolts were seized and they ended up having to heat up the bolts or cut them off or something, I can't remember exactly what they said they had to do, but maybe that has something to do with the leak.
Posting Guru
Joined: Feb 2002
Posts: 1,534
Likes: 2
From: Warren, MI
P0171 & P0174
The EGR to upper intake is what makes removing the upper intake a pain! It's not a straight tube, it's bent toward the throttle plate. Your trying to come straight up off the studs and at the same time trying snake that bent tube thru a straight hole in the upper intake!
There are 2 or 3 rubber seals around that EGR tube into the upper intake. They are a bitch to get in while assembling. If your problem is there, you might try to seal that around the EGR tube just to see if it fixes your codes. Not sure what you could use because the tube gets very hot. It has to be something that'll take the heat.
Do they still sell that muffer patch tape because that would work?
I never tried to spray Quick Start after I repaired the gasket, so I can't say if mine has a slight leak there too.
Do you have a high idle speed too? Mine was idling at first at over 1000rpm and at 1800rpm just before the fix! Thank god it's a manual or it would have been undrivable!!
There are 2 or 3 rubber seals around that EGR tube into the upper intake. They are a bitch to get in while assembling. If your problem is there, you might try to seal that around the EGR tube just to see if it fixes your codes. Not sure what you could use because the tube gets very hot. It has to be something that'll take the heat.
Do they still sell that muffer patch tape because that would work?
I never tried to spray Quick Start after I repaired the gasket, so I can't say if mine has a slight leak there too.
Do you have a high idle speed too? Mine was idling at first at over 1000rpm and at 1800rpm just before the fix! Thank god it's a manual or it would have been undrivable!!
Thread Starter
|
New User
Joined: Mar 2003
Posts: 5
Likes: 0
P0171 & P0174
My idleing is just fine. Idles smooth at about 1000 rpm's on my in dash tach, no misses or stutters. Like I said before the truck runs fine, if the check engine light wasn't on I wouldn't even know there was a problem. I'm gonna try to find something to put around the pipe to see if my codes will clear like you said, then I'll know for sure if the problem is there or somewhere else. Thanks alot for your help. I'll let you know the outcome.
Posting Guru
Joined: Feb 2002
Posts: 1,534
Likes: 2
From: Warren, MI
P0171 & P0174
Even if you have a auto trans anything over 800rpm is higher than specs.
You could try cleaning your MAF. The two wires are way down in there and hard to see but squirt some carb, brake or throttle body cleaner on the wires. It can't hurt and it's easy to do too!
Just a thought but your IAC ports extra air around the throttle plate. If it's stuck and not working, hmmmm. If you unplug the connector at idle the speed should drop or even stall. If you replug it in quickly enough, you won't set a IAC circuit malfunction code.
You could try cleaning your MAF. The two wires are way down in there and hard to see but squirt some carb, brake or throttle body cleaner on the wires. It can't hurt and it's easy to do too!
Just a thought but your IAC ports extra air around the throttle plate. If it's stuck and not working, hmmmm. If you unplug the connector at idle the speed should drop or even stall. If you replug it in quickly enough, you won't set a IAC circuit malfunction code.