HELP with OBDII trouble code PO 171
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Joined: Apr 2003
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From: NYC
HELP with OBDII trouble code PO 171
Hi,
I have a 2000 Ford F150 5.4 with a KN FIPK,Granatelli mass airflow, throtlle body spacer JBA headers with a Bassani catback.I perchased an autotap from Anita at Performance Products To findout what's up with the check engine lite that came on. The code I got was PO171 the HELMS CD said a number of thing and I've been getting about 50 miles less per tanck of gas any ideas would be appreciated.
Tony
I have a 2000 Ford F150 5.4 with a KN FIPK,Granatelli mass airflow, throtlle body spacer JBA headers with a Bassani catback.I perchased an autotap from Anita at Performance Products To findout what's up with the check engine lite that came on. The code I got was PO171 the HELMS CD said a number of thing and I've been getting about 50 miles less per tanck of gas any ideas would be appreciated.
Tony
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Joined: Jan 2002
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otirado,
Do a search on the code or the word "lean" or code po171. You'll come up with mucho info.
Lean means too much air compared to fuel. The first thing to do is clean the MAF sensor. If it is dirty it will let more air through than the ECM will "see".
Next look for vacuum leaks...Here I did the search for you:
https://www.f150online.com/forums/se...der=descending
Good Luck,
Bill
Do a search on the code or the word "lean" or code po171. You'll come up with mucho info.
Lean means too much air compared to fuel. The first thing to do is clean the MAF sensor. If it is dirty it will let more air through than the ECM will "see".
Next look for vacuum leaks...Here I did the search for you:
https://www.f150online.com/forums/se...der=descending
Good Luck,
Bill
Former Sponsor
Joined: Mar 1998
Posts: 13,385
Likes: 4
From: Virginia
Hey Tony,
Your problem is very simple - that Granatelli MAF. Get it off of there, as it's causing the engine to run lean - no matter what the manufacturer says - we know, we sell 'em, too.
That's what that P0171 code means - it is telling you that Bank 1 is far too lean. Bank 2 is too lean as well, by the way - it's just not quite reporting it yet, but eventually it will and you'll have the P0174 code (bank 2 lean) present, too.
Remember, these OBD-II system cannot be relied upon to give the driver a warning of a too-lean condition until it's really lean - you won't get any kind of warning in at say, 15:1 A/F. Generally speaking, your truck has to be WAY lean to actually throw a hard code and finally trigger the dash light warning.
All aftermarket MAF's cause engine to lean out, by anywhere from 2.0-4.0 on the A/F's. That's 2 to 4 full points lean - I.E., turning a 12.0:1 A/F into anywhere from 14.0:1 - 16.0:1. This requires a new custom MAF transfer function to be written - which requires talent & know-how to actually do it right, and requires the vehicle owner to do multiple rounds of complete datalogging.
In short, these days, aftermarket MAF's really shouldn't be used in applications under 600 HP, as the are factory Ford pieces that can handle power levels that high, and that can easily be tuned for without multiple datalogging & testing go-rounds.
Because you have AutoTap, you actually can datalog and then send us that info to have us do a custom tune and develop a new custom transfer function for that Granatelli MAF, but it will take a number of rounds of program adjustments to get it really dialed in - meaning a number of rounds of datalogging & sending us that info, having us make rounds of adjustments to the program sending the chip back and forth as long as it takes to get it right. We generally don't advise that, as it can be inconvenient for the vehicle owner and we have to do a lot more work, too. Most vehicle owners don't want several rounds of adjustments, sending their chip back and forth and datalogging again each time after they get it back so we can dial in the MAF transfer.
Most people are far better off by having us just switch them over to a Ford 90mm MAF that we supply (its much less than a Granatelli, etc.), as then we can do a custom tune for that meter without all the numerous rounds of datalogging and the back & forth adjustments, etc. - usually just one datalog does it, and rarely are any further adjustments to the program required.
You basically have a couple of very viable options that I would recommend you choose between:
1.) The cheapest one is to just get that Granatelli off of there and put your stock MAF back on. Costs nothing more out of pocket now, & maybe you sell that MAF to someone else who can use it & use that to offset the cost of your next performance mod.
2.) Or, have us replace it with the Ford 90mm unit and a custom tune so it will run correctly - since you don't mention having any performance tuning installed among your mods so far, in case you haven't done this yet, having us do a nice tune for that truck will net you a nice power gain & performance increase as well as cure this lean problem. This way, you can gain up to 30-35 HP or so in the process, and have a truck that feels stronger and runs harder, quicker, faster.
Best of luck whatever you decide on this, & give us a call if you'd like to go over this in more detail!
Your problem is very simple - that Granatelli MAF. Get it off of there, as it's causing the engine to run lean - no matter what the manufacturer says - we know, we sell 'em, too.
