Dangers of diagnostic code "lean"
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Get it fixed?
Anyway, if it's an actual problem, it can heat your engine up and cause some damage, if it's severe enough.
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its saying it can't maintain the air fuel ratio it wants in closed loop, without adding lots of corrections to the base settings.
so its over 17% correction, because of a leak or fuel pressure issue.
how much damage it might cause will depend on how lean its getting on load and if whatevers causing it to overcorrect is big enough for it to lean out enough on load as well.
a small leak off load can make it throw the code, but it might not be big enough to upset it on load.
otherwise their is no way to know the damage potential since you don't know how much of a problem there is, but running much too lean can cause damage, especially in high load, high temp scenarios.
best to have it checked.
so its over 17% correction, because of a leak or fuel pressure issue.
how much damage it might cause will depend on how lean its getting on load and if whatevers causing it to overcorrect is big enough for it to lean out enough on load as well.
a small leak off load can make it throw the code, but it might not be big enough to upset it on load.
otherwise their is no way to know the damage potential since you don't know how much of a problem there is, but running much too lean can cause damage, especially in high load, high temp scenarios.
best to have it checked.
[OT]
Hi charliex, you don't know me, but i must contact you.
Can we talk with msn/skype?
Best Regards,
Pier
EDIT: sorry for the OT
[/OT]
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832 Posts
i had been trying to get it fixed by myself but was not successful:
1) i had replaced the just-cleaned-and-oiled green filter with the original OEM one
2) i had tried resetting the ECU using the two popular procedures but neither worked
3) i had tried taking off the MAF sensor to clean it but did not have a tool that would fit its screws well enough in such small space.
took it to the dealer. i suggested they clean the MAF sensor, but the annoying service advisor did not want to ("we have tried a hundred times on other cars and it didn't work"). the car waited in que for its turn two days, and then i took it back, without getting looked at, to drive to the track.
i drove at the track with the code until lunch. the car ran at the track perfectly, but idle would swing up and down afterwards. my humble expectation is that if the lean problem was dangerously serious there would have been other symptoms.
during the 2 hour lunch break, with advice and help of other people at the track, i took the entire intake (until throttle) out. there was a film of oil everywhere. cleaned it all, including the throttle body, and the MAF sensor still in its place in the box, with the special purpose "MAF cleaner" spray. put it back, had the code cleared by someone's tool and it hasn't come back since (the remainder of the track day and couple of days of street driving). i still have the swingy idle, but less often.
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Is it possible that a "just oiled filter" might have been "over oiled" and caused the MAF to get a slight film on it? Would that condition then cause the MAF to read less air than is actually going in, cause less fuel to be squirted in than should be, resulting in the O2 sensor seeing a lean condition?
xtn
xtn
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5,094 Posts
not a good idea to take any car to the track that isnt %100.
if it were my car, I would fix it before i put the car through the ringer on the track.
remember the old fram filter comercial, "pay me now, or pay me later".
paying now ( to fix one thing)will be much cheaper than paying later( to fix a lot of things).
its called car prep.
if it were my car, I would fix it before i put the car through the ringer on the track.
remember the old fram filter comercial, "pay me now, or pay me later".
paying now ( to fix one thing)will be much cheaper than paying later( to fix a lot of things).
its called car prep.
System too lean means while operating closed loop (correcting for what the O2 reads) it has reached the maximum allowable fuel trim and was still unable to achieve the mixture it wanted. CharlieX says that's 17% there you have it and 17% is a lot of fuel! Typically on an OE car you see a max of 3-5%
If the problem is the O2 sensor then it may be saying the system is lean when it really isn't. Check for soot on the bumper. Normally you will get a no activity on O2 type code as that code normally has precedence.
If the MAF sensor is reading less air than you really have then it will calculate a load value that is insufficient for the fuel required and can cause this problem. A vacuum leak can cause it too since you're letting in unmetered air. On TC'd cars where the owner has installed an atmospheric BOV and it's leaking this is a common problem.
Hope that helps.
-Michael
If the problem is the O2 sensor then it may be saying the system is lean when it really isn't. Check for soot on the bumper. Normally you will get a no activity on O2 type code as that code normally has precedence.
If the MAF sensor is reading less air than you really have then it will calculate a load value that is insufficient for the fuel required and can cause this problem. A vacuum leak can cause it too since you're letting in unmetered air. On TC'd cars where the owner has installed an atmospheric BOV and it's leaking this is a common problem.
Hope that helps.
-Michael
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yeah if the 02 is damaged, more than likely you'd see a no activity first. since the op was a few weeks ago it could be the maf sensor, people often over oil the filters, not uncommon at all.
when the maf sensor reads low it does read the wrong breakpoint and the fueling is leaner, however it also reads the base afr table incorrectly too, so the mixture is being demanded to read leaner too, and since its in closed loop its always looking for 14.6 in that area, so i'd expect it running in the low to high mid 15's. the stock ecu has a fairly large area for when it wants to be in closed loop. if the maf is way off it'll end up reading in the decel/off throttle area of the map which is much richer than it'd be at idle.
so its looking for 14.6 , getting over 17% short term CLC fuelling and throws a code.
maf, cold air intake or a vacuum leak is the usual cause.
bad injector would cause rougher running and misfires.
when the maf sensor reads low it does read the wrong breakpoint and the fueling is leaner, however it also reads the base afr table incorrectly too, so the mixture is being demanded to read leaner too, and since its in closed loop its always looking for 14.6 in that area, so i'd expect it running in the low to high mid 15's. the stock ecu has a fairly large area for when it wants to be in closed loop. if the maf is way off it'll end up reading in the decel/off throttle area of the map which is much richer than it'd be at idle.
so its looking for 14.6 , getting over 17% short term CLC fuelling and throws a code.
maf, cold air intake or a vacuum leak is the usual cause.
bad injector would cause rougher running and misfires.
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+1
I really have no idea what this means. Charliex's posts are usually far beyond my understanding of internal combustion engines. (is this where you put the gas in??) So I've always felt an urge to '+1' one of his posts. Feels kinda good!
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