P0171 & P0174 Codes
#32
#34
Originally Posted by Neal
HI!... My compression with my heads is 8.42:1
im still deciding if i want a flat torque curve or not.. i might go with a small dish or a flat top. either way you make the same power on internals it all comes down to how you want your torque curve to act and if u want any power before boost hits.
#35
Join Date: Dec 1997
Location: Windsor,Ontario,Canada
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Originally Posted by Bluegrass
Steve is correct.
You have "unaccounted" for air 'after' the air meter.
Many people mis-understand the 172/174 codes.
With this condition the codes always come up in pairs because unaccounted for air affects both sides about equally unless there is an air in leak at one cylinder runner.
The meaning of the codes is that they tell you the fuel tables have been leaned as far as they can go in the PCMs effort to correct, in actuallaty, a rich condition, not a lean condition, that you have already confimed with you wide band.
Again, codes are reflecting the state of the PCM reaction from sensor inputs and not the engine it'self. In this case, they are oppisite.
It's there, just have to find it.
You have "unaccounted" for air 'after' the air meter.
Many people mis-understand the 172/174 codes.
With this condition the codes always come up in pairs because unaccounted for air affects both sides about equally unless there is an air in leak at one cylinder runner.
The meaning of the codes is that they tell you the fuel tables have been leaned as far as they can go in the PCMs effort to correct, in actuallaty, a rich condition, not a lean condition, that you have already confimed with you wide band.
Again, codes are reflecting the state of the PCM reaction from sensor inputs and not the engine it'self. In this case, they are oppisite.
It's there, just have to find it.
JMC
#36
Originally Posted by JMC
Correct me if I am wrong but the 171/174 codes mean that the engine is running lean and the PCM has run out of rich calibration numbers in the tables, meaning it can no longer add enough fuel to compensate for the lean condition. A vacuum leak will casue this condition, too much air and not enough fuel, hence lean.
JMC
JMC
here neal... something to cheer u up... lean wit it teletubbie remix!!
http://youtube.com/watch?v=fNnv7IjCw94
#39
My 1999 5.4 F150 supercab just showed these codes Monday.Two months ago,I had a misfire #6 code.I then replaced one cop and all has been fine until this week.I erased the lean both banks codes from Monday and they have not yet reappeared (but they will). I suspect that some of the cops on both sides might be periodically missfiring because the truck sometimes does bauble when running.Also,with one failed cop,what is the likely condition of the other seven?Another thing we have been experiencing for a few years is longer and longer cranking for first starts (any temperature).Now a first start can take as long as eight to ten seconds.I also suspect that the fuel pressure regulator is cutting back,but I have not yet checked the psi.If I cycle the key for prime,there is a black rich cloud rolling out of the pipe when it does start eight seconds later. Now you have my known facts. What do you all think? Could it be seven cops going a little bad? Could the pressure regulator be faulty (I'll soon get a gauge set)? Could it be water in the fuel causing periodic misses? To the best of my knowledge, I don't have any vacuum leaks
(other than a possible small inconsequential leak at a vent door). Thanks for your help in advance , edman
(other than a possible small inconsequential leak at a vent door). Thanks for your help in advance , edman
#40
I am coming to the end of a search project on a low load and cruise missing condition that does not generate codes.
I have found that the Ford reccomended replacement spark plugs are not the same as the original typed.
Two sets of these new designations have failed in a short time.
The difference is the center electrode resistance is nearly double that of the originals.
It is looking like this higher resistance is the cause of the random and light throttle missing.
The new plugs fire fine until some errosion occurrs then a 'lean miss' becomes random miss.
I would not blame the COP for this condition.
Consultation with a dealer parts department shows the original plugs are no longer stocked but some dealers still have some if they can be found.
Be awhere that his could be a problem for some of you rather than the COP being bad.
Here are some stats.
1. The center electrode resistance on the original plugs is about 3000 ohms +/-.
2. the new replacment plugs are about 6000 ohms +/-.
3. The coil resistence is about 11,000 ohms +/-.
The combination of the coil resistance and the plug resistance becomes too high with the new plugs after some errosion takes place and the gap begins to increase..
At light loads and speed, the EGR is called to operate. This cuts back fuel and advances the timing. The lean fuel/air mix is much harder to fire so a 'lean miss' becomes a high possibility.
Be awhere of this. Benifit from my experience and testing. Check the the plugs resistance to see what you have and use another type that has low resistance.
FYI. This has been found to be a problem by other sources as well as I have now discovered and varified it.
If you get away with the new plugs then you may have COPs that are somewhat different in there mfger and have some luck.