That's what that P0171 code means - it is telling you that Bank 1 is far too lean. Bank 2 is too lean as well, by the way - it's just not quite reporting it yet, but eventually it will and you'll have the P0174 code (bank 2 lean) present, too.
Remember, these OBD-II system cannot be relied upon to give the driver a warning of a too-lean condition until it's really lean - you won't get any kind of warning in at say, 15:1 A/F. Generally speaking, your truck has to be WAY lean to actually throw a hard code and finally trigger the dash light warning.
All aftermarket MAF's cause engine to lean out, by anywhere from 2.0-4.0 on the A/F's. That's 2 to 4 full points lean - I.E., turning a 12.0:1 A/F into anywhere from 14.0:1 - 16.0:1. This requires a new custom MAF transfer function to be written - which requires talent & know-how to actually do it right, and requires the vehicle owner to do multiple rounds of complete datalogging.
In short, these days, aftermarket MAF's really shouldn't be used in applications under 600 HP, as the are factory Ford pieces that can handle power levels that high, and that can easily be tuned for without multiple datalogging & testing go-rounds.
Because you have AutoTap, you actually can datalog and then send us that info to have us do a custom tune and develop a new custom transfer function for that Granatelli MAF, but it will take a number of rounds of program adjustments to get it really dialed in - meaning a number of rounds of datalogging & sending us that info, having us make rounds of adjustments to the program sending the chip back and forth as long as it takes to get it right. We generally don't advise that, as it can be inconvenient for the vehicle owner and we have to do a lot more work, too. Most vehicle owners don't want several rounds of adjustments, sending their chip back and forth and datalogging again each time after they get it back so we can dial in the MAF transfer.
Most people are far better off by having us just switch them over to a Ford 90mm MAF that we supply (its much less than a Granatelli, etc.), as then we can do a custom tune for that meter without all the numerous rounds of datalogging and the back & forth adjustments, etc. - usually just one datalog does it, and rarely are any further adjustments to the program required.
You basically have a couple of very viable options that I would recommend you choose between:
1.) The cheapest one is to just get that Granatelli off of there and put your stock MAF back on. Costs nothing more out of pocket now, & maybe you sell that MAF to someone else who can use it & use that to offset the cost of your next performance mod.
2.) Or, have us replace it with the Ford 90mm unit and a custom tune so it will run correctly - since you don't mention having any performance tuning installed among your mods so far, in case you haven't done this yet, having us do a nice tune for that truck will net you a nice power gain & performance increase as well as cure this lean problem. This way, you can gain up to 30-35 HP or so in the process, and have a truck that feels stronger and runs harder, quicker, faster.
Best of luck whatever you decide on this, & give us a call if you'd like to go over this in more detail!
Senior Member
Joined: Jan 2002
Posts: 222
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otirado,
Needless to say, Mike knows his "stuff" like 100x more than I. Sell your Gran MAF on E-Bay. Go back to the stock MAF or upgrade to the 90mm Ford MAF and have him do the Custom Tune. Your choice.
"Nobody knows everything. But, the smart ones know from whom to take advice." You can quote me on that.
Good Luck
Needless to say, Mike knows his "stuff" like 100x more than I. Sell your Gran MAF on E-Bay. Go back to the stock MAF or upgrade to the 90mm Ford MAF and have him do the Custom Tune. Your choice.
"Nobody knows everything. But, the smart ones know from whom to take advice." You can quote me on that.
Good Luck
Former Sponsor
Joined: Mar 1998
Posts: 13,385
Likes: 4
From: Virginia
Hi wmcnally,
Good to see you again, as always!
I wouldn't discount what you suggest, especially with regard to looking for vacuum leaks, etc. - that is certainly valid when diagnosing a lean condition, so I don't want to give the appearance of disagreeing with that - it's sound advice, and one of "the basics" i diagnosing lean conditions in general.
It's just that in this particular case, because he is using an aftermarket MAF, and because we know that ALL the aftermarket MAF's for these truck (and many other vehicles) cause a leaning out of the A/F (and a very gross lean out at that - 2 to 4 full points in our experience), our advice is to get it off of there and put the stock one back on for a quick & cheap immediate fix. And then if he's like to have this taken care of any get some real sustainable power & performance gains, having us put him in the 90mm Ford unit and doing a custom tune would give him far more than just what that Granatelli MAF did, and without causing that lean problem.
As always, thanks for your contributions here & being willing to help others out - that's what makes F-150 Online the place it is!
Good to see you again, as always!
I wouldn't discount what you suggest, especially with regard to looking for vacuum leaks, etc. - that is certainly valid when diagnosing a lean condition, so I don't want to give the appearance of disagreeing with that - it's sound advice, and one of "the basics" i diagnosing lean conditions in general.
