On Sun, 4 Jan 2015 12:44:12 -0800, "Jeff Strickland"
It's not the octane rating, or the fact that it is premium gas - He
needs to try ethanol free gasoline - and Shell Premium has no ethanol
- which is why I recommended it for troubleshooting purposes
If the car is not designed for E10, or worse yet E15 fuel, the engine
will run lean with the adulterated fuel
He is better off to just buy a simple code scanner for his purposes.
Same price and no downloading, and no compatability problems if he
doesn't have the right kind of phone.
That's fine if he is a geek or knows what to look for. Doesn't strike
me as being that technically inclined (no offence intended)
Exactly. So take it to someone who knows what they are doing. A
cracked/damaged vacuum hose is highly probable on something that old but
so is a leaking intake manifold gasket. The first step is to monitor,
verify, and manipulate O2 sensor operation using graphing mode on the
scan tool. If the lean condition is only at idle, a vacuum leak is most
likely. If the lean code is at cruise, then fuel supply/delivery is
and it's not an OH it's a 0. P0171, etc.
Those codes mean that the car is detecting a LEAN condition, there is more
air than fuel.
When the system works right, air enters and goes past the MAF (Mass Air
Flow) sensor. Some manufacturers use a different device that does
essentially the same thing in another way, so do not get bogged down on the
exact name of the device. The idea is that the MAF measures the quality of
the air -- density and temp -- to help the computer set the fuel delivery so
that a ratio of 14.7:1 is attained. This ratio is not critical for the
engine, but the CATs need the ratio so that the exhaust molecules are
divided evenly to convert the crap in the exhaut into basically air, water,
and carbon dioxide.
That's the plan.
The error you are seeing says that there is too much air in the contents of
the exhaust. Either this is false or there really is too much air. Assuming
there is too much air -- by far the most common reality -- then you have a
leak somewhere after the MAF, but before the intake manifold. Basically, the
MAF is measuing air, then additional air is getting into the intake that has
not been measured, and therefore there is insufficient fuel delivered and
the result is LEAN.
Since the issue began after some other service, then it is safe to assume
that something -- a hose or duct -- broke during the service and air is
entering through the hole that results.
THIS IS WHERE YOU START YOUR DIAGNOSTICS.
Since the code came after service, then be sure the service was competent
and correct before you satart looking for parts to replace. The First Rule
of Auto Repair states that you should do the simple and cheap stuff first.
This includes fixing stuff that was "fixed" a week ago.
On Sun, 4 Jan 2015 12:34:03 -0800, "Jeff Strickland"
You know what ASS U ME means, right??
Make no assumptions. Just as likely something else went wrong
unrelated to the oil change. The light was on when he picked it up -
car had not been driven since the oil change enough to go closed loop
and check the sensors and cats.
I've had too many customers come back and say things like "you just
changed my wipers and now the muffler fell off - You must have done
something to damage it" or You put new tires on last week, and now the
engine is smoking and knocking - what the H%$$ did you do to my car?"
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