My original plugs were replaced at 53,000 mile for general replacement only (no faults). The new plug type has not done so well for me.
I might add that any other fault that makes the air/fuel leaner will aggravate this condition on top of the plug condition and make it nearly impossible for the average owner to figure out two problems at the same time.
I have found that the Ford reccomended replacement spark plugs are not the same as the original typed.
Two sets of these new designations have failed in a short time.
The difference is the center electrode resistance is nearly double that of the originals.
It is looking like this higher resistance is the cause of the random and light throttle missing.
The new plugs fire fine until some errosion occurrs then a 'lean miss' becomes random miss.
I would not blame the COP for this condition.
Consultation with a dealer parts department shows the original plugs are no longer stocked but some dealers still have some if they can be found.
Be awhere that his could be a problem for some of you rather than the COP being bad.
Here are some stats.
1. The center electrode resistance on the original plugs is about 3000 ohms +/-.
2. the new replacment plugs are about 6000 ohms +/-.
3. The coil resistence is about 11,000 ohms +/-.
The combination of the coil resistance and the plug resistance becomes too high with the new plugs after some errosion takes place and the gap begins to increase..
At light loads and speed, the EGR is called to operate. This cuts back fuel and advances the timing. The lean fuel/air mix is much harder to fire so a 'lean miss' becomes a high possibility.
Be awhere of this. Benifit from my experience and testing. Check the the plugs resistance to see what you have and use another type that has low resistance.
FYI. This has been found to be a problem by other sources as well as I have now discovered and varified it.
If you get away with the new plugs then you may have COPs that are somewhat different in there mfger and have some luck.
My original plugs were replaced at 53,000 mile for general replacement only (no faults). The new plug type has not done so well for me.
I might add that any other fault that makes the air/fuel leaner will aggravate this condition on top of the plug condition and make it nearly impossible for the average owner to figure out two problems at the same time.
Last edited by Bluegrass; 10-11-2006 at 02:40 PM.
#41
Too bad the codes don't start this way:Fix this....! My sparkplugs are about three and a half years old and are aftermarket platinums. The recent missfire I had set a cyl#6 missfire code.A new Chinese cop fixed all symptoms two months ago.As of today,the lean bank 1&2 codes have not yet reappeared (they popped up this week).I will be doing a major vacuum leak search this weekend,but I expect to find nothing wrong.I am curious about the long term and short term fuel corrections you guys are talking about.Just what new tool do I have to get in order to track this?Those answers will, I believe,conclusively define what causes my lean codes.As for our eight second first start issue,I think only low fuel pressure causes that, right?That would imply that my regulator is leaking back.And,perhaps that itself is causing a lean condition.Has anyone out there already my our symptoms and made the fix?
#42
Same Situation
I have a 1998 Ford Expedition 4.6L XLT. The truck seems to be running fine, But I keep generating P0171 and P0174 codes. The CEL stays on, If I reset the ODB by disconnecting the battery, the CEL comes on within approximately 25 Miles.
I have not tried any of the measures posted in the thread, I was just wondering where I should start. I guess by cleaning the contacts on the MAF sensor? This is all new to me.
1 Should the Battery be disconnected when I clean the sensor contacts?
2 Will the ODB reset itself when connecting the battery
Any help that you may provide will be greatly appreciated.
I have not tried any of the measures posted in the thread, I was just wondering where I should start. I guess by cleaning the contacts on the MAF sensor? This is all new to me.
1 Should the Battery be disconnected when I clean the sensor contacts?
2 Will the ODB reset itself when connecting the battery
Any help that you may provide will be greatly appreciated.
#43
Jkewl99, I had all the same issues, tried all, soapy water, MAF,IAC, resets..ect.. it came down to a vacuum leak. The 90 degree rubber boot right behind the throttle body(that points down on the upper manifold), tight to reach..but you can (other end of tube goes to the PVC chech valve)...it was gummy and rotted thru... as a quick fix, I used a 90 degree boot off of an old spark plug wire...lights gone, power is back, shifts good..rpms stabalized. Good luck...
#44
Neal I have been following your engine buildup for a while. Man you have been through hell trying to get someone to build your 5.4 so it runs and stays running. If I were you I would have burned the whole truck to the ground back on engine number 3. It is a badass truck though, just try a different engine builder.
#45
i have the same p0171 and p0174 codes and i havent went into depth in diagnosing the truck but would like to start by checking the fuel pressure. how can i go about doing this?also what is a cop? and also the truck stalls out when you give it the gas, if you barely press the gas it will rev a lil but it eventually stalls out. the idle is fine though.