It's just that in this particular case, because he is using an aftermarket MAF, and because we know that ALL the aftermarket MAF's for these truck (and many other vehicles) cause a leaning out of the A/F (and a very gross lean out at that - 2 to 4 full points in our experience), our advice is to get it off of there and put the stock one back on for a quick & cheap immediate fix. And then if he's like to have this taken care of any get some real sustainable power & performance gains, having us put him in the 90mm Ford unit and doing a custom tune would give him far more than just what that Granatelli MAF did, and without causing that lean problem.
As always, thanks for your contributions here & being willing to help others out - that's what makes F-150 Online the place it is!
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Joined: Apr 2003
Posts: 55
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From: NYC
Hi guys,
what to let you know I was tired and overwhelmed by this problem.
As a result I took my vehicle to a mechanic twice. He replaced the oxygen sensor, and the problem persisted. With the help of you all , the internet site and God I found the problem to be the crankcase ventilation tub to be disconected.Once I conected the hose now the PVC valve started making noise,I check PVC valve and found to be defective. Replace PVC vavle for $2.77 and the truck is running like new. I conected auto tap and found computer to have no trouble codes but the P1000 the book says to performe OBD 11 drive cycle and that will clear that code,Thanks a lot guys most appreciated
what to let you know I was tired and overwhelmed by this problem.
As a result I took my vehicle to a mechanic twice. He replaced the oxygen sensor, and the problem persisted. With the help of you all , the internet site and God I found the problem to be the crankcase ventilation tub to be disconected.Once I conected the hose now the PVC valve started making noise,I check PVC valve and found to be defective. Replace PVC vavle for $2.77 and the truck is running like new. I conected auto tap and found computer to have no trouble codes but the P1000 the book says to performe OBD 11 drive cycle and that will clear that code,Thanks a lot guys most appreciated
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Superchips_Distributor (Mike),
Thank you. I learn from every one of your posts. I am also one of your very satisfied cutomers!
otirado,
Thank you for posting your results! Many people ask a question, get answers(s), but never follow-up with the final result. We need to know "what really fixed it" to learn anything. We like to learn from your experience!
Now, if I may. From my experience. Superchips_Distributor knows his stuff. If he says your running "lean", you ARE running lean with that Gran MAF. The "lean" condition caused by the PCV leak may have set the DTC but you 're still running lean. Check it out before you damage your engine!
Bill
Thank you. I learn from every one of your posts. I am also one of your very satisfied cutomers!
otirado,
Thank you for posting your results! Many people ask a question, get answers(s), but never follow-up with the final result. We need to know "what really fixed it" to learn anything. We like to learn from your experience!
Now, if I may. From my experience. Superchips_Distributor knows his stuff. If he says your running "lean", you ARE running lean with that Gran MAF. The "lean" condition caused by the PCV leak may have set the DTC but you 're still running lean. Check it out before you damage your engine!
Bill
Last edited by wmcnally; Mar 31, 2004 at 02:15 AM.
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Joined: Apr 2004
Posts: 24
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From: Ohio
Hi guys,
I am having the same problems with my OBDII. System too lean, banks 1 and 2. I installed an aftermarket air intake system but it used the original Ford Mass Air Sensor and air intake piece that it was screwed onto. I have taken the truck to a Ford dealer who ran a diagnostic and couldn't find anything wrong with it. This is for the Ohio E-check money scam so I took it to an approved E-check service center. They worked on it for 3 days and couldn't find anything wrong with it. After reading the thread here, I replaced the aftermarket intake with the stock intake. Cleaned the mass air sensor like you said to do while I had it apart. I cleaned the fuel injectors. I service the truck religiously. New plugs, everything that was supposed to be changed at the 60,000 mile check up was done. Light has been on for a year and nobody can find out what to do. Runs great with only a little pinging on exceleration. I don't mind spending any amount of money as long as it fixes the problem. But this is getting old, any ideas at all will be greatly appreciated.
I am having the same problems with my OBDII. System too lean, banks 1 and 2. I installed an aftermarket air intake system but it used the original Ford Mass Air Sensor and air intake piece that it was screwed onto. I have taken the truck to a Ford dealer who ran a diagnostic and couldn't find anything wrong with it. This is for the Ohio E-check money scam so I took it to an approved E-check service center. They worked on it for 3 days and couldn't find anything wrong with it. After reading the thread here, I replaced the aftermarket intake with the stock intake. Cleaned the mass air sensor like you said to do while I had it apart. I cleaned the fuel injectors. I service the truck religiously. New plugs, everything that was supposed to be changed at the 60,000 mile check up was done. Light has been on for a year and nobody can find out what to do. Runs great with only a little pinging on exceleration. I don't mind spending any amount of money as long as it fixes the problem. But this is getting old, any ideas at all will be greatly appreciated.